Fig 14 - uploaded by Esteban M Rodríguez
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Frontal section of the medulla oblongata at the level indicated by broken line in Fig. I0 (Plane VIII of Fig. 1). Pathway 8 is seen lateral to the tractus pyramidalis (TP) and close to the ventral surface. At this level neurophysin fibers are already visualized in the fasciculus solitarius (FS). Fibers of pathway 5 are seen in the subependymal region of the fourth ventricle, x 40. Insert A: The fibers of pathway 8 appear transversally cut, whereas in insert of Fig. 10 the same bundle appears longitudinally cut. x 100. Insert B: Fibers in the fasciculus solitarius, x 130
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The hypothalamo-extrahypophyseal neurophysin pathways (HEH) and the three hypothalamic nuclei secreting neurophysins, the supraoptic (SON), paraventricular (PVN) and suprachiasmatic (SCN) nuclei, of normal and hypophysectomized rats were studied by application of the immunoperoxidase procedure. Eight well-defined HEH pathways were recognized. Their...
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... Thus, one striking morphological observation derived from hypophysectomy, regardless of the final survival time, was the loss of neurons in the nSO, eliciting a reduction in the central size of the nucleus -close to 48%with respect to the untreated animals. This was also observed by Yulis and Rodríguez (1982). The main cause of the reduction in nuclear size was the massive destruction of magnocellular neurons as a result of a retrograde degeneration, which was seen at 10 days of survival and which persisted with no significant changes up to 30 days post-hypophysectomy. ...
... The main cause of the reduction in nuclear size was the massive destruction of magnocellular neurons as a result of a retrograde degeneration, which was seen at 10 days of survival and which persisted with no significant changes up to 30 days post-hypophysectomy. The percentage of neuronal loss detected here -about 40%-is similar to that reported in other publications in adult hypophysectomised rats (Moll and De Wied, 1962;Kawashima et al., 1966;Yulis and Rodríguez, 1982;Kawamoto andKawashima, 1985, 1987). Other phenomena accompanying nerve lesions, such as spongiosis and a glial reaction in the nSO have been reported by Rasmussen (1940) and Vázquez et al. (1993). ...
The hypothalamic-neurohypophyseal system offers an ideal model to study the processes of nerve degeneration/regeneration after lesions caused by cutting the hypophyseal stalk, or hypophysectomy. Additionally, the magnocellular neurons comprising it contain nitric oxide, and its enzyme, neural nitric oxide synthase, shows important variations in functional alterations of the hypothalamic-neurohypophyseal system. Currently, there is still some controversy as regards whether nitric oxide exerts neurodegenerative or neuroprotective effects in the nervous system. Here we performed a quantitative and qualitative study of the variations in the neuronal activity of nitric oxide synthase, using immunohistochemistry, and of its mRNA, by in situ hybridization, in the magnocellular neurons of the supraoptic nucleus of the hypothalamus of hypophysectomised rats with survival periods of 10-30 days. Our morphological and morphometric results and those pertaining to neuronal quantification and optical density point to a neuroprotective effect of nitric oxide on magnocellular neurons during the regenerative process of the supraoptic nucleus that occurs after hypophysectomy.
... Extrahypophysial projections of the neurosecretory system have been described in mammals (Buijs, 1978;Yulis and Rodríguez, 1982) and they have been suggested to be involved in autonomic and humoral cardiovascular control, behaviour and memory processes (Swanson and Sawchenko, 1983;Buijs, 1985). Extrahypothalamic distribution of neurohypophyseal peptides has also been described in birds (Bons, 1980;Blähser, 1981;Panzica et al., 1986Panzica et al., , 1999Kiss et al., 1987), amphibians (Jokura and Urano, 1987;Smeets, 1992, 1997), teleost (Dungen et al., 1982;Holmqvist and Ekströ m, 1995) and cartilaginous fishes (Meurling et al., 1996). ...
