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Determination of glycosidase activity in porcine oviductal fluid at the different phases of the estrous cycle

L Carrasco, Physiology, University of Murcia, Murcia, Spain
R Romar, Physiology, University of Murcia, Murcia, Spain
M Aviles, Cellular Biology and Histology, University of Murcia, Murcia, Spain
J Gadea, Physiology, University of Murcia, Murcia, Spain
P Coy, Physiology, University of Murcia, Murcia, Spain

Correspondence: Raquel Romar, Email: rromar{at}um.es

Abstract

Sperm-oocyte binding and gamete-oviductal epithelium interactions are carbohydrate mediated events occurring in the oviductal fluid (OF). Thus, knowledge about the activity of glycosidases (enzymes catalyzing hydrolytic cleavage of terminal sugar residues) in this milieu would help our understanding of the molecular mechanisms involved in these events. This work was carried out to investigate the glycosidase activity, protein content and volume of OF collected from gilts and sows. Oviducts were classified into four phases of the estrous cycle (early follicular, late follicular, early luteal and late luteal) based on appearance of the ovaries. Oviductal fluid was aspirated, centrifuged, measured for volume and frozen until assay. Substrates conjugated to 4-methylumbelliferyl were used to screen the activity for seven different glycosidases at physiological pH (7.2). -L-fucosidase and β-N-acetyl-glucosaminidase activity increased at the late follicular phase to decrease after ovulation. β-D-galactosidase, -D-mannosidase and β-N-acetyl-galactosaminidase showed the higher activity at the early follicular phase decreasing after ovulation. N-acetyl-neuraminidase and -D-galactosidase did not show activity at any phase of estrous cycle neither in sows nor in gilts at pH 7.2, although it did at acidic pH (4.4) in follicular and luteal phase samples. Total protein also changed during the cycle showing the maximum secretion at late follicular phase (2118.57 ±200.65 µg/oviduct). Highest volumes of OF were collected from oviducts at late follicular phase (50.62 ± 1.26 µl/oviduct). These results indicate that OF from sows and gilts shows glycosidase activity varying throughout the estrous cycle suggesting a role of these enzymes in carbohydrate-mediated events.