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Dentate granule cells and hilar interneurons are damaged after pilocarpine seizures in rats pretreated with lithium. Scattered eosin fluorescence is seen in a 2-week-old pup 24 hr after SE ( A). A 3-week-old pup shows extensive damage to the hilar and outer granule cells ( B). Damaged hilar cells are also visible in a 4-week-old ( C) and an adult rat ( D). Scale bar, 100 m.
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The lithium-pilocarpine model of status epilepticus (SE) was used to study the type and distribution of seizure-induced neuronal injury in the rat and its consequences during development. Cell death was evaluated in hematoxylin- and eosin-stained sections and by electron microscopy. Damage to the CA1 neurons was maximal in the 2- and 3-week-old pup...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) stain-positive neurons were Figure 3. Permanent cell loss is seen several months after SE as pups. Cresyl violet staining shows a reduction of cells in the CA1 region of a rat subjected to LiPC at 2 weeks ( A) when compared with that of a control ( B) 6 months after treatment. The hilus of a rat treated with LiPC at 3 weeks ( C) lacks many of the large cells seen within the tip of the hilus and in the region between the superior blade of the dentate granule cell layer and the CA3c neurons of a control ( D). Cell loss is also seen in the CA3a region of a rat given LiPC at 3 weeks of age ( E) as compared with a control ( F). Scale bar (shown in A): A, B, 200 m; C-F, 100 m. seen in large numbers only in the 2-and 3-week-old pups after SE. The distribution of these neurons was age-dependent, with the 2-week-olds demonstrating such injury predominantly in the CA1 region (Fig. 4 A,C), the subiculum, and the thalamus, with lesser labeling of the inner dentate granule cells. In the 3-week-old animals, only the inner layer of the dentate granule cells (Fig. 4 B,D) and a few thalamic neurons were TUN EL -positive. Fluo- rescence microscopy of EtBr-stained sections (Fig. 5A,B) revealed fragmented nuclei in the same areas that were TUN EL-stained. In the 3-week-old animals, the neuronal injury delineated by the TUNEL and EtBr methods (Figs. 4 B,D, 5B) seen in the inner layer of the granule cells was different from that seen in the outer granular layer neurons visualized by their eosinophilic cytoplasm (Fig. 2 B). Two types of damage also appear to coexist in the CA1 subfield of 2-week-old pups subjected to ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) stain-positive neurons were Figure 3. Permanent cell loss is seen several months after SE as pups. Cresyl violet staining shows a reduction of cells in the CA1 region of a rat subjected to LiPC at 2 weeks ( A) when compared with that of a control ( B) 6 months after treatment. The hilus of a rat treated with LiPC at 3 weeks ( C) lacks many of the large cells seen within the tip of the hilus and in the region between the superior blade of the dentate granule cell layer and the CA3c neurons of a control ( D). Cell loss is also seen in the CA3a region of a rat given LiPC at 3 weeks of age ( E) as compared with a control ( F). Scale bar (shown in A): A, B, 200 m; C-F, 100 m. seen in large numbers only in the 2-and 3-week-old pups after SE. The distribution of these neurons was age-dependent, with the 2-week-olds demonstrating such injury predominantly in the CA1 region (Fig. 4 A,C), the subiculum, and the thalamus, with lesser labeling of the inner dentate granule cells. In the 3-week-old animals, only the inner layer of the dentate granule cells (Fig. 4 B,D) and a few thalamic neurons were TUN EL -positive. Fluo- rescence microscopy of EtBr-stained sections (Fig. 5A,B) revealed fragmented nuclei in the same areas that were TUN EL-stained. In the 3-week-old animals, the neuronal injury delineated by the TUNEL and EtBr methods (Figs. 4 B,D, 5B) seen in the inner layer of the granule cells was different from that seen in the outer granular layer neurons visualized by their eosinophilic cytoplasm (Fig. 2 B). Two types of damage also appear to coexist in the CA1 subfield of 2-week-old pups subjected to ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... neuronal damage in the CA3 region of the 2-week-old rats was barely discernible at 1%. The damage at 3, 4, and 9 -12 weeks (20 9, 18 7, and 14 3%, respectively) did not differ significantly (Table 1). Two-week-old rat pups were resistant to SE-induced hilar damage. The extent of damage in the 3-week- old rat pups (31 2%) was comparable to that in the 4-week-old (27 2%) and adult rats (28 2%) ( Table 1, Fig. 2 A-D). Damage to the dentate granule cells is also shown in Figures 2 A-D. The 3-week-old rat pups demonstrated a special vulnera- bility to SE-induced damage in this cell population (33 7%) that is different from that seen in younger or older animals (5 0.5, 7 2, and 5 1% in 2-, 4-, and 9 -12-week-old animals, respectively) (Table 1, Fig. 2 A-D). The cell injury demonstrated by eosin fluorescence at 24 hr after SE was confirmed as perma- nent loss of cells by cresyl violet-stained sections in selected animals 6 months after the initial SE (Fig. 3A-F ). We have reported previously on the age-related SE-induced damage to extrahippocampal structures ( Sankar et al., 1997b). The neocor- tex, caudate, and septum showed damage scores similar to adults by 3 weeks of age, whereas the damage to amygdala showed a trend toward progressively increasing damage with age. Damage to the thalamus was maximal in the 2-and 3-week-old rats and decreased with age ( Sankar et al., ...
