Localization of prolactin uptake by the kidney of the teleostean, Colisa lalia

Abstract

Although evidence has been presented that the hormone prolactin specifically binds to the kidneys of the teleost Sarotherodon mossambicus ( J. N. Fryer, 1979, Gen. Comp. Endocrinol. 39, 397–403.) prolactin has not previously been shown to become localized at any particular morphological sites in fishes. This problem has been investigated in the dwarf gourami, Colisa lalia. Ovine prolactin was labeled with 125I and injected intramuscularly. Fish were sacrificed after 15, 30, and 90 min. Other animals were injected with an excess of unlabeled prolactin, growth hormone, or luteinizing hormone 2 min prior to administration of the label. Paraffin-embedded tissues were sectioned, coated with Kodak NTB-3, and exposed for 3–5 weeks. After developing, samples of several body tissues were stained and examined for the presence of silver grains. The results indicate that, as in rat and frog, kidney tubules of C. lalia are sites of prolactin localization. No other sites of prolactin localization were identified.