engleski

Semen quality and reproductive endocrine function with regard to blood cadmium in Croatian male subjects

Introduction. Although many experimental animal studies show that toxic and essential metals are interactive, very little information is available on their possible combined effect on human male reproductive function. Both cadmium (Cd) and lead (Pb) can adversely affect male reproductive system and can interfere with the metabolism of essential metals such as copper (Cu), zinc (Zn), and selenium (Se), which are required for optimum activity of important antioxidant enzymes, superoxide dismutase (Cu, Zn-SOD) and glutathione peroxidase (Se-GPx). This study considers the relationship between simultaneously measured parameters of semen quality and of reproductive endocrine function with respect to blood Cd (BCd) in men with no occupational exposure to metals, after adjusting for possible confounding variables such as age, smoking habits, alcohol consumption, and biomarkers of Pb, Cu, Zn, and Se by multiple regression. Methods. In 123 Croatian men 19-48 years of age, including those from couples suspected of infertility and voluntary semen donors for artificial insemination, the following parameters were measured: BCd, blood Pb (BPb), activity of delta-aminolevulinic acid dehydratase (ALAD), erythrocyte protoporphyrin (EP), serum Cu (SCu), serum Zn (SZn), serum Se (SSe), activity of glutathione peroxidase (GPx) in blood, parameters of semen quality (including sperm concentration, motility, and morphology by using CASA technique), indicators in seminal plasma (LDH-C4, fructose, Zn, acid phosphatase, and citric acid), and reproduction hormones in serum (FSH, LH, prolactin, testosterone, and estradiol). The interrelationship of all potential explanatory variables (BCd, BPb, ALAD, EP, SCu, SZn, SSe, GPx, age, smoking, and alcohol) with respect to each reproductive parameter was calculated by forward stepwise multiple regression. Results. BCd levels in 61 smokers were significantly (p<10^-16) higher than in 62 nonsmokers ; the median and range BCd values were 2.94 (0.49-11.93) micro-g/L and 0.59 (0.20-3.71) micro-g/L, respectively. A highly significant (p<0.0001) positive correlation was found between smoking habits (cigarettes/day) and BCd. Smoking habits also significantly correlated with an increase in SCu (p<0.05) and alcohol consumption (p<0.05), and with a decrease in ALAD (p<0.01), SSe (p<0.01) and GPx (p<0.01), whereas BCd significantly correlated with a decrease in SSe (p<0.05) and GPx (p<0.05). After adjusting for all of the potential confounding variables (including smoking habits) by multiple regression, BCd was significantly associated with an increase in serum estradiol (p<0.04) and FSH (p<0.05), and marginally with an increase in serum testosterone (p<0.06) and percentage of abnormal sperm with thin shape (p<0.09). On the other hand, smoking habits were significantly associated only with a decrease in serum prolactin (p<0.006), after adjusting for all of the potential confounding variables (including BCd). Several parameters of decreased semen quality were significantly associated with biomarkers of Pb (within the BPb range of 25-149 micro-g/L in 123 subjects) and/or with a decrease in SCu, SZn, and SSe. Conclusions. The study results indicate the need of simultaneous determination of several relevant metals (essential and toxic), and controlling for other potential confounders (including age, smoking, and alcohol) in order to enable reliable assessment of the influence of a particular metal on reproductive function in men. Within the Cd exposure range in this study (BCd of 0.20-11.93 micro-g/L), a significant Cd-related effect was found only on male reproductive endocrine function, i.e., an increase in serum estradiol and FSH.

blood cadmium; smoking; human male reproductive function; sperm parameters; serum hormones

nije evidentirano