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Journal of Undergraduate Research

Keywords

neurosteroid pregnenolone sulfate, hippocampal physiology, disorders

College

Family, Home, and Social Sciences

Department

Psychology

Abstract

Several recent studies have established a role for estrogens in ameliorating specific neurodegenerative disorders, mainly those associated with the cholinergic neurons of the basal forebrain and their targets in the cortex and hippocampus. We have previously demonstrated that endogenous and exogenous application of the neurosteroid dehydroepiandrosterone sulfate (DHEAS) markedly reduces GABA-mediated recurrent inhibition and synchronizes hippocampal unit activity to theta rhythm. In this study, I evaluated the role of muscarinic receptors in mediating the effects of the GABA-modulating neurosteroid, pregnenolone sulfate (PREGS) on monosynaptic evoked potential responses, paired-pulse inhibition, paired-pulse facilitation and GABA interneuron activity in the dentate gyrus and CA1 subfields of the rat hippocampus. Systemic administration of PREGS did not alter monosynaptic evoked potentials, but significantly increased PPI in CA1. These findings suggest that select GABA-modulating neurosteroids and neuroactive estrogen sulfates alter septohippocampal cholinergic modulation of hippocampal GABAergic interneurons mediating recurrent, but not feedforward, inhibition of hippocampal principal cell activity.

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