TUMOR NECROSIS FACTOR ALPHA MODIFIES THE CILIARY BEAT FREQUENCY (CBF) OF OVIDUCTAL CILIATED, THROUGH THE PROSTAGLANDINS AND THE NITRIC OXIDE PATHWAY

Abstract

Mucociliary transport (MCT) is a mechanism that is responsible for the movement of gametes and embryos through the oviduct and serves as physical barrier in the epithelium, to prevent microorganisms invasion. The rate of MCT depends on the ciliary beat frequency (CBF) of ciliated cells of the epithelium. The CBF is regulated by several molecules that are secreted by gametes, embryos or even the epithelium itself, such as ATP, prostaglandins (PG) and nitric oxide. ATP and PG increased the CBF, while NO antagonized this effects, in this system. Other molecule that is secreted by the oviductal epithelium is Tumor Necrosis factor-a (TNFα). High concentrations of this molecule are produced in pathological conditions, causing sloughing of ciliated cells. By the other hand, in physiological conditions TNF is present at low concentrations in the oviductal fluid. Although, in the oviduct there is no evidence about control of CBF by TNFα and the impact on the MTC. In others ciliated epitheliums, TNFα modifies the CBF, effects that are mediated by the nitric oxide pathway. In the oviduct, however there is no evidence about NO production in response to TNFα, but it was established that this molecule induce the synthesis of PG by the epithelial cells. The main goal of this work was to determine the concentration-dependent effect of TNFα, over the CBF in the rat oviduct, and the involvement of prostaglandins and nitric oxide pathways in this effect. Methods: Using microphotodensitometric analysis of primary cultured rat oviductal ciliated cells, we determined changes in CBF in response to TNFα, (0,01-100 ng/ml), in the presence or absence of an inhibitor of arachidonic acid release (AACOCF3 50 μM), an inhibitor of prostaglandins (Indometacin 100 μM), and nitric oxide (L-NAME 100 μM) production. Results: TNFα, in a concentration range of 0,1–10 ng/ml increased the CBF, while concentrations of 50 and 100 ng/ml did not affect the CBF. The concentration-response curve fit to a biphasic curve, with an ascending EC50 of 6,123 × 10−12 M (0,1 ng/ml) and a descending EC50 of 2,03 × 10−9 M (36 ng/ml). The increase in CBF observed with TNFα, 1 ng/ml is inhibited in the presence of AACOCF3 and Indometacin, while TNFα 50 ng/ml in the presence of L-NAME, increased CBF in a similar way as TNFα, 1 ng/ml. Conclusion: TNFa show a biphasic effect on the CBF that is concentration-dependent. The ascending phase of the CBF, observed at low concentration of TNFα, seems to be PG–dependent, while the nitric oxide pathway seems to be involve in the descending phase of CBF, observed at higher concentrations of TNFα, suggesting that nitric oxide pathway, is a negative regulator of the CBF, at this conditions. Our results suggest that TNFα, may have dual effects on the CBF and the MCT in the oviduct. FONDECYT 1040804. (poster)