Maternal consumption of moderate levels of ethanol causes subtle cognitive and behavioral aberrations in offspring. In rats, feat alcohol exposure (FAE) has been associated with decrements in various measures of learning, including spatial learning, operant learning and learned fear. We hypothesize that alterations in phosphatidylinositol-specific phospholipase C-beta1a (PLC-beta1a)-dependent signaling may underlie these learning deficits. In support of this hypothesis, we have found that PLC-beta1a enzyme activities and protein levels in rat HPC (HPC) and medial frontal cortex (MFC) are altered one and twenty-four hours following one-trial fear conditioning (OTFC) and that FAE modifies these responses. In order to further characterize the role of PLC-beta1A in OTFC and to assess the effect of FAE on PLC-beta1a-dependent signaling, we propose:
AIM 1 : To determine the time course of OTFC-induced changes in PLC- beta1a subcellular distribution and catalytic activity in rats exposed or not, to moderate novels levels of ethanol through gestation. Our initial studies demonstrate that FAE alters PLC-beta1a responses measured one and twenty-four following OTFC. These studies do not, however, provide sufficient data to conclude whether FAE simply alters the magnitudes of the responses only at these times following conditioning or whether it alters the temporal patterns of the response. In the present studies we will address this by measuring PLC-beta1a enzyme activities and protein levels at several other times following conditioning. By obtaining a more detailed profile of the effects of OTFC on PLC-beta1 in control and FAE rats, we will be able to determine if FAE alters the temporal patterns or the magnitudes of the responses to OTFC.
AIM 2 : To determine the effects of OTFC and FAE on the kinetics of PLC-beta1a enzyme activity. Previously, we reported that FAE reduces basal PLC-beta1 enzyme activity in rat HPC and MHC. In preliminary studies, we have found that this decrease may be the result of a change in the kinetics of the enzyme-catalyzed reaction. We do not know, however, whether, the FAE-dependent changes in PLC-beta1a enzyme activity that we measured and twenty-four hours following OTFC are the result of alterations in enzyme kinetics. In the present studies, we will perform detailed analyses of the effects of OTFC and FAE on the kinetics of PLC- beta1 enzyme activity. These determinations will provide significant insight into the mechanism(s) through which OTFC and FAE regulate PLC-beta1 enzyme activity. Identification of the neurochemical abnormalities that underlie the cognitive and behavioral deficits associated with FAE will facilitate the development of rationale treatment strategies.
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