Hypocretins (HCRT), also known as orexins, includes two neuroexcitatory peptides, HCRT-1 and HCRT-2 (orexin A y B, respectively), synthesized by neurons located in the postero-lateral hypothalamus, whose projections and receptors are widely distributed throughout the brain, including the medial preoptic area (mPOA). HCRT have been associated with a wide range of physiological functions including sleep-wake cycle, maternal behavior and body temperature, all regulated by the mPOA. Previously, we showed that HCRT in the mPOA facilitates certain active maternal behaviors, while the blockade of HCRT-R1 increases the time spent in nursing. As mother rats mainly sleep while they nurse, we hypothesize that HCRT in the mPOA of lactating rats reduce sleep and nursing, while intra-mPOA administration of a dual orexin receptor antagonist (DORA) would cause the opposite effect. Therefore, the aim of this study was to determine the role of HCRT within the mPOA, in the regulation and integration of the sleep-wake cycle, maternal behavior and body temperature of lactating rats. For that purpose, we assessed the sleep-wake states, maternal behavior and body temperature of lactating rats following microinjections of HCRT-1 (100 and 200 µM) and DORA (5mM) into the mPOA. As expected, our data show that HCRT-1 in mPOA promote wakefulness and a slightly increase in body temperature, whereas DORA increases both NREM and REM sleep together with an increment of nursing and milk ejection. Taken together, our results strongly suggest that the endogenous reduction of HCRT within the mPOA contribute to the promotion of sleep, milk ejection and nursing behavior in lactating rats.

伪君子 (HCRT)，也称为食欲素，包括两种神经兴奋肽 HCRT-1 和 HCRT-2（分别为食欲素 A 和 B），由位于下丘脑后外侧的神经元合成，其投射和受体广泛分布于整个大脑，包括内侧视前区 (mPOA)。HCRT 与广泛的生理功能相关，包括睡眠-觉醒周期、母体行为和体温，所有这些都由 mPOA 调节。此前，我们发现 mPOA 中的 HCRT 促进了某些积极的母亲行为，而 HCRT-R1 的阻断增加了护理时间。由于母鼠主要在哺乳时睡觉，我们假设哺乳期大鼠 mPOA 中的 HCRT 会减少睡眠和哺乳，而双食欲素受体拮抗剂 (DORA) 的 mPOA 内给药会产生相反的效果。因此，本研究的目的是确定 HCRT 在 mPOA 中的作用，在调节和整合哺乳期大鼠的睡眠-觉醒周期、母体行为和体温中。为此，我们评估了将 HCRT-1（100 和 200 µM）和 DORA（5mM）微量注射到 mPOA 后哺乳大鼠的睡眠-觉醒状态、母体行为和体温。正如预期的那样，我们的数据显示 mPOA 中的 HCRT-1 促进清醒和体温略微升高，而 DORA 增加 NREM 和 REM 睡眠，同时增加护理和排乳。总之，我们的结果强烈表明 mPOA 内 HCRT 的内源性减少有助于促进睡眠，