Effects of prenatal ethanol exposure on phospholipase C-beta 1 and phospholipase A2 in hippocampus and medial frontal cortex of adult rat offspring.

Previous studies in our laboratory using a rat model of fetal alcohol exposure (FAE) suggest that FAE-induced behavioral deficits are, in part, linked to neurochemical and electrophysiological deficits in long-term potentiation (LTP) in the entorhinal cortical perforant path projection to the hippocampal formation. Several findings suggest that signal-activated phospholipase C (PLC) and phospholipase A2 (PLA2) are critical to the induction and maintenance of LTP. Thus, alterations in phospholipid metabolism may play a significant role in the LTP deficits observed in FAE offspring. To test this hypothesis, we measured PLC-beta 1 and PLA2 activities in the hippocampus and medial frontal cortex of adult rats prenatally exposed to ethanol. PLC-beta 1 activities were significantly decreased by 20 to 30% in both the hippocampus and medial frontal cortex of FAE rats, compared with ad libitum and pair-fed controls. Total Ca(2+)-dependent PLA2 activity was 25% lower in the medial frontal cortex of FAE rats, but did not significantly differ from controls in the hippocampal formation. Approximately 30% of the measured activity in both the medial frontal cortex and hippocampal formation of ad libitum and pair-fed animals was associated with an 85 kDa cytosolic PLA2 form. Cytosolic PLA2 activities were significantly reduced in both the medial frontal cortex and hippocampal formation of FAE rats, compared with controls. These changes in Ca(2+)-dependent PLA 2 and PLC-beta 1 activities, coupled with reports of FAE-induced deficits in protein kinase C activity, indicate that prenatal exposure to moderate quantities of ethanol causes profound and long-lasting deficits in the cellular signaling mechanisms associated with activity-dependent synaptic plasticity and memory formation.