Corticosterone-Induced Changes in Inhibitory Neurotransmission in Hippocampal Field CA1 Synapses Depending on the Activity of Inhibitory Synapses Expressing Cannabinoid Receptors

Abstract

Objectives. To study the effects of corticosterone (100 nM) on spontaneous inhibitory postsynaptic currents(sIPSC) in pyramidal neurons in hippocampal field CA1 and to identify the role of inhibitory synapses expressing cannabinoid receptors in the changes induced by corticosterone. Materials and methods. Experiments were performed on living slices of rat ventral hippocampus using a patch clamp method in the whole cell configuration. Results and conclusions. Addition of corticosterone led to a significant increase in the frequency of sIPSC in the first 10 min, after which the magnitude of this parameter returned to baseline. In addition, the use of corticosterone led to a significant decrease in sIPSC amplitude 40 min after the start of exposure. Activation of cannabinoid CB1 receptors had weak effects on the properties of sIPSC, though addition of corticosterone did not induce the rapid rise in sIPSC frequency occurring at 10 min in controls or the drop in sIPSC amplitude (at 40 min in controls). These data indicate that both the rapid and slow effects of corticosterone developing in the ventral hippocampus are associated with the activity of CB1-expressing inhibitory synapses.