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第4日　5月18日（金）　　ポスター会場

4P-04　　PDF

セロトニンによる精子超活性化の調節機構について

(獨協医大)
^o藤ノ木政勝

After ejaculation, mammalian sperm are transported to the female reproductive organs and begin to be capacitated. In the oviduct, sperm are capacitated and exhibit hyperactivation. Hyperactivation creates the propulsive force for swimming in the viscous oviductal fluid and for penetrating the zona pellucida. Recently, I have reported that serotonin affected hyperactivation^{1, 2)}. Serotonin acts through 5HT receptors. 5HT receptors are G-protein coupled receptors and affect adenylyl cyclase (AC) or phospholipase C (PLC).
In this study, I showed regulatory mechanisms of serotonin-enhanced hyperactivation in hamster sperm. Serotonin stimulated a PLC through a 5HT₂ receptor and introduced activation of sAC. Serotonin also stimulated a tmAC through a 5HT₄ receptor. PKA was stimulated by activation of both AC.
Mammalian sperm are hyperactivated through activation of sAC and PKA. Because calcium is an activator of sAC, it seems that serotonin enhances hyperactivation through activation of sAC by increasing of calcium concentration via 5HT₂ receptor. In addition, it seems that serotonin supplies cAMP by activation of tmAC via 5HT₄ receptor in order to activate PKA and enhances hyperactivation.
1) Fujinoki et al. (2016) J Physiol Sci, 66, 207-212.
2) Fujinoki & Takei (2017) J Reprod Dev, 63, 67-74.