Cytokines release and oxidative status in semen samples from rabbits treated with bacterial lipopolysaccharide

This study was aimed to evaluate the effects of a lipopolysaccharide- (LPS) induced inflammation on cytokines release and oxidative status of semen samples from buck rabbits at different times after treatment. Semen analysis was performed by optical microscopy and sperm motility evaluation by the computer-assisted sperm analyzer. The presence of activated macrophages and apoptotic/necrotic sperm was evaluated by fluorescent microscopy. A panel of cytokines, interleukin (IL)-6, IL-8, IL-1 beta, and tumor necrosis factor-alpha, were detected and quantified in seminal plasma using the Bio-Plex Cytokine assay. Reactive oxygen metabolite and thiobarbituric acid reactive substance determinations were carried out by spectrophotometry and tocopherol analysis by high performance liquid chromatography. The sperm motility and track speed were reduced in LPS-treated rabbits. The activated macrophages in LPS-treated buck rabbits significantly increased from 0.50 x 10(6)/mL (baseline) to 27 x 10(6)/mL on Day 21; successively, there was a progressive reduction. Apoptotic and necrotic sperm in LPS rabbits followed more or less the same trend. The reactive oxygen metabolite levels in semen from LPS-treated rabbits showed higher values compared with those evaluated in controls, particularly during the lag time, Days 1 to 3. The sperm thiobarbituric acid reactive substances highlighted a peak in LPS-treated rabbits compared with those of controls on Day 1 after LPS treatment, and the different T isoforms (alpha, delta, and gamma+beta) showed a similar trend with a significant decrease on Day 1 after injection and a recovery on Days 30 to 56. Until Days 3 to 21 from the treatment, higher levels of IL-1 beta and tumor necrosis factor-alpha were detected in seminal plasma of LPS-treated rabbits. Interleukin-6 showed a peak on Day 3 after LPS treatment, and on Day 7, the value was similar to the control group. In conclusion, this study confirms that the buck rabbit is a good model for mimicking and understanding the inflammation mechanisms, which may induce male infertility, in particular that a systemic inflammatory status causes alterations to the sperm cells through a shift in the balance between the oxidant and antioxidant system.