ABSTRACT

Ethane-1,2-dimethanesulphonate (EDS) destroys Leydig cells in the testis of the adult rat and subsequently a new population of Leydig cells develops. It has been reported that EDS is not cytocidal to the new immature Leydig cell population. In the present study, the effect of increasing the time-interval between injections of EDS on cytotoxicity to Leydig cells was examined. At time-intervals of 4–10 weeks between injections the response was similar to that seen after a single injection of EDS to the adult rat. Four days after the second injection, EDS was found to reduce substantially serum testosterone concentrations and in-vitro binding of ¹²⁵I-labelled human chorionic gonadotrophin (hCG) to testicular LH receptors which can be correlated with Leydig cell destruction. However, when the interval was only 2 or 3 weeks there was no reduction in serum testosterone, and ¹²⁵I-labelled hCG binding was not so markedly reduced. During days 1–6 after a second injection of EDS, administered 3 weeks after the first, there were marked reductions in serum testosterone concentrations and in ¹²⁵I-labelled hCG binding to testis homogenates within 24 h. Recovery from the effects of EDS was rapid, and increased Leydig cell activity was seen from 2 to 6 days after injection. In contrast to the established changes in the adult rat, there was only a 50% reduction in the number of Leydig cells positive for 3β-hydroxysteroid dehydrogenase 2 days after the second injection of EDS, and after 6 days the number of cells had increased. These experiments show that the immature Leydig cell of the rat is sensitive to the cytotoxic effects of EDS but that the temporal changes in Leydig cell activity after EDS treatment are different in developing and mature Leydig cell populations. The data are consistent with the view that EDS is preferentially cytotoxic towards steroidogenically active Leydig cells, allowing the resident population of precursor cells to continue to respond to the prevailing homeostatic mechanisms.

Journal of Endocrinology (1989) 123, 197–203

ABSTRACT

A single injection of ethane-1,2-dimethanesulphonate (EDS; 100 mg/kg) selectively destroys Leydig cells in the testis of the adult rat; however, unconfirmed reports indicate that Leydig cells in the immature rat are not affected. In this study the effect of EDS was examined 2 days after treatment of rats aged 20, 25 or 35 days. There was a large reduction in the in-vitro binding of ¹²⁵I-labelled human chorionic gonadotrophin (hCG) to the homogenates of testes from EDS-treated immature rats. EDS reduced the testosterone content of the testes at all ages studied, but 2 days after injection had only significantly lowered the serum testosterone concentration of 25- or 35-day-old animals. Light microscopic examination of the testis of the 22-day-old rat, 2 days after treatment with EDS, indicated that there were still many cells staining for 3β-hydroxysteroid dehydrogenase. The interstitium also contained numerous atypical cells which did not stain for 3β-hydroxysteroid dehydrogenase. Electron microscopy of testes from the 22-day-old EDS-treated rat showed that Leydig cells were still present in the interstitium together with macrophages and fibroblast-like cells. Six days after EDS treatment of 20-day-old rats, but not 35-day-old rats, there was an increase in the binding of ¹²⁵I-labelled hCG to testis homogenate to 70% of control value. Testicular testosterone content 6 days after treatment of the 20-day-old rat had risen to 50% of the control testis value. These changes documented in the 20-day-old rat after EDS treatment can be explained by either a cytocidal effect with subsequent repopulation of new Leydig cells which has been described in the adult rat or by a reversible cytotoxic action which has not previously been documented.

J. Endocr. (1988) 119, 475–482

ABSTRACT

The Leydig cell cytotoxic ethylene dimethanesulphonate (EDS) was administered s.c. daily (50 mg/kg) to male rats aged 5–16 days. Apart from loss of weight and that the eyelids unfused earlier, no gross toxicity was observed during treatment. On day 17 testis weights, serum testosterone concentrations, testicular serum testosterone content and ¹²⁵I-labelled human chorionic gonadotrophin (hCG) binding to testicular homogenates were reduced. Serum LH and FSH concentrations were elevated.

The testes did not recover from EDS treatment and at 63 and 120 days were minute (<2% of control), and the prostate and seminal vesicles were small although not completely atrophied. In addition, body weights were substantially reduced. Serum and testicular testosterone and ¹²⁵I-labelled hCG binding to testicular homogenates were reduced but not absent. Serum LH and FSH concentrations were increased. Light microscopy of the adult testes showed that EDS treatment inhibited the development of the seminiferous tubules. Most of the tubules were devoid of germ cells and Sertoli cells were rare. Occasionally tubules also contained spermatogonia and spermatocytes but no signs of spermiogenesis. The testes were composed mainly of closely packed interstitial tissue with no lymphatic space. The interstitial cells resembled Leydig cells and stained for 3β-hydroxysteroid dehydrogenase. Histochemically identified Leydig cells were absent during treatment but reappeared when treatment was withdrawn. Testicular Leydig cell numbers were only 7% of control values in the 63-day-old EDS-treated rat. The effect on the testis of EDS treatment administered at a crucial time of testicular development may be explained by withdrawal of androgen; however, the systemic effects indicate non-specific toxicity so any explanation of these changes must be viewed with caution.

J. Endocr. (1988) 119, 467–474