PARTICIPATION OF HIPPOCAMPAL NICOTINIC RECEPTORS IN ACQUISITION, CONSOLIDATION AND RETRIEVAL OF MEMORY FOR ONE TRIAL INHIBITORY AVOIDANCE IN RATS

D. MARTI´ BARROS, M. R. RAMIREZ, E. A. DOS REIS AND I. IZQUIERDO

NEUROSCIENCE

Elsevier

Año: 2004 vol. 126 p. 651 - 656

0306-4522

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:PT-BR; mso-fareast-language:PT-BR; mso-bidi-language:AR-SA;} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Abstract—One-trial step-down inhibitory avoidance in rats involves the activation of two separate memory types, a short-term system (STM) that lasts 3–6 h, and a long-term system (LTM) that takes 3–6 h to be formed and lasts for many days or even months. Here we investigate the effect of nicotinic receptor (nAChR) ligands infused bilaterally in the hippocampus on STM and LTM formation and on LTM retrieval of this task. Rats were implanted with chronic cannulae in the CA1 region of the dorsal hippocampus, trained using a 0.5 mA foot shock, and tested twice, first 1.5 h after training to measure STM, and again at 24 h to measure LTM. The drugs used were the nAChR antagonists, mecamylamine (1, 3 and 10 _g/side) and dihydro-_-erythroidine (DH_E; 2, 6 and 18 _g/side) and the agonist, nicotine (0.6, 1 and 3 _g/ side). They were given either 15 min before training, immediately after training or 15 min prior to LTM retrieval. Mecamylamine and DH_E impaired and nicotine enhanced STM, LTM and retrieval similarly. The results indicate that nAChRs in CA1 participate in the regulation of both STM and LTM formation, and on the retrieval of LTM.