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... deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) stain-positive neurons were Figure 3. Permanent cell loss is seen several months after SE as pups. Cresyl violet staining shows a reduction of cells in the CA1 region of a rat subjected to LiPC at 2 weeks ( A) when compared with that of a control ( B) 6 months after treatment. The hilus of a rat treated with LiPC at 3 weeks ( C) lacks many of the large cells seen within the tip of the hilus and in the region between the superior blade of the dentate granule cell layer and the CA3c neurons of a control ( D). Cell loss is also seen in the CA3a region of a rat given LiPC at 3 weeks of age ( E) as compared with a control ( F). Scale bar (shown in A): A, B, 200 m; C-F, 100 m. seen in large numbers only in the 2-and 3-week-old pups after SE. The distribution of these neurons was age-dependent, with the 2-week-olds demonstrating such injury predominantly in the CA1 region (Fig. 4 A,C), the subiculum, and the thalamus, with lesser labeling of the inner dentate granule cells. In the 3-week-old animals, only the inner layer of the dentate granule cells (Fig. 4 B,D) and a few thalamic neurons were TUN EL -positive. Fluo- rescence microscopy of EtBr-stained sections (Fig. 5A,B) revealed fragmented nuclei in the same areas that were TUN EL-stained. In the 3-week-old animals, the neuronal injury delineated by the TUNEL and EtBr methods (Figs. 4 B,D, 5B) seen in the inner layer of the granule cells was different from that seen in the outer granular layer neurons visualized by their eosinophilic cytoplasm (Fig. 2 B). Two types of damage also appear to coexist in the CA1 subfield of 2-week-old pups subjected to ...
Citations
... Glutamatergic neurotransmission is responsible for many cognitive, motor, sensory, and autonomic nervous activities [220][221][222]. Neuroexcitotoxicity induced by glutamate has been demonstrated in a number of neurological and psychiatric disorders, including PD [223][224][225][226][227], epilepsy [228,229], traumatic brain injury [230,231], MS [232][233][234], AD [223,224,235,236], HD [223,[237][238][239], ALS [223,239,240], etc. ...
Objective:
L-carnitine (LC), a vital nutritional supplement, plays a crucial role in myocardial health and exhibits significant cardioprotective effects. LC, being the principal constituent of clinical-grade supplements, finds extensive application in the recovery and treatment of diverse cardiovascular and cerebrovascular disorders. However, controversies persist regarding the utilization of LC in nervous system diseases, with varying effects observed across numerous mental and neurological disorders. This article primarily aims to gather and analyze database information to comprehensively summarize the therapeutic potential of LC in patients suffering from nervous system diseases while providing valuable references for further research.
Methods:
A comprehensive search was conducted in PubMed, Web Of Science, Embase, Ovid Medline, Cochrane Library and Clinicaltrials.gov databases. The literature pertaining to the impact of LC supplementation on neurological or psychiatric disorders in patients was reviewed up until November 2023. No language or temporal restrictions were imposed on the search.
Results:
A total of 1479 articles were retrieved, and after the removal of duplicates through both automated and manual exclusion processes, 962 articles remained. Subsequently, a meticulous re-screening led to the identification of 60 relevant articles. Among these, there were 12 publications focusing on hepatic encephalopathy (HE), while neurodegenerative diseases (NDs) and peripheral nervous system diseases (PNSDs) were represented by 9 and 6 articles, respectively. Additionally, stroke was addressed in five publications, whereas Raynaud's syndrome (RS) and cognitive disorder (CD) each had three dedicated studies. Furthermore, migraine, depression, and amyotrophic lateral sclerosis (ALS) each accounted for two publications. Lastly, one article was found for other symptoms under investigation.
