Erowid References Database
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Murakami N, Sakata Y.
“A Possible Role of the Serotonergic System in Thermoregulation in the Rabbit”.
Neuropharmacology. 1980;19(9):891-95.
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Abstract
The role of the serotonergic system in thermoregulation in the rabbit was examined. Methods Male rabbits (2.6-3.5 g) were fitted with cannulae, inserted into the nucleus raphe dorsalis (NRD) or the nucleus raphe magnus (NRM) under thiamyl sodium (80-90 mg/kg i.m.) anesthesia. Rectal, ear- and back-skin temperatures were continuously recorded during the experiments 2 wk later. Lysergic acid diethylamide (LSD) was administered i.v. (12-17 mcg/kg) or via the cannula into the raphe nuclei (1 -10 mcg) at ambient temperatures of 15, 25 or 35 ¡C. Metabolic hr at production was calculated from oxygen consumption. Results LSD administered i.v. caused hyperthermic responses at all temperatures. The magnitude of the responses was greater between 15 and 25¡ than at 35'. Attempts to lower the LSD-induced hyperthermia by administration of dipyr one (Sulpyrine, 160 mg/kg Daiichi) or serotonin (5-HT) 3 mg/kg (Sigma) were ineffective. LSD injected into both raphe nuclei caused a dose-dependent increase in rectal temperature and a fall in ear-skin temperature. Marked vasoconstriction was apparent even at 29 ¡C. Administration of LSD into the NRD increased heat production slightly even at the ambient temperature of 29 ¡, but no changes occurred over the 180 min period following administration of the drug into the ARM. Conclusion The afferent input through cold fibers makes a synapse with 5 HT inhibitory receptors on the warm-responsive neurons in the midbrain and also connects with an excitatory synapse in the heat production system.
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