ETHANOL-INDUCED CHANGES IN TYROSINE-HYDROXYLASE ACTIVITY IN BRAINS OF MICE SELECTIVELY BRED FOR DIFFERENCES IN SENSITIVITY TO ETHANOL

The effects of ethanol on tyrosine hydroxylase (TH) activity in 5 brain areas were analyzed in 2 lines of mice selectively bred for their differences in sensitivity to ethanol. Following a 4.1 g/kg dose of ethanol, i.p., short sleep (SS) mice lose their righting reflex for a duration of 20 min and long sleep (LS) mice fail to regain their righting reflex until 120 min. A significant increase in TH activity occurred in the striatum, locus coeruleus and frontal cortex in both lines of mice .apprx. 25 min following ethanol administration. A decrease in TH activity occurred in the substantia nigra of SS mice at 5 min following ethanol administration. There was no significant difference in TH activity in any of these 4 brain regions between LS and SS mice at any time following ethanol administration. In contrast, hypothalamic, TH activity was significantly increased at 25 min in the SS mice and at 125 min in the LS mice, following the administration of ethanol, times which coincided with the regaining of the righting reflex. Apparently, activation of TH in the hypothalamus of LS and SS mice in response to ethanol is associated with arousal from ethanol induced narcosis.