HIPPOCAMPAL NITRIC-OXIDE SYNTHASE IN THE FETAL GUINEA-PIG - EFFECTS OF CHRONIC PRENATAL ETHANOL EXPOSURE

The effects of chronic maternal administration of ethanol on nitric ox ide synthase (NOS) activity and the numbers of NOS containing neurons, and CA1 and CA3 pyramidal neurons in the hippocampus of the near term fetal guinea pig at,gestational day (GD) 62 were investigated. Pregna nt guinea pigs received oral administration of 4 g ethanol/kg maternal body weight (n = 5), isocaloric sucrose/pair feeding (n = 5) or water (n = 5), or no treatment (NT; n = 5) from GD 2 to GD 61. NOS activity in the 25,000 X g supernatant of hippocampal homogenate was determine d using a radiometric assay. The numbers of NOS containing neurons, an d CAI and CA3 pyramidal neurons were determined using NADPH diaphorase histochemistry and cresyl violet staining, respectively. The chronic ethanol regimen produced a maternal blood ethanol concentration of 193 +/- 13 mg/dl at 1 h after the second divided dose on GD 57. Chronic e thanol exposure produced fetal body, brain, and hippocampal growth res triction and decreased fetal hippocampal NOS activity compared with th e isocaloric sucrose/pair feeding, water, and NT experimental groups, but did not affect the number of NOS containing and CAI or CA3 pyramid al neurons. These data demonstrate that, in the near term fetus, chron ic maternal administration of ethanol suppresses hippocampal NOS activ ity and consequent formation of NO, without loss of NOS containing neu rons and prior to loss of CA1 pyramidal neurons that occurs in the adu lt. (C) 1998 Elsevier Science B.V.