Septal TRH in alcohol-naive P and NP rats and following alcohol challenge.

Regional brain content of TRH was evaluated in selectively bred alcohol-preferring (P) and -nonpreferring (NP) rats before, during, and upon awakening from ethanol sedation. TRH content was significantly lower in both the medial and lateral septum of alcohol-naive P rats compared with alcohol-naive NP rats. Following a sedating dose of ethanol, P rats righted themselves sooner than NP rats. TRH content in the medial septum of P and NP rats was significantly higher when the rats regained their righting reflex. While sedated, TRH in the medial septum of P rats was insignificantly increased. These data are the first to show that endogenous TRH in the medial septum may be involved in arousal from drug-induced sedation and that the events preceding arousal may occur sooner in P than in NP rats. In addition, innate differences in septal TRH may be associated with preference for ethanol.