Characterization of the Sperm Proteome and Reproductive Outcomes with in Vitro, Fertilization after a Reduction in Male Ejaculatory Abstinence Period

Abstract

Semen samples from men after a short ejaculatory abstinence show improved sperm quality and result in increased pregnancy rates, but the underlying mechanisms remain unclear. Herein, we report that ejaculates from short (1-3 hours) compared with long (3-7 days) periods of abstinence showed increases in motile sperm count, sperm vitality, normal sperm morphology, acrosome reaction capacity, total antioxidant capacity, sperm mitochondrial membrane potential, high DNA stainability, and a decrease in the sperm DNA fragmentation index (P < 0.05). Sperm proteomic analysis showed 322 differentially expressed proteins (minimal fold change of ±1.5 or greater and P < 0.05), with 224 up-regulated and 98 down-regulated. These differentially expressed proteins are profoundly involved in specific cellular processes, such as motility and capacitation, oxidative stress, and metabolism. Interestingly, protein trimethyllysine modification was increased, and butyryllysine, propionyllysine, and malonyllysine modifications were decreased in ejaculates from a short versus long abstinence (P < 0.05). Finally, the rates of implantation, clinical pregnancy, and live births from in vitro fertilization treatments were significantly increased in semen samples after a short abstinence. Our study provides preliminary mechanistic insights into improved sperm quality and pregnancy outcomes associated with spermatozoa retrieved after a short ejaculatory abstinence.

Sperm Parameters before and after Swim-Up of a Second Ejaculate after a Short Period of Abstinence

“…The improvement may also depend on the increase in the total antioxidant capacity (TAC) of semen and lower sperm membrane lipid peroxidation (LPO), as recently reported [9,23,24]. This hypothesis is further supported by the decrease in the percentage of spermatozoa with fragmented DNA in semen samples collected after shorter abstinence periods [17,25]. Indeed, Hussein and colleagues found a significant improvement in DNA integrity in the second semen sample collected after 1-3 h to the first one from 20 infertile patients with idiopathic OAT [25].…”

“…Indeed, Hussein and colleagues found a significant improvement in DNA integrity in the second semen sample collected after 1-3 h to the first one from 20 infertile patients with idiopathic OAT [25]. Shen and colleagues described that sperm DNA fragmentation index significantly decreased (p < 0.05) in semen samples collected after 1-3 h of abstinence compared with that of spermatozoa collected after a long period (3-7 days) [17].…”

“…Shen and colleagues used a proteomic approach to confirm the potential molecular difference of spermatozoa in ejaculates after 3-7 days and 1-3 h of abstinence. They found that proteins highly involved in sperm motility and capacitation were differentially expressed and that the acrosome reaction capability of spermatozoa was markedly higher after 1-3 h [17]. Recently, cyclooxygenase 1 (COX-1) was indicated as a biomarker that may identify spermatozoa of a better quality [28].…”

“…Shen and colleagues have recently found that sperm DNA fragmentation index decreased in a statistically significant manner in semen samples after a short (1-3 h) period of abstinence compared with a long (3-7 days) one. Interestingly, they also described that the rates of implantation, clinical pregnancy and live births significantly increased in the ejaculate collected after a short period of abstinence [17].…”

A role for KIF9 in male fertility

“…We confirmed the presence of KIF9 at the protein level in the spermatocytes using an antipeptide antibody. Proteomic studies have revealed the presence of KIF9 in human sperm [12][13][14] as well as sperm of several mouse species [15]. Thus, based on studies in lower organisms and localization in mammalian sperm, we anticipated that there would be a strong motility defect.…”