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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #318313
Title: Profiling of relaxin and its receptor proteins in boar reproductive tissues and spermatozoa

Author
item FEUGANG, J - Mississippi State University
item GREENE, J - Mississippi State University
item SANCHEZ-RODRIGUEZ, H - Mississippi State University
item STOKES, J - 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: 5/8/2015
Publication Date: 5/20/2015
Citation: Feugang, J.M., Greene, J.M., Sanchez-Rodriguez, H.L., Stokes, J.V., Crenshaw, M.A., Willard, S.T., Ryan, P.L. 2015. Profiling of relaxin and its receptor proteins in boar reproductive tissues and spermatozoa. Reproductive Biology and Endocrinology. 13(46).

Interpretive Summary: Relaxin is a small polypeptide found in reproductive tissues and secretions of male and female. Its physiological effects are well-described in female reproduction, but remain investigated at lesser extend in males. Here we examined the protein distribution of both relaxin and its receptors (RXFP1 and RXFP2) within the boar reproductive tissues and spermatozoa. Both relaxin and receptors were ubiquitously detected in all samples, which indicate possible existence of autocrine and/or paracrine actions. It appeared that relaxin detected in seminal plasma, in other studies, may originate from both prostate and testis and may have long-term effects on sperm function during the transit of the female genital tract and fertilization.

Technical Abstract: Background: Relaxin levels in seminal plasma have been associated with positive effects on sperm motility and quality, and thus having potential roles in male fertility. However, the origin of seminal relaxin, within the male reproductive tract, and the moment of its release in the vicinity of spermatozoa remain unclear. Here, we assessed the longitudinal distribution of relaxin and its receptors RXFP1 and RXFP2 in the reproductive tract, sex accessory glands, and spermatozoa of adult boars. Methods: Spermatozoa were harvested from three fertile boars and reproductive tract (testes and epididymis) and sex accessory gland (prostate and seminal vesicles) tissues were collected post-mortem from each boar. Epididymis ducts were sectioned into caput, corpus, and cauda regions, and spermatozoa were mechanically collected. All samples were subjected to immunofluorescence and/or western immunoblotting for relaxin, RXFP1, and RXFP2 detection. Immunolabeled-spermatozoa were submitted to flow cytometry analyses and data were statistically analyzed with ANOVA. Results: Both receptors were detected in all tissues, with a predominance of mature and immature isoforms of RXFP1 and RXFP2, respectively. Relaxin signals were found in the testes, with Leydig cells displaying the highest intensity compared to other testicular cells. The testicular immunofluorescence intensity of relaxin was greater than that of other tissues. Epithelial basal cells exhibited the highest relaxin immunofluorescence intensity within the epididymis and the vas deferens. The luminal immunoreactivity to relaxin was detected in the seminiferous tubule, epididymis, and vas deferens ducts. Epididymal and ejaculated spermatozoa were immunopositive to relaxin, RXFP1, and RXFP2, and epididymal corpus-derived spermatozoa had the highest immunoreactivities across epididymal sections. Both vas deferens-collected and ejaculated spermatozoa displayed comparable, but lowest immunofluorescence signals among groups. The entire sperm length was immunopositive to both relaxin and receptors, with relaxin signal being robust in the acrosome area and RXFP2, homogeneously distributed than RXFP1 on the head of ejaculated spermatozoa. Conclusions: Immunolocalization indicates that relaxin-receptor complexes may have important roles in boar reproduction and that spermatozoa are already exposed to relaxin upon their production. The findings suggest autocrine and/or paracrine actions of relaxin on spermatozoa, either before or after ejaculation, which have possible roles on the fertilizing potential of spermatozoa.