Pablo Vivanco

University of Murcia | UM · Department of Physiology

Exposure of mice to a brief light stimulus during their nocturnal active phase induces several simultaneous behavioral or physiological responses, including circadian rhythm phase shifts, a drop in core body temperature (Tc), suppression of locomotor activity and sleep. Each response is triggered by light, endures for a relatively fixed interval an...

Daily rhythms in different biochemical and hematological variables have been widely described in either diurnal or nocturnal species, but so far no studies in the rhythms of these variables have been conducted in a dual-phasing species such as the degus. The Octodon degus is a rodent that has the ability to switch from diurnal to nocturnal activity...

Octodon degus is a primarily diurnal rodent that presents great variation in its circadian chronotypes due to the interaction between two phase angles of entrainment, diurnal and nocturnal, and the graded masking effects of environmental light and temperature. The aim of this study was to test whether the circadian system of this diurnal rodent can...

There are two main processes involved in the expression of circadian rhythmicity: entrainment and masking. Whereas the first operates via the central pacemaker to anticipate predictable environmental conditions, masking (mainly induced by light) functions as a direct modulator of the circadian output signal induced by nonpredictable events. The Chi...

Body temperature regulation within a physiological range is a critical factor for guaranteeing the survival of living organisms. The avoidance of high ambient temperatures is a behavioral mechanism used by homeothermic animals living in extreme environmental conditions. As the circadian system is involved in these thermoregulatory responses, precis...

Octodon degus, a mainly diurnal rodent, characterized by its ability to shift to a nocturnal locomotor pattern under laboratory conditions, was studied to determine whether restricted food access during the scotophase could induce nocturnalism. To address this question, wheel running activity, feeding, and body temperature rhythms were analyzed for...

El Octodon degus es un roedor endémico de Chile que ha sido caracterizado como diurno tanto en su medio natural como en condiciones de laboratorio. Sin embargo, se ha descrito que algunos individuos invierten su actividad a nocturna cuando se les permite hacer ejercicio en una rueda giratoria instalada en su jaula. Esta tesis doctoral tiene como ob...

Recently it has been shown that over 3-year-old wild-type South American rodents, Octodon degus, the "common degu" or degu, of their own accord develop Alzheimer's disease neuropathological hallmarks: amyloid-β-peptide depositions and accumulation of tau-protein. Here we analyzed brains of 1-, 3- and 6-year-old degu's, bred in standard animal facil...

Processes involved in the operation of the circadian pacemaker are well characterized; however; little is known about what mechanisms drive the overt diurnal, nocturnal, or crepuscular behavior in a species. In this context, dual-phasing rodents, such as Octodon degus, emerge as a useful model to decipher these keys. Two main chronotypes, nocturnal...

Rats exposed to sweetened water with glucose show binge drinking response whereas rats exposed to sweetened water with sucralose do not show binge drinking response. This result is similar although it modified the sweetener presentation sequence. The objective of this work was to replicate the obtained results in rats with other species of rodent:...

Melatonin is an essential component for circadian system function, whose daily plasma secretory rhythm is driven by the suprachiasmatic nucleus (SCN), contributing to the communication of temporal messages from the central circadian clock to all cells. Melatonin secretion peaks in the dark, regardless of whether animals are diurnal or nocturnal. To...