beta-Endorphin-immunoreactive neurons in the hypothalamus and medulla of the rat brain: Effect of prenatal ethanol.
The number and distribution of beta-endorphin neurons in the hypothalamus and medulla of rats is compared among three experimental treatment groups: prenatally ethanol-exposed rats, pair-fed control rats, and normally fed control rats. Quantitative analysis of beta-endorphin-immunoreactive neurons in 12 sections through the rostral-caudal extent of the mediobasal hypothalamus revealed no significant difference in the total number or distribution of beta-endorphin neurons among any of the three treatment groups. The mean number of beta-endorphin neurons was consistently less in each of the 12 sections of pair-fed rats compared to normally fed rats, but there was no consistent difference between the mean number of neurons/section in prenatally ethanol-exposed rats compared to the normally fed controls. The distribution and time of appearance of a second population of beta-en-dorphin neurons was analyzed in the caudal medulla. beta-endorphin-immunoreactive neurons were easily visualized in the caudal medulla of rats from each treatment group on Postnatal Days 9-11. However, this population could not be identified with antisera against beta-endorphin on Postnatal Days 19-21 in any treatment group, even though neurons in the hypothalamus of the same rats were easily visualized histochemically at this age. These data suggest that the well-characterized prenatally ethanol-induced alterations in central opioid systems cannot be attributed to changes in the number, distribution, or time of appearance of beta-endorphin neurons in the brain.
Baker
R A
RA
Neuroscience Program University of Connecticut School of Medicine, Farmington, Connecticut 06030, USA.
Shoemaker
W J
WJ