Intrinsic activation of the coagulation pathway induces mouse sciatic nerve hypoexcitability.

Background: Thrombin and its protease-activated receptor 1 (PAR1) modulate neuronal function in experimental settings, but the effects of activating intrinsic neuronal coagulation factors remain unclear. We investigated how activation of this pathway influences peripheral nerve function in an isolated mouse sciatic nerve model.

Methods: We used an ex vivo mouse sciatic nerve model to evaluate the effects of coagulation activation on neural excitability. Isolated nerves from male C57BL/6J mice were treated with Russell's viper venom factor X (FX) activator (RVV-X, 0.3 U/ml), FX inhibitor (apixaban, 1 μM), thrombin (200 U/ml), or a PAR1 antagonist (SCH 79797, 1 μM). Electrophysiological recordings assessed evoked neural responses. Thrombin and FX activity were quantified in tissue and artificial cerebrospinal fluid (aCSF). mRNA and immunofluorescence analyses localized coagulation-related components.

Results: RVV-X and thrombin treatments significantly attenuated neural responses to repeated stimulation (p < 0.0001), while apixaban and the PAR1 antagonist prevented these effects (p > 0.9999). RVV-X markedly increased thrombin activity in aCSF (p < 0.0001). mRNA and immunofluorescence analyses confirmed that coagulation-related components were primarily expressed in the paranodal region of the sciatic nerve.

Conclusions: The FX-thrombin pathway is intrinsically present and functionally active in sciatic nerves of mice. Activation of this pathway reduces neuronal excitability via PAR1, suggesting a finely tuned feedback mechanism between coagulation factors and neural function. These findings highlight the potential role of coagulation-mediated mechanisms in peripheral nerve pathologies, which may serve as biomarkers and therapeutic targets for neurological diseases.