Spatial cognition and sexually dimorphic synaptic plasticity balance impairment in rats with chronic prenatal ethanol exposure

Abstract

Prenatal ethanol exposure can lead to long-lasting impairments in the ability of rats to process spatial information, as well as produce long-lasting deficits in long-term potentiation (LTP), a biological model of learning and memory processing. The present study aimed to examine the sexually dimorphic effects of chronic prenatal ethanol exposure (CPEE) on behavior cognition and synaptic plasticity balance (SPB), and tried to understand a possible mechanism by evaluating the alternation of SPB. The animal model was produced by ethanol exposure throughout gestational period with 4 g/kg bodyweight. Offspring of both male and female were selected and studied on postnatal days 36. Subsequently, the data showed that chronic ethanol exposure resulted in birth weight reduction, losing bodyweight gain, microcephaly and hippocampus weight retardation. In Morris water maze (MWM) test, escape latencies were significantly higher in CPEE-treated rats than that in control ones. They also spent much less time in the target quadrant compared to that of control animals in the probe phase. In addition, it was found that there was a more severe impairment in females than that in males after CPEE treatment. Electrophysiological studies showed that CPEE considerably inhibited hippocampal LTP and facilitated depotentiation in males, while significantly enhanced LTP and suppressed depotentiation in females. A novel index, developed by us, showed that the action of CPEE on SPB was more sensitive in females than that in males, suggesting that it might be an effective index to distinguish the difference of SPB impairment between males and females.

Keywords: CF; CM; CNS; CPEE; CPEE female; CPEE male; Cognitive deficit; DEPI; DI; EF; EM; Ethanol; HPA; IT; LTP; LTPI; MWM; Morris water maze; Offspring rats; PF; PM; RT; SET; SPB; SPBI; Sexual dimorphism; Synaptic plasticity balance; central nervous system; chronic prenatal ethanol exposure; control female; control male; depotentiation index; directional index; fEPSPs; field excitatory postsynaptic potentials; hypothalamic-pituitary-adrenal; initial training stage; long-term potentiation; long-term potentiation index; pair-fed male; poair-fed female; reversal training; space exploring test; synaptic plasticity balance index; synaptic plasticiy balance.