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Effect of noise stress on male rat fertility, and the protective effect of vitamins C and E on its potential effect

Effect of noise stress on male rat fertility, and the protective effect of vitamins C and E on... Arab Journal of Urology (2013) 11, 101–105 Arab Journal of Urology (Official Journal of the Arab Association of Urology) www.sciencedirect.com UROSCIENCE ORIGINAL ARTICLE Effect of noise stress on male rat fertility, and the protective effect of vitamins C and E on its potential effect a, b c Ali Fathollahi , Majid Jasemi , Ghasem Saki Emam Khomeini Hospital, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Urology Ward, Golestan Hospital, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Physiology Research Center, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Received 10 November 2012, Received in revised form 22 November 2012, Accepted 5 December 2012 Available online 24 January 2013 KEYWORDS Abstract Objective: To evaluate the effect of noise on the fertility of male rats, and to assess the effect of vitamins C and E on its potential effect. Noise; Materials and methods: Forty adult male rats were randomly divided into five Male infertility; equal groups. Group 1 (control) was not exposed to noise. Groups 2–5 were exposed Vitamins; to noise of 90–130 dB and 300–350 Hz from 19.00 to 07.00 h every day for 50 days; FSH; group 2 received vitamin C and group 3 received vitamin E. Group 4 received vita- LH mins C and E concomitantly and group 5 received no vitamins. After 50 days, the serum levels of follicle-stimulating hormone (FSH), luteinising hormone (LH) and ABBREVIATION testosterone were measured. Each rat was then left for 1 week with three female rats, LH, luteinising for mating. Pregnant females were killed humanely after 19 days of pregnancy and hormone evaluated for the presence and number of viable, dead and absorbed fetuses. Results: The mean serum FSH level was statistically significantly different between the control and groups 2 (P < 0.05) and 5 (P < 0.001). The mean serum LH level differed significantly between the control and groups 2 (P = 0.05), 3 (P < 0.05) and 5 (P < 0.001). The mean serum testosterone level was significantly different between the control and group 5 (P < 0.001). Serum FSH, LH and testos- terone levels in group 5 were significantly different from all the others (P < 0.001). Corresponding author. Tel.: +98 9121957991. E-mail addresses: patronager@yahoo.com (A. Fathollahi), mjasemizergani@yahoo.com (M. Jasemi). Peer review under responsibility of Arab Association of Urology. Production and hosting by Elsevier 2090-598X ª 2013 Arab Association of Urology. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aju.2012.12.002 102 Fathollahi et al. The pregnancy rates in females mated with groups 1 and 5 were statistically different (P < 0.05). Comparing groups 1–4, there was no difference in the occurrence of abnormal pregnancy (P > 0.05), but group 5 values were significantly different from the others (P < 0.001). Conclusion: These data strongly suggest that noise stress has a significant effect on the fertility of male rats. ª 2013 Arab Association of Urology. Production and hosting by Elsevier B.V. All rights reserved. Introduction Materials and methods Of all cases of infertility in humans, 20% are due en- This experimental study was conducted in the Physiol- tirely to a male factor, with an additional 30–40% ogy Research Centre of Ahwaz Joundi Shapour Univer- involving both male and female factors [1]. One of the sity of Medical Sciences from September 2010 to goals when evaluating an infertile man is to identify December 2010. Male rats (200–250 g) of the Wistar reversible conditions that are responsible for infertility. strain (Rattus norvegicus) were used, acclimated to Various conditions can cause infertility. Moreover, there 22±1 C and maintained under conditions of 12-h of are many controversies about environmental factors and light and dark, with free access to tap water and com- occupational exposure to physical agents that might mercial rat food. All procedures were approved by inter- affect fertility [2]. Exposure to chemical toxins, and the national guidelines and by the Institute Research Ethics effect of heat and cigarette smoking, have long been and Animal Care and Use Committee of the authors’ studied [3]. However, the effects of noise stress on differ- institution. Every effort was made to minimise the num- ent systems related to fertility have yet to be elucidated. ber of animals used and their suffering. Some have suggested that the teratogenic action of noise Experimental design is primarily the result of decreased