Effect of Unilateral and Bilateral Castration and Cryptorchidism on Serum Gonadotrophins in the Rat

Abstract

The effects of unilateral and bilateral cryptorchidism and castration on serum concentrations of testosterone, FSH and LH in adult male rats were examined. The results provide no evidence for compensatory growth or development of the remaining scrotal testes up to 32 days after unilateral castration, although the scrotal testis of unilaterally cryptorchid rats showed enlargement when compared with those of control rats (P less than 0 - 05) at 32 days. Unilateral treatments had few significant effects on serum hormones, but testosterone was increased on day 4 (P less than 0 - 05) in unilaterally cryptorchid rats and on day 32 (P less than 0 - 05) in unilaterally castrated rats, compared with controls, and FSH levels were higher in unilaterally castrated rats on day 16 (P less than 0 - 05). Bilateral cryptorchidism caused an increase in serum FSH within 4 days (P less than 0 - 05) and in serum LH by 8 days (P less than 0-05) after surgery, with both hormones reaching levels double those found in control rats (P less than 0 - 01) by day 16, while testosterone levels were maintained at or above control values. Bilateral castration resulted in a marked decrease in testosterone levels (P less than 0 - 01) and a sharp increase in serum gonadotrophins. FSH had nearly doubled (P less than 0 - 01) and LH had increased fourfold (P less than 0 - 01) 4 days after castration, their levels reaching 773% (LH) and 287% (FSH) of control values by 32 days (P less than 0 - 01). The observations support the hypothesis of a separate, testosterone-independent feedback system of the testis on the hypophysis.

Androgen secretion and characteristics of testicular hCG binding in cryptorchid rats

“…. Increased numbers (Clegg, 1961) and size of Leydig cells (Damber, Bergh & Janson, 1978;Kerr et al, 1979) A transient decrease in serum testosterone has been noted after induced cryptorchidism (Gomes & Jain, 1976), but near-normal androgen concentrations were attained in the present study by 30 days after surgery. The responses of normal and cryptorchid rats to intravenous hCG were also equivalent in this study, although Kerr et al (1979) reported a diminished testo¬ sterone response to hCG administration in cryptorchid rats.…”

“…Induced cryptorchidism in rats results in testicular damage which is accompanied by increased circulating levels of LH and FSH (Swerdloff, Walsh, Jacobs & Odell, 1971; Rager, Zarzychi, Eichner & Gupta, 1975;Gomes & Jain, 1976; Kretser, Sharpe & Swanston, 1979;Kerr, Rich & de . Similar responses are obtained after heat treatment of the testes (Aafjes, Vreeburg & Schenck, 1978).…”

Androgen response of cryptorchid and intact rams to ovine LH

“…The ability of the cryptorchid testis to secrete testosterone is thought to be impaired relative to that of the normal scrotal testis because serum levels of testosterone in cryptorchid rats are normal or below normal when serum levels of LH are significantly increased (Swerdloff, Walsh, Jacobs & Odell, 1971; Rager, Zarzychi, Eichner & Gupta, 1975;Gomes & Jain, 1976; Sharpe, Kerr & de Kretser, 1978). Similar findings have been reported for cryptorchid rams (Schanbacher & Ford, 1977) and bulls (Schanbacher, 1978(Schanbacher, , 1979.…”

Effect of Unilateral Orchidectomy on Plasma FSH Concentration: Evidence for a Direct Neural Connection between Testes and CNS

“…Radiofrequency lesions placed unilaterally in the same side of the dorsal anterior hypothalamic area as the hemiorchidectomy partially blocked the selective FSH release following unilateral orchidectomy, while contralateral or sham le sions had no effect. These results suggest that the gonad has a volved in selective FSH release following hemiorchidectomy.Selective FSH release following unilateral castration has been reported in immature male and female and in adult male rats [7,15,19]. Since serum LH levels were usually un changed, or were not elevated as much as FSH, the decre ment of the negative feedback effect of gonadal steroids as a consequence of removal of one gonad, is not sufficient to explain this dissociation in LH and FSH release.…”

“…Since serum LH levels were usually un changed, or were not elevated as much as FSH, the decre ment of the negative feedback effect of gonadal steroids as a consequence of removal of one gonad, is not sufficient to explain this dissociation in LH and FSH release. In fact, se rum testosterone levels were reported to be increased [7], decreased [15] or unchanged [11] following hemiorchiedectomy.In the meantime, during the past few years it has been suggested that peripheral endocrine organs such as the tes tis, the ovary and the adrenal cortex have a direct neural connection with the central nervous system (CNS). These observations were first made by Halasz and Szenldgoihai [8] for the adrenal glands, and were later extended to the gon ads by Gerendai et al [4,5].…”