Whitten R D, Youngstrom T G, Bartness T J
Department of Psychology, Georgia State University, Atlanta 30303.
Physiol Behav. 1993 Jul;54(1):175-8. doi: 10.1016/0031-9384(93)90062-k.
Serum prolactin (PRL) concentrations, as well as body, epididymal white adipose tissue (EWAT), and testes weights, decrease in Siberian hamsters (Phodopus sungorus sungorus) following short-photoperiod exposure. Previously, we have shown that lesions of the suprachiasmatic nucleus of the hypothalamus (SCNx) block regression of the testes and decreases in body weight and EWAT caused by short day-like, timed daily subcutaneous melatonin infusions in pinealectomized Siberian hamsters and elevate dramatically serum PRL concentrations. We also have shown that SCNx, as well as lesions of the paraventricular nucleus of the hypothalamus (PVNx) and an area immediately ventral to the PVN (subPVN), promote accelerated testicular recrudescence, increases in EWAT and body weights, and increases in serum PRL concentrations, in short-day (SD)-housed, photoregressed Siberian hamsters. The stimulation of the testes seen in these previous studies could have been due to the lesion-induced increases in serum PRL concentrations. Therefore, the purpose of the present experiment was to test whether experimentally induced hyperprolactinemia could stimulate testicular recrudescence. This was accomplished by giving photoregressed, SD-housed Siberian hamsters chronic subcutaneous infusions of ovine PRL (oPRL) to mimic either long-day- or lesion-induced serum concentrations of hamster prolactin (hPRL). No increase in testes, body, or EWAT weights were observed following 5 weeks of oPRL infusions in either group compared with their vehicle-infused counterparts. These data suggest that hyperprolactinemia was not solely responsible for the stimulation of testicular recrudescence in SCNx or PVNx photoregressed, or SCNx pinealectomized hamsters receiving timed melatonin infusions seen previously.
在短光照周期暴露后，西伯利亚仓鼠（Phodopus sungorus sungorus）的血清催乳素（PRL）浓度以及体重、附睾白色脂肪组织（EWAT）和睾丸重量都会下降。此前，我们已经表明，下丘脑视交叉上核损伤（SCNx）可阻止睾丸退化，并防止松果体切除的西伯利亚仓鼠因每日定时皮下注射褪黑素而导致体重和EWAT下降，同时会显著提高血清PRL浓度。我们还表明，SCNx以及下丘脑室旁核损伤（PVNx）和PVN正下方的一个区域（subPVN）可促进短日照（SD）饲养、光退化的西伯利亚仓鼠睾丸加速再生、EWAT和体重增加以及血清PRL浓度升高。在这些先前的研究中观察到的对睾丸的刺激可能是由于损伤导致血清PRL浓度升高所致。因此，本实验的目的是测试实验诱导的高催乳素血症是否能刺激睾丸再生。这是通过给光退化、SD饲养的西伯利亚仓鼠长期皮下注射羊催乳素（oPRL）来模拟长日照或损伤诱导的仓鼠催乳素（hPRL）血清浓度来实现的。与注射赋形剂的对照组相比，两组在接受5周oPRL注射后，睾丸、体重或EWAT重量均未增加。这些数据表明，高催乳素血症并非先前观察到的SCNx或PVNx光退化或接受定时褪黑素注射的SCNx松果体切除仓鼠睾丸再生刺激的唯一原因。
