Effect of Hypothalamic Deafferentation on Lactation in Rats.

Abstract

Postero-bilateral and antero-bilateral deafferentations of the hypophysiotrophic area were carried out in 10 lactating Sprague-Dawley rats by the procedure of Halasz and Pupp. In 2 rats deafferented postero-bilaterally, bilateral deafferentation was started 0.5 mm posteriorly, so that the lateral deafferentation was incomplete. The operated animals, (with the exception of these 2 rats deafferented incompletely), failed to rear their pups. This failure is ascribed to the blockade of milk ejection since pups could obtain milk when the mother was injected with exogenous oxytocin. Severe diabetes insipidus was observed in 2 out of 3 animals deafferented antero-bilaterally. Since only one of the 4 rats deafferented postero-bilaterally showed any diabetes insipidus, yet all showed loss of reflex discharge of oxytocin, the pathways of the latter mechanism to the hypophysiotrophic area must enter laterally, and they cannot be identical to the supra-optic o-hypophy seal tract.