Studies on Testis, Sperm Characteristics and Teratogenic aspects after Vas occlusion by a co-polymer of styrene maleic anhydride - RISUG and its reversal in rats

The non-hormonal contraceptive, named RISUG (an acronym for Reversible Inhibition of Sperm under Guidance) has expected to provide a valuable addition to the current options of male contraception. The present study was conducted to determine the reproductive functional success, safety of vas occlusion by RISUG, and its reversal by dimethylsulphoxide (DMSO), followed by multigenerational (F1-F3) teratogenicity studies in rats. RISUG a copolymer of styrene maleic anhydride (SMA) dissolved in 0.01 ml DMSO was injected into the lumen of the vas deferens bilaterally at the dose levels of 0.25, 0.50 and 1.00 mg/vas/rat. Control rats injected with 0.01 ml DMSO only. Results showed that the vas-occlusion by RISUG-injection caused sperm abnormality in ejaculated sperms and inhibited pregnancy in female rats. But, it did not affect testicular spermatogenesis, daily sperm production rate (DSP) and epididymal sperm counts (ESC) after a post-injection period of 70 days. Vas occlusion reversal of 60 days restored sperm morphology and fertility profile without causing any significant changes in the body and reproductive organ weights, DSP, ESC, and embryological/teratological aspects in F1-F3 progenies. Results indicate that the intra-vasal injection of RISUG, inhibits pregnancy in female rats may be due to affecting sperm characteristics but not testicular function.