Immunohistochemical localisation of substances reactive to antisera against alpha- and beta-endorphin and met-enkephalin in the brain of Rana temporaria L.

In the brain of Rana temporaria, two distinct systems reactive with alpha- and beta-endorphin antisera, respectively, and with a met-enkephalin antiserum, have been detected immunohistochemically. Neurons reacting with alpha- and beta- endorphin antisera are located (1) in the preoptic nucleus, and (2) in the pars ventralis of the tuber cinereum. Immunoreactive nerve fibres of both groups of perikarya end in the infundibular floor near the capillaries and the preoptico-hypophysial tract. Control reactions have shown that the immunoreactivity is suppressed by the corresponding antigens, but also by beta-LPH. In view of these results the immunoreactive systems examined correspond to an alpha/beta-endorphin system or a lipotropinergic system. neurons reacting with the met-enkephalin antiserum are located in the paraventricular organ. Intense immunofluorescence was observed in the infundibular floor. Controls show that the labelling by met-enkephalin antiserum is exclusively suppressed by met-enkephalin. In the pituitary gland, on the other hand, alpha- and beta-endorphin antisera reveal: 1) the MSH/ACTH-like cells of the pars intermedia and 2) the ACTH-like cells of the pars distalis.