Gonadotropin binding and stimulation of cyclic adenosine 3': 5' monophosphate and testosterone production in isolated Leydig cells

摘要: Gonadotropin binding and stimulation of cyclic adenosine 3':5'-monophosphate (cyclic AMP) formation testosterone synthesis were studied in collagenase-dispersed interstitial cells from the adult rat testis. Binding 125I-human chorionic gonadotropin (hCG) by isolated Leydig was high affinity (Ka = 10(10) M-1) low capacity, equivalent to approximately 6000 sites/cell. The data consistent with presence a single order receptors, no interaction between sites. Stimulation increasing concentrations hCG completely dissociated changes AMP formation, maximum activation steroidogenesis induced which had effect upon production. Kinetic analysis gonadotropin-induced responses dispersed also showed marked dissociation nucleotide formation. Low caused production not accompanied rise at any time after addition gonadotropin. Higher elevations progressively earlier intervals, but did alter 20 30 min lag period required for induction synthesis. These observations indicated that occupancy receptors occurs over much wider range concentration than steroidogenesis.