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Effect of smoking on semen quality of infertile men in Shandong, China

Jin-Ping ZHANG, Qing-Yu MENG1, Qiang WANG, Lei-Jia ZHANG1, Yi-Long MAO1, Zhuo-Xiang SUN1

Department of Histology/Embryology, Jining Medical College, Shandong 272113, China
1Affiliated Hospital, Jining Medical College, Shandong 272129, China

Asian J Androl  2000 Jun; 2: 143-146
Keywords: tobacco use disorder; smoking; semen; male infertility
Abstract
Aim: To study the effect of smoking on the semen quality in infertile men in Shandong Province, China. Methods: Adult non-drinker males attending the infertility clinic, including 110 non-smokers and 191 smokers, were recruited for the study. Sixty-one fertile, non-smoker and non-drinker males, who had one or more children, served as the controls. The smokers were divided into subgroups according to the amount and duration of smoking. Semen parameters (semen volume and sperm density, viability, motility, and morphology) were examined and seminal plasma contents of Zn , Cu and superoxide dismutase (SOD) determined. Results: The semen volume and acidity, and the sperm density, viability and forward progression, as well as the seminal plasma contents of Zn, Cu and SOD were much lower in the medium, heavy and long-term smokers than in the non-smokers (P<0.01). The sperm density, viability and forward progression, and the seminal plasma Zn, Cu and SOD levels were negatively correlated with the amount  and duration of cigarette smoking (P<0.01). Conclusion: Medium, heavy and long-term smoking adversely affected the semen quality in a population of men visiting the infertility clinic in Shandong, China.

1 Introduction

As a large number of men smokes worldwide and the fact that cigarette smoke contains known mutagens and carcinogens, there has been much concern that smoking may have unfavorable effects on male reproduction. Experimental studies have indicated that in male rats exposed to smoking, serum levels of nicotine and cotinine were increased which adversely affected spermatogenesis and sperm fertilizing potential[1,2]. However, in regard to the clinical studies on the relationship between smoking and male reproduction, the literature results have been non-conclusive. Osser et al[3] showed that cigarette smoking did not adversely affect sperm concentration, motility or morphology in a population of Swedish infertile men. However, Merino et al[4] and Chia et al[5] reported that in infertile populations of Mexico and Singapore, smokers had significantly lower sperm density, motility, viability, and percentage of normal sperm morphology as compared with the non-smokers. Vine et al[6] believed that the association between male smoking and semen quality was stronger in healthy men (e.g. volunteers and sperm donors) than in the infertile population. The aim of this study was to examine the relationship between cigarette smoking and semen quality and seminal plasma concentrations of zinc, copper and SOD in a population of Chinese infertile men.

2 Materials and methods

2.1 Subjects and grouping

Adult non-drinker males attending the infertile clinic undergoing infertility investigation, aged 25-43 years, including 110 non-smokers and 191 smokers, were recruited for the study. They did not have child after having been married for more than 2 years. The subjects were otherwise healthy without any reproductive tract infection and varicocele, and did not have a history of being in contact with any hazardous material. They had a normal sexual life and had never used any contraceptive. Their spouses were apparently fertile women as indicated by various laboratory and physical examinations. Sixty-one fertile, non-smoker and non-drinker males, 25-32 years of age, who had one or more children, served as the controls.

A detailed smoking history was obtained by a direct interview. The smokers were divided into the following subgroups according to the amount and duration of smoking:
Amount of smoking:
      Light:    1-10 cigarettes/day (n=58)
      Medium: 11-20 cigarettes/day (n=68)
      Heavy:   >20 cigarettes/day (n=65)
                            Total=191
Duration of smoking:
      Short-term:   1-10 years (n=148)
      Long-term:  11-20 years (n=43)
                         Total=191

Their age differences between various groups were insignificant (P>0.05).

