Investigating the effects of nicotine on the male reproductive system

[摘要] ENGLISH ABSTRACT: Much has been documented about the detrimental effects of adverse lifestyle factorexposure on the body. Exposure to factors, such as cigarette smoke, have proved to notonly be a burden on global health and economy, but have also led to growing concernsabout effects on systemic functions such as reproduction. The aim of the present study wasto determine the effects of in utero and in vitro nicotine exposure on spermatozoal functionand the antioxidant enzyme activity and lipid peroxidation (LPO) status of the malereproductive system. A better understanding of this process is necessary to combat therespective burdens of smoking and male infertility and for the prospective development oftreatment strategies.Two experimental models were employed: Wistar rats were exposed to nicotine in uterowhile human and rat spermatozoa were exposed to nicotine in vitro. In utero studies wereachieved by selecting healthy pregnant rats and treating them with 1 mg/kg-bodyweight/daynicotine or 1 ml/kg-bodyweight/day 0.85% physiologic saline throughout gestation andlactation. Male rat pups were selected and sacrificed at each of the following age groups(n=6): 42 days, 84 days and 168 days old. The pups were only exposed to thetreatment/saline via placental uptake or lactation. Biochemical analyses of the tissuecomprised of measurement of LPO and antioxidant enzyme activity. Results indicated asignificant association of maternal nicotine exposure to decreased levels of primaryantioxidant enzymes in rat testes. Of particular note was the observation that the treatmentgroup, of which each of the respective antioxidant enzyme levels were significantly less thanthe control group, was the oldest (d168) rat group.In vitro studies were achieved by collecting sperm samples from healthy human donors(n=12), healthy rats (n=6) and obese rats (n=6). Samples were washed and exposed todifferent concentrations of high levels of nicotine (Control, 0.1mM, 1mM, 5mM, 10mM) invitro. Semen parameters such as motility, viability and acrosome reaction were monitored atdifferent time points (30min, 60min, 120min, 180min). Results revealed increasing in vitro nicotine concentrations were associated with decreased viability and acrosomal status ofhuman spermatozoa and decreased progressive motility and viability of rat spermatozoa.Obesity was also associated with decreases in progressive motility and viability of ratspermatozoa.These results indicate that the acute in vitro exposure of spermatozoa to high levels ofnicotine could adversely affect semen quality and may be an additive factor to theimpediment of male fertility. In utero results reveal maternal nicotine exposure adverselyaffects male fertility in later life and seems to elicit more detrimental effects on thereproductive system than that of direct nicotine exposure to spermatozoa. Obesity alsoinhibits parameters of male fertility and these effects are exacerbated by nicotine exposure.The authors believe these adverse effects on the reproductive system to be related to anincreased activation of leukocytes, excess production in reactive oxygen species (ROS) andconsequent onset of oxidative stress (OS). Nevertheless this study agrees with other studiesthat nicotine exposure may be an additive factor to the impediment of male fertility.

[发布机构] Stellenbosch University