GABAA Receptors in the Dorsal Hippocampus are Involved in Sate-dependent Learning Induced by Lithium in Mice

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 ìg/mouse) increased the effect of the lower dose of lithium. pre-test intra-ca1 injection of muscimol (0.05 ìg/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 ìg/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.