Altered concentrations of gonadotrophin, prolactin and GnRH receptors, and endogenous steroids in the abdominal testes of adult unilaterally cryptorchid rats

Abstract

Testicular descent was prevented unilaterally in newborn rats by cutting the gubernaculum testis. At 100 days of age, the number of Leydig and Sertoli cells per testis, the concentration of receptors for LH, FSH, prolactin and GnRH, and endogenous concentrations of progesterone and testosterone were determined. The weight of the abdominal testes was reduced by 80%, but in spite of this they contained as many Sertoli (32.8 ± 1.3 x 106, mean ± s.e.m., n=6) and Leydig (28.2 ± 1.7 x 106) cells as did scrotal testes (32.1 ± 2.5 x 106 and 24.3 ± 1.2 x 106 respectively). The numbers of receptors for LH (3.2 ± 0.2 and 1.0 ± 0.2 pmol/testis, mean ± s.e.m., n=11), FSH (358 ± 11.0 and 96.3 ± 12.6 fmol/testis) and prolactin (535 ± 32.7 and 92.4 ± 13.2 fmol/testis) were reduced (P<0.001) in abdominal testes, but the number of GnRH receptors was unaffected (8.9 ± 1.4 and 12.1 ± 1.8 fmol/testis, n=6). Testicular testosterone concentration (30.9 ± 4.4 vs 15.4 ± 3.2 ng/g, n=11, P<0.001), but not that of progesterone (0.87 ± 0.10 vs 1.01 ± 0.21 ng/g), was decreased in abdominal testes. The decreased receptor and androgen values reflect functional disturbances in the abdominal testes. The changed local milieu within abdominal testes may reduce hormone receptor concentrations which are then involved in the observed Leydig cell dysfunction.