uroplacental blood flow, resulting in foetal hypoxia, and increased secretion of maternal catecholamines [4]. Geber [4] reported a sig- The rats were randomly divided into five groups of eight nificantly reduced litter size and a significant increase in each, and thus the fertility of each group was considered the number of resorptions per litter amongst pregnant comparable to the other groups at the baseline. Group 1 rats exposed to noise. Others [5] exposed mice to noise (controls) was not exposed to noise. The rats in groups at 83–95 dB during gestation, and reported increased 2–5 were exposed to noise at 90–130 dB and 300– pre-implantation mortality, decreased litter size, and de- 350 Hz from 19.00 to 07.00 h each day for 50 days. creased embryo size and weight amongst the exposed For this exposure the groups were transported to a room offspring. There was no significant effect on the number of 3 · 4 · 3 m, lined by wood and acoustic segments of litter resorptions. However, these data are inconsis- (‘anti-loud’ voice), within which ‘white noise’ was pro- tent amongst the various experimental conditions [6– duced [13], and a timer was arranged so that after 1 h 8]. These different results might be due to variability of exposure the noise was turned off for 15–60 min be- in acoustic stimuli, exposure regimens, test species, and fore continuing the exposure. This intermittent exposure other variables [9]. was to prevent the rats from becoming adapted to the Antioxidants are the main defence against oxidative noise. The intensity and frequency of the noise was stress induced by free radicals. There are preventive anti- changed automatically within the range of minimum oxidants and scavenger antioxidants. Preventive antiox- and maximum every 2–3 min, and this also contributed idants, e.g. metal chelates and metal-binding proteins, to preventing adaptation to the noise [14]. The amount block the formation of new free radicals, whereas scav- and intensity of noise were measured using a noise level enger antioxidants remove the free radicals that have al- meter and the rate and intensity were controlled in this ready formed [10]. way. Group 2 received vitamin C (125 mg/kg/day) and Oxidative stress can be limited by using chain-break- group 3 received vitamin E (75 mg/kg/day) [3]. Group ing antioxidants such as vitamins E and C as drug sup- 4 received vitamins C and E concomitantly. Group 5 re- plements [11]. More specifically, these vitamins have ceived no vitamins. been shown to have protective effects on the testis and After 50 days (7 weeks is the time needed for a com- on fertility [3,12]. plete spermatogenesis cycle in male rats) a blood sample In the present study we evaluated the effect of was drawn with a syringe from each rat’s tail, between noise stress on male rat fertility and administered 08.00 and 11.00 h, and analysed for serum FSH, LH vitamins C and E to assess any change in the effects and testosterone levels using an ELISA technique. As of noise. all rats had been assigned randomly to the groups at Effect of noise stress on male rat fertility 103 the beginning of study, serum levels in the control group not significantly different (P > 0.05), but the pregnancy were referred to as the normal range and levels in the rate in groups 1 and 5 were statistically different other groups were compared with those. Each rat was (P < 0.05). The presence and frequency of dead and/ then left with three female rats, for mating, for 1 week. or absorbed fetuses in impregnated rats are also given Every morning, females with positive vaginal plaques in Table 1. Comparing groups 1–4 with each other, there (pregnant females) were identified and separated. Preg- was no significant difference in the occurrence of abnor- nant females were killed humanely on the 19th day of mal pregnancy outcome (P > 0.05). By contrast, the pregnancy (the duration of normal pregnancy in the values in group 5 differed significantly from the others rat is 21 days) by cervical dislocation under anaesthesia (P < 0.001). (an acceptable method of euthanasia of rats used for sci- entific purposes). Their uteri were then evaluated for the Discussion presence and number of viable, dead and absorbed fetuses. While previous studies had only assessed single hor- Data are reported as the mean (SD) and percentage, mones, in the present study the complete pituitary–testis where appropriate. The statistical significance of differ- hormonal axis of the male rats was assessed after expo- ences between the control and experimental groups sure to noise. We also evaluated the possibility of a pro- was determined by anova for the hormonal studies. tective effect of antioxidants on both