Conclusion:
In summary, LC has demonstrated favorable therapeutic effects in the management of HE, Alzheimer's disease (AD), carpal tunnel syndrome (CTS), CD, migraine, neurofibromatosis (NF), PNSDs, RS, and stroke. However, its efficacy appears to be relatively limited in conditions such as ALS, ataxia, attention deficit hyperactivity disorder (ADHD), depression, chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica.
... When administered to animals, pilocarpine can induce seizures that closely resemble human temporal lobe epilepsy. These seizures often lead to neuronal death in the hippocampus, a critical brain region involved in memory and learning [5,6,34,56,57]. However, in the present study, we found that amlodipine treatment increased the survival of neurons following seizures. ...
Epilepsy, marked by abnormal and excessive brain neuronal activity, is linked to the activation of L-type voltage-gated calcium channels (LTCCs) in neuronal membranes. LTCCs facilitate the entry of calcium (Ca2+) and other metal ions, such as zinc (Zn2+) and magnesium (Mg2+), into the cytosol. This Ca2+ influx at the presynaptic terminal triggers the release of Zn2+ and glutamate to the postsynaptic terminal. Zn2+ is then transported to the postsynaptic neuron via LTCCs. The resulting Zn2+ accumulation in neurons significantly increases the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, contributing to reactive oxygen species (ROS) generation and neuronal death. Amlodipine (AML), typically used for hypertension and coronary artery disease, works by inhibiting LTCCs. We explored whether AML could mitigate Zn2+ translocation and accumulation in neurons, potentially offering protection against seizure-induced hippocampal neuronal death. We tested this by establishing a rat epilepsy model with pilocarpine and administering AML (10 mg/kg, orally, daily for 7 days) post-epilepsy onset. We assessed cognitive function through behavioral tests and conducted histological analyses for Zn2+ accumulation, oxidative stress, and neuronal death. Our findings show that AML’s LTCC inhibition decreased excessive Zn2+ accumulation, reactive oxygen species (ROS) production, and hippocampal neuronal death following seizures. These results suggest amlodipine’s potential as a therapeutic agent in seizure management and mitigating seizures’ detrimental effects.
... In rodents two weeks old or younger, damage to the hippocampus, amygdala complex or thalamus is small or even minuscule and the extent of neurodegeneration as well as the number of damaged structures increases with age at SE induction. In 3-week-old or older rats is comparable to those seen in adults [54][55][56]. ...
The aim of the present study was to analyze the location of degenerating neurons in the dorsal (insular) claustrum (DCL, VCL) and the dorsal, intermediate and ventral endopiriform nucleus (DEn, IEn, VEn) in rat pups following lithium–pilocarpine status epilepticus (SE) induced at postnatal days [P]12, 15, 18, 21 and 25. The presence of Fluoro-Jade B-positive neurons was evaluated at 4, 12, 24, 48 h and 1 week later. A small number of degenerated neurons was observed in the CL, as well as in the DEn at P12 and P15. The number of degenerated neurons was increased in the CL as well as in the DEn at P18 and above and was highest at longer survival intervals. The CL at P15 and 18 contained a small or moderate number of degenerated neurons mainly close to the medial and dorsal margins also designated as DCl (“shell”) while isolated degenerated neurons were distributed in the VCl (“core”). In P21 and 25, a larger number of degenerated neurons occurred in both subdivisions of the dorsal claustrum. The majority of degenerated neurons in the endopiriform nucleus were found in the intermediate and caudal third of the DEn. A small number of degenerated neurons was dispersed in the whole extent of the DEn with prevalence to its medial margin. Our results indicate that degenerated neurons in the claustrum CL and endopiriform nucleus are distributed mainly in subdivisions originating from the ventral pallium; their distribution correlates with chemoarchitectonics of both nuclei and with their intrinsic and extrinsic connections.
