Changes in intratesticular testosterone, cytoplasmic androgen receptors and ABP content of the ram testis after a single endogenous pulse of LH

The effects of an endogenous LH pulse on the testicular concentration of testosterone, cytoplasmic androgen receptor content and androgen binding protein (ABP) content was studied in rams. Blood was collected from 36 rams for at least 14 h and their testes then removed. Animals were then grouped according to the interval from their last LH pulse and the time of slaughter. The concentration of testosterone in the testis was highest during the first h following the LH pulse and returned to its baseline within 5 h. There was a 60% reduction in the testicular content of cytoplasmic androgen receptors at 3 h after the LH pulse, followed by slow replenishment. The testicular content of ABP was highest at 4 h after the LH pulse. It is in the testis concluded that the pulsatility of LH and testosterone induces a pulsatile translocation of cytoplasmic androgen receptors.