Chemotactic responsiveness of human spermatozoa to follicular fluid is enhanced by capacitation but is impaired in dyspermic semen.

PURPOSE: Our purpose was to study the chemotactic responsiveness of human spermatozoa from normal and pathological semen samples to follicular fluid (FF), as well as the effect exerted by capacitation on sperm chemotaxis. METHODS: The chemotactic responsiveness of human spermatozoa to FF was tested by an accumulation assay chamber in which they were allowed to migrate through a microporous membrane and accumulate in a compartment filled with FF or control medium. The percentage of cells with hyperactivated motility among migrated sperm was objectively assessed by CASA and its relationship to the accumulation rate was studied. Single FFs were tested with single normospermic or dyspermic semen samples; the same FF was tested with different semen specimens. The influence of capacitation onto the chemotactic responsiveness to FF was investigated by comparing the accumulation rate of spermatozoa from normal and pathological samples after incubation under capacitating conditions for 1 or 6 hr. RESULTS: Some FFs ("active" FFs) effectively attracted human spermatozoa from normospermic samples up to a dilution factor of 1:500 (v:v) with control medium. A wide range of responses was observed when the same FF was tested with different normal semen samples. A longer time under capacitating conditions increased both the chemotactic responsiveness of normal semen and its ability to undergo the acrosome reaction (AR) in response to A23187. Pathological semen had an impaired chemotactic responsiveness to "active" FF that was not enhanced by increasing the time spent under capacitating conditions. Dyspermic semen was also less responsive to A23187, a finding suggesting incomplete capacitation. CONCLUSIONS: Chemotactic responsiveness to FF is acquired in parallel to or as part of the capacitation process. Dyspermic semen samples have an impaired capacity to achieve both capacitation and chemotactic responsiveness to follicular factors.

Effects of the neuropeptide Y on estradiol and progesterone secretion by human granulosa cells in culture.

OBJECTIVE: To investigate the possible effects of neuropeptide Y on steroid release by human granulosa cells in culture. DESIGN: Prospective study. SETTING: A university laboratory and the division of obstetrics and gynecology in a hospital. PATIENT(S): Sixteen normally ovulating women. INTERVENTION(S): Ovulation induction for IVF-ET with an LH-releasing hormone analogue and gonadotropins. MAIN OUTCOME MEASURE(S): E2 and progesterone were assayed in the media conditioned by granulosa cells with the use of a double-antibody RIA. RESULT(S): Neuropeptide Y stimulates E2 production in a dose-dependent fashion. Preincubation for 3 hours with hCG led to a statistically significant increase in neuropeptide Y-induced E2 secretion. In contrast, whereas 3 hours of preincubation with 10(-7) mol/L of neuropeptide Y did not elicit a statistically significant increase in hCG-induced E2 secretion, coincubation for 48 hours significantly increased hCG-stimulated secretion. Unlike E2, progesterone secretion did not undergo any statistically significant or dose-dependent variation after treatment with neuropeptide Y. CONCLUSION(S): Neuropeptide Y plays a role in human ovarian steroidogenesis directly at the level of the granulosa cells of the follicles in the early stage of luteinization. In this way, neuropeptide Y could play an important role in controlling the positive feedback effect exerted by the ovarian steroids on LH-releasing hormone and gonadotropins in humans.