Measurement of redox potential and steroid concentrations in the follicular fluid of growing and regressing follicles of mares

Abstract

The aim of this study was to prove if oxidation-reduction levels in the follicular fluid were new functional indices of follicular health and whether there was a high level of accordance with endocrinological parameters and with the growth stage as detected by ultrasound monitoring of individual follicles during the oestrous cycle in mares. Follicles were classified as growing and regressing follicles using ultrasonography. Altogether 48 follicles with a diameter from 20 to 56 mm were aspirated by transvaginal ultrasound guided follicular aspiration. Follicular concentration of oestradiol and progesterone in relation to the diameter of growing follicles showed correlations of r = 0.64 and r = 0.57, respectively. The redox potential derived index D2 varied from -448 to +431 in the collected fluids of the follicles. The accordance of the judgement of all follicles using both complexes of methods - endocrinological and ultrasonographic parameters vs. analysis of oxidation and reduction levels - reached 72.5%. This finding has shown that parameters of redox reactions do not correlate closely with the stage of follicular growth or regression as determined by in vivoscanning of ovaries or by assessment of follicular steroid concentrations. However, the measurement of redox potentials offers an opportunity to examine the whole process of metabolism in follicular cells and to forecast impairments of cellular performances. Changes of redox parameters in growing follicles enable an earlier prediction of their further development. The data demonstrate that growing and regressing follicles do not represent nonatretic, early atretic and atretic follicles, respectively.