Hypoploidy and hyperplasia in the developing brain exposed to alcohol in utero

Cytometric investigations on hemocytes of the American oyster, Crassostrea virginica

Pericardial hemolymph was obtained from American Oysters (Crassostrea virginica) and the hemocytes characterized by flow cytometry. The cells were found to have a broad unimodal size distribution with a median diameter of 7 micrometers. Total protein measured by flow cytometric fluorescence of dansylated cells also revealed a broad unimodal distribution similar to that obtained for size. The proportion of hemocytes in each stage of the cell cycle was measured using DNA-specific DAPI fluorescence. Histograms showed a single peak representing the G(0)/G(1) population. There was no evidence of S or G(2)+M phases of the cell cycle, nor was polyploidy seen. The forward and orthogonal light scatter of fixed hemocytes showed no evidence of sub-populations on the basis of cytoplasmic granularity. Thus, in terms of these parameters, oyster hemocytes appear to represent a single population exhibiting graded cellular differences.

Second trimester prenatal alcohol exposure alters development of rat corpus callosum

Prenatal alcohol exposure produces many developmental defects of the central nervous system (CNS), such as in the corpus callosum (CC). This study was designed to observe the effect of prenatal alcohol exposure during the second trimester equivalent on the development of dendritic arbors of CC projection neurons (CCpn) in rat visual cortex. In addition, the effect of second trimester equivalent prenatal alcohol exposure on brain weight was determined. Pregnant dams received 1.2-6.0 g/kg ethanol (EtOH) during gestational day (G) 11-20. Controls consisted of normal and nutritionally matched pairfed (PF) dams. Pups were sacrificed on the day of birth, G26, G29 and G33. DiI crystals were placed in the midsagittal CC bundle to retrogradely label CCpn. Images of visual cortex were obtained from tissue slices using a confocal laser scanning microscope. The number and length of apical and basilar dendrite branches were determined. The results show that prenatal alcohol exposure restricted to the second trimester equivalent alters the development of the CCpn dendritic arbor and the brain weight in a blood alcohol concentration (BAC)-dependent manner. The alteration in the EtOH CCpn is manifested as an increase in the number and length of CCpn apical and basilar dendrite branches, while brain weight is reduced compared with Controls.

Disorders of brain development in the progeny of mothers who used alcohol during pregnancy

Brain development has been studied in 44 embryos (gestational age: 5-12 weeks) and three fetuses (gestational age: 14 weeks) obtained from mothers who used alcohol during pregnancy, and compared with a control group comprising 16 cases of comparable ages. In 34 cases out of 47 in the alcohol group (75.5%), features indicative of abnormal morphological brain development were found. In all, nine variants of brain pathology are described. Abnormalities in the formation of the lateral ventricle walls and disorders of the development of the cortical laminae occurred most frequently (70.6% and 57.9%, respectively). When the cases were sorted according to maternal alcohol intake it was found that the children of severely alcoholic mothers (100-500 ml ethanol per day, 4-7 days per week) had abnormal brain morphology in 100% of cases. In those cases where maternal alcohol use was systematic and frequent (100-200 ml ethanol per day, 2-4 times per week), brain pathology was identified in 83.3% of cases. In systematic maternal use of alcohol (100-200 ml of ethanol taken on one day per week), and in episodic use (35-100 ml of ethanol taken on three occasions during pregnancy), 97.3% and 28.5% were affected, respectively.

Generation of neurons in the rat dentate gyrus and hippocampus: effects of prenatal and postnatal treatment with ethanol

