Identification of Cyclo(His-Pro)-Like Immunoreactivity in Human Follicular Fluid

Abstract

OBJECTIVE: The purpose of this study was to evaluate human follicular fluid (FF) for the presence of cyclo(His-Pro)-like immunoreactivity (CHP-LI). After verifying its presence, we quantitated the levels and investigated correlations with other follicular parameters, including hormone levels.

METHODS: Follicular fluid was collected from female volunteers undergoing controlled ovarian hyperstimulation. Fluid was collected by follicular puncture, either transvaginally (in vitro fer tilization) or laparoscopically (gamete intrafallopian transfer) at the time of oocyte retrieval (N = 137). Follicular size was determined ultrasonographically. Assays for steroid and peptide hor mones were determined with commercially available radioimmunoassay kits. CHP-LI was mea sured using a previously reported assay; parallel dilution curves and column chromatography aided in immunoidentity.

RESULTS: The mean FF CHP-LI concentration (13.10 ± 1.83 nmol/L; N = 137) was greater than the corresponding serum values (9.42 ± 2.45 nmol/L; N = 21) (P < .05). Large follicles (20 mm or greater; 14.45 ± 1.74 nmol/L) contained significantly more CHP-LI than either medium follicles (16-19 mm; 11.51 ± 1.88 nmol/L) or small follicles (15 mm or smaller; 10.83 ± 2.12 nmol/L) (P < .05). Positive correlations were found between FF CHP-LI values and corresponding FF progesterone and prolactin concentrations (r = 0.67 and 0.62, respectively; P < .05).

CONCLUSION: Mean CHP-LI levels in the FF are greater than those in the corresponding serum. We suggest that the neuropeptide may be originating from either peptidase cleavage of precursor peptides or from granulosa cell production. (J Soc Gynecol Invest 1994;1:220-4)

Keywords

Cyclo(His-Pro)follicular fluid oocyte progesterone prolactin.

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