Role of hippocampal CA1 area gap junction channels on morphine state-dependent learning

Morphine produces a state dependent learning. The hippocampus is involved in this kind of learning. Gap junctions (GJs) are involved in some of the effects of morphine and exist in different areas of the hippocampus. We investigated the effects of blocking GJ channels of the hippocampal CA(1) area, by means of pre-test bilateral injection of carbenoxolone (CBX), on morphine state dependent learning, using a passive avoidance task. Post training subcutaneous administrations of morphine (0.5, 2.5, 5 and 7.5 mg/kg) dose dependently impaired memory retrieval. Pre-test administration of morphine (0.5, 2.5, 5 and 7.5 mg/kg) induced a state dependent retrieval of the memory acquired under post training morphine influence. Pre-test injections of CBX (25, 75 and 150 nM) dose dependently prevented memory retrieval by post training (7.5 mg/kg) and pre-test (0.5, 2.5, 5, 7.5 mg/kg) injections of morphine. The results suggest that intercellular coupling via GJ channels of the hippocampal CA(1) area modulates morphine state dependent learning. (C) 2014 Elsevier B.V. All rights reserved.