BIOCHEMICAL MARKERS OF EARLY AND LATE SPERMATOGENESIS - RELATIONSHIP BETWEEN THE LACTATE DEHYDROGENASE-X AND CREATINE KINASE-M ISOFORM CONCENTRATIONS IN HUMAN SPERMATOZOA

As part of our research program on biochemical markers of sperm maturi ty, we have studied sperm creatine kinase-(CK) and lactate dehydrogena se (LDH) concentrations and the ratios of the CK-M [divided by CK-M/(C CU-M + CU-B)] and LDH-x[divided by-LDH-X/(LDH-X + LDH-a)] isoforms in 50 oligospermic and 95 normospermic men. Because the synthesis of LDH- X is initiated in early spermatogenesis, and that of CK-M commences in late spermiogenesis simultaneously with cytoplasmic extrusion, we pro posed two working hypotheses: (1) LDH and CK concentrations reflect th e retained cytoplasm in sperm, thus the activities of both enzymes wil l be related and will be higher in oligospermic specimens, which have a higher incidence of immature spermatozoa; and (2) because in normall y developed sperm both LDH-X and CK-M are present, there will be a cor relation between LDH-X and CK-M ratios in the mature sperm populations . However, among men with immature sperm samples with late spermiogene tic defect and diminished CK-M ratios, there will be two groups: one w hich completed spermatogenesis prior to spermiogenetic failure (normal LDH-X and diminished CK-M ratios), and another group with defects in both spermatogenesis and spermiogenesis (low LDH-X and diminished CK-M ratios). Because of this heterogeneity, LDH-X ratios will be a poor p redictor of sperm maturity. The data support the hypotheses: (1) LDH a nd CK concentrations were higher in oligospermic vs, normospermic men (P < 0.001). (2) The LDH and CK concentrations were related (r = 0.65, P < 0.001, N = 145), and there were inverse correlations between CK, LDH, LDH-X, or CK-M ratios vs. sperm concentrations (P < 0.001 in all four). (3) The CK-M and LDH-X ratios were different between the oligos permic and normospermic groups (P < 0.001), although the means of the LDH-X ratios were narrower (LDH-X:1:1.3; CK-M:1:1.9). (4) Dividing the 145 samples by the cut-off value of mean minus 1 SD of the CK-M and L DH-X ratios (11% and 32%, respectively) demonstrated that the CK-M rat ios discriminated better than LDH-X ratios between the samples with ma ture and immature sperm. These data on the biochemical markers of earl y and late spermatogenesis support the studies in which CK better refl ected sperm quality than LDH or LDH-X (Orlando et al., 1994: Int J And rol 17:13-18) and the >10% sperm CK-M ratio predicted with a rate of 3 0.4% per cycle in the occurrence of pregnancies in a blinded study of 84 IVF couples (Huszar et al., 1992: Fertil Steril 57:882-888). (C) 19 96 Wiley-Liss, Inc.