EFFECT OF CENTRAL NERVOUS SYSTEM LESIONS ON BARBITURATE SLEEPING TIME IN THE RAT

¹ Departments of Pharmacology, Psychology and Anatomy, The University of Chicago, Chicago, Illinois

Rats with bilateral stereotaxically placed electrolytic lesions of the septal area of the telencephalon or of the dorsomedial tegmentum of the brain stem demonstrated 3.5- to 4-fold increases in either thiopental or barbital sleeping time. Both lesions also decreased barbital induction time by one-half. There were no comparable effects produced by the other lesions investigated in this study. Rats with combined lesions of the septal area and dorsomedial tegmentum slept 8.36 times longer than normal controls and significantly longer than either rats with septal area or dorsomedial tegmentum lesions alone. The effects of septal area and dorsomedial tegmentum lesions on barbiturate sleeping time are therefore additive.

Adrenalectomy or cortisone replacement failed to abolish septal sensitivity to barbital. Although septal rats show a decreased time of onset and increased duration of barbital sleep, there were no measurable effects of the lesion on total brain levels of C¹⁴ barbital. The results were discussed with respect to the anatomical relationships of the septal area with the dorsomedial tegmentum.