Indirect determination of stallion sperm capacitation based on esterase release from spermatozoa challenged with lysophosphatidylcholine.

The research outlined in this paper details how the level of stallion sperm capacitation can be indirectly determined through measuring the amount of esterase that is released from spermatozoa when introduced to lysophosphatidylcholine. This method could potentially offer a more efficient way to capacitate stallion sperm for in vitro fertilization procedures.

Research Method

• The authors developed a spectrophotometric assay – an analytical procedure used to measure quantities of substances. This was used to measure the amount of esterase (an enzyme) released from stallion spermatozoa.
• The potency of a spermatozoon (male germ cell) to fertilize an ovum is determined by its capacitated state. Capacitation refers to the physiological changes sperm undergo to be able to penetrate and fertilize an egg.
• The assay was then engaged to ascertain the percentages of capacitated stallion sperm. The presence off capacitation was gauged by the spermatozoa’s ability to endure an acrosome reaction and let out esterase in response to challenge from lysophosphatidylcholine. The acrosome reaction is a step in the biological process of sperm fusing with eggs.

Findings

• The conditions under which the spermatozoa were incubated were set up to increase the levels of intracellular calcium and cAMP; compounds which induce sperm capacitation.
• During the first experiment, when induced with 100 nmol calcium ionophore A23187 l(-1), 66% of the stallion spermatozoa capacitated after an hour of incubation at 37 degrees Celsius.
• The impact of increased cAMP concentrations on stallion spermatozoa was then evaluated. It was observed that when A23187 was combined with isobutyl-methylxanthine (IBMX), a molecule that prevents cell division and thereby increases cAMP levels, the spermatozoa capacitated after a period of 240 minutes.
• However, when a combination of A23187, 8-bromo cAMP and IBMX was used, the spermatozoa capacitated in a much quicker timeframe of 40 minutes at the same temperature.

Implications

• The researchers argue that the treatment of spermatozoa with a combination of compounds known to increase intracellular calcium and cAMP could offer an effective method to capacitate stallion sperm in preparation for in vitro fertilization procedures.