hormones and The pregnancy rate and number of dead/absorbed fertility. fetuses were compared amongst groups using the Noise decreased the serum testosterone level in the chi-square test. Differences between the means were present rats but supplementing the rats with either vita- considered to be significant at P < 0.05. min C or E, or a combination of both, resulted in testos- terone returning to the normal range. This result is Results similar to that reported by Chandralekha [15], in which male albino rats were exposed to 100 dB of noise for 1 h Hormones and 3 h in an acute group, and a daily 1-h exposure for 60 days and 90 days in a chronic group. In that study The mean serum values of FSH, LH and testosterone there was also a significant reduction in serum testoster- are shown in Table 1; the difference in mean serum one levels. Armario and Castellanos [16] also showed FSH was statistically significant between the controls that the testosterone response in mice was impaired by and groups 2 (P < 0.05) and 5 (P < 0.001). There was water restriction, heat exposure and immobilisation. a large difference in serum FSH level between group 5 However, interestingly, an acute noise stress of 80 dB in- and all other groups (P < 0.001). For LH the difference creased the testosterone level. In the present study noise was significant for the control and groups 2 (P = 0.05), increased the serum FSH levels. By adding vitamin E or 3(P < 0.05) and 5 (P < 0.001). Again there was a con- vitamins C and E to the regimen, rats exposed to noise spicuous difference between group 5 and all other were protected from the effect on FSH level. However, groups (P < 0.001). The mean serum testosterone level vitamin C alone did not compensate for the negative ef- was statistically different between the control and group fect of noise stress. 5(P < 0.001), and again the group 5 values were very Serum LH level was also decreased by noise to an ex- significantly different from all the others (P < 0.001). tent that vitamin C or E could not reverse. However, the Fertility combination of vitamins C and E had a protective effect on LH levels against noise stress. Table 1 also gives the pregnancy rates for the five In contrast with previous studies that mainly focused groups. The pregnancy rates amongst the groups were on the effect of noise on female rat fertility, the present Table 1 Serum FSH, LH and testosterone levels, and pregnancy data, in the five groups. Variable Group FSH 2.24 3.23 2.60 2.36 9.04 LH 2.11 2.85 3.45 2.26 7.51 Testosterone 8.89 7.89 8.36 8.49 3.49 Pregnancy rate, n/N (%) 23/24 (96) 20/24 (83) 18/24 (75) 20/24 (83) 16/24 (67) Frequency of dead and/or absorbed fetuses 2/23 (9) 2/20 (10) 2/18 (11) 2/20 (10) 10/16 (63) in impregnated mates, n/N (%) P < 0.001, vs. group 1. P < 0.05, vs. group 1. 104 Fathollahi et al. study assessed the fecundity of the male rat. In a study it had no protective effect on the level of LH, but the by Kimmel et al. [6] pregnant mice were exposed to FSH level was improved. Likewise, a combination of 100 dB of noise on days 3–6, 7–10 or 11–14 of gestation. vitamins C and E normalised the pregnancy rate and There were significantly increased resorption rates and the rate of foetal abortion and death. Importantly, the fewer live fetuses per litter in each of the treated groups. combination normalised the FSH and LH levels. How- We also had similar results, as there were more pregnant ever, according to Agarwal et al. [11], many studies rats containing any dead and/or absorbed fetuses than failed to examine the effect of antioxidants on a specific in those that had mated with noise-exposed male rats. group of infertile patients with high oxidative stress. Moreover, in females mating with noise-exposed males Last, we did not conduct a histological evaluation, but who had received vitamins, either alone or in combina- considering the large changes in the hormonal milieu, it tion, this effect was corrected. could be assumed that noise would cause structural Nawrot et al. [7] exposed mated female mice to either changes leading to abnormalities in FSH, LH and testos- semi-continuous 126-dB low-frequency noise, intermit- terone levels. Our data are in contrast with those in the tent 110-dB mid-frequency noise, or semi-continuous, study by Gunther [21], who examined the effect of noise very high-frequency (18–20 kHz) 113-dB noise on days on the fertility of 21 male guinea pigs. Noise at 110 dB 1–6 or 6–15 of gestation. There was significantly greater lasted 3–5 h daily over 22–31 days. Histological exami- embryo and foetal mortality, decreased foetal weight, nation of the testicular tissue showed no disorders of and a decreased pregnancy