Chlordiazepoxide normalizes behaviour and adrenal response abnormalities in septal rats in a dose and time dependent...

Rats lesioned in the septal nuclei display a dramatic syndrome characterized by hypoactivity in a novel environment, but exaggerated behavioural and corticosterone responses to environmental stimuli. These abnormal responses are normalized 2 hours following 15 mg/kg i.p. of chlordiazepoxide (Seggie, CCNP, 1980). The present study was undertaken to map the dose and time response characteristics of this effect and see if behaviour and corticosterone respond in parallel fashion. Chlordiazepoxide in doses of 7.5-30 mg/kg affected the hyperreactivity of septal rats is a 'U' shaped function without affecting the behaviour of non-lesioned rats. Corticosterone levels in non-lesioned rats were unaffected by chlordiazepoxide, while drug treated septal rats had corticosterone levels undistinguishable from non-lesioned control rats. The drug effects were transitory, maximal at 2 hours after injection, but absent as 48 hours after injection. General abnormalities of behaviour and corticosterone responsiveness were altered in parallel fashion by the drug, but some evidence of differences in sensitivity to the effect of the drug were noticed. Locomotion, was unaffected by the drug in lesioned and non-lesioned rats. The possibility of a GABA mechanism underlying the abnormalities of responsiveness, but not activity in septal rats is discussed.