GABA/progesterone-induced polyphosphoinositide (PPI) breakdown and its role in the acrosome reaction of guinea pig spermatozoa in vitro

Science in China. Series C, Life Sciences
Y Y YuanS Xu

Abstract

To investigate whether GABA/progesterone (P(4)) stimulates PPI breakdown and its role in the acrosome reaction (AR), spermatozoa of guinea pig were preincubated in MCM-LCa(2+) for 5.5 h and then labeled with [(32)P]pi for 1 h. Samples were washed through a three-step gradient Percoll, adjusted to 5x10(7) cells/mL and exposed to 2 mmol/L Ca(2+), 5 micromol/L GABA, 10 micromol/L P(4) and other agents. Lipids were separated by t.l.c. and radioactivity in spots determined by scintillation counting. The AR was assessed by phase-contrast microscopy. The results showed that (i) when spermatozoa were treated with GABA,(32)P-label diminished rapidly in phosphatidylinositol 4, 5-bisphosphate (PIP(2)), phosphatidylinositol 4-phosphate (PIP), and increased in phosphatidic acid (PA). The loss of label from PPI was almost completed by 10 min. The time-course of the AR was much slower than PPI when spermatozoa reached a maximal response by 15 min; (ii) the pattern of PPI hydrolysis and stimulation of AR was similar for the three agonists tested; their potency followed the order A23187>progesterone> or =GABA; (iii) GABA-induced PIP(2) hydrolysis and rise in PA and the AR were prevented by inclusion of 10 mmol/L neomycin; (iv) the loss of PIP(2...Continue Reading

References

Apr 1, 1997·Biology of Reproduction·M A de las HerasL J Perez
Aug 1, 1997·Molecular Human Reproduction·Q X ShiE R Roldan
Jun 30, 1998·Trends in Biochemical Sciences·M N HodgkinM J Wakelam
Apr 25, 2000·Biology of Reproduction·C PatratP Jouannet

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Citations

Jun 1, 2012·Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology·María Cecilia Gramajo-BühlerGraciela Sánchez-Toranzo
Jun 29, 2010·The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology·Daniel J FieldRobert E Shadwick

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