ISSN:
1432-1912
Keywords:
Clonidine
;
5-Hydroxytryptamine
;
Hypothermia
;
Metabolic rate
;
Cutaneous vasodilatation
;
Respiration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. The thermoregulatory outputs (including metabolic, respiratory and vasomotor activities) produced by an injection of clonidine or 5-hydroxytryptamine (5-HT) into the third cerebral ventricle of conscious rabbits were assessed at three different ambient temperatures (T a) of 2, 22 and 32°C. 2. When injected into the third cerebral ventricle, both clonidine and 5-HT produced a dose-dependent hypothermia in rabbits at both 2 and 22°C T a. The hypothermia was due to a decrease in metabolic heat production (M) at 2°C T a, while at 22°C T a the hypothermia was due to cutaneous vasodilatation. There were no changes in respiratory evaporative heat loss. 3. Furthermore, the clonidine-induced hypothermia was greatly reduced by pretreatment of the animals with either 5,6-dihydroxytryptamine (impairment of central 5-HT pathways) or yohimbine (alpha-adrenergic blocking agent), but not by 6-hydroxydopamine (impairment of central catecholamine pathways). 4. The results indicate that clonidine may act on the α-adrenergic receptors located on central 5-HT pathways to produce a hypothermic action by promoting a decrease in heat production or an increase in heat loss in the rabbit.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00499835
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