The motility of human spermatozoa as influenced by prostasomes at various pH levels

Human semen contains several components among which spermatozoa, membranous vesicles called 'prostasomes', secreted by the prostate gland and unorgani zed material. Prostasomes possess an unusual lipid composition, contain a n umber of proteins and small molecules and have been claimed to take a part in the immune response, in seminal fluid liquefaction and in sperm motility . Since sperm may come in contact with an. acidic environment in the vagina , it may be of some interest to know whether prostasomes may affect spermat ozoon motility or may protect spermatozoa upon the exposure to an acidic mi lieu. Human semen was supplied by donors. From whole semen we collected spe rmatozoa by centrifugation and used the supernatant to prepare prostasomes (centrifugation at 105 000 g for 120 min, followed by purification step on Sephadex G 200); spermatozoa were then collected by a swim-up procedure and exposed to an acidic pH medium (from 5 to 7) in the presence or absence of : prostasomes. Spermatozoa motility was subsequently assessed with a superi mposed image analysis system (SIAS). Results indicate that the motility of spermatozoa was affected by the pH value of the medium. Acidic media reduce d the percentage of motile cells and decreased the straight line velocity o f spermatozoa (VLS). Prostasomes had a protective effect and increased the percentage of motile cells. However, they did not change the characteristic s of motility (curvilinear and straight). Prostasomes may be considered as a system for counteracting the negative effects of acidic pH values that ma y be present in the vagina after coitus. (C) Elsevier, Paris.