Unilateral reversible inactivations of the nucleus tractus solitarius and amygdala attenuate the effects of bombesin on memory storage

This study examined the role of the nucleus tractus solitarius (NTS) and am ygdala in mediating the effects of bombesin (BBS) on retention of inhibitor y avoidance training by reversibly inactivating these regions with lidocain e immediately following training. In Expt. 1, peripheral injection of diffe rent doses of BBS (1, 2.5, 5, 10 or 20 mu g/kg) to unoperated rats immediat ely after training in one trial inhibitory avoidance task(1 mA, 1.5 s foots hock) produced a dose-dependent response on retention test scores which was given two days after training. In Expts. 2 and 3, rats were surgically imp lanted unilaterally with cannula tip placed above the NTS or amygdala, were trained in task and then received unilateral injections of saline or lidoc aine (2%, 0.5 mu l) into the NTS or amygdala and peripheral injections of s aline or BBS (5 mu g/kg). The results showed that the memory enhancing effe ct of BBS was attenuated by unilateral inactivation of the NTS or amygdala. These findings indicate that the NTS and amygdala are involved in mediatin g the memory modulating effects of peripheral BBS on memory storage. (C) 19 98 Elsevier Science B.V. All rights reserved.