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Effect of methyl‐β‐cyclodextrin on the acrosomal responsiveness of human sperm
Author(s) -
Cross Nicholas L.
Publication year - 1999
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199905)53:1<92::aid-mrd11>3.0.co;2-q
Subject(s) - sperm , acrosome reaction , andrology , biology , acrosome , incubation , cholesterol , endocrinology , biochemistry , medicine
Human sperm incubated in vitro gradually become capable of acrosome‐reacting in response to the agonist, progesterone (P 4 ). Loss of unesterified cholesterol is an obligatory step in the development of acrosomal responsiveness. These experiments tested the ability of methyl‐β‐cyclodextrin (MβCD) to accelerate sperm cholesterol loss and the development of acrosomal responsiveness. Incubating sperm 30 min in MβCD (2.5–10 mM) decreased sperm cholesterol by as much as 89% in a dose‐dependent fashion. MβCD caused some sperm (maximum of 16% following treatment with 5 mM MβCD) to become responsive to P 4 , and it caused a dose‐dependent increase in spontaneous acrosome reactions. The number of responsive sperm increased in the first 3 hr following their removal from MβCD. Continuing incubation to 24 hr increased the numbers of spontaneously reacted sperm and dead sperm, but not P 4 ‐responsive sperm. It appears, therefore, that up to 3 hr are required for the full expression of P 4 ‐responsiveness in cholesterol‐depleted sperm. The observed effects of MβCD are due to its cholesterol‐depleting properties, because including sufficient cholesterol with MβCD to reduce the loss of sperm cholesterol inhibited the effects of MβCD on cell viability, spontaneous acrosome reactions, and responsiveness to P 4 . MβCD accelerates the appearance of the functional stages that sperm normally pass through during incubation in vitro, reinforcing the view that cholesterol loss is an important determinant of the rate at which sperm become acrosomally responsive. Mol. Reprod. Dev. 53:92–98, 1999. © 1999 Wiley‐Liss, Inc.