rate amongst the exposed spermatogenesis. Nevertheless, Gunther noted that the mice. The negative effect of noise was also reported by negative result was attributed to failings in the test Cosa and Cosa [8], who reported abnormalities in repro- arrangement. Exposure to noise only lasted for at most duction, and a significant decrease in pregnancy rate and 31 days, but the duration of spermatogenesis in guinea lethal effect in mice embryos exposed to high frequencies pigs is 40 days. Moreover, the exposure was only 5 h/ of noise. Again, in the present study, on assessing the day, yet the recovery took 4–5 times longer every day. pregnancy rate, overall there was no significant differ- Consequently, the daily short-term depression of the ence, except when comparing rats in the control group neuroendocrine system affected gonadotrophin secretion with noise-exposed rats, when the difference was signif- in a similar pattern to the daily biorhythmic variation. icant; this is in line with previous results. Therefore, the expected inhibition of fertility by the neu- In a follow-up study, Nawrot et al. [17] exposed ma- roendocrine route could not be confirmed. ted female mice to high-frequency 110-dB noise on days In conclusion, the present data strongly suggest a 6–15 of gestation. There was a lower pregnancy rate and negative role for noise stress on the fertility of the male mean foetal weight, and increased foetal mortality, rats. However, these results should be further assessed in amongst the exposed mice. As in the earlier study [7], humans (e.g. factory workers, those living near airports, there was no significant effect on the frequency of foetal etc.). It is also recommended that the effect of noise on malformation or litter resorption amongst the mice ex- testicular size, weight and histology be evaluated in posed to noise. By contrast, we found noise stress to pre- other studies. dict a higher occurrence of abnormal pregnancy, defined Conflict of interest as foetal resorption and/or death. However, vitamin supplementation could potentially prevent these effects. This might be interpreted as a This project was financially supported by the research more teratogenic or detrimental effect of noise stress deputy of Ahwaz Jundi Shapour University of Medical on male fertility rather than on the female reproductive Sciences (AJUMS). state. Vitamin C neutralises hydroxyl, superoxide and Source of Funding hydrogen peroxide radicals, and prevents sperm aggluti- nation [11]. Lewis et al. [18] found reduced levels of vita- None. min C in the seminal plasma of infertile men. Akmal et al. [19] showed that vitamin C supplementation in References infertile men might improve the sperm count, sperm motility and sperm morphology. As in previous studies, [1] Mosher WD, Pratt WF. Fecundity and infertility in the United we showed that vitamin C had a protective effect on the States: incidence and trends [editorial comment]. Fertil Steril fertility rate and foetal abortion and death; however, its 1991;56:192–3. effect on FSH and LH was not significant. [2] McCormack R. Transmission link to cancer feared by EPRI. Energy Daily 1986;14(230):1–2. In a randomised cross-over study, vitamin E im- [3] Erat M, Ciftci M, Gumustekin K, Gul M. Effects of nicotine and proved sperm function, as assessed by the zonal binding vitamin E on glutathione reductase activity in some rat tissues test [20]. In the present study, vitamin E could prevent in vivo and in vitro. Eur J Pharmacol 2007;554:92–7. the negative effect of noise on the pregnancy rate and [4] Geber W. Developmental effects of chronic maternal audiovisual the rate of foetal death and abortion. Like vitamin C, stress on the rat fetus. J Embryol Exp Morph 1966;16:1–16. Effect of noise stress on male rat fertility 105 [5] Zakem HB, Alliston CW. The effects of noise levels and elevated [14] Sarkaki A, Karami K. Impaired learning due to noise stress ambient temperatures upon selected reproductive traits in female during pregnancy in rats offspring. J Res Med Sci 2004;9: Swiss–Webster mice. Lab Anim Sci 1974;24:469–75. 