Hormonal contraception for human males:prospects

Development of an ideal hormonal contraceptive for man has been the goal of several research workers during thepast few decades. Suppression of pituitary gonadotropic hormones, which in turn would inhibit spermatogenesis whilemaintaining normal libido and potentia has been the approach for a contraceptive agent. Intramuscularly administeredand orally active testosterone or testosterone in combination with progesterone have been shown to cause inhibition ofspermatogenesis resulting in azoospermia in normal men. Similarly testosterone has been used in combination with go-nadotropin releasing hormone antagonists and agonists to inhibit pituitary gonadotropic hormone release. Immunologicalapproach to neutralize the circulating levels of follicle stimulating hormone has also been shown to cause inhibition ofspermatogenesis. The available literature shows that testosterone causes reversible azoospermia without any significantside effects in Asian population effectively and appears to be a promising chemical for control of fertility in man.

Novel functional association of rat testicular membrane-associated cytosolic glutathione S transferases and cyclooxygenase in vitro

Aim:To analyze the role of cytosolic glutathione S-transferases (cGSTs) and membrane-associated cytosolic GSTs (macGSTs) in prostaglandin biosynthesis and to evaluate the possible interaction between glutathione S-transferases (GSTs) and cyclooxygenase (COX) in vitro.Methods:SDS-PAGE analysis was undertaken for characterization of GSTs,thin layer chromatography (TLC) to monitor the effect of GSTs on prostaglandin biosynthesis from arachi- donic acid (AA) and spectrophotometric assays were done for measuring activity levels of COX and GSTs.Results: SDS-PAGE analysis indicates that macGSTs have molecular weights in the range of 25-28 kDa.In a coupled assay involving GSTs,arachidonic acid and cyclooxygenase-1,rat testicular macGSTs produced prostaglandin E2 and F2~, while the cGSTs caused the generation of prostaglandin D2,E2 and F_(2α).In vitro interaction studies on GSTs and COX at the protein level have shown dose-dependent inhibition of COX activity by macGSTs and vice versa.This effect, however,is not seen with cGSTs.The inhibitory effect of COX on macGST activity was relieved with increasing concentrations of reduced glutathione (GSH) but not with 1-chloro 2,4-dinitrobenzene (CDNB).The inhibition of COX by macGSTs,on the other hand,was potentiated by glutathione.Conclusion:We isolated and purified macGSTs and cGSTs from rat testis and analyzed their involvement in prostaglandin biosynthesis.These studies reveal a revers- ible functional interaction between macGSTs and COX in vitro,with possible interactions between them at the GSH binding site of macGSTs.

Purification and characterization of rat testicular glutathione S-transferases:role in the synthesis of eicosanoids

Aim: Purification of glutathione S-transferases (GSTs) from rat testis; separation and identificationunits and their role in eicosanoid biosynthesis. Methods: Purification of mt testicular GSTs by affit?phy, employing S-hexylglutathione-linked epoxy-activated Sepharose 6B column and separation of indiby reverse phase-high pressure liquid chromatography (RP-HPLC). Characterization of affinity purified,um dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Westem blot analysis. The roGSTs in eicosanoid biosynthesis was determined by incubating GSTs with 5, 6-Leukotriene A_4Me (prostaglandin H_2 (PGH_2) and analyzing the products formed on HPLC/TLC. Results: The present stumajority of rat testicular GSTs are of Y_b size (60%) with molecular weight of 27 kDa. The most preunits, however, are GST Y_(n2) (27% ), followed by GST Y_c (24% ) and GST Y_(nl) (20%). These testiculavery high Leukotriene C_4 (LTC_4) synthase activity with 5, 6-Leukotriene A4Me (LTA_4Me) as theprostaglandin D (PGD) synthase activity with prostaglandin H_2 (PGH_2) as the substrate. Conclusion:testicular GSTs are Y_b sized and are involved in the synthesis of eicosanoids like LTC_4 and PGD_2.(Asian J Androl 2000 Dec; 2: 277-282)