2.2 Semen collection and analysis

Semen samples were collected by masturbation after 5-7 days of abstinence. Semen examination (semen volume and sperm density, viability, motility, and morphology) was performed as soon as the samples were liquefied according to the routine method described by the World Health Organization[7]. Then seminal plasma was obtained through centrifugation. The seminal plasma Zn and Cu contents were determined by means of potentiometic stripping analysis (WVCV-I, Beijing Instrument Factory) and SOD by radioimmunoassay[8] (FJ- 2011 -counter, Xi' an No. 262 Factory); the kits were provided by the Beijing Northern Biological Technology Institute.

2.3 Data analysis

Data were presented as means, if applicable, and the significance of differences were analyzed by t or 2 test, wherever applicable. Statistical analysis was performed by means of SPSS 7.5 for WINDOWS software packet. The significance of differences was set at P<0.05.

3 Results

3.1 Semen quality in the infertile and fertile groups

As can be seen from Table 1, the semen volume and acidity, and the sperm density, viability and forward progression were much lower in the smokers than in the non-smokers, as well as in case of seminal plasma contents of  Zn, Cu and SOD (P<0.01). The semen parameters were much lower in the non-smokers of infertile men than in the fertility men (P<0.01).

Table 1. Semen quality of infertile and fertile groups. cP<0.01 vs the corresponding values of the Infertile Non-smokers and Fertile Controls. fP<0.01 vs the corresponding values of the Fertile Controls.

 

Infertile Smokers 
(n=191)

Infertile Non-smokers 
(n=110)

Fertile controls
(n=61)

Semen volume (mL)

2.420.07c

2.690.07f

2.930.09

Semen pH

7.900.01c

7.800.03f

7.760.03

Sperm density (106/mL)

43.151.94c

52.052.47f

90.543.48

Sperm viability (%)

43.132.37c

50.222.09f

79.841.34

Sperm forward progression (grade)

2.480.05c

2.670.07f

3.130.04

Seminal plasma Zn (ng/mL)

79.712.44c

90.782.38f

114.161.32

Seminal plasma Cu (ng/mL)

0.940.01c

0.970.01f

1.060.01

Seminal plasma SOD (nmol/L)

380.1912.14c

442.2414.52f

664.9314.94

3.2 Semen quality in different subgroups

Table 2 shows that the semen quality in the light, medium and short-term smokers is not significantly different from that of the non-smokers, while most semen parameters in the heavy and long-term smokers are significantly lower than their corresponding values in the non-smokers (P<0.05 or 0.01).

Table 2. Semen quality of different subgroups. bP<0.05, cP<0.01 vs the corresponding values of the non-smokers.

 

Amount (cigarettes/day)

Duration (years)

Non-smokers

1-10

10-20

>20

1-10

11-20

n

58

68

65

148

43

110

Semen volume 
(mL)

2.560.09

2.490.12

2.120.11c

2.480.07b

2.420.10b

2.690.07

Semen pH

7.880.03

7.900.03b

7.920.02c

7.870.02

7.890.03b

7.800.03

Sperm density
(106/mL)

47.102.17

43.151.94c

42.192.99c

49.012.08

38.563.54c

52.052.47

Sperm viability 
(%)

46.412.63

43.782.23c

40.122.37c

49.971.63

38.933.60c

50.222.09

Sperm forward 
progression (grade)

2.590.05

2.510.03b

2.380.04c

2.600.07

2.400.05c

2.670.07

Seminal plasma Zn (ng/mL)

84.332.29

80.563.63b

69.712.61c

85.702.10

63.654.13c

90.782.38

Seminal plasma Cu (ng/mL)

0.960.01

0.950.01b

0.940.01c

0.970.01

0.940.01b

0.980.01

Seminal plasma SOD (nmol/L)

440.6421.42

360.6318.39c

319.9018.41c

440.9411.61

279.5319.27c

442.2414.52

3.3 Correlation between semen quality and amount and duration of smoking

It can be seen from Table 3 that there was a negative correlation between the amount and  duration of smoking and the sperm density, viability and forward progression, and the seminal plasma contents of Zn, Cu and SOD (P<0.01), while the correlation between the amount and duration of smoking and the semen volume and pH was insignificant (P>0.05).