26–30. [6] Kimmel CA, Cook RO, Staples RE. Teratogenic potential of [15] Chandralekha G. The effect of noise induced stress on the male noise in mice and rats. Ibxicol Appl Pharmacol 1976;36:239–45. reproductive endocrine glands of albino rats. PhD Thesis, M.G.R [7] Nawrot PS, Cook RO, Staples RE. Embryotoxicity of various Medical University and Research Chennai; 2002. noise stimuli in the mouse. Teratology 1980;22:279–89. [16] Armario A, Castellanos JM. Effects of noise stress on testosterone [8] Cosa M, Cosa G. Annoyance, disturbance and damage caused by secretion in mice. IRCS Med Sci 1984;12:208–10. noise and vibration. Ann Lg 1989;1:133–56. [17] Nawrot PS, Cook RO, Hamm CW. Embryotoxicity of broadband [9] Meyer RE, Aldrich TE, Easterly CE. Effects of noise and high-frequency noise in the CD-1 mouse. J Toxicol Environ electromagnetic fields on reproductive outcomes. Environ Health Health 1981;8:151–7. Prospect 1989;81:193–200. [18] Lewis SE, Sterling ES, Young IS, Thompson W. Comparison of [10] Sanocka D, Kurpisz M. Reactive oxygen species and sperm cells. individual antioxidants of sperm and seminal plasma in fertile and Reprod Biol Endocrinol 2004;2:12. infertile men. Fertil Steril 1997;67:142–7. [11] Agarwal A, Nallella KP, Allamaneni SS, Said TM. Role of [19] Akmal M, Qadri JQ, Al-Waili NS, Thangal S, Haq A, Saloom antioxidants in treatment of male infertility: an overview of the KY. Improvement in human semen quality after oral supplemen- literature. Reprod Biomed Online 2004;8:616–27. tation of vitamin C. J Med Food Fall 2006;9:440–2. [12] Rajeswary S, Mathew N, Akbarsha MA, Kalyanasundram M, [20] Kessopoulou E, Powers HJ, Sharma KK, Pearson MJ, Russell Kumaran B. Protective effect of vitamin E against carbendazim- ID, Cooke ID, et al. A double-blind randomized placebo cross- induced testicular toxicity histopathological evidences and over controlled trial using the antioxidant vitamin E to treat reduced residue levels in testis and serum. Arch Toxicol reactive oxygen species associated male infertility. Fertil Steril 2007;81:813–21. 1995;64:825–31. [13] Helmstetter FJ, Bellgowan PS. Hypoalgesia in response to sensi- [21] Gunther E. Animal experimental studies on the effects of noise tization during acute noise stress. Behav Neurosci 1994;108:77–85. stress on male infertility. Andrologia 1976;8:95–100. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arab Journal of Urology Taylor & Francis

Effect of noise stress on male rat fertility, and the protective effect of vitamins C and E on its potential effect

Fathollahi, Ali; Jasemi, Majid; Saki, Ghasem
Arab Journal of Urology , Volume 11 (1): 5 – Mar 1, 2013
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© 2013 Arab Association of Urology
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2090-598X
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10.1016/j.aju.2012.12.002
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Abstract

Arab Journal of Urology (2013) 11, 101–105 Arab Journal of Urology (Official Journal of the Arab Association of Urology) www.sciencedirect.com UROSCIENCE ORIGINAL ARTICLE Effect of noise stress on male rat fertility, and the protective effect of vitamins C and E on its potential effect a, b c Ali Fathollahi , Majid Jasemi , Ghasem Saki Emam Khomeini Hospital, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Urology Ward, Golestan Hospital, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Physiology Research Center, Ahwaz Joundi Shapour University of Medical Sciences, Ahwaz, Iran Received 10 November 2012, Received in revised form 22 November 2012, Accepted 5 December 2012 Available online 24 January 2013 KEYWORDS Abstract Objective: To evaluate the effect of noise on the fertility of male rats, and to assess the effect of vitamins C and E on its potential effect. Noise; Materials and methods: Forty adult male rats were randomly divided into five Male infertility; equal groups. Group 1 (control) was not exposed to noise. Groups 2–5 were exposed Vitamins; to noise of 90–130 dB and 300–350 Hz from 19.00 to 07.00 h every day for 50 days; FSH; group 2 received vitamin C and group 3 received vitamin E. Group 4 received vita- LH mins C and E concomitantly and group 5 received no vitamins. After 50 days, the serum levels of follicle-stimulating hormone (FSH), luteinising hormone (LH) and ABBREVIATION testosterone were measured. Each rat was then left for 1 week with three female rats, LH, luteinising for mating. Pregnant females were killed humanely after 19 days of pregnancy and hormone evaluated for the presence and number of viable, dead and absorbed fetuses. Results: The mean serum FSH level was statistically significantly different between the control and groups 2 (P < 0.05) and 5 (P < 0.001). The mean serum LH level differed significantly between the control and groups 2 (P = 0.05), 3 (P < 0.05) and 5 (P < 0.001). The mean serum testosterone level was significantly different between the control and group 5 (P < 0.001). Serum FSH, LH and testos- terone levels in group 5 were significantly different from all the others (P < 0.001). Corresponding author. Tel.: +98 9121957991. E-mail addresses: patronager@yahoo.com (A. Fathollahi), mjasemizergani@yahoo.com (M. Jasemi). Peer review under responsibility of Arab Association of Urology. Production and hosting by Elsevier 2090-598X ª 2013 Arab Association of Urology. