Prenatal protein malnutrition results in increased frequency of miniature inhibitory synaptic currents in rat CA1 pyramidal cells

There is growing evidence for an effect of prenatal protein malnutrition on the GABAergic neurotransmitter system in the rat hippocampus and associate d structures. In the present study, we examined the functional electrophysi ological consequences of observed alterations in GABAA and benzodiazepine r eceptor systems. Whole-cell patch clamp recordings of spontaneous and of mi niature inhibitory postsynaptic currents (mIPSCs) generated by CA1 pyramida l cells were performed in in vitro hippocampal slices prepared from control and prenatally protein malnourished adult male rats. The characteristics o f spontaneous synaptic currents were unaltered by the prenatal insult, as w ere the amplitudes and kinetics of GABA, receptor-mediated mIPSCs. The freq uency of mIPSCs, however, was significantly increased in CA1 pyramidal cell s in slices prepared from prenatally malnourished vs. control rats. The eff ect of the benzodiazepine receptor agonist chlordiazepoxide on the characte ristics of mIPSCs was also examined and found to be the same in cells from both nutritional groups. The increased frequency of mIPSCs together with th e lack of a change in amplitude, kinetics, or modulation by benzodiazepines of mIPSCs in response to prenatal protein malnutrition indicate a presynap tic locus of effect of this insult. (C) 2000 Wiley-Liss, Inc.