Serotonergic mechanisms in the hypothalamus mediate thermoregulatory responses in rats

摘要: 1. Either electrical stimulation of midbrain raphe nuclei or administration 5-hydroxytryptamine (5-HT; serotonin) into the preoptic anterior hypothalamus caused hypothermia in conscious rats at ambient temperatures (Ta) both 8° C and 22°C. The was due to decreased metabolic heat production Ta=8°C, while Ta=22°C metabolism increased loss (cutaneous vasodilatation). However, Ta=30°C, intrahypothalamic injection 5-HT an insignificant change thermoregulatory responses. There no changes respiratory evaporative response these treatments various Ta's. 2. Direct serotonergic receptor antagonists such as cyproheptadine methysergide hyperthermia Ta's 8°C, 22°C 30°C. cutaneous vasoconstriction. 3. The induced by antagonized pretreatment with dose either Ta=22°C. 4. Inhibition neuronal activity regions also hyperthermia, vasoconstriction 30°C. 5. These observations tend suggest that functional receptors mediates responses rat. Activation decreases and/or increases loss, inhibition