ETHANOL, GROWTH-HORMONE AND TESTOSTERONE IN PERIPUBERTAL RATS

The deleterious effects of ethanol on the hypothalamic pituitary growt h hormone axis in adult male humans and animals have been well documen ted. It is also well established that ethanol has toxic effects on tes ticular function in adult humans and animals. Much less is known, howe ver, about the effects of ethanol on the growth hormone (GH) axis and testicular function in adolescence. Recent studies have established th at adolescent problem drinking is a widespread and growing threat to t he health of young people in the United States. In the present study, therefore, we investigated if acute ethanol exposure in peripubertal m ale Sprague-Dawley rats altered normal pituitary and testicular functi on. Serum levels of GH and testosterone were measured at 1.5, 3, 6, an d 24 h alter a single i.p. injection of either saline or 3 g/kg body w eight ethanol. Histologic analysis as well as serum testosterone level s allowed us to assign animals to either early puberty (35-day-old ani mals), mid-puberty (41-day-old animals), or young adult (51- and 66-da y-old animals) status. Ethanol produced significant decrements in seru m testosterone in the 51- and 66-day-old animals, with a trend toward suppression in the 41-day-old group. Furthermore acute ethanol adminis tration significantly decreased serum GH (P<0.0001 by 3 way ANOVA) dem onstrating a significant effect of ethanol on serum GH in all age grou ps and at all time points studied when compared with saline injected c ontrols (P<0.01 by Tukey's studentized range test). Despite this signi ficant fall in peripheral GH levels, there was no decrease in either G H mRNA or growth hormone-releasing factor (GRF) mRNA levels nor in hyp othalamic concentration of GRF peptide. We conclude that, as in adult animals, acute exposure to ethanol causes a prolonged and severe decre ment in serum GH which is possibly mediated at the level of secretion. In addition, there is attenuation in testosterone secretion. These da ta are all the more important since GH and testosterone play critical roles in organ maturation during this stage of development.