Polyclonal antibodies against vasotocin (AVT) and mesotocin (MST) were used to explore the distribution of these peptides in the brain of the snake Bothrops jararaca. Magnocellular AVT- and MST-immunoreactive (ir) perikarya were observed in the supraoptic nucleus (SON), being AVT-ir neurons more numerous. A portion of the SON, in the lateroventral margin of the diencephalon ventrally to optic tract, showed only AVT-ir perikarya and fibers. However, the caudal most portion displayed only mesotocinergic perikarya. Parvocellular and magnocellular AVT- and MST-ir perikarya were present in the paraventricular nucleus (PVN) being AVT-ir fibers more abundant than MST-ir. Vasotocinergic perikarya were also found in a dorsolateral aggregation (DLA) far from the PVN. Mesotocinergic perikarya were also present in the recessus infundibular nucleus and ependyma near to paraventricular organ. Nerve fibers emerging from supraoptic and paraventricular nuclei run along the diencephalic floor, internal zone of the median eminence (ME) to end in the neural lobe. Also a dense network of AVT- and MST-ir fibers was present in the external zone of the ME, close to the vessels of the hypophysial portal system. As a rule, all regions having vasotocinergic and mesotocinergic perikarya also showed immunoreactive fibers. Vasotocinergic and mesotocinergic fibers but not perikarya were found in the lamina terminalis (LT). Moreover AVT-ir fibers were present in the nucleus accumbens and MST-ir fibers in the septum. In mesencephalon and rhombencephalon MST-ir fibers were more numerous than AVT-ir fibers. Vasotocinergic and mesotocinergic fibers in extrahypothalamic areas suggest that these peptides could function as neurotransmitters and/or neuromodulators in the snake B. jararaca.
... The overall distribution of the extrahypophysial neurophysin pathways in N. maura and M. caspica is, in general, in accord with the patterns described in lizards (Bons 1983;Stoll and Voorn 1985) and dosel y resembles the main Nps projections of mammals (Buijs 1978;Yulis and Rodríguez 1982;Kawata et al. 1983;Silverman and Zimmerman 1983;Sofroniew 1985;De Vries et al. 1985) and birds (Bons 1980;Bliihser 1981;Panzica et al. 1986a ;Kiss et al. 1987). ...
An immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake Natrix maura and the turtle Mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. Arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. The same cells appeared to be stained by the anti-oxytocin-neurophysin and antimesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina termialis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunoreactive fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.
... The median eminence of NPOX-SAL rats, in contrast, shows a greater than normal density of VP-immunoreactive fibers in the external lamina. Proliferation of VP-positive fibers within the hypertrophied median eminence of NPOX-SAL treated rats is consistent with previous reports (Yulis and Rodriguez, 1982) and reiterates that the reestablishment of a neurohemal connection via the median eminence vasculature is the likely structural substrate for reorganization and functional recovery of the magnocellular neurosecretory system. ...
Regeneration and functional recovery of the hypothalamoneurohypophysial system (HNS) in neurohypophysectomized rats treated with either saline or vasopressin (VP) were analyzed utilizing specific immunohistochemical and physiological measures. Neural lobe ablation combined with VP administration precipitated a profound diabetes insipidus (following cessation of VP delivery) that persisted for the duration of the experiment. Diabetes insipidus was correlated with a drastic reduction in the number of VP-positive neurons in magnocellular hypothalamic nuclei. In contrast, large numbers of oxytocin (OT)-positive neurons survived neurohypophysectomy in VP-treated neurohypophysectomized rats; OT neurons accounted for the vast majority of magnocellular profiles observed in Nissl-counterstained sections. VP-immunoreactive fibers could be observed in limited quantities in the external lamina of the median eminence of VP-treated neurohypophysectomized rats, with little staining evident in the internal lamina. Saline-treated neurohypophysectomized rats exhibited the recovery of antidiuretic function characteristically seen following this lesion, with evidence of survival of considerable numbers of VP and OT neurons and median eminence hypertrophy. Both the internal and external laminae of the median eminence were densely innervated by large-caliber VP and OT fibers. Sham-operated animals receiving VP treatment did not show any long-term deficit in water metabolism, changes in the complement of VP or OT perikarya in hypothalamus, or changes in the innervation of the median eminence. Results indicate that VP treatment following neurohypophysectomy results in extensive retrograde degeneration of magnocellular VP neurons without affecting the survival of OT cells.
