RESUMEN
This study examined the role of the nucleus tractus solitarius (NTS) and amygdala in mediating the effects of bombesin (BBS) on retention of inhibitory avoidance training by reversibly inactivating these regions with lidocaine immediately following training. In Expt. 1, peripheral injection of different doses of BBS (1, 2.5, 5, 10 or 20 microg/kg) to unoperated rats immediately after training in one trial inhibitory avoidance task (1 mA, 1.5 s footshock) produced a dose-dependent response on retention test scores which was given two days after training. In Expts. 2 and 3, rats were surgically implanted unilaterally with cannula tip placed above the NTS or amygdala, were trained in task and then received unilateral injections of saline or lidocaine (2%, 0.5 microl) into the NTS or amygdala and peripheral injections of saline or BBS (5 microg/kg). The results showed that the memory enhancing effect of BBS was attenuated by unilateral inactivation of the NTS or amygdala. These findings indicate that the NTS and amygdala are involved in mediating the memory modulating effects of peripheral BBS on memory storage.