Extended intervention time and evaluation of sperm suppression by dienogest plus testosterone undecanoate in male rat

Complete sperm suppression in rats with dienogest plus testosterone undecanoate is facilitated through apoptosis in testicular cells

Complete suppression of the production of sperm in rats with dienogest (DNG, 40 mg/kg body weight [bw]) plus testosterone undecanoate (TU, 25 mg/kg bw), every 45 days, was found to be associated with a significant increase in germ cell apoptosis. Caspase 3 activity and expression in testis were simultaneously upregulated. Rise in the activities of caspase 8 and 9 was associated with overexpression of upstream marker proteins from extrinsic (Fas [Fatty acid synthase], FasL [Fatty acid synthase ligand], and caspase 8) and intrinsic (Bax [Bcl2-associated-x protein], Bcl2 [B-cell lymphoma 2], and caspase 9) pathways of apoptosis. Apart from the germ cells, interstitial cell apoptosis was also observed along with a decline in the number of functional Leydig cells. It is therefore concluded that complete suppression of the production of sperm with DNG + TU is facilitated mainly through the removal of precursor germ cells through apoptosis. The process is largely modulated by upregulation of upstream and downstream marker proteins from intrinsic as well as extrinsic pathway of metazoan apoptosis.

Clomiphene citrate potentiates the adverse effects of estrogen on rat testis and down-regulates the expression of steroidogenic enzyme genes

OBJECTIVE

To investigate the antiestrogenic effect of clomiphene citrate (CC) in male rats estrogenized with estradiol-3-benzoate (EB).

DESIGN

Prospective experimental study.

SETTING

Laboratory.

ANIMALS

Adult male albino rats (Holtzman strain).

INTERVENTION(S)

CC was given alone or in combination with EB.

MAIN OUTCOME MEASURE(S)

Testicular function and steroidogenic enzyme gene expression were evaluated in control versus treated groups.

RESULT(S)

EB after 30 days of treatment induced a rise in TUNEL-positive germ cells adversely affecting spermatogenesis with complete absence of elongated spermatids or sperms. CC alone had only a moderate effect. In contrast, CC+EB synergistically inflicted more adverse effects as apoptotic germ cells per tubule rose further. Significant down-regulation in expression of testicular steroidogenic enzyme genes StAR, p450scc, 3β-HSD, and p450c17 was observed. In the EB-alone group, aromatase gene expression in the testis was up-regulated but reversed in brain and liver tissues. CC alone had little modulatory effect on aromatase expression. On the other hand, CC+EB countered the EB-induced rise of aromatase expression in the testis.

CONCLUSION(S)

The above findings indicate that CC in the presence of estrogen synergistically potentiates more adverse effects in testis, inhibiting expression of upstream steroidogenic enzyme genes and leading to disruption of steroidogenesis.

Complete sperm suppression induced by dienogest plus testosterone undecanoate is associated with down-regulation in the expression of upstream steroidogenic enzyme genes in rat testis

BACKGROUND

We had shown that dienogest (DNG) + testosterone undecanoate (TU) induced complete sperm suppression in rats when administered together every 45 days. On the other hand, individual drugs given alone in a similar fashion failed to achieve the same result.

STUDY DESIGN

The present study was therefore undertaken to determine the reason for such a differential sperm suppression and to correlate it with the expression of steroidogenic enzyme genes in the rat testis.

RESULTS

Administration of DNG (40 mg/kg body weight [bw]) + TU (25 mg/kg bw) every 45 days for a duration of 90 days induced spermatogenic arrest, leading to a significant reduction in testicular weight and number of precursor germ cells. Flow cytometric analysis further confirmed the same result, leading to a significant shift in the distribution of haploid cells. Measurement of testosterone (serum and intratesticular) was significantly low. Complete sperm suppression coincided with significant down-regulation in the expression of upstream steroidogenic enzyme genes represented serially by cytochrome P450 side-chain cleavage, P450 17α-hydroxylase, 3β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein (StAR) in the testis. On the other hand, rats administered with either DNG or TU alone demonstrated incomplete sperm suppression in which the expression of all the above genes remained characteristically nonuniform.

CONCLUSION

Taken together, the above findings corroborate the fact that regulation of expression of three of the upstream steroidogenic enzymes genes and the StAR protein in rat testis is crucial in leading to complete sperm suppression as observed with DNG+TU treatment.