RESUMO
Using metrizamide gradient centrifugation two populations of Leydig cells were found in both 60-90 day-old and 24 month-old rats. Cells from both Band 2 (B2) and Band 3 (B3) responded to LH stimulation with increased cyclic AMP formation; however, only B3 cells produced significant amounts of testosterone. Cells from both B2 and B3 of the old rats synthesized less cyclic AMP and testosterone than cells from their younger counterparts. In response to LH stimulation, 0.01 - 1.0 mIU/ml, no appreciable difference of cyclic AMP formation could be detected between young and old Leydig cells. Maximal testosterone production occurred when 1 mIU/ml LH was used. Only when LH concentration was increased to 10 and 100 mIU/ml, did young Leydig cells produce significantly more cyclic AMP than old Leydig cells. After addition of 5X10(-7)M of pregnenolone or progesterone to the incubation medium, both young and old Leydig cells produced comparable amounts of testosterone. These results demonstrate no impairment of old rat Leydig cells to synthesize testosterone from pregnenolone and progesterone.
Assuntos
Envelhecimento , Células Intersticiais do Testículo/classificação , Testosterona/biossíntese , Animais , Centrifugação com Gradiente de Concentração , AMP Cíclico/fisiologia , Técnicas In Vitro , Células Intersticiais do Testículo/metabolismo , Hormônio Luteinizante/fisiologia , Masculino , Pregnenolona/metabolismo , Progesterona/metabolismo , RatosAssuntos
Agressão/efeitos dos fármacos , Glicemia/metabolismo , Eletrochoque , Escopolamina/farmacologia , Agressão/fisiologia , Comportamento Agonístico/efeitos dos fármacos , Comportamento Agonístico/fisiologia , Animais , Humanos , Masculino , Ratos , Receptores Adrenérgicos/fisiologia , Receptores Colinérgicos/efeitos dos fármacos , Receptores Colinérgicos/fisiologiaRESUMO
6-Mercaptopurine and mitomycin C were used in combination drug therapy to produce a prolongation of skin allograft survival.
