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Seasonal decrease in thermogenesis and increase in vasoconstriction explain seasonal response to N 6 ‐cyclohexyladenosine‐induced hibernation in the Arctic ground squirrel ( Urocitellus parryii )
Author(s) -
Frare Carla,
Jenkins Mackenzie E.,
McClure Kelsey M.,
Drew Kelly L.
Publication year - 2019
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/jnc.14814
Subject(s) - hibernation (computing) , medicine , endocrinology , ground squirrel , adenosine , thermogenesis , agonist , biology , dorsal raphe nucleus , nucleus raphe magnus , thermoregulation , receptor , serotonin , adipose tissue , serotonergic , state (computer science) , algorithm , computer science
Hibernation is a seasonal phenomenon characterized by a drop in metabolic rate and body temperature. Adenosine A 1 receptor agonists promote hibernation in different mammalian species, and the understanding of the mechanism inducing hibernation will inform clinical strategies to manipulate metabolic demand that are fundamental to conditions such as obesity, metabolic syndrome, and therapeutic hypothermia. Adenosine A 1 receptor agonist‐induced hibernation in Arctic ground squirrels is regulated by an endogenous circannual (seasonal) rhythm. This study aims to identify the neuronal mechanism underlying the seasonal difference in response to the adenosine A 1 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 (N 6 ‐cyclohexyladenosine), an adenosine A 1 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 in 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 tuberomammillary 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 CHA‐induced hibernation. Cover Image for this issue: doi: 10.1111/jnc.14528 .