Stress and nursing in the XXXX : role of HPA axis and endogenous opioid peptides.

@entity1510 @entity1707 @entity701
To determine the effect of stress on nursing, and the roles of HPA activity and opioid peptides, nine sows had their piglets removed for 2 h and were treated as follows: (a) control; (b) nose-snare restraint for 20 min; (c) @entity1510 injections (i.v. 2 mg/kg); and (d) snare + @entity1510 . After the treatment, the piglets were returned, milk ejections were timed, and the sows' blood sampled every 10 min for @entity701 , growth hormone (GH), and prolactin assays. Piglet removal increased @entity701 and decreased prolactin and GH. This was reversed when the piglets were returned. Restraint increased @entity701 and decreased GH, but did not affect prolactin. @entity1510 alone increased @entity701 and decreased GH but did not increase the effect of restraint. The rise in GH following the piglets' return was abolished by the combination of restraint and @entity1510 . Neither restraint nor @entity1510 delayed the latency to first milk ejection or reduced the frequency. No unsuccessful nursings were observed. First milk ejections occurred when @entity701 levels were elevated. Stress-induced activity of the hypothalamo-pituitary-adrenocortical (HPA) axis does not inhibit milk ejection in the @entity1707 , but this is not due to a protective opioid action. Endogenous opioids protect lactogenic hormones against inhibition by stress.
