Release of prolactin and growth-hormone by pituitary grafts. Role of the neurointermediate lobe.

ABSTRACT

The release of prolactin (PRL) and growth hormone (GH) of pituitary grafts and in situ glands was investigated using perifusion techniques. Whole pituitary or anterior lobe grafts were used. The grafts or the in situ glands were incubated alone in a chamber. The hypophysis of dioestrous-1 glands were used as controls. Both types of grafts released PRL an GH to the medium, being the PRL release of the anterior lobe graft higher than that of the whole pituitary graft. The in situ pituitary glands of grafted animals released less PRL than the control dioestrous glands. Also, the in situ glands of whole pituitary grafted animals released less PRL than the hypophysis of animals which bore grafts of only the anterior lobe. No difference in GH secretion, either by the graft or by the in situ gland was observed when whole pituitary or anterior grafts were used. These results provide a further support to the hypothesis that a pituitary graft under the kidney capsule exerts profound modifications in the function of the in situ hypophysis. The presence of the neurointermediate lobe (NIL) in the graft is modulatory to the release of PRL.