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The response of human spermatozoa to chemoattractants

Morales Garcia, Auden Andres (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

The effect of the chemoattractant bourgeonal on [Ca\(^{2+}\)]i and chemotaxis in human sperm was investigated. Burgeonal induced a dose-dependent, slowly-developing tonic elevation in [Ca\(^{2+}\)]i, The response was dependent on capacitation. In low-Ca\(^{2+}\) or EGTA-buffered saline the response to bourgeonal was inhibited. Pretreating spermatozoa with bis-phenol (20μM) to release stored Ca\(^{2+}\) did not alter the response. Thus bourgeonal acts primarily by inducing Ca\(^{2+}\) influx. Treatment of sperm with bourgeonal caused an increase in [cAMP]. When cells were pretreted with bourgeonal in low-Ca\(^{2+}\)saline, subsequent introduction of Ca\(^{2+}\) resulted in a single, large [Ca\(^{2+}\)]i transient in >75% of the cells, indicating that sudden influx of Ca\(^{2+}\) caused closure of the bourgeonal-sensitive Ca\(^{2+}\)- channel. This negative feedback was not modulated by IBMX (1mM) or dbcAMP (1mM), indicating that cAMP was not involved and that a direct action Ca\(^{2+}\) was more likely. Both Ni\(^{2+}\) (10μM) and La\(^{3+}\) (100μM) inhibited the action of bourgeonal on [Ca\(^{2+}\)]i, suggesting a possible role of CNG channels. Exposing sperm to a temporal bourgeonal gradient caused a series of transient [Ca\(^{2+}\)]i elevations in >20% of the cells. A gradient of progesterone (another characterised chemoattractant for human sperm) induced similar Ca\(^{2+}\) oscillations (in >20% of the cells), which increased in amplitude and frequency in response to the increasing progesterone concentration. Human spermatozoa responded chemotactically to a 1nM bourgeonal gradient, Chemotaxis was dependent on capacitation. The response was inhibited in low [Ca\(^{2+}\)]o but was unaltered by TMB-8 (an inhibitor of stored Ca\(^{2+}\) store release), thus showing a dependence on Ca\(^{2+}\) influx similar to the [Ca\(^{2+}\)]i signal.

Type of Work:Ph.D. thesis.
Supervisor(s):Publicover, Stephen J.
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QH301 Biology
Institution:University of Birmingham
ID Code:630
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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