ntroduction
Of all cases of infertility in humans, ≈20% are due entirely to a male factor, with an additional 30–40% involving both male and female factors [1]. One of the goals when evaluating an infertile man is to identify reversible conditions that are responsible for infertility. Various conditions can cause infertility. Moreover, there are many controversies about environmental factors and occupational exposure to physical agents that might affect fertility [2]. Exposure to chemical toxins, and the effect of heat and cigarette smoking, have long been studied [3]. However, the effects of noise stress on different systems related to fertility have yet to be elucidated. Some have suggested that the teratogenic action of noise is primarily the result of decreased uroplacental blood flow, resulting in foetal hypoxia, and increased secretion of maternal catecholamines [4]. Geber [4] reported a significantly reduced litter size and a significant increase in the number of resorptions per litter amongst pregnant rats exposed to noise. Others [5] exposed mice to noise at 83–95 dB during gestation, and reported increased pre-implantation mortality, decreased litter size, and decreased embryo size and weight amongst the exposed offspring. There was no significant effect on the number of litter resorptions. However, these data are inconsistent amongst the various experimental conditions [6], [7] and [8]. These different results might be due to variability in acoustic stimuli, exposure regimens, test species, and other variables [9].
Antioxidants are the main defence against oxidative stress induced by free radicals. There are preventive antioxidants and scavenger antioxidants. Preventive antioxidants, e.g. metal chelates and metal-binding proteins, block the formation of new free radicals, whereas scavenger antioxidants remove the free radicals that have already formed [10].
Oxidative stress can be limited by using chain-breaking antioxidants such as vitamins E and C as drug supplements [11]. More specifically, these vitamins have been shown to have protective effects on the testis and on fertility [3] and [12].
In the present study we evaluated the effect of noise stress on male rat fertility and administered vitamins C and E to assess any change in the effects of noise.