Seasonal decrease in thermogenesis and increase in vasoconstriction explain seasonal response to 6N ‐cyclohexyladenosine‐induced hibernation in the Arctic Ground Squirrel (Urocitellus parryii)

This study aims to identify the neuronal mechanism underlying the seasonal difference in response to the adenosine A1 receptor agonist. Arctic ground squirrels were implanted with body temperature transmitters and housed at constant ambient temperature (2 °C) and light cycle (4L:20D). We administered CHA (6N ‐cyclohexyladenosine), an adenosine A1 receptor agonist in euthermic ‐summer phenotype and euthermic‐winter phenotype and used cFos and phenotypic immunoreactivity to identify cell groups affected by season and treatment. We observed lower core and subcutaneous temperature in winter animals and CHA produced a hibernation‐like response in winter, but not summer. cFos‐ir was greater in the median preoptic nucleus and the raphe pallidus in summer after CHA. CHA administration also resulted in enhanced cFos‐ir in the nucleus tractus solitarius and decreased cFos‐ir in the tuberomammaliary nucleus in both seasons. In winter, cFos‐ir was greater in the supraoptic nucleus and lower in the raphe pallidus than in summer. The seasonal decrease in the thermogenic response to CHA and the seasonal increase in vasoconstriction, assessed by subcutaneous temperature, reflect the endogenous seasonal modulation of the thermoregulatory systems necessary for CH A‐induced hibernation.This article is protected by copyright. All rights reserved.
Source: Journal of Neurochemistry - Category: Neuroscience Authors: Tags: Original Article Source Type: research