Effect of inflammation on the fertilizability of spermatozoa exposed to gamma-rays

Research Project

Project/Area Number	18K11637
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 63020:Radiation influence-related
Research Institution	Obihiro University of Agriculture and Veterinary Medicine
Principal Investigator	WATANABE Hiroyuki 帯広畜産大学, 畜産学部, 講師 (90608621)
Project Period (FY)	2018-04-01 – 2022-03-31
Project Status	Completed (Fiscal Year 2021)
Budget Amount *help	¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000) Fiscal Year 2021: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000) Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000) Fiscal Year 2019: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Keywords	精子形成 / 炎症 / 放射線 / DNA損傷 / 受精 / 受精能 / 精子 / 精子の運動パターン / 精子運動性
Outline of Final Research Achievements	In this study, analyses of motility and DNA integrity of sperm collected from male mice after γ-ray irradiation were performed. In addition, the effect of inflammation during spermatogenesis on the viability of germ cells and sperm characteristics was investigated. Irradiation with γ-ray to the neonatal mice (2-14 days of age) affected DNA integrity of sperm, whereas there was no effect on the sperm motility. When the oocytes were fertilized in vitro with spermatozoa collected from male mice that were induced continuous inflammation by LPS administration, the rate of fertilization was lower than that of IVF eggs in the control group. Embryonic development of IVF eggs using LPS-administrated male was also impaired after the 4-cell stage. These results demonstrated that spermatozoa derived from male mice irradiated with γ-ray at the neonatal stage accumulated DNA damages. There was a possibility that continuous inflammation in testis decreased the fertilizability of spermatozoa.
Academic Significance and Societal Importance of the Research Achievements	これまで放射線の影響はDNA損傷に起因する細胞死に主眼が置かれ論じられてきた。一方、予備研究において、新生仔期にγ線を照射した雄マウスから回収した精子を体外受精に使用したとき、受精率が低下することが明らかとなった。本研究課題では、γ線照射後に生産された精子に生じた変化を特定し、γ線照射時に起きる炎症が精子の受精能やその後の胚発生能に及ぼす影響を明らかにした。これら一連の成果は雄性生殖細胞が被る放射線影響の発生機序の解明に繋がると期待される。