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aju.2012.12.002 102 Fathollahi et al. The pregnancy rates in females mated with groups 1 and 5 were statistically different (P < 0.05). Comparing groups 1–4, there was no difference in the occurrence of abnormal pregnancy (P > 0.05), but group 5 values were significantly different from the others (P < 0.001). Conclusion: These data strongly suggest that noise stress has a significant effect on the fertility of male rats. ª 2013 Arab Association of Urology. Production and hosting by Elsevier B.V. All rights reserved. Introduction Materials and methods Of all cases of infertility in humans, 20% are due en- This experimental study was conducted in the Physiol- tirely to a male factor, with an additional 30–40% ogy Research Centre of Ahwaz Joundi Shapour Univer- involving both male and female factors [1]. One of the sity of Medical Sciences from September 2010 to goals when evaluating an infertile man is to identify December 2010. Male rats (200–250 g) of the Wistar reversible conditions that are responsible for infertility. strain (Rattus norvegicus) were used, acclimated to Various conditions can cause infertility. Moreover, there 22±1 C and maintained under conditions of 12-h of are many controversies about environmental factors and light and dark, with free access to tap water and com- occupational exposure to physical agents that might mercial rat food. All procedures were approved by inter- affect fertility [2]. Exposure to chemical toxins, and the national guidelines and by the Institute Research Ethics effect of heat and cigarette smoking, have long been and Animal Care and Use Committee of the authors’ studied [3]. However, the effects of noise stress on differ- institution. Every effort was made to minimise the num- ent systems related to fertility have yet to be elucidated. ber of animals used and their suffering. Some have suggested that the teratogenic action of noise Experimental design is primarily the result of decreased uroplacental blood flow, resulting in foetal hypoxia, and increased secretion of maternal catecholamines [4]. Geber [4] reported a sig- The rats were randomly divided into five groups of eight nificantly reduced litter size and a significant increase in each, and thus the fertility of each group was considered the number of resorptions per litter amongst pregnant comparable to the other groups at the baseline. Group 1 rats exposed to noise. Others [5] exposed mice to noise (controls) was not exposed to noise. The rats in groups at 83–95 dB during gestation, and reported increased 2–5 were exposed to noise at 90–130 dB and 300– pre-implantation mortality, decreased litter size, and de- 350 Hz from 19.00 to 07.00 h each day for 50 days. creased embryo size and weight amongst the exposed For this exposure the groups were transported to a room offspring. There was no significant effect on the number of 3 · 4 · 3 m, lined by wood and acoustic segments of litter resorptions. However, these data are inconsis- (‘anti-loud’ voice), within which ‘white noise’ was pro- tent amongst the various experimental conditions [6– duced [13], and a timer was arranged so that after 1 h 8]. These different results might be due to variability of exposure the noise was turned off for 15–60 min be- in acoustic stimuli, exposure regimens, test species, and fore continuing the exposure. This intermittent exposure other variables [9]. was to prevent the rats from becoming adapted to the Antioxidants are the main defence against oxidative noise. The intensity and frequency of the noise was stress induced by free radicals. There are preventive anti- changed automatically within the range of minimum oxidants and scavenger antioxidants. Preventive antiox- and maximum every 2–3 min, and this also contributed idants, e.g. metal chelates and metal-binding proteins, to preventing adaptation to the noise [14]. The amount block the formation of new free radicals, whereas scav- and intensity of noise were measured using a noise level enger antioxidants remove the free radicals that have al- meter and the rate and intensity were controlled in this ready formed [10]. way. Group 2 received vitamin C (125 mg/kg/day) and Oxidative stress can be limited by using chain-break- group 3 received vitamin E (75 mg/kg/day) [3]. Group ing antioxidants such as vitamins E and C as drug sup- 4 received vitamins C and E concomitantly. Group 5 re- plements [11]. More specifically, these vitamins have ceived no vitamins. been shown to have protective effects on the testis and After 50 days (7 weeks is the time needed for a com- on fertility [3,12]. plete spermatogenesis cycle in male rats) a blood sample In the present study we evaluated the effect of was drawn with a syringe from each rat’s tail, between noise stress on male rat fertility and administered 08.00 and 11.00 h, and analysed for serum FSH, LH vitamins C and E to assess any change in the effects and testosterone levels using an ELISA technique. As of noise. all rats had been assigned randomly to the groups at Effect of noise stress on male rat fertility 103 the beginning of study, serum levels in the control group not significantly different (P > 0.05), but the pregnancy were referred to as the normal range and levels in the rate in groups 1 and 5 were statistically different other groups were compared with those. Each rat was (P < 0.05). The presence and frequency of dead and/ then left with three female rats, for mating, for 1 week. or absorbed fetuses in impregnated rats are also given Every morning, females with positive vaginal plaques in Table 1. Comparing groups 1–4 with each other, there (pregnant females) were identified and separated. Preg- was no significant difference in the occurrence of abnor- nant females were killed humanely on the 19th day of mal pregnancy outcome (P > 0.05). By contrast, the pregnancy (the duration of normal pregnancy in the values in group 5 differed significantly from the others rat is 21 days) by cervical dislocation under anaesthesia (P < 0.001). (an acceptable method of euthanasia of rats used for sci- entific purposes). Their uteri were then evaluated for the Discussion presence and number of viable, dead and absorbed fetuses. While previous studies had only assessed single hor- Data are reported as the mean (SD) and percentage, mones, in the present study the complete pituitary–testis where appropriate. The statistical significance of differ- hormonal axis of the male rats was assessed after expo- ences between the control and experimental groups sure to noise. We also evaluated the possibility of a pro- was determined by anova for the hormonal studies. tective effect of antioxidants on both hormones and The pregnancy rate and number of dead/absorbed fertility. fetuses were compared amongst groups using the Noise decreased the serum testosterone level in the chi-square test. Differences between the means were present rats but supplementing the rats with either vita- considered to be significant at P < 0.05. min C or E, or a combination of both, resulted in testos- terone returning to the normal range. This result is Results similar to that reported by Chandralekha [15], in which male albino rats were exposed to 100 dB of noise for 1 h Hormones and 3 h in an acute group, and a daily 1-h exposure for 60 days and 90 days in a chronic group. In that study The mean serum values of FSH, LH and testosterone there was also a significant reduction in serum testoster- are shown in Table 1; the difference in mean serum one levels. Armario and Castellanos [16] also showed FSH was statistically significant between the controls that the testosterone response in mice was impaired by and groups 2 (P < 0.05) and 5 (P < 0.001). There was water restriction, heat exposure and immobilisation. a large difference in serum FSH level between group 5 However, interestingly, an acute noise stress of 80 dB in- and all other groups (P < 0.001). For LH the difference creased the testosterone level. In the present study noise was significant for the control and groups 2 (P = 0.05), increased the serum FSH levels. By adding vitamin E or 3(P < 0.05) and 5 (P < 0.001). Again there was a con- vitamins C and E to the regimen, rats exposed to noise spicuous difference between group 5 and all other were protected from the effect on FSH level. However, groups (P < 0.001). The mean serum testosterone level vitamin C alone did not compensate for the negative ef- was statistically different between the control and group fect of noise stress. 5(P < 0.001), and again the group 5 values were very Serum LH level was also decreased by noise to an ex- significantly different from all the others (P < 0.001). tent that vitamin C or E could not reverse. However, the Fertility combination of vitamins C and E had a protective effect on LH levels against noise stress. Table 1 also gives the pregnancy rates for the five In contrast with previous studies that mainly focused groups. The pregnancy rates amongst the groups were on the effect of noise on female rat fertility, the present Table 1 Serum FSH, LH and testosterone levels, and pregnancy data, in the five groups. Variable Group FSH 2.24 3.23 2.60 2.36 9.04 LH 2.11 2.85 3.45 2.26 7.51 Testosterone 8.89 7.89 8.36 8.49 3.49 Pregnancy rate, n/N (%) 23/24 (96) 20/24 (83) 18/24 (75) 20/24 (83) 16/24 (67) Frequency of dead and/or absorbed fetuses 2/23 (9) 2/20 (10) 2/18 (11) 2/20 (10) 10/16 (63) in impregnated mates, n/N (%) P < 0.001, vs. group 1. P < 0.05, vs. group 1. 