title: Body temperature daily rhythms in the striped mouse Rhabdomys pumilio: the effects of alpha and beta blockade.
abstract: Body temperature (Tb) daily rhythms and the effects of alpha and beta blockade were studied in the South African diurnal striped mouse Rhabdomys pumilio. Eleven mice (8 males and 3 females) with a body mass of 42.7+/-7.8 g (mean +/- SD) were tested. Mice were acclimated to a 13 h:11 h light-dark photoperiod at an ambient temperature of 25 degrees C. To assess the daily rhythm of pineal melatonin secretion, urinary 6-sulfatoxymelatonin (6-SMT) was determined. Mice displayed a robust Tb daily rhythm with an acrophase in the dark period, which is unexpected for a diurnal species. The nocturnal increase in Tb was accompanied by a significant rise in urinary 6-SMT. The beta blocker propranolol (4.5 mg/kg), injected 1 h before lights-off, resulted in a higher Tb value, whereas the alpha blocker prazosin (1 mg/kg) blocked the increase of Tb during the dark period. Prazosin also significantly attenuated the nocturnal increase of urinary 6-SMT. These results are in agreement with those obtained from the golden spiny mouse Acomys russatus and support the idea that small diurnal mammals retain the Tb rhythm of a nocturnal rodent. They also suggest that pineal melatonin secretion in these rodents is regulated by alpha rather than by beta receptors.
authors.affiliation: Department of Biology, University of Haifa at Oranim, Kiryat Tivon, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Haim
authors.forename: R J
authors.initials: RJ
authors.lastname: Van Aarde
authors.forename: N
authors.initials: N
authors.lastname: Zisapel
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D005260:Female; D008297:Male; D008550:Melatonin / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009115:Muridae; D010870:Pineal Gland / Q000187:drug effects / Q000502:physiology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D008550:Melatonin; D011224:Prazosin