4 Explain the results that suggest that A23187 tr Bookmark 4

4) Explain the results that suggest that A23187 tr... Bookmark 4) Explain the results that suggest that A23187 treatment could overcome defects in signaling pathways upstream of the intracellular Ca2+ increase required for capacitation and diagram this in a sperm cell with regard to the cAMP pathway.

Solution

Ans.) A23187 treatment is basically application of Ca2+ ionophore which increases the intracellular Ca2+ concentration as a result triggers the acrosome reaction of mammalian spermatozoa. For example, sperm capacitation allows spermatozoa to proceeds the acrosome reaction and to display vigorous motility that is known as hyperactivation. At the molecular level, capacitation is triggered with activation of a cAMP-dependent pathway and also with the increase of intracellular pH and Ca2+ concentrations.

Once, the ionophore was washed away, spermatozoa recovered motility, showed hyperactivation and were ready to fertilize cumulus-intact eggs. In this condition, sperm cell acquired fertilizing capability even when the cAMP pathway is not active. Hence, it can be concluded that a short elevation of intracellular Ca2+ overcomes the required signaling pathways during capacitation and restore sperm fertile.