Opioids have been implicated in @entity4998 and in the regulation of reproductive behavior and endocrinology of mammals. Previous studies have indicated that @entity172 administration in adults regulates preproenkephalin MRNA levels in several hypothalamic brain nuclei. We have determined preproenkephalin mRNA levels in @entity172 -treated juvenile male and female @entity35 to investigate the developmental pattern of estrogenic regulation of enkephalinergic neurons in the medial preoptic area. @entity35 were treated with @entity4520 (20 microgram/kg/day) or oil from day 21 to 23. Sections of the medial preoptic area (mPOA) were studied by in situ hybridization histochemistry at the single cell level and quantified with the assistance of an image analysis system. Our data indicate that males contain higher levels of preproenkephalin mRNA per neuron than females. In addition, our results indicate that @entity172 causes an upward shift in the amount of mRNA expressed per cell, females demonstrating a greater response to @entity172 than males. An increase in soma cell area following @entity172 treatment was observed only in female mPOA enkephalinergic neurons. Taken together, these results indicate a sex difference in total @entity18812 levels and in estrogenic regulation of preproenkephalin mRNA in the POA of juvenile @entity35 . These results are discussed in relation to the differential role opioids may play in male and female reproductive physiology.

Sex differences in estrogenic regulation of preproenkephalin mRNA levels in the medial preoptic area of prepubertal XXXX .

@entity172 :: ('MESH:D004967', 'Chemical') :: ['estrogen'] @entity4998 :: ('MESH:D012734', 'Disease') :: ['sexual differentiation of the brain'] @entity35 :: ('10116', 'Species') :: ['Rats', 'rats'] @entity18812 :: ('MESH:C033660', 'Chemical') :: ['preproenkephalin'] @entity4520 :: ('MESH:C074283', 'Chemical') :: ['estradiol benzoate']
@entity35 :: (10116,Species) :: ['rats']
