Francine E. Lancaster

Brain myelination in the offspring of ethanol-treated rats: in Utero versus lactational exposure by crossfostering offspring of control, pairfed and ethanol treated dams

Pregnant Long-Evans rats were received on day 5 of gestation and divided into 4 treatment groups: (1) 27% calories provided as ethanol in a liquid diet; (2) pairfed i.e., isocaloric liquid diet restricted to match group (1); (3) liquid diet provided ad libitum; and (4) laboratory chow and water provided ad libitum. Litters were culled to 8 pups at birth and crossfostered across dams in all 4 groups to provide offspring falling into 16 different experimental groups, including some exposed to ethanol in utero only and some exposed only during lactation. At birth, blood alcohol levels of dams, culled pups and alcohol levels in the stomach contents of culled pups were measured. All pups were weaned and fed laboratory chow and water ad libitum from 21 days onward. At ages 16, 21, 30 and 52 days, pups were sacrificed, and organ/body weight ratios and brain myelin concentrations were determined. Ethanol treated dams had longer gestational periods. The offspring of ethanol treated dams which were crossfostered to pairfed and well nourished dams during lactation had delayed eye opening, persistent lag in body growth and slightly lower brain myelin concentrations. Offspring of dams which were either pairfed or well nourished during gestation, but crossfostered during lactation to ethanol treated dams, had abnormal organ weights, abnormal brain weights and severely depressed brain myelin concentrations persisting through 52 days of age. Thus, lactational ethanol effects on brain myelin were more severe than gestational effects; body growth was affected more severely by gestational exposure, and gestational effects were generally less severe with adequate nutrition.

The synthesis of myelin and brain subcellular membrane proteins in the offspring of rats fed ethanol during pregnancy

Pregnant Long-Evans rats received either: (1) liquid diet containing 5.15% ethanol; (2) liquid diet pair fed to (1) for total calories; or (3) liquid diet ad libitum. These special diets were administered from the 5th through the 18th days of gestation. Dams received standard laboratory chow and water ad libitum before and after the test interval. Additional dams received standard chow and water throughout the study. Birth weights of offspring in the ethanol group were lower than for offspring of the pair-fed or control groups, and their subsequent growth lagged behind the other groups. Neonate deaths in the ethanol group outnumbered other deaths. Eye opening was delayed, and brain weights appeared low from 16 to 30 days postnatal age, The onset of myelin synthesis was delayed by several days; however, by 30 days of age, the rate of myelin synthesis and net accumulation was comparable to the offspring of pair-fed controls. Thus, the effect of ethanol on brain myelination in the offspring of subject females appears as a delay in myelin initiation and cannot be fully explained by caloric undernourishment. An unexpected observation involved offspring of females fed standard chow throughout the study. The brain myelin concentration in this group was lower than for any of the other groups, which may relate to the higher fat content of the liquids diets and/or the comparatively slow weight gain of pregnant rats on standard chow.

Fetal ethanol exposure: a morphometric analysis of myelination in the optic nerve.

Pregnant Long‐Evans rats were fed a liquid diet containing ethanol during gestation. Controls consisted of both pair‐fed dams and dams fed ad libitum with an equivalent, iso‐caloric diet lacking ethanol. Subsequent effects of ethanol measured in the offspring include a significant lag in the rate at which non‐myelinated axons are lost in association with the initial overproduction of neurons. Additionally, there was a slight lag in the rate of acquisition of myelinated axons; and altogether there was a large increase in the ratio of non‐myelinated to myelinated axons. Frequency spectra of myelinated and non‐myelinated axons by size were normal, and the relationship between axon size and myelin lamellae was also normal. Measured against the dynamic, normal background of rapid cell‐loss and the progressive development of myelin, morphometric demonstration and evaluation of the comparatively small divergences associated with fetal alcohol exposure are difficult; nevertheless, these results are consistent with and help account for the marginal hypomyelination previously observed by quantitative neurochemistry.

Alcohol and the brain: what's NO got to do with it?

A potential role for nitric oxide in alcohol-induced changes in brain function is discussed. Chronic alcohol exposure may lead to excitotoxicity partially due to increased levels of nitric oxide (NO). Excessive NO has been linked to cytotoxicity in neurons, glia and myelin. Cytokines produced in response to cell injury may trigger increased production of NO. These events may be involved in alcohol-induced brain damage. Formation of NO has recently been linked to increased preference for and tolerance to alcohol. A hypothesis for prevention and treatment of alcohol-induced brain damage, and craving and alcohol intake by alcoholics is proposed.

