Study on the inhibitory control system of nonshivering thermogenesis by gene signal analysis.

棕色脂肪组织(BAT)是冷习服过程中非颤抖产热(NST)的主要部位。BAT的生热活性主要受交感神经去甲肾上腺素(NA)和胰升糖素的调节，但对BAT的抑制调控因素知之甚少。因此，本研究探讨了催乳素(PRL)对BAT活性的抑制作用。在雄性大鼠冷暴露1小时或1天后，血浆PRL水平下降，但冷习服后血浆PRL水平恢复到温习服对照水平。注射生理盐水后血浆催乳素水平升高，这种升高可被去甲肾上腺素(NA)阻断。反复束缚大鼠束缚应激时血浆催乳素水平的升高被阻断。遗传耐热FOK大鼠的静息血浆PRL水平低于其他品系。在雌性动物中，氟哌啶醇引起的高催乳素血症受到抑制，而溴隐亭引起的低催乳素血症则增强了蝙蝠对胰高血糖素的体外反应性，但对NA没有影响。多巴胺模拟了蝙蝠对溴隐亭的反应。这些结果有力地表明，PRL抑制NST，特别是通过改变BAT中胰高血糖素的生热作用。但在BAT中未检测到PRL受体的可见mRNA。需要进一步研究PRL受体-mRNA的亚型来阐明PRL对BAT活性的作用。

Brown adipose tissue (BAT) is the major site of nonshivering thermogenesis (NST) during cold acclimation. It is well established that the thermogenic activity of BAT is mainly regulated by sympathetic noradrenaline (NA) and pancreatic glucagon, but little is known about the factor concerning inhibitory control of BAT.Therefore, the present research was undertaken to evaluate the possibility of inhibitory role of prolactin (PRL) on BAT activity.In male rats cold-exposure for 1 hr or 1 day decreased plasma PRL levels, but after cold-acclimation the plasma levels returned to the warm-acclimated control levels. Saline injection elevated the plasma PRL level and this elevation was blocked by noradrenaline (NA). In repeatedly-immobilized rats the elevation of plasma PRL level during immobilization stress was blocked. The resting plasma PRL level of genetically heat-tolerant FOK rats was lower as compared with those of other strains. In female animals haloperidol-treatment, causing hyper-prolactinemia, suppressed, while bromocriptine-treatment, causing hypo-prolactinemia, enhanced the in vitro responsiveness of BAT to glucagon, but not to NA.Dopamine mimicked the responses of BAT to bromocriptine. These results strongly suggest that PRL inhibits NST,especially by modifying the thermogenic action of glucagon in BAT.However, visible mRNA for PRL receptor was not detected in BAT.Further study on the subtypes of PRL receptor-mRNA is needed to clarify the role of PRL on BAT activity.