Verapamil stimulates Ca(++)-uptake and Ca(++)-ATPase in plasma membrane vesicles of guinea pig spermatozoa

Verapamil-induced ion channel and miRNA expression changes in rat testis and/or spermatozoa may be associated with male infertility

The effect of verapamil, a calcium channel blocker, on male fertility in terms of ion channel and miRNA gene expressions in testis/spermatozoa was evaluated in this study. Rats were divided into sham and verapamil groups (n = 15). Verapamil was performed orally for 60 days. Sperm parameters and levels of serum follicle-stimulating hormone (FSH), luteinising hormone (LH) and testosterone (T) hormones were analysed. Alterations of microRNA (miRNA) and ion channel gene expressions in spermatozoa/testis were detected by using qPCR. Verapamil treatment reduced sperm concentration. Increased serum FSH, LH and T hormone levels were detected. Upregulated transient receptor potential cation channel subfamily V member 5 (TRPV5) and potassium voltage-gated channel subfamily J member 11 (KCNJ11) gene expressions and downregulated miR-let-7b, miR-10a, miR-320 and miR-760 expressions were found in testis of verapamil group. However, upregulated anoctamin 1 (ANO1), ATP-binding cassette subfamily C member 9 (ABCC9), miR-27a and miR-130a expressions and downregulated miR-20a, miR-92a, miR-132, miR-320 and miR-760 expressions were detected in spermatozoa. In addition, these altered gene expressions were found to be associated with decreased sperm concentration. The results indicate that the changes in testicular and/or spermatozoal ion channels and miRNA expressions due to verapamil treatment may affect male fertility.

Antifertility effect of calcium channel blockers on male rats: association with oxidative stress

PURPOSE

Calcium ions are vital in many biologic processes including a variety of enzymatic reactions, activation of excitable cells, coupling of electrical activation to cellular secretion, haemostasis, bone metabolism and sperm functions. Calcium channel blockers (CCB) appear to have a reversible anti-fertility effect on male rats which does not occur through inhibition of the pituitary-gonadal axis. While the effects of CCB on male reproductive function have been investigated, less information is available regarding other reproductive indices and the underlying mechanism in the pathogenesis of male reproductive dysfunction. Therefore, the involvement of oxidative mechanisms in the adverse manifestation induced by CCB on male reproductive functions is investigated in this study.

METHODS

For this purpose, lipid peroxidation; enzymatic antioxidants such as superoxide dismutase, catalase and glutathione reduced; epididymal sperm count, motility; histopathology of the testes, epididymis, seminal vesicle, prostate glands; and reproductive performance were determined.

RESULTS

CCB administration in rats causes significant oxidative stress in the male reproductive milieu in term of increase in malondialdehyde (MDA) level and a concomitant decrease in catalase, superoxide dismutase and reduced glutathione enzyme activities in the testes. In addition, CCB treatment significantly decreased the sperm count, sperm motility, fertility index, implantation count, and litter size in this study.

CONCLUSION

There is substantial evidence that CCB induces significant oxidative stress in the testes, which appears to be responsible for the adverse effects of decreased sperm count and motility ultimately leading to reduced fertility in rats.

Antireproductive effect of calcium channel blockers on male rats

Introduction

Drugs have been shown to adversely affect male fertility and recently anti-hypertensive drugs were added to the list. The anti-fertility effects of nifedipine and similar calcium channel blockers are well-illustrated in in vitro experiments but not in vivo.

Purpose

The present study was designed to experimentally elucidate the sub-chronic effect of nifedipine, verapamil and diltiazem on sperm functions and reproductive hormone levels in vivo.

Methods

Male rats (150-200 g) were divided into four groups of ten rats each. Group 1 (control) received distilled water; Group 2 received nifedipine 0.57 mg/kg BW; Group 3 were given verapamil 3.40 mg/kg BW and Group 4 were given diltiazem 2.57 mg/kg BW. Each drug-treated group had its own recovery group from which treatment was discontinued for 30 days before the animals were sacrificed. Blood samples were collected for hormonal assay of FSH, LH and testosterone. Semen evaluation was done and the testes, seminal vesicle, epididymis and prostate were removed, and weighed immediately.

Results

Nifedipine, verapamil and diltiazem significantly decreased (P < 0.05) sperm count and motility in drug treated groups. The weight of the epididymis was significantly reduced (P < 0.05) in the drug treated rats. Semen parameters and other associated changes were restored after 30 days of drug withdrawal.

Conclusion

Calcium channel blockers appear to have a reversible anti-fertility effect on male rats which does not occur through inhibition of the pituitary-gonadal axis.

Calcium transport and Ca(++)-ATPase activity in spermatozoal plasma membrane vesicles of nifedipine-administered guinea pigs

Spermatozoal plasma membrane vesicles isolated from distal portion of the epididymis and vas deferens were found to contain Ca(++)-activated ATPase and calcium transport activities. Nifedipine was administered at two different doses (1.0 and 2.5 mg/kg b.w./day) and the effect was observed for both short- (4 week) and long-term (12 week) period. The cellular ionic calcium content and Ca(++)-ATPase activity were observed to be enhanced in the drug-treated animals. The recovery studies carried out after 4 and 6 weeks of withdrawal of the drug treatment exhibited partial to complete restoration of observed changes. The stimulatory rather than inhibitory effect of Nifedipine, a specific calcium channel blocker, on calcium uptake may suggest that voltage-sensitive calcium channels may be lacking in guinea pig spermatozoa. The stimulatory effect of the drug is speculated to be either by inhibition of Na(+)-Ca++ antiporter or G-protein activated agonistic effect or probably due to altered physicochemical properties of the drug-treated sperm plasma membranes.