Estradiol Binding Capacity in the Cryptorchid Rat Testis

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Abstract
Mature male Sprague-Dawley rats were made surgically cryptorchid at 47-50 days old. Animals were sacrified as controls and at 7, 14 and 21 days post-surgery. The testes were removed and utilized to determine the effects of cryptorchidism on tissue weight loss, histological changes and cytoplasmic estradiol binding capacity. Testis weight decreased from a mean .+-. SE of 1.1 .+-. 0.09 to 0.41 .+-. 0.02 g during the 21 day period, a 66% decrease in weight. Light microscopy revealed that the process of spermatogenesis was inhibited, the germinal epithelium had degenerated and the tubules had become smaller in diameter. The interstitial tissue volume pregressively increased through day 21 post-surgery. The cytoplasmic estradiol binding capacity, expressed as fmol [3H]-estradiol/mg cytosol protein increased markedly from a control of 16 .+-. 1.1 to 36 .+-. 8.0 at day 7 after surgery; this represented a 126% increase in binding capacity in 1 wk. Binding capacity was equivalent to 54 .+-. 7.4 and 58 .+-. 10.5 fmol/mg on days 14 and 21 post-surgery, respectively. Testicular content of cytoplasmic estrogen receptors increased from 349 to a maximum of 575 fmol/testis at day 7. Receptor content then declined slowly to a value of 481 at day 21. Testicular content of receptor is presumed to reflect an alteration in the Leydig cells induced by cryptorchidism.