104 Fathollahi et al. study assessed the fecundity of the male rat. In a study it had no protective effect on the level of LH, but the by Kimmel et al. [6] pregnant mice were exposed to FSH level was improved. Likewise, a combination of 100 dB of noise on days 3–6, 7–10 or 11–14 of gestation. vitamins C and E normalised the pregnancy rate and There were significantly increased resorption rates and the rate of foetal abortion and death. Importantly, the fewer live fetuses per litter in each of the treated groups. combination normalised the FSH and LH levels. How- We also had similar results, as there were more pregnant ever, according to Agarwal et al. [11], many studies rats containing any dead and/or absorbed fetuses than failed to examine the effect of antioxidants on a specific in those that had mated with noise-exposed male rats. group of infertile patients with high oxidative stress. Moreover, in females mating with noise-exposed males Last, we did not conduct a histological evaluation, but who had received vitamins, either alone or in combina- considering the large changes in the hormonal milieu, it tion, this effect was corrected. could be assumed that noise would cause structural Nawrot et al. [7] exposed mated female mice to either changes leading to abnormalities in FSH, LH and testos- semi-continuous 126-dB low-frequency noise, intermit- terone levels. Our data are in contrast with those in the tent 110-dB mid-frequency noise, or semi-continuous, study by Gunther [21], who examined the effect of noise very high-frequency (18–20 kHz) 113-dB noise on days on the fertility of 21 male guinea pigs. Noise at 110 dB 1–6 or 6–15 of gestation. There was significantly greater lasted 3–5 h daily over 22–31 days. Histological exami- embryo and foetal mortality, decreased foetal weight, nation of the testicular tissue showed no disorders of and a decreased pregnancy rate amongst the exposed spermatogenesis. Nevertheless, Gunther noted that the mice. The negative effect of noise was also reported by negative result was attributed to failings in the test Cosa and Cosa [8], who reported abnormalities in repro- arrangement. Exposure to noise only lasted for at most duction, and a significant decrease in pregnancy rate and 31 days, but the duration of spermatogenesis in guinea lethal effect in mice embryos exposed to high frequencies pigs is 40 days. Moreover, the exposure was only 5 h/ of noise. Again, in the present study, on assessing the day, yet the recovery took 4–5 times longer every day. pregnancy rate, overall there was no significant differ- Consequently, the daily short-term depression of the ence, except when comparing rats in the control group neuroendocrine system affected gonadotrophin secretion with noise-exposed rats, when the difference was signif- in a similar pattern to the daily biorhythmic variation. icant; this is in line with previous results. Therefore, the expected inhibition of fertility by the neu- In a follow-up study, Nawrot et al. [17] exposed ma- roendocrine route could not be confirmed. ted female mice to high-frequency 110-dB noise on days In conclusion, the present data strongly suggest a 6–15 of gestation. There was a lower pregnancy rate and negative role for noise stress on the fertility of the male mean foetal weight, and increased foetal mortality, rats. However, these results should be further assessed in amongst the exposed mice. As in the earlier study [7], humans (e.g. factory workers, those living near airports, there was no significant effect on the frequency of foetal etc.). It is also recommended that the effect of noise on malformation or litter resorption amongst the mice ex- testicular size, weight and histology be evaluated in posed to noise. By contrast, we found noise stress to pre- other studies. dict a higher occurrence of abnormal pregnancy, defined Conflict of interest as foetal resorption and/or death. However, vitamin supplementation could potentially prevent these effects. This might be interpreted as a This project was financially supported by the research more teratogenic or detrimental effect of noise stress deputy of Ahwaz Jundi Shapour University of Medical on male fertility rather than on the female reproductive Sciences (AJUMS). state. 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Journal

Arab Journal of Urology – Taylor & Francis

Published: Mar 1, 2013

Keywords: Noise; Male infertility; Vitamins; FSH; LH; LH, luteinising hormone

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