Abstract
This study evaluated the relationship between LH, cyclic AMP, cyclic GMP, and testosterone
using in vitro incubation of decapsulated rat testes and sampling incubation medium.
With added LH (1.0, 5.0, 100, and 500 mIU/ml) there were statistically significant
increases in cyclic AMP at 5 mIU/ml or more LH, and progressively greater titers of
this nucleotide were produced as LH was increased. For cyclic GMP all levels of added
LH caused significant increments in titers of nucleotide; however, peak cyclic GMP
concentrations occurred with 5 mIU/ml of LH.
The addition of 10-3 and 10-4 M 8-bromo-cyclic AMP caused significant increases in testosterone production, while
no changes in production of this androgen were found with 10-3 , 10-4 or 10-5 M 8-bromo-cyclic GMP.
Neither cyclic AMP nor cyclic GMP titers were altered by the addition of 1 to 50 µg/ml
of testosterone to medium bathing the rat testes.
The dose response curves of cyclic AMP and cyclic GMP to LH are different. Progressive
increments in added LH cause parallel increases of cyclic AMP and a biphasic change
of cyclic GMP. 8-bromo-cyclic GMP does not cause testosterone generation, suggesting
that cyclic GMP does not result in androgen synthesis. However, cyclic GMP may be
involved in other Leydig cell functions.
Key words
In Vitro Incubation of Testes - LH - Cyclic AMP - Cyclic GMP - Testosterone
