title: Phase-specific central regulatory systems of hibernation in Syrian hamsters.
abstract: The central body temperature (T(b)) regulation system during hibernation was investigated in Syrian hamsters of either sex. Hibernation induced in Syrian hamsters by housing them in a cold room under short day-light/dark cycle was confirmed by marked reductions in the heart rate, T(b) and respiratory rate. The hibernation of hamsters was classified into (i) entrance, (ii) maintenance and (iii) arousal phases according to T(b) changes. In hibernating hamsters, T(b) elevations were phase-selectively elicited by intracerebroventricular (ICV) injection of 8-cyclopenthyltheophylline (CPT; a selective A1-adenosine receptor antagonist) and naloxone (a non-selective opioid receptor antagonist) during the entrance and maintenance phases, respectively. Moreover, a similar T(b) elevation tendency during the maintenance phase was also induced by ICV naloxonazine, (a selective mu1-opioid receptor antagonist), although such was not the case for naltrindole (a selective delta-opioid receptor antagonist) or nor-binaltorphimine (nor-BNI, a selective kappa-opioid receptor antagonist). Furthermore, T(b) elevations in hibernating hamsters were similarly induced with ICV thyrotropin-releasing hormone (TRH) during the entrance and maintenance phases. Furthermore, ICV injection of the anti-TRH antibody ameliorated the T(b) elevations induced by tactile stimulation. These results suggest that activation of the A1-receptor by adenosine is important for the generation of hypothermia in the entrance phase, and that activation of the mu1-opioid receptor by opioid peptides is required for perpetuation of hypothermia in the maintenance phase. In addition, TRH is a key endogenous substance involved in T(b) elevations during the arousal phase of hibernating hamsters.
authors.affiliation: Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, 1-gakuen-cho, Fukuyama, 729-0292, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
authors.forename: Mitsuteru
authors.initials: M
authors.lastname: Shintani
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nakamura
authors.forename: Mayuko
authors.initials: M
authors.lastname: Monden
authors.forename: Hirohito
authors.initials: H
authors.lastname: Shiomi
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D058916:Adenosine A1 Receptor Antagonists; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D001481:Basal Metabolism / Q000187:drug effects / Q000502:physiology*; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D006224:Cricetinae; D005260:Female; D006605:Hibernation / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D008647:Mesocricetus / Q000502:physiology*; D009292:Narcotic Antagonists / Q000494:pharmacology; D018847:Opioid Peptides / Q000378:metabolism*; D043682:Receptor, Adenosine A1 / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors / Q000378:metabolism; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D013806:Theophylline / Q000031:analogs & derivatives* / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism* / Q000494:pharmacology; D013997:Time Factors
chemical_list: D058916:Adenosine A1 Receptor Antagonists; D000906:Antibodies; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D043682:Receptor, Adenosine A1; D017450:Receptors, Opioid, mu; C053907:8-cyclopentyl-1,3-dimethylxanthine; D013973:Thyrotropin-Releasing Hormone; D013806:Theophylline; D000241:Adenosine