The aim was to study the effect of 4-phenylfuroxan-3-carbonitrile (Fx), a NO-releasing agent, and carbetocin, an oxytocin receptor agonist, on matrix metalloproteinases-2 (MMP-2) activity and PGE2 production in cervix from cycling sheep. Cervical explants were incubated during 12h with MEM supplemented with increasing concentrations of Fx in DMSO (2%) (0 to 300μg/mL) with Cb (100ng/mL) (Experiment 1, n=15) and DMSO (2%), DMSO+Cb (100ng/mL) or DMSO+Fx (30μg/mL) (Experiment 2, n=10), and their respective controls. In the supernatants, activated (A) and latent (L) MMP-2 activities were determined by a SDS-PAGE zymography, PGE2 concentration by immunoassay and NO production indirectly as nitrites by spectrophotometry. Data were analyzed by ANOVA. The Cb treatment increase the A MMP-2 activity in DMSO (Experiment 1 at follicular phase and Experiment 2) or alone (Experiment 2) and increase the L MMP-2 activity (Experiments 1 and 2) (P<0.02). The DMSO treatment also increase the L MMP2 activity (Experiment 2) (P<0.0001). Treatment with Fx+DMSO increased the concentration of accumulated nitrites in the supernatant (P<0.0001) (Experiment 1), but did not affect or decrease the activity of A and L MMP-2 (P<0.04) (Experiments 1 and 2). The PGE2 concentration trend to increase with Cb treatment (P=0.0614) and decrease with Fx+DMSO treatment (P<0.0001) (Experiment 2). In conclusion, Cb and/or DMSO treatment of cervical explants increase the MMP-2 activity through PGE2-independent mechanisms, but Fx in DMSO fail in this, suggesting that the pre-treatment with Cb and/or DMSO could be used to increase cervical dilation in ewes.
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