1997 Fiscal Year Final Research Report Summary
A Study of sperm fertilizing ability and intracellular calcium.
| Project/Area Number |
07671769
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Obstetrics and gynecology
|
|---|
| Research Institution | Tokyo Medical and Dental University |
|---|
Principal Investigator |
SHIMIZU Yasufumi TMDU,Faculty of Medicine, Assistant, 医学部, 助手 (80242197)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ASO Takeshi TMDU,Faculty of Medicine, Prof., 医学部, 教授 (60093176)
KUBOTA Toshiro TMDU,Faculty of Medicine, Assoc.Prof., 医学部, 助教授 (50126223)
KOI Hideki TMDU,Faculty of Medicine, Assistant, 医学部, 助手 (20280969)
|
|---|
| Project Period (FY) |
1995 – 1997
|
| Keywords | sperm / fertilizing ability / calcium / signal transduction / progesterone / prostaglandin / follicular fluid |
|---|
| Research Abstract |
1. Progesterone, prostaglandin and follicular fluid are reported to enhance the acrosome reaction through the influx of extracellular calcium into the cytoplasm of human spermatozoa. Prostaglandins are present within the male reproductive tract, and high concentrations of prostaglandins exist in seminal fluid, In order to investigate the mechanisms by which prostaglandins enhance the acrosome reaction through calcium influx, the intracellular calcium response induced by progesterone, prostaglandinEl, prostaglandinE2 and follicular fluid was measured using fura-2. ProstaglandinEl and prostaglandinE2 promoted calcium influx dose dependently through dihydropyridine insensitive calcium channels. Refractoriness of the elevation of intracellular Ca concentration ([Ca^2^+]i) to a second stimulus occurred when 6Omug/ml prostaglandinEl or 1mug/ml progesterone was administrated 100 seconds after the prior administration. Refractoriness also occurred when 6Omug/ml prostaglandinEl was administrate
… More
d after the prior addition of 6Omug/ml prostaglandinE2, but did not occur between prostaglandinEl and progesterone. Pertussis toxin(PTX) did not modify the changes in [Ca^2^+]i after the addition of prostaglandinEl or prostaglandinE2. In conclusion, prostaglandinEl and prostaglandinE2 promoted calcium influx through PTX-insensitive calcium channels which appeared to be recognized by a common receptor different from that of progesterone.
2. The increase of [Ca^2^+]i induced by follicular fluid or progesterone promotes an acrosome reaction in human sperm. We previously reported that sperm from infertile men with abnormal morphology exhibited lower mean peak progesterone-evoked [Ca^2^+]i than morphologically normal sperm by cell-suspension methods. In this study, the change of [Ca^2^+]i induced by human follicular fluid in individual normally and abnormally shaped spermatozoa was compared. [Ca^2^+]i of normally shaped spermatozoa increased rapidly after the administration of human follicular fluid. The response reached a peak within 2-3 seconds and then slowly declined to the plateau phase. The fluorescence of baseline and peak of the spermatozoa with abnormal morphology was lower when compared with normal sperm. Follicular fluid-induced [Ca^2^+]i increase (expressed as percent increase of [Ca^2^+]i over basal) in abnormal shaped sperm was 7.1*6.4%(n=22), smaller than that of normally shaped sperm(20.5*24.0%, n=46. p<0.05). Moreover, the spatial distribution of the increase of [Ca^2^+]i in single sperm was investigated. The increase in [Ca^2^+]i was observed only in the head of spermatozoon, and there was no [Ca^2^+]i increase in the sperm tail. This study raises the possibility that spermatozoa with abnormal morphology have disorders of signal transduction leading to an impaired acrosome reaction, which result in infertility. Less
|
