AUTORADIOGRAPHIC LOCALIZATION OF GROWTH-HORMONE BINDING-SITES IN SPARUS-AURATA TISSUES USING A RECOMBINANT GILTHEAD SEABREAM GROWTH-HORMONE

Growth hormone (GH) binding sites iii tissues of gilthead seabream, Sp arus aurata, were localized by using an in vitro autoradiographic anal ysis. Cryomicrotome sections of liver, spleen, kidney, heart and skele tal muscle were mounted on gelatin-coated slides and incubated with a radioiodinated recombinant gilthead seabream GH (0.54 ng/100 mu l buff er) for 24 h at 4 degrees C. Slides were coated with autoradiographic emulsion and exposed for 1-9 weeks. The highest density of GH binding sites was found in liver. This specific binding was evident on hepatoc ytes. Blood cells in hepatic vascular system also showed GH binding wh ile intrahepatic exocrine pancreas did not. In spleen, a high density of GH binding sites was found surrounding melanomacrophage centers. Sp lenic ellipsoid cells also showed a strong GH binding while splenic pu lp exhibited a weak GH binding. Kidney GH binding sites were present i n renal tubules and renal haemopoietic tissue. Cardiac muscle exhibite d an intense GH binding. However, GH binding sites were not detected i n body skeletal muscle. This study confirms and extends, by using auto radiographic techniques, previous results obtained by radioreceptor as says.