DEFECTIVE MITOCHONDRIAL OXIDATIVE-PHOSPHORYLATION IN VARICOCELE-BEARING TESTICLES

Objectives. Our previous study revealed a decreased blood flow in vari cocele-bearing testicles. For further understanding of the possible me chanism of varicocele-induced infertility, we investigated the changes in energy metabolism in varicocele-bearing testicles. Methods. Partia l ligation of the left renal vein was performed in 40 Wistar rats to i nduce dilation of the internal spermatic vein, and sham operations wer e performed in 20 other age-matched Wistar rats serving as controls. O rchiectomy was done at 1, 2, 4, and 6 months after induction of varico cele (or sham operation) in both groups. The histologic changes in the testicles were evaluated under the light microscope. The concentratio n of adenine nucleotides was determined by high-performance liquid chr omatography, and various enzyme activities of mitochondria were determ ined by a spectrophotometer. Results. Histologic studies of varicocele -bearing testicles showed a lower Johnsen score (8.5 +/- 0.7 versus 9. 3 +/- 0.5) and a decreased mean testicular tubular diameter (280.0 +/- 3.2 versus 295.0 +/- 1.4 mu m) compared with the testicles in the sha m-operated group. The energy charge decreased from 0.71 +/- 0.04, 0.70 +/- 0.03, 0.69 +/- 0.06, and 0.64 +/- 0.03 to 0.62 +/- 0.08, 0.59 +/- 0.05, 0.58 +/- 0.05, and 0.56 +/- 0.02 at 1, 2, 4, and 6 months, resp ectively. The reduced nicotinamide-adenine dinucleotide-cytochrome c r eductase activities were decreased from 136.6 +/- 4.9, 127.3 +/- 10.7, 121.6 +/- 7.8, and 118.9 +/- 8.5 to 96.3 +/- 13.9, 95.6 +/- 27.8, 88. 3 +/- 13.8, and 80.4 +/- 8.7 nmol/min/mg of protein, respectively; the succinate-cytochrome c reductase activities were decreased from 50.4 +/- 2.7, 49.0 +/- 4.7, 49.6 +/- 7.1 1.6 to 40.3 +/- 7.3, 41.0 +/- 11.5 , 40.2 +/- 5.7, and 32.0 +/- 1.3 nmol/min/mg of protein, respectively; and the cytochrome c oxidase activities were decreased from 361.2 +/- 23.4, 350.3 +/- 25.5, 223.5 +/- 12.9, and 194.1 +/- 18.3 to 253.7 +/- 32.9, 256.4 +/- 38.8, 178.2 +/- 15.7, and 147.1 +/- 17.2 nmol/min/mg of protein at 1, 2, 4, and 6 months, respectively. Conclusions. We thu s suggest that defective energy metabolism plays an important role in the impairment of spermatogenesis of varicocele-bearing testicles.