Involvement of sympathetic activation and brown adipose tissue in calcitonin gene-related peptide-induced heat production in the rat.
We previously reported that microinjection of calcitonin gene-related peptide (CGRP; 1.6-8.0 pmol, 0.2-1.0 microliter) into the ventromedial hypothalamus (VMH) increased oxygen consumption (VO(2)), heart rate (HR), colonic temperature (T(co)), and temperature of interscapular brown adipose tissue (T(IBAT)). In the present study, we investigated whether the autonomic nervous system is involved in the CGRP-induced heat production in urethane-anesthetized rats. Intraperitoneal administration of the ganglion blocker hexamethonium (20 mg/kg) or the beta-adrenergic antagonist propranolol (5 mg/kg) suppressed the CGRP-induced increases in VO(2), HR, T(co), and T(IBAT). Pretreatment with the alpha-adrenergic antagonist phentolamine (5 mg/kg) partly attenuated the heat production response but did not affect the tachycardiac response. Bilateral sectioning of the nerves supplying the IBAT attenuated the CGRP-induced increase in T(IBAT) but not significantly that in VO(2) or T(co). In rats with adrenal demedullation, the effects of CGRP were similar to those in intact rats. These results suggest that the CGRP-induced heat production is mediated by the sympathetic nervous system and, at least in part, by the BAT through the alpha- and beta-adrenoceptors.
Kobayashi
A
A
Showa Women's University Graduate School, 1-7 Taishido, Setagaya-ku, Tokyo, Japan.
Osaka
T
T
Namba
Y
Y
Inoue
S
S
Kimura
S
S
D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology*; D015740:Calcitonin Gene-Related Peptide / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D010101:Oxygen Consumption / Q000187:drug effects; D010646:Phentolamine / Q000008:administration & dosage / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*
D018738:Hexamethonium; D011433:Propranolol; D015740:Calcitonin Gene-Related Peptide; D010646:Phentolamine