Gender Differences in Animal Studies

The reasons for gender differences in alcohol intake, responses to alcohol, and consequences of alcohol abuse in humans and in animals are poorly understood. Animal models for the study of alcoholism have been focused primarily on the study of male rodents, although researchers have observed that female rodents drink more alcohol than males and have sex-related differences in drinking patterns and responses to alcohol. In humans, the difference between the sexes is the opposite of rodents, with males drinking more than females. These results suggest differences between the sexes and differences between humans and rodents in drinking behavior and responses to alcohol which may be based on a complex interaction of social, genetic, hormonal, neurobiologic, and environmental factors. Four new studies are introduced to identify sex-distinct genetic influences in alcohol-related phenotypes, sex-based differences in behavioral responses to alcohol, sex differences in responses of brain reward systems to alcohol, and interactions of the anxiolytic effects of alcohol with steroids and the estrous cycle.

Synaptic density of caudate-putamen and visual cortex following exposure to ethanol in utero

Pregnant Long‐Evans rats were fed a liquid diet containing ethanol (30% of total calories) during days 3–19 of gestation. Controls were given ad libitum access to liquid diet lacking ethanol, or pair‐fed isocaloric amounts based on consumption by the animals in the ethanol group. Brain development of female offspring was evaluated by analysis of electron micrographs of caudate‐putamen and visual cortex. Numbers of presynaptic terminals and synaptic junctions (synaptic density) per unit area were compared for 14‐ and 28‐day‐old offspring of dams from the three treatment groups. Synaptic density of the caudate‐putamen and visual cortex was not affected by ethanol at 14 or 28 days. Although exposure to ethanol during a period comparable to the first two trimesters of human development with minimal or no undernutrition did not affect numerical density of synapses in visual cortex or caudateputamen, synaptogenesis of caudate‐putamen was altered in offspring of pair‐fed animals.

Maternal ethanol exposure with adequate protein in the diet: influence on offspring development

Abstract Pregnant rats (n=45) were fed alcohol (29% of kcal) in a high protein (31% of kcal) liquid diet on days 6 through 19 of gestation. On day 1 (day 0 is day of birth), litters were culled to 8 pups, 4 males and 4 females when possible. Samples for blood assays, organ weights and thymus samples for histologic preparation were obtained from pups culled from the litters. Pups were randomly selected for urinary pH testing, blood assays, thymus studies and liver lipid assays on days 1, 16, 21 and 30 and for sciatic nerve myelin assay on day 21. Hematology, thymus protein and structure, liver lipids and cholesterol, and sciatic nerve myelin were unharmed by in utero alcohol exposure in the presence of a high protein diet. At day 16, body and brain weights of alcohol exposed pups were decreased and urinary pH levels were higher than those of pairfed and ad libitum controls. In utero alcohol exposure (29%) in a diet containing 31% kcal as protein did not affect hematology, liver and thymus structure or peripheral nerve myelin; but did have early affects on body, brain, kidney and thymus weights and urinary pH levels.

Effects of dihydroergotoxine (hydergine) on peripheral blood alcohol levels.

Abstract To examine the effects of dihydroergotoxine (DHET) on peripheral blood ethanol levels of adult female mice, ethanol (2 g/kg) was administered orally, either alone or in combination with DHET (2, 4, or 8 mg/kg). Blood was drawn after the first day of drug administration (acute study) and again after 21 days (chronic study). Two additional groups of mice received a single dose of ethanol (2 g/kg) and DHET (2 mg/kg) 15 minutes apart, one group receiving ethanol first, the other DHET as the first dose. Blood samples (100μ1) were collected from the tail vein at 5, 15, 30, 60, 120 and 180 minutes after treatment. Samples were analyzed by headspace gas chromatography. Results indicate that (a) combining ethanol with DHET significantly reduced blood ethanol levels compared to administration of ethanol alone, (b) chronic conditions produced higher blood ethanol levels, and (c) administration of ethanol 15 minutes before DHET produced a 27% lowering of peripheral blood alcohol levels compared to the reverse order of administration. These data suggest that DHET may be useful for alleviating some of the symptoms associated with alcohol intoxication.