MODULATION OF PREOPTIC REGULATORY FACTOR-II (PORF-2) MESSENGER-RNAS BY CASTRATION AND HYPOPHYSECTOMY

Neuropeptides are central to the regulation of mammalian gender-depend ent development and reproduction. Preoptic regulatory factor-2 is a ne uropeptide gene that is known to be expressed in rat brain and testis (1). In the brain, expression is gender-dependent and age-dependent (2 ,3). Tissue-specific transcripts are found in the preoptic area (POA) of the hypothalamus and in the testis (1). In order to investigate the effects of reproductive hormone status on expression of porf-2 in the male rat, porf-2 transcripts were studied by Northern blot analysis i n intact, hypophysectomized, and castrated rat POA, medial basal hypot halamus (MBH), cerebral cortex (CC), testis, and liver. Castration or hypophysectomy increased levels of the brain-specific 0.84 kb 5' porf- 2 transcript in the POA, but did not affect levels of this transcript in the CC. There was a small decrease in the MBH following castration. Hypophysectomy also resulted in a fourfold increase in the 5' 1.1 kb testis-specific transcript. The affected transcripts are localized to the cytoplasm. A nontissue specific 3' transcript was also detected. I nterestingly, this 0.6 kb transcript became nondetectable in all tissu es examined following hypophysectomy. Porf-2 mRNA was also detected in human hypothalamus, testis, adrenal, placenta, and prostate with uniq ue transcripts in each tissue examined. It has been shown elsewhere th at porf-2 is a unique single copy gene in the rat genome. These data d emonstrate that expression of the porf-2 gene is differentially regula ted at the pretranslational level by intrinsic tissue-specific, as wel l as extrinsic pituitary and gonadal factors. The selected responses t o reproductive hormonal status suggest that porf-2 may play a role in hypothalamic pituitary-gonadal interactions.