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Title: RELAXIN IN PERIPHERAL PLASMA OF BOARS DURING DEVELOPMENT, COPULATION, AFTERADMINISTRATION OF HUMAN CHORIONIC GONADOTROPIN, AND AFTER CASTRATION

Author
item JUANG H H - IOWA STATE UNIV., AMES
item MUSAH A I - IOWA STATE UNIV., AMES
item SCHWABE C - MED UNIV SOUTH CAROLINA
item FORD J JOE - 5438-01-10
item ANDERSON LLOYD L - IOWA STATE UNIV., AMES

Submitted to: Journal of Reproduction and Fertility
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Relaxin is found in boar semen, and relaxin stimulates motility of washed porcine spermatozoa. The present study was conducted to determine if secretion of relaxin was coordinated with changes in testosterone secretion. We observed that plasma relaxin concentration changed minimally throughout development and after castration of boars, and its concentration in plasma is less than in semen. Thus, relaxin in plasma may not be of testicular origin. These observations will aid in the design of subsequent studies.

Technical Abstract: Relaxin concentrations in peripheral plasma during prepubertal development, copulation, and after castration were determined in Yorkshire boars. An increase (P < 0.05) of circulating relaxin (484 +/- 27 pg ml - 1) was detected at 11 weeks of age but with no correlation between testicular development and peripheral plasma relaxin levels at earlier or later stages of development. In mature boars, plasma relaxin concentrations fluctuated in a manner that was not indicative of pulsatile or diurnal rhythm of secretion. Relaxin levels decreased (P < 0.05) after sexual behavior, which included mating, compared with that in unstimulated boars (325 versus 430 pg ml -1). Relaxin levels did not decrease significantly within 48 h after castration of boars at 90, 115, 160 and 200 days of age. Although hCG treatment significantly increased and maintained high plasma concentrations of testosterone during 54 h compared d with diluent-treated controls, circulating relaxin concentrations remaine consistently low. These studies revealed no striking hormone dependent effects on relaxin production and secretion in the boar.