Nicotine-induced hypothermia through an indirect dopaminergic mechanism.

The effect of nicotine on core body temperature was studied in mice. Intraperitoneal (i.p.) injection of nicotine (0.5, 1 and 2 mg/kg) induced a dose-dependent hypothermia. The response was inhibited by reserpine (5 mg/kg), the centrally active nicotinic receptor antagonist mecamylamine (0.1-1 mg/kg) and the D-2 dopamine receptor antagonist sulpiride (25-100 mg/kg). The β-adrenoceptor antagonist propranolol (5 and 10 mg/kg) and the serotonergic blocker methysergide (5 and 10 mg/kg) did not inhibit but increased the nicotine response. The α-adrenoceptor antagonist phenoxybenzamine, the antimuscarinic agent atropine, the D-1 dopamine receptor antagonist SCH 23390, the peripheral dopamine antagonist domperidone and the peripheral nicotinic antagonist hexamethonium did not alter the nicotine-induced hypothermia. It is concluded that nicotine may cause a fall in core body temperature through a central dopaminergic mechanism.