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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #318311
Title: Beneficial effects of relaxin on motility characteristics of stored boar spermatozoa

Author
item FEUGANG, J - Mississippi State University
item RODRIGUEZ-MUNOZ, J - Mississippi State University
item DILLARD, D - Mississippi State University
item CRENSHAW, M - Mississippi State University
item WILLARD, S - Mississippi State University
item RYAN, P - Mississippi State University

Submitted to: Reproductive Biology and Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2015
Publication Date: 3/31/2015
Citation: Feugang, J.M., Rodriguez-Munoz, J.C., Dillard, D.S., Crenshaw, M.A., Willard, S.T., Ryan, P.L. 2015. Beneficial effects of relaxin on motility characteristics of stored boar spermatozoa. Reproductive Biology and Endocrinology. 13(24).

Interpretive Summary: Artificial insemination (AI) is the preferred method of breeding in commercial livestock farms. In swine, AI is mainly performed with fresh extended semen due to their poor resistance to cryopreservation. Therefore, the maintenance of high quality spermatozoa in AI doses could be jeopardized during long-term conservation or transportation. Recent studies have found positive correlations between seminal plasma relaxin levels and sperm motility. Here we tested the impact of relaxin on motility characteristics of spermatozoa after a prolonged storage. This study was undertaken to replicate the field or real-world conditions of unexpected uphold (during transportation) or delayed inseminations, in which relaxin may serve as a motility booster of “aged” spermatozoa to be used for inseminations. The findings indicate beneficial effects of relaxin on various motility characteristics of spermatozoa, while upholding the fast decline of sperm motility/viability during storage. Indeed, the motility parameters associated with sperm progressiveness were significantly increased (straightness, linearity, and straight-line velocity), which has potential to translate into higher fertility of such spermatozoa.

Technical Abstract: Background: Relaxin is detected in seminal plasma of many species and its association with sperm motility may be beneficial in some aspects of assisted reproduction. Here, we immunolocalized relaxin receptors and investigated the effects of exogenous relaxin on motility characteristics, viability, and cAMP content of boar spermatozoa after storage. Methods: Commercial doses of boar semen were obtained on the collection day (Day 0) and kept in shipping containers at room temperature for up to 4 days (Day 4). On Day 0, spermatozoa were fixed for immunofluorescence detection of relaxin receptors RXFP1 and RXFP2 (Experiment 1). Semen aliquots were taken from the same dose at Day 0, Day 1, and Day 2 (Experiment 2a), and Day 2 and Day 4 (Experiment 2b) for analyses. Alive spermatozoa were purified and incubated (1 h-37°C) with 0, 50, or 100 ng relaxin/ml (Experiment 2a) and 0, 100, or 500 ng relaxin/ml (Experiment 2b). Afterward, aliquots of each treatment group were subjected to motility (Experiments 2), viability (Experiment 3) analyses, and cAMP quantification (Experiment 4). Data (3–4 independent replicates) were statistically analyzed (ANOVA followed by pairwise comparisons) and p values less or equal to 0.05 was set for significant difference. Results: Both RXFP1 and RXFP2 receptors were immunolocalized on the entire spermatozoon. Relaxin concentration of 100 ng/ml significantly improved the proportions of motile, progressive, and rapid spermatozoa up to Day 2. Only 500 ng relaxin/ml provided beneficial effects on Day 4. The viability of spermatozoa was not affected by relaxin (100 ng/ml) during storage, but the extent of mitochondria membrane damages was significantly decreased. Furthermore, relaxin did not affect the cAMP contents of spermatozoa during storage, in our conditions. Conclusions: Relaxin could be a valuable motility booster of stored- or aged-spermatozoa for assisted reproduction techniques. However, the related-intracellular signaling cascades of relaxin in boar spermatozoa remain undetermined.