Neurons in the rat hippocampal formation (the dentate gyrus and the hippocampus) are born over a protracted period, from gestational day (G) 15 into adulthood. Dentate gyral neurons born prenatally are generated from the ventricular zone, whereas those born postnatally are derived from a secondary proliferative zone, the intrahilar zone. In contrast, hippocampal pyramidal neurons are generated only prenatally from the ventricular zone. In the neocortex, ethanol depresses the proliferation of cells in the ventricular zone and stimulates the proliferation of cells in the secondary proliferative zone. The present study tests the hypotheses that prenatal treatment with ethanol has a different effect on the generation of dentate gyral neurons than does postnatal ethanol treatment, and that these differences are determined by the timing of the ethanol exposure relative to the period and site of neuronal generation. Rats were treated with ethanol between G6 and G21 or between postnatal day (P) 4 and P12. They were given an injection of [3H]thymidine on G15, G18, G21, P6, P9, or P12. Rats were killed on P30-P35. The tissue was processed by standard autoradiographic methods and assessed using rigorous stereological procedures. The total number of neurons and the density of radiolabelled neurons in both the dentate gyrus and the CA1 region of the hippocampus were determined. Prenatal ethanol treatment decreased the total number of neurons in the CA1 segment of the hippocampus and had little impact on neuronal number in the dentate gyrus. Likewise, the number of hippocampal and dentate gyral neurons generated daily was significantly lower in ethanol-treated rats than in controls. Postnatal treatment to ethanol, however, significantly increased the total number of dentate gyral neurons and the density of neurons generated postnatally. These postnatal changes depended on the blood ethanol concentration (BEC). At moderate BECs, the total number of neurons in the dentate gyrus and the number of neurons generated was increased. At high BECs, however, neuronal number and neuronal generation were decreased. Postnatal ethanol treatment had no effect on the number of (total or radiolabeled) CA1 neurons. Thus, pre- and postnatal exposure to ethanol have opposite effects both on the number of neurons in the dentate gyrus and on the generation of neurons. These paradoxical effects likely result from three causes: the differential effects of ethanol on the two proliferative zones, the critical period of neuronal development, and the potentially opposite effects of moderate and high BEC.

Cell cycle kinetics in fetal rat cerebral cortex: effects of prenatal treatment with ethanol assessed by a cumulative labeling technique with flow cytometry

The effects of ethanol on the cell cycle kinetics of cortical precursor cells during the period of cortical neuronogenesis [between gestational day (G) 12 and G21] was systematically examined. Samples of dissociated cortical cells were harvested from the cerebral cortices of 13-, 15-, 17-, 19-, and 21-day-old fetuses. The fetuses were obtained from pregnant rats: (a) fed a liquid diet containing 6.7% (v/v) ethanol (Et) ad libitum, (b) pair-fed an isocaloric liquid control diet (Ct), or (c) fed chow and water (Ch) ad libitum. Before harvesting the cells, the fetuses were administered a series of 1-5 injections of bromodeoxyuridine (BrdU). The proportion of cells that incorporated the BrdU was assessed. Using these raw data, the S-phase length (Ts), total cell cycle length (Tc), and the growth fraction (GF; the fraction of the total population that was actively cycling) were determined with a cumulative labeling procedure. The Ts was approximately 8-9 hr, regardless of either the date of the injection or the dietary treatment of the dam. On the other hand, the Tc for the Ct- and Ch-treated rats increased over the gestational period. That is, the Tc was shortest on G13 and longest on G21. The Tc for Et-treated rats, however, did not change between G13 and G21. For the Ch- and Ct-treated groups, the GF decreased > 15-fold between G13 and G21. The decline (5-fold) for the Et-treated group over the same period, however, was not as great as it was for the Ct-treated fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of prenatal alcohol exposure on the dimensions and binucleation of cardiac myocytes in neonatal and weanling rats

Sprague-Dawley rats were exposed to ethyl alcohol in utero. The effect of chronic prenatal exposure was examined by giving mature females alcohol in isocaloric liquid diets which served as the sole source of liquid and caloric intake before mating and throughout gestation. Controls consisted of females maintained on laboratory chow or an isocaloric liquid diet minus alcohol before and during gestation. The offspring were sacrificed at 21 days of age (weanlings) and the hearts dissociated enzymatically to give purified cardiac myocytes. The effects of daily acute prenatal alcohol exposure were studied by gastric intubation of alcohol to chow-fed females for the duration of pregnancy. The doses used approximated 4 and 5 shots of 80 proof liquor per day by a person weighing 150 lb. These offspring were sacrificed at 2, 6, and 21 days postnatal and cardiac myocytes prepared as above. Heart weights were determined and cardiac myocytes were analyzed for cell length, volume, cross-sectional area, and percent binucleation. Additionally, nuclear DNA content was measured in all of the 21 day offspring. Statistical analysis of the data showed no significant differences between hearts exposed to prenatal alcohol and nonexposed controls with either regimen with the exception of percent binucleation which was significantly but only slightly higher in the 6-day-old hearts. These findings are discussed in relation to anatomical heart defects found in patients with full fetal alcohol syndrome.

