Hammer R P, Bogic L, Handa R J
Department of Anatomy and Reproductive Biology, University of Hawaii School of Medicine, Honolulu 96822.
Brain Res Mol Brain Res. 1993 Jul;19(1-2):129-34. doi: 10.1016/0169-328x(93)90157-k.
Endogenous opioid peptides and their receptors are regulated by gonadal steroid hormones in the rat hypothalamus. Recent evidence suggests that gonadal steroids are capable of regulating the expression of proenkephalin (PE) mRNA in the ventromedial hypothalamus (VMH) of female, but not male rats. Therefore, we examined the effect of gonadectomy with or without four weeks of hormone treatment on PE mRNA expression in adult male Fisher 344 rats using quantitative in situ hybridization histochemistry. Gonadectomy reduced plasma testosterone and dihydrotestosterone (DHT) levels compared to intact rats, while subsequent estradiol (E2) or DHT treatment increased plasma E2 and DHT levels, respectively. Furthermore, gonadectomy reduced PE mRNA expression in the VMH, but not in the striatum nor the olfactory tubercle compared to intact rats, and this reduction was prevented in the presence of E2, but not DHT. The results suggest that the activation of estrogen receptors normally functions to maintain the level of VMH PE mRNA expression, which is sensitive to hormonal regulation in adult male rats. Thus gonadal steroid hormones might regulate those reproductive functions which are modulated by PE-derived opioid peptides in the male rat brain.
内源性阿片肽及其受体在大鼠下丘脑中受性腺甾体激素的调节。最近的证据表明，性腺甾体能够调节雌性大鼠腹内侧下丘脑（VMH）中前脑啡肽（PE）mRNA的表达，但对雄性大鼠则无此作用。因此，我们使用定量原位杂交组织化学方法，研究了成年雄性Fisher 344大鼠去势并给予或不给予四周激素治疗对VMH中PE mRNA表达的影响。与完整大鼠相比，去势降低了血浆睾酮和双氢睾酮（DHT）水平，而随后的雌二醇（E2）或DHT治疗分别提高了血浆E2和DHT水平。此外，与完整大鼠相比，去势降低了VMH中PE mRNA的表达，但纹状体和嗅结节中未降低，并且在有E2存在时这种降低被阻止，但DHT则不能。结果表明，雌激素受体的激活通常起到维持VMH中PE mRNA表达水平的作用，而成年雄性大鼠的VMH中PE mRNA表达水平对激素调节敏感。因此，性腺甾体激素可能调节雄性大鼠脑中那些受PE衍生的阿片肽调节的生殖功能。
