180 FATTY ACID COMPOSITION IN FOLLICULAR FLUID OF PREPUBERTAL GOAT OVARIES IN WINTER AND AUTUMN

Abstract

Fatty acids (FA) in follicular fluid (FF) play an important role on oocyte quality and embryo development (Fouladi-Nashta et al. 2007 Biol. Reprod. 77, 9–17). In our laboratory, we have shown in prepubertal goat differences in the percentage of blastocysts produced in vitro according to season. Thus, we have found in winter 15.8% and in autumn a decrease up to 4.7% of blastocysts that were produced from oocytes of 1 month old suckling Murciano-Granadina goat females and IVF with fresh semen. The aim of this study was to analyse composition of FF in order to find an explanation to seasonal changes in in vitro embryo production. Ovaries were recovered in winter and autumn from 1 month suckling goats (Murciano-Granadina) from a local slaughterhouse and the FF of all visible follicles was recovered using a sterile syringe. Each sample containing a pool of FF of different ovaries was frozen at –80°C until chromatography analysis. For the FA analysis, the Sukhija and Palmquist (1988 J. Agric. Food Chem. 36, 1202–1206) protocol with some adaptations was used. Briefly, 200 μL of FF sample was vortexed for 60 s with 250 μL of toluene and 1 mL of HCL (5%) and then warmed in a water bath for 1 h at 70°C. Subsequently 1.25 mL of K₂CO₃ (12%) and 500 μL of toluene was added, vortexed for 30 s and centrifuged for 5 min (3000 rpm). Finally the supernatant was recovered and dried with Na₂SO₄. The extracted samples were maintained in –20°C until gas chromatographic analysis (123–2362, Agilent Technologies Inc., Santa Clara, CA). The results in Table 1 express the mean of 3 replicates of follicular fluid pool as micromolar concentration of FA in FF. The FA profile in FF showed significant higher concentrations of α-linolenic (C18:3n3), eicosapentaenoic (EPA), docosahexaenoic (DHA), and omega-3 (n-3 polyunsaturated fatty acid; PUFA) in winter compared to autumn. This could be indicating that these PUFA have a positive effect on oocyte quality because of the higher embryo development of these oocytes during winter. Studies in our laboratory have shown that sperm penetration and normal zygotes were similar in both seasons even though the blastocyst yield was statistically higher in winter. We can speculate that fatty acids in the follicular environment are affecting the oocyte quality, increasing the possibility of reaching the blastocyst stage in prepubertal goat according to season. Further studies should be done to reach a more accurate conclusion.

Table 1.  Concentration (µM) of fatty acids in FF of prepubertal goat during winter and autumn (3 replicates)