母乳喂养对母婴健康至关重要，但是在我国保持纯母乳喂养达6个月以上的母亲，不足全部产妇的30%。授乳失败主要是由于早产、剖腹产以及各种形式的母子分离所致的"乳汁不足"。成功的授乳依赖催产素分泌系统的正常活动；该系统活动的紊乱可以导致乳汁不足。本课题组的初步研究表明，母子分离所致催产素分泌系统活动的紊乱发生在多个细胞与分子层次。 但是，不同因素所致催产素分泌系统活动紊乱的程度及其细胞与分子机制, 迄今为止在国内外尚无研究报道。为此，本研究利用授乳大鼠，采用行为学评估、体内外电生理记录、免疫组织化学、蛋白质交联与酶联免疫等技术，来观察母子分离、剖腹产和陌生雄性大鼠侵入等刺激对射乳反射和催产素分泌系统活动的影响。最后，本研究还将观察经鼻腔应用催产素改善催产素分泌系统的活动对早期母子分离效应的影响。这项研究将确定产后乳汁不足的主要神经生理机制，并探讨应用催产素来预防与治疗授乳失败的可能性。

Breastfeeding is essential for maternal and child health；however, in our country it is less than 30% of all mothers who can keep pure breastfeeding up to six months. Lactation failure is mainly due to "milk shortage" because of premature birth, cesarean section, and various forms of maternal separation from the babies. Successful breastfeeding depends on the normal activity of oxytocin-secreting system; disorders of the activity of this system can cause low milk availability. Our preliminary studies showed that disorders of the activity of oxytocin-secreting system evoked by the separation of mothers from the babies occur at multiple cellular and molecular levels. However, there is neither report so far at home and abroad to indicate the extent of disorders of oxytocin-secreting system activity under the stimuli of various adverse factors nor their underlying mechanisms at cellular and molecular levels. To resolve these questions, this study will use lactating rats to observe effects of the separation of dams from their pups, cesarean section and unfamiliar male rat invasion on the milk-ejection reflex and the activity of oxytocin-secreting system. The methods to be used in this study include behavioral assessments, in vivo and in vitro electrophysiological recordings, immunohistochemistry, co-immunoprecipitation, enzyme-linked immunoassay, etc. Finally, the study will observe effects of oxytocin application through nasal approaches on the consequence of early dam-pup separation. This study will determine the major neurophysiological reasons of postpartum milk shortage, and explore possibilities of prevention and treatment of lactation failure by nasal application of oxytocin.