Release of gastrin and insulin in response to suckling in lactating dogs

Abstract

The concentration of gastrin and insulin was determined in peripheral blood of 4 lactating dogs during suckling. Suckling induced an immediate rise of gastrin and insulin levels, 2-fold and 3-fold, respectively. A peak was reached at .apprx. 5 min after suckling was started, and basal levels were reached again within 15-20 min. The increase in gastrin and insulin levels coincided with the let-down reflex, i.e., it occurred when the puppies started to obtain milk from their mothers. Sham feeding and feeding induce a vagally-mediated increase of gastrin and insulin release in dogs. Apparently, the changes in the gastrin and insulin levels observed in the lactating dogs reflect a similar vagal activation induced by suckling. Possible effects of the suckling-induced release of gastrin and insulin on milk ejection and secretion are discussed.