Sin-Tak Chu

A Seminal Vesicle Autoantigen of Mouse Is Able to Suppress Sperm Capacitation-Related Events Stimulated by Serum Albumin

Abstract We studied the effect of a mouse seminal vesicle autoantigen (SVA) on BSA-stimulated functions of mouse sperm. Uncapacitated, capacitated, and acrosome-reacted stages of sperm were morphologically scored, and the cellular zinc content was examined cytologically in a modified Tyrode solution at 37°C for 80 min. More than 85% of control cells remained uncapacitated. Addition of 0.3% SVA to the cell incubation did not affect the cell status. Approximately 65% of cells were capacitated in the incubation medium containing 0.3% BSA. Only 30% of the cells became capacitated after incubation with 0.3% BSA and 0.3% SVA together. The decapacitation effect by 0.3% SVA could be subdued by more than 3% BSA in the cell incubation. Whereas BSA did, SVA did not cause removal of Zn2+ from sperm, but SVA could suppress the BSA effect. The tyrosine phosphorylated proteins in sperm were detected after incubation in a modified HEPES medium containing 0.3% BSA and/or 0.3% SVA at 37°C for 90 min. Whereas BSA enhanced greatly, SVA did not cause phosphorylation of proteins in the range of Mr 40 000–120 000. The BSA-stimulated protein tyrosine phosphorylation could be suppressed by SVA in the cell incubation.

Arsenic trioxide impairs spermatogenesis via reducing gene expression levels in testosterone synthesis pathway.

Arsenic trioxide (As2O3) has recently received a great deal of attention because of its capacity to cause complete remission of acute promyelocytic leukemia (APL). To evaluate possible toxicity on the male reproductive system during arsenic therapy, male mice were used as a model. Outbred mice (ICR/CD1 and S-W, 6 weeks old) were subcutaneously administered As2O3 continuously for 5 days, with a 2-day interval, for a period of 3 weeks. As2O3 doses were 0, 0.15, 0.3, 1.5, and 3.0 mg/kg of body weight, respectively. No mice died in any dosage group. Our data showed no significant changes in food consumption or in the weight of the body, liver, testis, or epididymis after As2O3 treatment. Using histological observation to identify the stages of seminiferous tubules, we showed that As2O3 treatment resulted in the inhibition of spermatogenesis. The frequency of mature seminiferous tubules (stages VII and VIII) was markedly decreased after As2O3 treatment. A significant decrease in sperm motility and viability also was found with computer-assisted sperm analysis (CASA) and a SYBR14/PI staining assay. Using an enzyme-linked immunosorbent assay (ELISA), we found a significant decrease in levels of plasma luteinizing hormone (LH) at a dose of 3.0 mg/kg body weight. No significant difference was found in plasma follicle-stimulating hormone (FSH) in all dosages. A significant decrease was found in plasma testosterone in all dosages, but no difference in intratesticular testosterone, with the exception of As2O3 at a dose of 3.0 mg/kg body weight. Moreover, there was a significant decrease in the levels of mRNA involved in testicular testosterone synthesis, cytochrome P450 side chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), and cytochrome P450 17-alpha hydroxylase/C17-20 lyase (Cyp17). The use of immunohistological observation showed no obvious difference in the testosterone level of Leydig cells of mice treated with As2O3 at doses of 0.3 and 1.5 mg/kg body weight. We concluded that As2O3 treatment caused damage to sperm mobility and viability. As2O3 treatment disturbed spermatogenesis via reducing gene expression of the key enzymes in testosterone synthesis.

Snake venom cardiotoxin induces G-actin polymerization

Snake venom cardiotoxin showed the ability to induce polymerization of G-actin from rabbit skeletal muscle in a low ionic strength buffer composed of 0.2 mM CaCl2/0.2 mM ATP/0.5 mM mercaptoethanol/2.0 mM Tris-HCl, pH 8.0. The activity was enhanced greatly when 0.4 mM MgCl2 was present in the buffer and could be inhibited if G-actin was preincubated with deoxyribonuclease I. Furthermore, the DNAase could also partially depolymerize actin polymer previously formed by the interaction of G-actin with the toxin.