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Ph.D. Defence by Hiva Alipour

"Improved conventional and functional seminal parameters after short versus long ejaculation abstinence" by Hiva Alipour.

Time

16.10.2017 kl. 13.00 - 16.10.2017 kl. 17.00

Description

Abstract

Assisted reproductive techniques (ART) have developed considerably in recent years. How-ever, approximately 1/3 of patients undergoing ART still experience failed attempts to reach live birth, with an increasing number of studies pointing towards the importance of sperm-related factors in ART. Based on the current guidelines in ART, 4-7 days of ejaculatory ab-stinence is required to achieve optimum semen quality and treatment outcome. Despite the general decrease in the volume and number of sperm after a sub-optimal abstinence period, several studies have observed a significant improvement in other parameters of sperm quality (motility, morphology, DNA fragmentation, etc.) following shorter abstinence periods. The present study utilized computer aided sperm analysis (CASA) to assess the conventional and functional parameters of semen samples collected after 2 h versus 4–7 days of ejaculation abstinence from normozoospermic males. Samples were also assessed for the level of DNA fragmentation using the sperm chromatin dispersion (SCD) and sperm chromatin structure assay (SCSA) techniques. Furthermore, metabolomic profiles of the seminal plasma were prepared using 1H Nuclear magnetic resonance (NMR) spectroscopy and compared between the consequent ejaculates. Semen samples were collected in accordance with WHO semen sampling guidelines after 4-7 days of ejaculatory abstinence, followed by a second sample after two hours and assessed for volume, sperm counts, motility and kinematic parameters using CASA. The results demonstrated a significantly lower semen volume, sperm concentration and counts but significantly higher percentages of spermatozoa with higher velocity, progressive-ness and hyperactivation in the ejaculates following 2h vs 4-7 days of ejaculation abstinence. Shorter abstinence period also demonstrated a lower level of DNA fragmentation compared to longer abstinence. Metabolomic profiles of ejaculates collected after a short abstinence period demonstrated lower absolute amounts of all seminal metabolites but significantly higher absolute amount per spermatozoon of pyruvate and taurine, when compared to that collected after a long abstinence period. The differences observed in the concentration and absolute amounts of seminal metabolites per sperm, following different abstinence times can be considered as one of the underlying causes of the aforementioned differences in sperm kinematics and DNA fragmentation after short versus longer abstinence. It can be concluded that despite the lower sperm concentration and counts after shorter absti-nence, the higher number of sperm with better motility and lower DNA fragmentation in the normozoospermic cases, could result in a better collection of sperm to use in ART procedures.

Address

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