... Nevertheless, after 10 days and 1.5 months, only the CA1 region displayed observable differences between the post-FS and control groups. These findings are consistent with data from other immature animal seizure models (lithium-pilocarpine model of status epilepticus and kainic acid model of temporal lobe epilepsy), where the hippocampal CA1 neurons have been shown to be more vulnerable than other hippocampal regions [34][35][36]. One possible explanation for why the CA1 neurons in the hippocampus are more prone to febrile seizures at P10 is the delayed development of synaptic inhibition in the CA1 compared to CA3 region during early postnatal ontogeny [37]. ...
Febrile seizures during early childhood may result in central nervous system developmental disorders. However, the specific mechanisms behind the impact of febrile seizures on the developing brain are not well understood. To address this gap in knowledge, we employed a hyperthermic model of febrile seizures in 10-day-old rats and tracked their development over two months. Our objective was to determine the degree to which the properties of the hippocampal glutamatergic system are modified. We analyzed whether pyramidal glutamatergic neurons in the hippocampus die after febrile seizures. Our findings indicate that there is a reduction in the number of neurons in various regions of the hippocampus in the first two days after seizures. The CA1 field showed the greatest susceptibility, and the reduction in the number of neurons in post-FS rats in this area appeared to be long-lasting. Electrophysiological studies indicate that febrile seizures cause a reduction in glutamatergic transmission, leading to decreased local field potential amplitude. This impairment could be attributable to diminished glutamate release probability as evidenced by decreases in the frequency of miniature excitatory postsynaptic currents and increases in the paired-pulse ratio of synaptic responses. We also found higher threshold current causing hind limb extension in the maximal electroshock seizure threshold test of rats 2 months after febrile seizures compared to the control animals. Our research suggests that febrile seizures can impair glutamatergic transmission, which may protect against future seizures.
... Nevertheless, after 10 days and 1.5 months, only the CA1 region displayed observable differences between post-FS and control groups. These findings are consistent with data from other immature animal seizure models (lithium-pilocarpine model of status epilepticus and kainic acid model of temporal lobe epilepsy), where hippocampal CA1 neurons have been shown to be more vulnerable than other hippocampal regions [24][25][26]. One possible explanation for why CA1 neurons in the hippocampus are more prone to febrile seizures at P10 is the delayed development of synaptic inhibition in CA1 compared to CA3 during early postnatal ontogeny [27]. ...
Febrile seizures in early childhood can lead to developmental disorders in the CNS. However, the specific mechanisms behind the impact of febrile seizures on the developing brain are not well-understood. To address this gap in knowledge, we employed a hyperthermic model of febrile seizures in 10-day-old rats and tracked their development over two months. Our objective was to determine the degree to which the properties of the hippocampal glutamatergic system are modified. We analyzed whether pyramidal glutamatergic neurons in the hippocampus die after febrile seizures. Our findings indicate that there is a reduction in the number of neurons in various regions of the hippocampus in the first two days after seizures. The CA1 field showed the greatest susceptibility, and the reduction in the number of neurons in post-FS rats in this area appeared to be long-lasting. Electrophysiological studies indicate that febrile seizures cause a reduction in glutamatergic transmission, leading to decreased local field potential amplitude. This impairment could be attributable to diminished glutamate release probability as evidenced by decreases in frequency of miniature excitatory postsynaptic currents and increases in pair-pulse ratio of synaptic responses. We also found higher threshold current causing hindlimb extension in the maximal electroshock seizure threshold test of rats 2 months after febrile seizures compared to control animals. Our research suggests that febrile seizures can impair glutamatergic transmission, which may protect against future seizures.
... These levels were applied to remove the background, binarized corrected images, and underwent auto-thresholding. H&E has been used previously to evaluate neuronal pathology following chemo-convulsant-induced SE (Fujikawa, 1996;Sankar et al., 1998a;Gao and Geng, 2013;McCarren et al., 2020). H&E staining of viable neurons presents with pronounced basophilic cytoplasmic staining of large pyramidal cell bodies allowing for the exclusion of non-neuronal/glial cells, which show as dense nuclei with little to no cytoplasmic staining. ...
... Another limitation of our study is that we used H&E staining to evaluate neuronal loss exclusively in the DG hilus at the chronic time. Studies have demonstrated variations in the level and severity of neuronal pathology following OP-induced SE (Sankar et al., 1998a;Jiao and Nadler, 2007;de Araujo Furtado et al., 2012;Dingledine et al., 2014;Rojas et al., 2022). Additionally, our inclusion criteria for the severity of POX and DFP-indued SE was limited to animals with severe class 4-5 SE. ...
