Eriksson M, Björkstrand E, Smedh U, Alster P, Matthiesen A S, Uvnäs-Moberg K
Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden.
Acta Physiol Scand. 1994 Aug;151(4):453-9. doi: 10.1111/j.1748-1716.1994.tb09767.x.
The aim of this study was to investigate the role of vagal nerve activity for the release of oxytocin, prolactin and gastrointestinal (GI) hormones during suckling as well as for the secretion of milk in lactating rats. We have therefore performed experiments on vagotomized lactating rats. The animals were decapitated and trunk blood was collected from nonsuckling rats and from suckling rats in connection with milk ejection. Oxytocin, prolactin, vasoactive intestinal polypeptide (VIP), somatostatin, insulin, glucagon and glucose levels in plasma were measured by RIA-technique. In addition, maternal weight as well as the weight of the litters were recorded 7 d after vagotomy. As expected, oxytocin and prolactin levels rose in response to suckling in sham-operated controls. In vagotomized animals the suckling-induced increase of oxytocin was blocked and prolactin levels were significantly decreased. VIP levels in plasma increased following suckling in sham-operated animals and failed to respond after vagotomy. In contrast, somatostatin levels that rose significantly in sham-operated rats were even more significantly raised in vagotomized animals. In addition, insulin but not glucagon levels were increased by suckling. The insulin response, however, persisted after vagotomy. Interestingly, suckling was followed by a lowering of blood-glucose levels in vagotomized, but not in sham-operated animals. The vagotomized rats ate as much and increased in weight as sham-operated rats during the 7 d of vagotomy. The litters of vagotomized rats, however, gained significantly less weight in comparison with control litters. In conclusion, this study shows that vagal nerve activity is of importance for the release of oxytocin, prolactin, vasoactive intestinal polypeptide and somatostatin during suckling.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是调查迷走神经活动在哺乳期间对催产素、催乳素和胃肠（GI）激素释放以及对泌乳大鼠乳汁分泌的作用。因此，我们对切断迷走神经的泌乳大鼠进行了实验。将动物断头，从非哺乳大鼠以及与排乳相关的哺乳大鼠中采集躯干血。采用放射免疫分析法测定血浆中催产素、催乳素、血管活性肠肽（VIP）、生长抑素、胰岛素、胰高血糖素和葡萄糖水平。此外，在切断迷走神经7天后记录母鼠体重以及窝仔重量。正如预期的那样，假手术对照组中，催产素和催乳素水平因哺乳而升高。在切断迷走神经的动物中，哺乳诱导的催产素增加被阻断，催乳素水平显著降低。假手术动物哺乳后血浆VIP水平升高，切断迷走神经后无反应。相反，假手术大鼠中显著升高的生长抑素水平在切断迷走神经的动物中升高得更显著。此外，哺乳使胰岛素水平升高，但胰高血糖素水平未升高。然而，切断迷走神经后胰岛素反应仍持续存在。有趣的是，切断迷走神经的动物哺乳后血糖水平降低，而假手术动物则不然。在切断迷走神经的7天里，切断迷走神经的大鼠进食量与假手术大鼠相同，体重也增加。然而，与对照窝仔相比，切断迷走神经的大鼠的窝仔体重增加明显较少。总之，本研究表明迷走神经活动在哺乳期间对催产素、催乳素、血管活性肠肽和生长抑素的释放具有重要作用。（摘要截短至250字）
