Effects of Ureaplasma urealyticum infection on the male reproductive system in experimental rats

To study the effects of Ureaplasma urealyticum (Uu) infection on the male reproductive system, the mechanism of infertility induced by Uu infection was investigated in experimental rats. Male Sprague-Dowley rats were infected with Uu4 (serotype 4) through repeated natural sexual intercourse for 8 weeks to establish infection. After 8 weeks, the blood samples of the animals were collected and analysed for cytokine production, and the animals were microdissected for the analysis of the reproductive system. Morphological study showed that spermatozoa exhibited curling and breaks in the rats infected at different dosages. Of the infected rats, 27.5% had both soft and hard calculi in the urinary tract, compared with 12% in the control groups. Uu infection resulted in a decline of sperm quality, eventually leading to the death of the spermatozoa. In the infected animals, the serum interleukin 6 and interleukin 8 levels increased significantly (P < 0.05), while tumour necrosis factor-alpha and interferon-gamma showed only modest changes. Our observations showed that Uu infection has an impact on sperm morphology, leading to the death of the spermatozoa. It is plausible that the morphological alterations of spermatozoa induced by Uu infection are one of the possible factors that contribute to male infertility.