Craniopharyngiomas are extremely rare epithelial tumors of the sellar region in human beings and domestic and laboratory animals. A craniopharyngioma, 0.6 cm in diameter, was observed grossly in the sellar and parasellar regions of an untreated 23-month-old male Wistar-derived rat sacrificed moribund. The tumor was composed of cords, columns, and nests of neoplastic stratified squamous epithelium with marked hyperkeratosis and parakeratosis. Neoplastic cells formed solid or cystic areas, infiltrating the base of the skull, brain, and pituitary gland. Immunocytochemical evaluation revealed a strong cytoplasmic reaction for keratin in all tumor cells. Malignant craniopharyngioma should be considered a differential diagnosis in the rat when a tumor with stratified squamous epithelial features and a locally aggressive growth pattern is observed in the sellar or suprasellar region.
Vasopressin and oxytocin are hormones of the neurohypophysis (the posterior pituitary “gland”) best known for their peripheral endocrine effects: regulation of antidiuresis and blood pressure, contraction of smooth muscles of the uterus during labour and of the mammary gland during milk ejection respectively. Additional actions on various peripheral organs have been described, e. g., blood clotting (Mannucci et al. 1975), and liver metabolism (Keppens and De Wulf 1979; Martin and Baverel 1981).
Vasopressin (VP) and oxytocin (OX) have long been known to be synthesized in the two nuclei of the hypothalamus, the paraventricular nucleus (PVN) and supraoptic nucleus (SON) and secreted into the circulation in the neural lobe of the pituitary (see Chapter 1, this volume). As a result of this origin from the hypo-thalamus-neurohypophysial system (HNS), these two neuropeptides were known as hypothalamic hormones; it is not so long ago that, through the pioneering work of De Wied (1965, 1971), the notion came to be accepted that these peptides might affect the central nervous system (CNS) as well (see Chapter 14, this volume).
An immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake Natrix maura and the turtle Mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. Arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. The same cells appeared to be stained by the anti-oxytocin-neurophysin and anti-mesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina terminalis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunore-active fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.
Neurons projecting from the brain to the pineal gland via the pineal stalk were investigated in the golden hamster with the use of the retrograde horseradish-peroxidase tracing method both in vivo and in vitro. Labelled perikarya were observed in the medial and lateral habenular nuclei as well as in the posterior commissure. Single cells located in the ependymal lining of the pineal- and suprapineal recesses were also retrogradely labelled. These results show that a distinct central innervation of the pineal gland exists in the golden hamster, in agreement with findings in other mammalian species investigated by means of a similar methodology. In addition, also direct signals from the cerebrospinal fluid to the parenchyma might be conducted via cells located within the ependymal layer of the pineal- and suprapineal recesses.
A possible feedback of circulating vasopressin (VP) on the expression of its gene in the hypothalamoneurohypophyseal system was studied in rats with depleted stores of neurohypophyseal hormones. The neural lobe of the pituitary gland was disconnected by anterolateral deafferentation of the basal hypothalamus using a Halasz knife cut. One group of lesioned animals was substituted continuously with VP using mini-osmopumps. After 1 week, the lesion had caused a complete disappearance of neurohypophyseal hormones from the neurointermediate pituitary and induced a 2-fold increase in water intake and an increase in plasma osmolality of approximately 7 m0sm/kg. VP mRNA levels of the supraoptic nucleus (SON), paraventricular nucleus (PVN) and suprachiasmatic nucleus (SCN) were measured in punched tissue by Northern blot analysis and dot-blot analysis. VP mRNA levels of the SON and PVN were reduced by 50% due to the deafferentiation, which might have been caused by degeneration. VP substitution of the lesioned animals normalized water intake but not plasma osmolality. In the VP-substituted animals, VP mRNA levels of the SON were 2-fold reduced compared to the nonsubstituted lesioned animals. The VP mRNA levels of the PVN were not affected by VP substitution. The VP mRNA levels of the SCN increased 2-fold after the lesion but were not influenced by VP substitution. Concomitant determination of oxytocin (OT) mRNA showed that OT mRNA levels in the PVN and SON were not affected by the deafferentiation and did not respond to VP substitution.(ABSTRACT TRUNCATED AT 250 WORDS)