Organophosphate (OP) compounds are highly toxic and include pesticides and chemical warfare nerve agents (CWNA). OP exposure inhibits the acetylcholinesterase enzyme, causing cholinergic overstimulation that can evolve into status epilepticus (SE) and produce lethality. Furthermore, OP-induced SE survival is associated with mood and memory dysfunction and spontaneous recurrent seizures (SRS). In Male Sprague-Dawley rats, we assessed hippocampal pathology and chronic SRS following SE induced by administration of OP agents POX (2 mg/kg, s.c.), DFP (4 mg/kg, s.c.) or GB (2 mg/kg, i.m.), immediately followed by atropine and 2-PAM. At 1-h post-OP-induced SE onset, midazolam was administered to control SE. Approximately 6 months after OP-induced SE, SRS were evaluated using video and EEG monitoring. Histopathology was conducted using Hematoxylin and Eosin (H&E), while silver sulfide (Timm) staining was utilized to assess Mossy Fiber Sprouting (MFS). Across all the OP agents, over 60% of rats that survived OP-induced SE developed chronic SRS. H&E staining revealed a significant hippocampal neuronal loss, while Timm staining revealed extensive MFS within the inner molecular region of the dentate gyrus. This study demonstrates that OP-induced SE is associated with hippocampal neuronal loss, extensive MFS, and the development of SRS, all hallmarks of chronic epilepsy. Significance Statement Models of OP-induced SE offer a unique resource to identify molecular mechanisms/ pathways contributing to neuropathology and the development of chronic OP morbidities. These models could allow the screening of targeted therapeutics for efficacious treatment strategies for OP toxicities.
... Abrupt and excessive neuronal excitability in the brain is thought to contribute to hippocampal sclerosis, a characteristic pathological finding in TLE patients (Steve et al., 2014;Tai et al., 2018). In animal models recapitulating TLE, prolonged seizure activities called status epilepticus (SE) can trigger multifaceted processes in the hippocampus, resulting in neuronal deaths that feature both apoptosis and necrosis (Sloviter et al., 1996;Sankar et al., 1998;Fujikawa et al., 2000b). Necroptosis, an inflammationassociated novel mode of cell death, has been proposed as one of the complicated mechanisms for neuronal death after SE (Dingledine et al., 2014;Choi et al., 2021). ...
Temporal lobe epilepsy (TLE) is one of the most common neurological disorders, but still one-third of patients cannot be properly treated by current medication. Thus, we investigated the therapeutic effects of a novel small molecule, NecroX-7, in TLE using both a low [Mg ²⁺ ] o -induced epileptiform activity model and a mouse model of pilocarpine-induced status epilepticus (SE). NecroX-7 post-treatment enhanced the viability of primary hippocampal neurons exposed to low [Mg ²⁺ ] o compared to controls in an MTT assay. Application of NecroX-7 after pilocarpine-induced SE also reduced the number of degenerating neurons labelled with Fluoro-Jade B. Immunocytochemistry and immunohistochemistry showed that NecroX-7 post-treatment significantly alleviated ionized calcium-binding adaptor molecule 1 (Iba1) intensity and immunoreactive area, while the attenuation of reactive astrocytosis by glial fibrillary acidic protein (GFAP) staining was observed in cultured hippocampal neurons. However, NecroX-7-mediated morphologic changes of astrocytes were seen in both in vitro and in vivo models of TLE. Finally, western blot analysis demonstrated that NecroX-7 post-treatment after acute seizures could decrease the expression of mixed lineage kinase domain-like pseudokinase (MLKL) and phosphorylated MLKL (p-MLKL), markers for necroptosis. Taken all together, NecroX-7 has potential as a novel medication for TLE with its neuroprotective, anti-inflammatory, and anti-necroptotic effects.
... SE is a clinical emergency associated with high mortality and morbidity (Towne et al., 1994;Shorvon, 2013). SE is known to produce multifocal neuronal injury (Sankar et al., 1998) and is also a significant risk factor for developing recurrent seizures or acquired epilepsy (Hesdorffer et al., 1998). Long-term SE and epilepsy outcomes include neurological morbidities, depression (Fiest et al., 2013), and cognitive deficits (Helmstaedter, 2007). ...
