6-OHDA BILATERAL LESIONS TO THE NUCLEUS SEPTI LATERALIS ATTENUATE VASOPRESSIN IMPROVEMENT OF RECALL IN RATS

The investigation was aimed at investigating whether the dopaminergic projection arriving at the nucleus septi lateralis (NSL) is involved i n the facilitatory effect of vasopressin (AVP) on memory retrieval. Th e bilateral 6-OHDA lesions to the NSL were made in 20 male Wistar rats before testing the intracerebroventricular (i.c.v.) AVP injection on recall in a passive avoidance situation. Eighteen additional rats serv ed as sham-operated controls. Thirty minutes before surgery rats were pre-treated with an intraperitoneal injection of 25 mg kg(-1) of desme thylimipramine, an inhibitor of norepinephrine uptake. Sixteen lesione d and 16 sham-operated rats were included in the study. AVP (1 mu g, i .c.v.) given 15 min before the retention testing significantly improve d latencies both in lesioned and in sham-operated rats in comparison w ith the respective i.c.v. saline-injected animals. However, bilateral lesions to the NSL significantly diminished the facilitatory effect of AVP on recall. The insignificant decrease of spontaneous psychomotor activity in rats lesioned to the NSL was unlikely to interfere with th e cognitive effect of AVP. These results suggest that dopaminergic pro jection to the NSL is involved in the facilitatory effect of AVP on th e retrieval process in a passive avoidance situation. (C) 1998 The Ita lian Pharmacological Society.