Table 3. Correlation between the semen quality and the amount or duration of smoking (n=191). cP<0.05 vs non-smokers.

 

Amount of smoking (r)

Duration of smoking (r)

Semen volume (mL)

-0.113

-0.132

Semen  pH

0.037

0.110

Sperm density (106/mL)

-0.282c

-0.308c

Sperm viability (%)

-0.256c

-0.271c

Sperm forward progression (grade)

-0.344c

-0.357c

Seminal plasma Zn

-0.303c

-0.337c

Seminal plasma Cu

-0.203c

-0.219c

Seminal plasma SOD (nmol/L)

-0.437c

-0.482c

4 Discussion

The results of the present study support the view that smoking dose affect the semen quality of infertile men, particularly in heavy and long-term smokers. We indicated that smoking significantly reduced the ejaculate volume; whether it was the consequence of the effect of smoking on the accessory gland is worthy of further study. The observation that the semen Zn levels were significantly lowered, was in accordance with the results reported by Oldereid et al[9]. Reduction in Zn secretion may diminish the content of chromatin Zn, and thereby the stability of the sperm chromatin; this may in turn contribute to reproductive failure or have consequences in fetal development[9]. Both Zn and Cu are linked with the structure/activity center of SOD, which is closely related to sperm motility. Decreases in the Zn and Cu levels will naturally lead to the lowering of the SOD activity. In addition, smoking increases the production of free radicals that will impair the synthesis and/or augment the consumption of SOD[10]. The observations in the present study lead to the conclusion that medium, heavy and long-term smoking adversely affects the semen quality of infertile men.

References

[1] Yamamoto Y, Isoyama E, Sofikitis N, Miyagawa I. Effects of  smoking on testicular function and fertilizing potential in rats. Urol Res 1998; 26: 45-8.
[2] Reddy A, Sood A, Rust PF, Busby JE, Varn E, Mathur RS, et al. The effect of nicotine on in vitro sperm motion characteristics. J Assist Reprod Genet 1995; 12: 217-23.
[3] Osser S, Beckman-Ramirez A, Liedbolm P. Semen quality of smoking and non-smoking men in infertile couples in a Swedish population. Acta Obstet Gynecol Scand 1992; 71: 215-8.
[4] Merino G, Lira SC, Martinez-Chequer JC. Effects of cigarette smoking on semen characteristics of a population in Mexico. Arch Androl 1998; 41: 11-5.
[5] Chia SE, Ong CN, Tsakok FM. Effects of cigarette smoking on human semen quality, a Singapore study. Arch Androl 1994; 33: 163-8.
[6] Vine MF. Smoking and male reproduction: a review. Int J Androl 1996; 19: 323-37.
[7] World Health Organization. Laboratory manual for the examination of human semen and spermcervical mucus interaction. 3rded. Cambridge: Cambridge University Press; 1992.
[8] Sun ZX, Zhang JP, Jin GX.Quantitative analysis of superoxide dismutase in seminal plasma by  RIA. Acta Jining Med College, 1998; 21: 31-2.
[9] Oldereid NB, Thomassen Y, Purvis K. Seminal plasma lead, cadmium and zinc in relation to tobacco consumption. Int J Androl 1994; 17: 24-8.
[10] Zhang JP, Zhang LJ, Meng QY, Sun ZX, Chen Y. The effects of smoking on the level of  seminal plasma superoxide dismutase and its relationship to male infertility. J Labour Med  1999; 16: 93-4.
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Correspondence to Dr Jin-Ping ZHANG, Department of Histology/Embryology, Jining Medical College, Shandong 272 103, China.
Tel: +86-537-220 3543   Fax +86-537-225 2776
E-mail: Lunrongzl@ji-public.sd.cninfo.net   Lunrongzl@public.sd.cninfo.net
Received 2000-01-08   Accepted 2000-05-24