Effects of methamphetamine and methyldopa on ethanol induced hypothermia in mice.

The effects of D-methamphetamine HCl (1, 2 and 4 mg/kg, i.p.) and alpha-methyldopa (1, 2 and 4 mg/kg, i.p.) on rectal temperature and on ethanol (3 g/kg, i.p.)-induced hypothermia have been investigated in mice. Methamphetamine caused a dose-dependent hyperthermia, but methyldopa induced hypothermia, which decreased with increases in dose. Methamphetamine antagonized the hypothermic effect of ethanol, but methyldopa (1 and 2 mg/kg) did not affect it. Methyldopa (4 mg/kg), however, reversed ethanol hypothermia. Ethanol pretreatment significantly potentiated the hypothermic effect of methyldopa (4 mg/kg), and it prevented methamphetamine-induced hyperthermia. A possible central action for the tested drugs on biogenic monoamines and a peripheral component in their thermoregulatory effects are discussed in this report.