REGULATION OF MILK LETDOWN IN NORMAL AND STRESSED RATS

乳汁排泄的调节涉及母体和后代的贡献。 这项建议涉及3个问题：禁食的机制 幼崽增加它们的摄入量，这是母体对 哺乳的变化，从而改变牛奶的释放，和抑制作用 压力对乳汁分泌的影响 口内负压的作用 通过慢性口腔插管记录幼鼠的吸吮。 变化 口内压力的频率、幅度和持续时间将 与禁食大鼠牛奶摄入量的变化相关。 排乳 将通过幼犬的体重变化来估计。 变化的方面， 母亲对哺乳的敏感性将被检查：（i）改变 哺乳信号传递到下丘脑的催产素 释放;（ii）改变敏感性的肌上皮细胞催产素。 在某些提升神经路径中的活动将被记录在 脊髓第一节。 肌上皮细胞对催产素的敏感性 将通过乳房内压的变化来测量。 对压力的研究 对乳汁释放的抑制作用将集中在随后的效果上 情绪激动，肾上腺皮质激素和 交感肾上腺髓质系统 本研究的长期目标 重点关注护理二分体对长期暴露于 不利的环境条件，如缺氧、低重力。 在 特别是，将进行研究1）以描述 环境压力，母亲和年轻人可以暴露在没有疾病 对后代的影响，以及2）确定抑制作用是否 压力对乳汁分泌的影响可以得到缓解，以保持正常 奶释放，从而提供了适当的营养需要的窝。

Regulation of milk letdown involves maternal and offspring contributions. This proposal is concerned with 3 problems: the mechanism by which fasted pups increase their intake, the mechanism by which maternal sensitivity to suckling changes, thereby altering milk release, and the inhibitory effect of stress on milk release. The negative intraoral pressures exerted during sucking by the pups will be recorded via a chronic oral cannula. Changes in the frequency, amplitude and duration of the intraoral pressures will be correlated with alterations in milk intake in fasted rats. Milk ejection will be estimated by pups' weight changes. The aspects of changes in maternal sensitivity to suckling that will be examined are: (i) altered transmission of the suckling signal to the hypothalamus for oxytocin release; (ii) altered sensitivity of the myoepithelial cells to oxytocin. Activities in certain ascending neural paths will be recorded at the level C1 of the spinal cord. The sensitivity of myoepithelial cells to oxytocin will be measured by changes in intramammary pressure. The study of stress on the inhibition of milk release will focus on the effect of the ensuing emotional arousal, that of the adrenocortical hormones and that of the sympathetic-adrenomedullary system. The long term objectives of this study are to focus on the adaptation of the nursing dyad to prolonged exposure to adverse environmental conditions such as hypoxia, hypogravity. In particular, studies will be conducted 1) to delineate the severity of environmental stress to which mother and young can be exposed without ill effect to the offspring, and 2) to determine whether the inhibitory effect of stress on milk letdown can be alleviated in order to maintain normal milk release, thus providing for the proper nutritional need of the litter.