Neurotensin and ethanol interactions on hypothermia and locomotor activity in LS and SS mice

Ethanol, i.p., produced a greater dose-dependent hypothermia in long sleep (LS) than in short sleep (SS) mice with significant decreases in rectal temperature observed only at doses greater than 3 g/kg, i.p. Likewise, at doses of 1 to 2 g/kg ethanol, i.p., these lines of mice differ markedly in locomotor activity. Neurotensin (NT), intracerebroventricular (I.C.V.), induced a similar hypothermia in both SS and LS mice at doses greater than 0.02 microgram. Doses of ethanol (1.0 g/kg) or NT (0.005 microgram, i.c.v.) that failed to cause hypothermia when administered separately produced a pronounced hypothermia when administered together. Potentiation of NT and ethanol-induced hypothermia was greater in SS than in LS mice. Sensitivity to NT-induced hypothermia was greater following i.c.v. administration than by infusion into the nucleus accumbens (NA) or the ventral tegmental area (VTA). Neurotensin, i.c.v. or intra-NA, markedly inhibited ethanol-induced increase in locomotor activity in both SS and LS mice; however, NT, intra-VTA, did not alter the effects of ethanol on locomotor activity. The results suggest that NT and ethanol act in a synergistic manner on specific neuronal processes mediating thermoregulation and spontaneous motor activity.