Prostaglandins in rainbow trout (Oncorhynchus mykissWalbaum, 1792) sperm biology - searching for answers

Abstract

Summary The purpose of this study was to determine the concentrations of prostaglandins E2 and F2α (PGE2 and PGF2α) in the blood, testis and seminal plasma of mature male rainbow trout and in the ovarian fluid to assess the effects of these prostaglandins on sperm motility parameters when present in activation media. Also prolonged incubation with prostaglandins on sperm motility and calcium influx were studied. The profile of PGE2 and PGF2α differed in concentration between blood, testicular supernatant and seminal plasma. PGE2 was predominant in the blood sample (0.29 ng ml−1) and testicular supernatant (3.1 ng ml−1) whereas their level in seminal plasma was lower than PGF2α (0.23 ng ml−1). The concentrations of PGF2α in blood, testis and seminal plasma were 0.04, 0.99, 1.3 ng ml−1, respectively. In the ovarian fluid the concentrations of both prostaglandins were higher than in the male reproductive tract. Adding both prostaglandins to activation buffer (at concentrations 15 and 70 ng ml−1) had no effect on any CASA parameters. Calcium influx related to rainbow trout sperm incubations with PGE2, and PGF2α was not detected. After 24 h incubation of sperm in artificial seminal plasma solution without and with prostaglandins all sperm samples increased their motility potential and intracellular calcium concentration. Therefore, this effect was not related to the presence of prostaglandins. In summary PGE2, and PGF2α were present in the rainbow trout male reproductive tract, and their profile varies from that of blood, testis and seminal plasma. The specific role of both prostaglandins in salmonid sperm biology remains unclear.