GABAA receptors in the dorsal hippocampus are involved in sate-dependent learning induced by lithium in mice

Document Type: Research article

Authors

1 Department of Pharmacology and Iranian National Center for Addiction Studies, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

2 Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran

3 Department of Pharmacology and Iranian National Center for Addiction Studies, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran School of Cognitive Sciences, Institute for Studies in Fundamental Sciences (IPM), P.O. Box 19395-57463,

Abstract

These experiments examined the effects of pre-test intra dorsal hippocampus (intra-CA1) administration of GABAA receptor agonist and antagonist, muscimol and bicuculline respectively, on state-dependent learning induced by lithium. Male NMRI mice were trained in a one-trial step-down inhibitory avoidance task, and immediately after training they received IP injections of either saline (10 mL/kg) or lithium (10 mg/kg). The animals were tested for step-down latency, as an index of inhibitory avoidance memory, 24 h after the training. The results showed that lithium (10 mg/kg) induced state-dependent learning. Although the decrease of step down latency due to post-training lithium (10 mg/kg) was not fully reversed by a lower dose of lithium (5 mg/kg) but pre-test intra-CA1 injection of bicuculline (0.25 µg/mouse) increased the effect of the lower dose of lithium. Pre-test intra-CA1 injection of muscimol (0.05 µg/mouse) by itself reversed the decrease of step-down latency induced by post-training lithium (10 mg/kg). Pre-test intra-CA1 injection of muscimol (0.03 and 0.05 µg/mouse) also disrupted state-dependent learning induced by lithium (10 mg/kg). The results suggest that a GABAA receptor mechanism in the dorsal hippocampus is involved in state-dependent induced by lithium.

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