Fetal Alcohol Exposure Alters GAP-43 Phosphorylation and Protein Kinase C Responses to Contextual Fear Conditioning in the Hippocampus of Adult Rat Offspring Daniel C. Tanner, Ann W. Githinji, Elizabeth A. Young, Karina Meiri, Daniel D. Savage, and Nora I. Perrone-Bizzozero Background: The growth- and plasticity-associated protein GAP-43 plays a significant role in the estab- lishment and remodeling of neuronal connections. We have previously shown that GAP-43 levels, protein kinase C (PKC) activity, and GAP-43 phosphorylation increase during contextual fear conditioning and that fetal alcohol exposure (FAE) decreases PKC activity and GAP-43 phosphorylation in the hippocampus of adult offspring. Drawing on these observations, we hypothesized that FAE manifests its cognitive impairment by disrupting PKC activation and membrane translocation, thereby decreasing GAP-43 phos- phorylation and function. Methods: Three groups of pregnant rat dams (FAE and two control diet groups) were placed on different diet regimens. Offspring from each of these groups were placed into each of four test groups, a contextual fear conditioned (CFC) group, a naïve unhandled group, and two nonlearning stress control groups. Hippocampi were dissected, homogenized, and used to prepare a cytosolic and a membrane fraction. These fractions were probed for total GAP-43, PKC-phosphorylated GAP-43, and several PKC subtypes. PKC activity also was measured in total homogenates. Results: Compared with both control diet groups, FAE animals showed a deficit in the activation of PKC in the hippocampus at 24 hr but not at 1.5 hr after CFC. Likewise, we found that the amount of GAP-43 and its phosphorylation were decreased 24 hr after CFC in FAE rats but not at early times after training. Analysis of the translocation of various PKC isoforms revealed that FAE animals had decreased levels of membrane-bound PKC  2 and PKC  24 hr after CFC. Conclusions: Considering the role of PKC activation and GAP-43 phosphorylation in synaptic plasticity, our results suggest that deficient translocation of PKC  2 and PKC  in the hippocampus may mediate the electrophysiological and behavioral deficits observed in fetal alcohol exposed animals. Key Words: GAP-43, PKC, Contextual Fear, Fetal Alcohol Exposure, Hippocampus. A LCOHOL CONSUMPTION DURING pregnancy has been associated with long-lasting intellectual impair- ments in affected children (Conry, 1990; Hanson et al., 1978; Jacobson et al., 1998; Shaywitz et al., 1980; Streiss- guth et al., 1990, 1991, 1994; Warren and Foudin, 2001; Whaley et al., 2001). The impact of heavy or binge drinking patterns on cognitive function is well recognized. However, increasing evidence indicates that moderate drinking dur- ing pregnancy may cause subtle, long-term cognitive im- pairments that may not become apparent until a child is challenged during the educational years and may increase in severity with maturation (Conry, 1990; Streissguth et al., 1990, 1991, 1994; Warren and Foudin, 2001; Whaley et al., 2001) Animal models of prenatal ethanol exposure have proven very useful for understanding the basis of alcohol- related learning disabilities (Berman and Hannigan, 2000; Blanchard et al., 1987, 1990; Gianoulakis, 1990; Kelly et al., 1988). Using one such model, Perrone-Bizzozero et al. (1998) and Sutherland et al. (2000) observed a number of electrophysiological and neurochemical deficits in rat off- spring whose mothers consumed moderate quantities of ethanol throughout gestation. Measuring both field excita- tory postsynaptic potentials and population spikes, Suther- land et al. (1997) found that fetal alcohol exposed (FAE) rats exhibited a significant decrease in their capacity to elicit long-term potentiation (LTP) in vivo. In support of this idea, in vitro studies in hippocampal slices revealed that glutamate release is also decreased in FAE animals on From the Department of Neurosciences (DCT, AWG, EAY, DDS, NP-B), University of New Mexico, Albuquerque, New Mexico; and the Department of Anatomy and Cellular Biology (KM), Tufts University, Boston, Massachusetts. Received for publication March 12, 2003; accepted October 21, 2003. Supported by Grants AA11336 (NPB) and AA12400 (DDS) from NIH. Reprint requests: Nora Perrone-Bizzozero, PhD, 915 Camino de Salud NE, Department of Neurosciences, Albuquerque, NM 87131; Fax: 505-272- 8082; E-mail: nbizzozero@salud.unm.edu. Copyright © 2004 by the Research Society on Alcoholism. DOI: 10.1097/01.ALC.0000106308.50817.B3 0145-6008/04/2801-0113$03.00/0 ALCOHOLISM:CLINICAL AND EXPERIMENTAL RESEARCH Vol. 28, No. 1 January 2004 Alcohol Clin Exp Res, Vol 28, No 1, 2004: pp 113–122 113