Modulation of human sperm by follicular fluid steroid hormones

Taiwo, Benjamin Gbenro (2017). Modulation of human sperm by follicular fluid steroid hormones. University of Birmingham. Ph.D.

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Abstract

Detailed steroid hormone profiling of human follicular fluid has paved the way for research into the modulation of human sperm by physiological concentrations of follicular fluid steroid hormones. Synthetic human follicular fluid (shFF), a novel steroid hormone analogue of human follicular fluid, based upon local data, was prepared consisting of 14 different steroid hormones including progesterone.

Exposure of human spermatozoa (>2000 cells) to shFF stimulus at physiological and standard laboratory temperatures resulted in a rapid biphasic elevation in [Ca2+]i characterised by an initial transient Ca2+ influx immediately followed by a sustained elevation of [Ca2+]i for the duration of shFF exposure. A significant increase in the percentage of acrosome-reacted spermatozoa was observed in shFF-treated sperm (P<0.05) however, this was significantly lower than the % AR in spermatozoa treated with progesterone alone (P<0.01).

With regards to shFF-induced sperm kinesis, a significant reduction in selected sperm motility parameters was observed 5 minutes post-incubation with shFF (P<0.05). The study of shFF-induced chemotaxis revealed a chemokinetic effect characterised by a significant inhibition of sperm migration up a gradient of shFF (P<0.05), possibly due to ‘hyperactivated trapping’.
We conclude that the high concentration of progesterone (13.5µM) present in the shFF mixture is likely to be responsible for the biphasic sperm [Ca2+]i influx characteristic of a progesterone stimulus. However, the data obtained from the sperm kinesis and AR experiments leads us to hypothesize that the other steroid hormones present in the shFF mixture exert antagonistic effects on progesterone-mediated physiological responses in human spermatozoa.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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