Plasma levels of C-reactive protein, leptin and glycosaminoglycans during spontaneous menstrual cycle: differences between ovulatory and anovulatory cycles

Abstract

To assess the plasma levels of the inflammatory markers such as C-reactive protein (CRP), leptin, and glycosaminoglycans (GAGs) during the menstrual cycle. Eighteen healthy volunteers were divided into two groups according to the presence of ovulatory or anovulatory menstrual cycles. Blood samples were collected at different time points: at the menstrual phase (days 2-3), periovulatory phase (days 12-13), and luteal phase (days 23-24). CRP and leptin concentrations were measured by enzyme immunoassay. GAGs were isolated using ion-exchange chromatography on DEAE-Sephacel and quantified as hexuronate. The structural characterization of chondroitin sulfate (CS) isomers was performed by fluorophore-assisted carbohydrate electrophoresis (FACE). In the women with ovulatory cycles, plasma GAG levels differed significantly during menstrual cycle, with increased values at the periovulatory with respect to the menstrual phase. No significant differences in CRP and leptin concentrations were observed through the menstrual cycle in both the examined cycles, but inter-group analysis revealed significant differences of CRP and leptin levels between the ovulatory and anovulatory cycles with higher values at periovulatory phase in the ovulatory cycles. There are no fluctuations of both total GAG concentration and CS isomer content during menstrual cycle in the anovulatory cycles. A significant correlation between CRP and gonadotrophins was found. There is no significant difference in CRP across the menstrual cycle among ovulatory cycles, but there is a trend toward higher CRP at the periovulatory than the other phases, consistent with the significant difference in CRP between ovulatory and anovulatory cycles at the periovulatory phase. Both the trend and the significant result suggest an elevation in CRP with ovulation. These observations provide additional evidences to the hypothesis that the ovulation is an inflammatory-like phenomenon.