Effects of formaldehyde exposure on sperm quality, serum sex hormone content and Leydig cell structure and function in adult male rats

Objective To explore the effects on sperm quality, serum sex hormones as well as Leydig cell structure and function in male rats after acute exposure to different doses of formaldehyde. Methods Totally 48 male SD rats were randomly divided into four groups (12 rats in each) exposed to high dose, medium dose and low dose of formaldehyde [10 mg/(kg·d), 1 mg/(kg·d) and 0.1 mg/(kg·d), respectively] and the control group (injected with saline). Seven days after intraperitoneal injection of formaldehyde, their sperm quality was analyzed, serum hormones were measured with radioimmunoassay, and the testicular tissue sections were observed under light microscope. All results were analyzed statistically. Results Compared to those in control group, the number and motility of sperms in various doses of formaldehyde exposure groups decreased significantly (P<0.05, P<0.001), and sperm abnormality rate significantly increased (P<0.001). The dose of formaldehyde exposure was positively correlated with serum levels of FSH (r=0.709, P<0.05) and LH (r=0.622, P<0.05) significantly, but negatively correlated with serum level of T significantly (r=-0.762, P<0.05). The interstitial tissues of the rat testis in high dose group became atrophic, with edema and reduced number of Leydig cells. Conclusion Acute exposure to formaldehyde of a certain dose can cause significant damages to the structure and function of rat testis, including sperm quality, serum sex hormone level as well as the structure and function of Leydig cells, which is one of the important manifestations of reproductive toxicity of formaldehyde.