Electrophoresis of phosphoglycerate kinase-2 to determine testicular damage induced by ethylene glycol monomethyl ether and sterility associated with chromosomal abnormality

Phosphoglycerate kinase (PGK, EC 2.7.2.3), which is expressed specifically in sperm and spermatids, is an enzyme in the Embden-Meyerhof pathway that converts glucose to pyruvate. We developed an electrophoresis method to determine relative PGK-2 quantity and applied it to evaluate spermatogenesis activity. In the ethylene glycol monomethyl ether (EGME)-induced testicular toxicity, relative PGK-2 quantity had not decreased until 4 weeks of exposure. Mean relative PGK-2 quantities, defined as PGK-2 quantity over PGK-1 quantity in a pooled spleen sample (±SD) were: 1.43±0.32 for control animals (N=10); 1.67±0.24 for the group exposed at 500 mg/kg for 5 days (N=6); 1.85±0.58 for the group exposed at 500 mg/kg for 2 weeks (N=6); 0.09±0.06 for the group exposed at 500 mg/kg for 4 weeks (N=6); not detectable in animals exposed at 500 mg/kg for 5 weeks (N=7); 0.208±0.103 for the group exposed at 250 mg/kg for 5 weeks (N=6); and 1.35±0.38 for the group exposed at 125 mg/kg for 5 weeks (N=6). These relative quantities showed a good correlation with sperm/spermatid counts (r=0.823,p<0.01) and histological findings. These findings suggest that EGME has toxicity on primary spermatocytes and spermatogonia. In the case of sterility associated with a chromosomal abnormality (chromosomal translocation between chromosome X and 16), relative PGK-2 quantity was not detected in any of the seven adult (12 weeks of age) mice, although many primary spermatocytes were detected by histological examination. Those findings suggest that cellular differentiation is arrested at meiosis due to the chromosomal abnormality. It was thus concluded that relative PGK-2 quantity provides information on testicular development and is therefore useful as an indicator of testicular function.