Relationship between seminal LDH-C4 and spermatozoa with acrosome anomalies

Cancer-testis antigen lactate dehydrogenase C4 as a novel biomarker of male infertility and cancer

A unique lactate dehydrogenase (LDH) isoenzyme designated as lactate dehydrogenase C4 (LDH-C4) is found in mammalian mature testis and spermatozoa. Thus far, LDH-C4 has been well studied with regard to its gene and amino acid sequences, structure, biological properties, and peptide synthesis. Accumulating evidence has shown that LDH-C4 is closely related to spermatic energy metabolism and plays a critical role in sperm motility, capacitation, and fertilization. Defects in the catalytic activity of LDH-C4 are key to pathophysiological abnormalities underlying infertility. LDH-C4 was originally thought to be present only in mature testis and spermatozoa; however, recent studies have implicated LDH-C4 as a cancer-testis antigen (CTA), owing to its aberrant transcription in a broad spectrum of human neoplasms. This review highlights the recent findings on LDH-C4 with particular emphasis on its role in male infertility and tumors.

Effects of cysteine and ascorbic acid in freezing extender on sperm characteristics and level of enzymes in post-thawed stallion semen

Present study aimed to investigate the effect of adding antioxidants, cysteine and ascorbic acid on the levels of glutamic oxaloacetic transaminase (GOT), glutamic‐pyruvate (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and γ‐glutamyl transpeptidase (GGT) enzymes of post‐thawed stallion sperm. Ten ejaculates were collected each from four healthy stallions and cryopreserved using HF‐20 freezing extender containing either 0 mg/ml cysteine or ascorbic acid, 0.5 mg/ml cysteine and 0.5 mg/ml ascorbic acid. All samples in freezing extender containing cysteine or ascorbic acid or none of them were assessed for sperm motility, viability, plasma membrane integrity, morphology and enzymes concentration. The ALP, LDH and GGT were significantly higher in 0‐group compared with cysteine and ascorbic acid groups. The sperm motility of frozen‐thawed semen with 0‐group was significantly better compared with cysteine and ascorbic acid groups. The variation on viability, sperm membrane integrity and morphology were insignificant between all treated groups. Therefore, these enzymes were reduced when using antioxidants in the freezing extender. Results of the present study suggest that concentration of ALP, LDH and GGT enzymes could be used as parameters for prediction of frozen‐thawed stallion semen.

This manuscript aims to evaluate the effect of cysteine and ascorbic acid to HF‐20 extender on the frozen semen enzyme and using these enzymes as markers of frozen semen quality in stallion's semen. It shows that the level of ALP, LDH and GGT enzyme steadily correlated with post‐thawed semen quality. The samples treated with cysteine and ascorbic acid showed a deleterious effect of sperm enzyme concentration and function compared with control group.

Boar spermatozoa encapsulated in barium alginate membranes: a microdensitometric evaluation of some enzymatic activities during storage at 18 °C

The customary dilution of boar semen for subsequent artificial insemination (AI) procedures damages the cell membrane of spermatozoa, resulting in a loss of enzymes and other cytoplasmic contents and acrosomal reactions. We encapsulated non-diluted boar semen in barium alginate membranes to optimize AI procedures and to improve the functional integrity of spermatozoal membranes during storage. The percentage of non-reacted acrosomes (NRA) and measurements of enzyme leakage (cytochrome c oxidase (COX), lactate dehydrogenase (LDH), and glucose-6-phosphate dehydrogenase (G6PDH)) were used as indices of the functional status of diluted, unencapsulated and encapsulated spermatozoa, stored for 72 h at 18 degrees C. Enzymatic activity was assessed in situ by microdensitometry, and non-reacted acrosomes were microscopically determined by staining. The percentage of acrosome integrity and the intracellular enzymatic activities during storage were different for unencapsulated and encapsulated semen. Semen dilution caused a rapid decline in enzymatic activities and concomitant acrosomal reactions. Encapsulated spermatozoa had significantly higher acrosome integrity (77% versus 55%; P < 0.01 after 72 h) and an overall higher in situ enzymatic activity. For cytochrome c oxidase and lactate dehydrogenase the greatest differences between encapsulated and unencapsulated spermatozoa were present after 72 h whereas for glucose-6-phosphate dehydrogenase significant differences were found within 24h of storage. The encapsulation process maintains a better preservation environment for boar spermatozoa and could be a promising, innovative technique to improve storage of these cells.

