ObjectiveTo investigate the effects of Zhibai Dihuang Decoction (ZDD) on sperm mitochondrial permeability transition (MPT) in the rat model of ureaplasma urealyticum (UU) infection (UUI).

METHODSNinety male SD rats were randomly divide into five groups: normal control, UUI model control, ZDD, doxycycline, and ZDD + doxycycline. The UUI model was established in the latter four groups of rats by UU injection into the bladder. On the second day after modeling, the animals of the normal control and UUI model control groups were treated intragastrically with 0.9% sodium chloride solution and those in the other groups with corresponding drugs, all for 21 consecutive days. At 24 hours after drug withdrawal, epididymal samples were obtained for detection of the protein and mRNA expressions of VDAC2 and ANT4 in the sperm mitochondria by RT-PCR and Western blot respectively and determination of the contents of adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) and energy charge (EC) in the sperm mitochondria by high-performance liquid chromatography.

RESULTSThe protein expressions of VDAC2 and ANT4 in the rat sperm mitochondria were 0.626 ± 0.074 and 0.527 ± 0.096 in the normal control group, 0.039 ± 0.011 and 0.044 ± 0.011 in the UUI model control group, 0.101 ± 0.037 and 0.127 ± 0.040 in the ZDD group, 0.236 ± 0.070 and 0.253 ± 0.054 in the doxycycline group, and 0.475 ± 0.064 and 0.367 ± 0.086 in the ZDD + doxycycline group, significantly lower in the UUI model control than in the normal control group (P<0.05 and P<0.01), but remarkably higher in the doxycycline and ZDD + doxycycline groups than in the UUI model control (P<0.01) and the ZDD group (P<0.05 and P<0.01), and the expression of VDAC2 was markedly higher in the ZDD + doxycycline than in the doxycycline group (P<0.01). The mRNA expressions of VDAC2 and ANT4 were 0.008 ± 0.001 035 and 0.026 50 ± 0.003 401 in the normal control group, 0.000 79 ± 0.000 226 and 0.001 64 ± 0.000 205 in the UUI model controls, 0.002 06 ± 0.000 861 and 0.005 04 ± 0.002 537 in the ZDD group, 0.003 34 ± 0.000 229 and 0.008 57 ± 0. 000 690 in the doxycycline group, and 0.004 85 ± 0.000 495 and 0.013 13 ± 0.000 826 in the ZDD + doxycycline group, significantly lower in the UUI model control than in the normal control group (P<0.05 and P<0.01), but remarkably higher in the ZDD, doxycycline and ZDD + doxycycline groups than in the UUI model controls (P<0.01) as well as in the doxycycline and ZDD + doxycycline groups than in the ZDD group (P<0.01) and in the ZDD + doxycycline than in the doxycycline group (P<0.01). The levels of ATP, ADP, AMP and EC in the sperm mitochondria were (203.41 ± 13.16) mg/L, (129.87 ± 14.68) mg/L, (149.05 ± 5.65) mg/L and 0.56 ± 0.01 in the normal control group, (96.22 ± 12.55) mg/L, (99.87 ± 3.28) mg/L, (212.53 ± 19. 43) mg/L and 0.36 ± 0.03 in the UUI model control group, (101.99 ± 5.97) mg/L, (104.99 ± 16.40) mg/L, (183.97 ± 12.43) mg/L and 0.40 ± 0.01 in the ZDD group, (159.44 ± 33.16) mg/L, (118.51 ± 12.99) mg/L, (160.64 ± 14.19) mg/L and 0.50 ± 0.06 in the doxycycline group, and (194.07 ± 9.36) mg/L, (121.62 ± 9.41) mg/L, (150.21 ± 12.87) mg/L and 0.55 ± 0.01 in the ZDD + doxycycline group. The levels of ATP and EC were significantly lower and that of AMP higher in the UUI model control than in the normal control group (P<0.01), while the former two were remarkably higher and the latter one lower in the doxycycline and ZDD + doxycycline groups than in the UUI model controls (P<0.05 and P<0.01). Compared with the ZDD + doxycycline group, the ZDD group showed significantly decreased ATP and EC but increased AMP, while the doxycycline group exhibited decreases in both ATP and EC (P<0.05 and P<0.01).

CONCLUSIONSZDD can upregulate the decreased protein and mRNA expressions of VDAC2 and ANT4 in the sperm mitochondria and improve sperm mitochondrial permeability transition and mitochondrial energy metabolism in rats with UU infection, which may be one of its action mechanisms in the treatment of UU infection-induced male infertility.