The effect of fetal alcohol exposure on postnatal pituitary cAMP content and growth hormone release
Garbouzova, Yelena N.
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This study investigates the effect of prenatal ethanol exposure and pair-feeding on the postnatal GRF- SRIF regulated cAMP system and GH release from the pituitary. Short-and long-term effects of ethanol and pair-feeding on cAMP and GH were examined at specific ages of development in respect to sexual dimorphic pattern of GH release. During pregnancy, ethanol dams consumed a liquid ethanol diet with 36% of calories derived from ethanol. Pair-fed dams were given the same amount of liquid diet consumed by ethanol dams the day before. Thus, their fetuses were exposed to ethanol or pair-feeding in utero. Pituitaries from 1-, 10-, and 60-day old pups were explanted and underwent incubation with SRIF (10~9M) or GRF (5x10"9M) . The media GH concentration was determined by radioimmunoassay. The tissue cAMP was extracted from the pituitary explants and cAMP content of pituitaries was determined by radioummunoassay. The weights of pups were measured on the day of the experiment in order to identify the influence of ethanol on growth. Our results indicate that the weights of male and female pups were reduced by ethanol. At 1 day of age both male and female pups weighed less than^both pair-fed and control pups. At 10 days of age the weight of ethanol- exposed male pups was significantly reduced compared to pair-fed and control pups. The weight of female pups at 10 days and both sexes at 60 days was not significantly different from the weight of pair-fed pups. The capacity of hypothalamic releasing factors to influence GH release and cAMP accumulation was altered by prenatal exposure to ethanol. Specifically, SRIF capacity to inhibit GH release and cAMP accumulation was decreased by ethanol. This depression was more evident in pituitaries from female pups than male pups. The capacity of GRF to stimulate GH release and cAMP accumulation was significantly decreased only in pituitaries from 10-day-old male pups. The decrease in GH release was not associated with decreased cAMP accumulation (if baseline cAMP was considered). This data suggests that prenatal exposure to ethanol altered GH and the GH regulatory system. Thus, pituitary sensitivity to GH releasing factors is altered by ethanol. Further, this effect of ethanol on pituitary sensitivity is sexually dimorphic. It is possible that the alteration in GH and GH regulatory system by prenatal exposure to ethanol may be related to retarded growth after birth and during development.