Docosahexaenoic acid supplementation fully restores fertility and spermatogenesis in male delta-6 desaturase-null mice

Relaxin was first identified in 1926 as a substance influencing the reproductive tract and was subsequently found to be a peptide hormone with a two-chain structure similar to insulin. It is now accepted that relaxin is a member of a family of peptide hormones that includes seven members in humans—three relaxin peptides (H1, H2, and H3) and insulin-like peptides (INSL) 3, 4, 5, and 6. All these genes evolved from an ancestral relaxin-3 gene in (lower) vertebrates. The reproductive hormone relaxin is the product of one gene in most species, RLN1. Among these genes, the physiological roles of relaxin and INSL3 have been more extensively studied. Relaxin-3 is likely an important neuropeptide but has no known roles in reproduction. In contrast, relaxin has vital physiological roles during pregnancy, although its actions vary between species. Hence, relaxin has essential actions on the cervix, pubic symphysis, vagina, uterus, and mammary apparatus during pregnancy. It is also a mediator of the important cardiovascular changes that occur during pregnancy in many species. Relaxin may also play a crucial role in implantation, especially in primates. In addition, relaxin has nonreproductive actions in wound healing, cardiac protection, and as an antifibrotic agent. INSL3 is essential for testis descent by promoting gubernacular development in the fetus. It also plays an important role in female and male germ cell maturation and survival, respectively. With the recent identification of relaxin family peptide receptors, future investigations should unravel the diverse actions of relaxin and relaxin family peptides and lead to novel therapeutic applications.

Physiology and Molecular Biology of the Relaxin Peptide Family

Hyaluronic acid (Sperm Select) improves retention of sperm motility and velocity in normospermic and oligospermic specimens.

Comparison of motility stimulants for cryopreserved human semen

The ability of pentoxifylline to stimulate the motion characteristics of antegrade and retrograde sperm collected at the time of electroejaculation with a rectal probe was assessed in six neurologically impaired men. Before electroejaculation, the bladder was rinsed and instilled with 20 to 30 ml Ham's F-10 medium. Washed sperm were incubated with various doses (0, 0.1, 1, and 3 mmol/L) of pentoxifylline. Video sequences were recorded at intervals from 0 to 4.5 hours and analyzed for sperm motion parameters using manual and computer-assisted semen analysis. The results were compared with equimolar concentrations of caffeine. Both pentoxifylline and caffeine demonstrated a dose-dependent stimulation of percent motility and other motion parameters. A maximal stimulation of two-fold to three-fold for both percent motility and curvilinear velocity, and 30% to 60% for straight line velocity was observed after incubation under these conditions. A significant increase in mean linearity was observed in samples incubated with 0.1 mmol/L pentoxifylline at 1.5 hours. Significant lateral head displacement was not observed at any time point. Two couples underwent gamete intrafallopian transfer (GIFT) in conjunction with this electroejaculation sperm stimulation procedure, and one has since delivered a normal child. These studies show that pentoxifylline stimulation can improve the movement characteristics of asthenospermic sperm from neurologically impaired men. Such sperm stimulation techniques do not affect the fertilization process and may improve the chances for conception in some cases of male-factor infertility.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.1991.tb00241.x

Frances Ginsburg

Papers

The effect of relaxin and prostaglandin E2 on the motility of human spermatozoa