Thyroid status during postnatal maturation of the brain in mice genetically bred for differences in ethanol...

The long-sleep (LS) and short-sleep (SS) mice represent established lines, genetically selected from a heterogeneous stock (HS) of mice for differences in the duration of the loss of righting reflex (sleep-time response) to acute ethanol administration. Presently, the dose of ethanol (20% v/v i.p.) required for approximately a 50-min sleep-time response is 2-fold higher in adult SS (5.0 mg/g) than in adult LS (2.5 mg/g) mice. The waking isohypnotic serum and brain ethanol levels for HS mice are intermediate to those for LS and SS mice. Ethanol sensitivity of the two lines of mice at different stages of postnatal central nervous system maturation has not been examined. We report that the central nervous system sensitivity to a 1-mg/g dose of ethanol is the same in 9-day-old LS and SS mice, since the sleep-time response and corresponding waking serum ethanol concentrations are not different. The SS mice do not lose the righting reflex by 11 days postpartum after a dose of ethanol of 1 mg/g. By day 13, LS mice also do not lose their righting reflex after 1 mg/g of ethanol. The difference in ethanol sensitivity to a dose of 4.1 mg/g continues to develop at day 14 and approaches adult levels by day 20. This postnatal change in ethanol sensitivity in LS and SS mice occurs during a time when significant base-line differences in the thyroid status occur.(ABSTRACT TRUNCATED AT 250 WORDS)