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Occurrence of D-aspartic acid in human seminal plasma and spermatozoa: Possible role in reproduction

      Objective

      To determine D-aspartic acid (D-Asp) in human seminal plasma and spermatozoa in fertile and infertile donors.

      Design

      Prospective observation study.

      Setting

      Department of Pathophysiology for Human Reproduction, Hospital “S. Luca,” Salerno, Italy, and Department of Neurobiology and Comparative Physiology, Zoological Station “A. Dohrn,” Naples, Italy.

      Patient(s)

      Ten normospermic, 10 oligoasthenoteratospermic, and 10 azoospermic (nonobstructive) men.

      Intervention(s)

      D-aspartic acid was determined by a specific enzymatic high-performance liquid chromatography method on purified seminal plasma and on isolated spermatozoa and by an immunohistochemical method using light and electronic microscopic techniques.

      Main Outcome Measure(s)

      Concentration of D-Asp in seminal plasma and in isolated spermatozoa; subcellular localization of D-Asp in the acrosome and nucleus.

      Result(s)

      The concentration of D-Asp in seminal plasma and in spermatozoa was significantly reduced in oligoasthenoteratospermic donors. In the seminal fluid of normospermic donors, D-Asp occurs at a concentration of 80 ± 12 nmol/mL semen (10.4 ± 1.5 μg/mL), whereas 26 ± 6 nmol/mL semen were found in oligoasthenoteratospermic donors, and 12 ± 1.5 nmol/mL semen were found in azoospermic donors. In spermatozoa from normospermic donors, D-Asp occurred at a concentration of 130 ±15 fmol per spermatozoa (17.0 ± 1.96 ng per spermatozoa), vs. 60.5 ± 5.0 fmol per spermatozoa from oligoasthenoteratospermic subjects. Other D-amino acids analyzed were not present in seminal plasma or in spermatozoa in a significant concentration compared with D-Asp.

      Conclusion(s)

      D-aspartic acid occurs in human seminal plasma and spermatozoa and is implicated in male fertility.

      Key Words

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