Effect of Dimethyl sulfoxide (DMSO) associated with Oxytocin (Carbetocin) on Collagenase Activity (in vitro) and Cervical Penetrability (in vivo) in Sheep

Cervical relaxation at insemination time is a major limitation for transcervical artificial insemination (AI) in sheep and depends on extracellular matrix (ECM) remodeling driven by matrix metalloproteinases (MMPs). This study examined the effects of dimethyl sulfoxide (DMSO) and carbetocin (Cb), a long-acting oxytocin analogue, on cervical collagenase activity in vitro and cervical penetrability in vivo. Cervical explants from follicular-phase ewes were incubated with DMSO (0-2%) with or without Cb (100 ng/mL), and gelatinase activity was assessed by zymography. In vivo, synchronized ewes received intravaginal DMSO (2%) alone or in combination with intramuscular Cb, 12 h before the expected AI time, and cervical penetrability was evaluated at 0, 42, 54, and 66 h post-eCG. DMSO at ≥0.5% increased latent MMP-2 activity in vitro, likely reflecting enhanced membrane permeability and release of intracellular pro-MMP-2. Cb produced similar increases, and the combination yielded additive effects on both latent and active MMP-2. No treatment modified MMP-9 activity. Basal MMP-2 activity was higher in the cranial than caudal cervix. In vivo, neither DMSO nor Cb improved cervical penetrability at the expected AI time. A modest, short-lived improvement occurred in the Cb+DMSO group between 42 and 54 h post-eCG. Precise timing and optimized formulation are essential for DMSO-based cervical dilation induction treatments, as DMSO alone or in combination with Cb does not consistently improve cervical penetrability despite its molecular effects on MMP-2.