Organophosphate (OP) compounds are highly toxic and include household, industrial, agricultural, and chemical warfare nerve agents (CWNA). OP exposure inhibits acetylcholinesterase enzyme, causing cholinergic overstimulation that can evolve into status epilepticus (SE) and produce lethality. Furthermore, OP-SE survival is associated with mood and memory dysfunction and spontaneous recurrent seizures (SRS). Here we assessed hippocampal pathology and chronic SRS following SE induced by OP agents in rats. Male Sprague-Dawley rats were injected with 1.5x LD50 of various OP agents, followed by atropine and 2-PAM. At 1-h post-OP-SE onset, midazolam was administered to control SE. Approximately 6 months following OP-SE, SRS were evaluated using continuous video-EEG monitoring. Histopathology was conducted using Hematoxylin and Eosin (H&E), while silver sulfide (Timm) staining was utilized to assess Mossy Fiber Sprouting (MFS). Over 60% of OP-SE surviving rats developed SRS with varying seizure frequencies, durations, and Racine severity scores. H&E staining revealed a significant hippocampal neuronal loss, while Timm staining revealed extensive MFS within the inner molecular region of the dentate gyrus of SRS-expressing OP-SE rats. This study demonstrates that OP-SE is associated with hippocampal neuronal loss, extensive MFS, and SRS, all hallmarks of chronic epilepsy.
... Our studies showed that seizures at postnatal Day 10 severely damage the rabbit hippocampus, 44 that seizures induced by perforant path stimulation at postnatal Day 14-15 in rats cause widespread neuronal injury 45 and that seizures induced by lithium-pilocarpine caused widespread neuronal injury in brain regions which vary with age at the time of seizures. 46 Later studies showed that seizure-induced neuronal injury occurs as early as in postnatal Day 7 rat pups. 47 Within the same brain region, the maturation stage of individual neuronal populations is a key component of their vulnerability and of the apoptotic versus necrotic type of cell death. ...
... Epilepsy & Behavior 141 (2023) 109142 [37], and a model of lithium/pilocarpine SE in P7 rat pups [38]. All models had strict body temperature control during and after SE, and in the rabbit model and P7 rat pup model, there was no anoxemia or major changes in blood gases. ...
... Top right: Electron microscopy leaves no doubt that this neuron is irreversibly injured. Bottom: left, hippocampus of P10 rabbit after lithium-pilocarpine SE [35]; 2d from left, the hippocampus of a 6-month-old child who died in SE shows a similar lesion distribution [38]; 3d from left, neuronal injury in hippocampus after SE induced by electrical stimulation of the perforant path [37]; 4th from left, CA1 injury after lithium-pilocarpine SE at P7 [39]; 5th from left, apoptotic morphology of neuronal injury at P7. Fig. 5. When paralyzed, ventilated rats received electrically-induced seizures for 30 minutes or more, they continued seizing spontaneously after the end of stimulation [41] (graph on the left). ...
This is a review of my laboratory's interest in status epilepticus (SE), which spanned five decades. It started with a study of the role of brain mRNAs in memory, and with the use of electroconvulsive seizures to disrupt recently acquired memories. This led to biochemical studies of brain metabolism during seizures, and to the serendipitous development of the first model of self-sustaining SE. The profound inhibition of brain protein synthesis by seizures had implications for brain development, and we showed that severe seizures and SE in the absence of hypoxemia and other metabolic complications can disrupt brain and behavioral development, a concept that was not widely accepted at that time. We also showed that many experimental models of SE can cause neuronal death in the immature brain, even at very young ages. Our studies of self-sustaining SE showed that the transition from single seizures to SE is accompanied by internalization and transient inactivation of synaptic GABAA receptors, while extrasynaptic GABAA receptors are untouched. At the same time, NMDA and AMPA receptors move to the synaptic membrane, creating a "perfect storm" combining failure of inhibition and runaway excitation. Major maladaptive changes in protein kinases and neuropeptides, particularly galanin and tachykinins, also contribute to the maintenance of SE. The therapeutic implications of these results are that our current practice to start the treatment of SE with benzodiazepine monotherapy leaves the changes in glutamate receptors untreated and that sequential use of drugs gives seizures more time to aggravate changes in receptor trafficking. In experimental SE, we showed that drug combinations based on the receptor trafficking hypothesis are far superior to monotherapy in stopping SE late in its course. Combinations that include an NMDA receptor blocker such as ketamine are much better than combinations that follow current evidence-based guidelines, and simultaneous delivery of the drugs is far more effective than sequential delivery of the same drugs at the same dose. This paper was presented as a Keynote Lecture at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.