Numbers of neurons and glia in mature rat somatosensory cortex: effects of prenatal exposure to ethanol

Stereological methods were used to examine the consequences of prenatal exposure to ethanol on the structure of area 3, primary somatosensory cortex, of the mature hooded rat. Pregnant rats were fed a liquid diet containing 6.7% (v/v) ethanol (Et), pair-fed an isocaloric liquid control diet (Ct), or fed a diet of chow and water (Ch). Cresyl violet-stained sections of 3-month-old pups were examined. The corrected mean size of the cell bodies of neurons in layers other than layer V was significantly smaller in the Et-treated rats; conversely, the mean somatic size of glia in each layer was significantly larger in the Et-treated rats. The laminar cell packing density for neurons and glia, however, was similar in rats from both treatment groups. The overall volume of area 3 and the volume of individual layers were about 33% smaller in Et-treated rats than in the pair-fed controls. Thus, the estimated total number of neurons in Et-treated rats (1.79 X 10(6] was significantly fewer than in Ch-treated rats (2.77 X 10(6] and in Ct-treated rats (2.66 X 10(6]. The total number of glia also was about 30% fewer in Et-treated rats than in the controls. Not all layers were affected equivalently. The space occupied by the neuropil was significantly greater in Et-treated rats, but only in layers II/III, IV, and VI; hence, the cell body/neuropil ratio in these layers was less in Et-treated rats than in the controls. Therefore, microcephaly caused by prenatal exposure to ethanol results not only from a miniaturization of the brain, but also from a permanent abnormal organization of cerebral cortex.

Effects of prenatal exposure to ethanol on neocortical development: II. Cell proliferation in the ventricular and subventricular zones of the rat

Prenatal exposure to ethanol alters the generation of neocortical neurons; ethanol reduces the numbers of neurons generated between gestational day (G) 12 and G19 but paradoxically increases neuronogenesis after G19. The present study used [3H]thymidine autoradiography to examine the effects of ethanol on the proliferation of cells in the two cortical germinal zones, the ventricular and subventricular zones. Pregnant rats were fed one of three diets: a liquid ethanol-containing (6.7% v/v) diet (Et), a nutritionally matched isocaloric liquid diet (Ct), or chow and water (Ch). Fetuses were administered with [3H]thymidine on G13, G17, or G20 and killed 45-60 minutes later. Autoradiographs were prepared to identify radiolabeled and mitotic cells. Additional brains from 13-23-day-old fetuses were processed for cytoarchitectonic analyses. The size of the lateral ventricles in the fetuses was not significantly affected by the prenatal exposure. Both the ventricular and subventricular zones were evident throughout the period from G13 to G23. In all three groups, the ventricular zone was thickest from G13 to G17, but from G15 on, the ventricular zone of Et-treated fetuses was significantly thinner than those of either controls. On G13, G17, and G20, the labeling index (the ratio of radiolabeled cells to the total population) was significantly less in Et-treated fetuses. The mitotic index was similar in Et-, Ch-, and Ct-treated fetuses. The subventricular zone of all fetuses was most prominent during later fetal ages and it was thicker in Et-treated fetuses than in controls. Moreover, the labeling and mitotic indices for the subventricular zone of Et-treated rats were significantly greater than for controls. Thus, ethanol had different effects on the two neocortical germinal zones: the proliferation of ventricular cells was inhibited, whereas the proliferation of subventricular cells was stimulated. These data suggest that ethanol-induced changes in neuronogenesis result from alterations in proliferative activity.