Enzyme activities in fish spermatozoa with focus on lactate dehydrogenase isoenzymes from herring Clupea harengus

The activities of NAD- and NADP-dependent dehydrogenases and creatine kinase were compared in extracts of spermatozoa from herring (Clupea harengus), carp (Cyprinus carpio) and catfish (Clarias gariepinus). The activity of malic enzyme in herring spermatozoa was approximately 5 and 36 times higher than in carp and catfish spermatozoa. In contrast, lactate dehydrogenase activity in herring spermatozoa was very low. Herring spermatozoa possess two isoenzymes of lactate dehydrogenase: LDH-A(2)B(2) and LDH-B(4). Both herring spermatozoa isozymes were separated, partly purified and characterized by kinetic and physico-chemical properties. The pH optima and K(m) values for pyruvate reduction were 7.1, 7.25, 7.6 and 0.22, 0.07, 0.09 mM for LDH-A(4), LDH-A(2)B(2) and LDH-B(4), respectively. The isoenzymes also have different thermostabilities. High activity of malic enzyme in herring spermatozoa suggests adaptation to metabolism at high oxygen tension.

Values of sperm thiobarbituric acid-reactive substance in fertile men

BACKGROUND

The objective of this study was to establish for the first time reference levels of sperm malondialdehyde, a stable lipid peroxidation product, in a cohort of fertile men.

METHODS

Sperm malondialdehyde, a thiobarbituric acid-reactive substance, was assayed using the 2-thiobarbituric acid method.

RESULTS

Sperm malondialdehyde levels, expressed in nM/10(8) spermatozoa, were normally distributed in our cohort of fertile men and averaged 0.0287 +/- 0.0162 (mean +/- S.D.).

CONCLUSIONS

Given the impact of lipid peroxidation on spermatozoa and thereby on male fertility, the assay of sperm membrane thiobarbituric acid-reactive substance is clearly of interest. Malondialdehyde levels found in our study form a basis for normal values of sperm thiobarbituric acid-reactive substance observed in the semen of fertile men.

Testosterone secretion and semen plasma enzyme activity in rams with genital pathology stimulated with GnRH

Testosterone secretion in response to GnRH stimulation and enzymatic activity of semen plasma was evaluated comparatively in rams with or without genital abnormality. Scrota, testes and epididymides of 128 rams between 1.5 and 6 years old from various breeds were examined clinically and ultrasonographically. Bilaterally cryptorchid rams (n = 2), and rams with focal testicular degeneration (n = 3) or unilateral sperm granuloma localized in the caput (n = 3) epididymis or the cauda epididymis (n = 3), diagnosed by either clinical or ultrasonographic examination, were selected for the further investigation of spermatologic parameters, testosterone secretion in response to GnRH stimulation, and enzymatic activity of semen plasma before histopathologic confirmation of lesions. Except for the cryptorchid rams, sperm parameters determined in ejaculates were similar to intact controls (n = 3). GnRH administration increased plasma testosterone levels significantly irrespective of the type of genital pathology (P < 0.01). The testosterone response calculated based on area under the curve following GnRH administration in rams having genital abnormality was not significantly different from the controls. Aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activity in the semen plasma varied between rams, with the lowest mean values in the bilaterally cryptorchid group (P < 0.05). Spermatic granuloma localized either in the caput or cauda of the epididymis was associated with a significant reduction in the semen plasma AST activity compared to controls (P < 0.01). In conclusion, our results indicated that the ability of testicular tissue to secrete testosterone in response to GnRH stimulation in rams with bilateral cryptorchidism, focal testicular degeneration and unilateral sperm granuloma was similar to that of intact controls, and that reduced semen plasma AST activity may have a diagnostic value in the diagnosis of the epididymal obstruction in rams. Focal testicular degeneration did not influence AST, alkaline phosphatase (ALP) and LDH activity in semen plasma.

Use of lectins to characterize plasma membrane preparations from boar spermatozoa: a novel technique for monitoring membrane purity and quantity

The object of this study was to develop a method to quantify the amount of outer acrosomal membrane material in isolated plasma membranes from boar sperm cells. The cells were fractionated by nitrogen cavitation, and plasma membranes were isolated by subsequent differential centrifugation steps. Marker enzyme measurement showed that the plasma membrane isolates were enriched in plasma membrane markers and did not contain nuclei, inner acrosomal membranes, or mitochondria. Since there is no marker enzyme known for the outer acrosomal membrane, lectins were used for the detection of this membrane. The membrane specificity of a number of lectin conjugates was tested with fluorescence microscopy and transmission electron microscopy. Membrane binding of these lectin conjugates was quantified with flow-cytometry and an enzyme-linked lectin binding assay. Wheat germ agglutinin was specific for the plasma membrane while peanut agglutinin was specific for the outer acrosomal membrane. The use of these lectins made it possible for the first time to discriminate between these two membranes. The isolated plasma membrane fraction was enriched more than 10-fold (17-fold after further purification by a sucrose gradient) in plasma membrane material compared to outer acrosomal membrane material. Highly purified sperm plasma membranes should prove to be useful for research on primary sperm-zona interactions.