Ghrelin increases learning consolidation and facilitates synaptic plasticity through mechanisms dependent on NR2B subunits of the NMDA receptor

BUTTELER FLORENCIA; MARISA GHERSI,; LAURA GABACH; MARIELA F. PEREZ; SUSANA R BARIOGLIO,

Huerta Grande, Cordoba

Congreso; IV Reunión Conjunta de Neurociencias, IVRCN; 2012

SAN

Ghrelin (Ghr) is a peptide synthesized both peripherally and in the central nervous system that participates in feeding control and learning and memory. Ghr receptors are expressed in the hypothalamus and in other brain structures such as the hippocampus (Hi), a structure involved in learning and memory processes. The biochemical memory pathways of as well as Hi long term potentiation (LTP) involve glutamatergic receptors (AMPA and NMDA) stimulation. Moreover, a critical requirement of NMDA receptor (NMDAR) containing NR2B subunits for the induction of LTP has been described. Previous results from our laboratory we demonstrated that intra-Hi Ghr administration in rats enhances memory consolidation in the step-down test (SDT) and reduces the threshold to induce LTP in Hi. However, the molecular and cellular basis of Ghr effects still remains unclear. In the present work we studied the participation of NMDAR containing NR2B subunits in Ghr effects by using a SDT and electrophysiological recordings. Our results showed that intra-Hi administration of a selective NR2B antagonist (Ro-256981) previous to Ghr partially blocked memory consolidation and increased threshold to generate Hi LTP when compared to intra-Hi Ghr administration suggesting that Ghr effects could be partially mediated by NMDAR containing NR2B subunits.