An experimental study on the optimal timing of modified pharyngeal electrical stimulation for the treatment of dysphagia after stroke in rats

As a novel neuroregulatory technique, modified pharyngeal electrical stimulation (mPES) has demonstrated clinical potential in improving swallowing function. However, there is a notable lack of animal studies exploring this approach. While our previous research validated the optimal parameters for post-stroke dysphagia (PSD) in rats, it did not establish the ideal timing for initiating treatment. This study aimed to identify the optimal time for mPES treatment in the rehabilitation of PSD. Seventy-four Sprague-Dawley (SD) rats were randomly assigned to six groups: a model group, a sham group, and four mPES groups (with treatment initiated at 24 h, 72 h, 5 days, and 7 days post-modeling). All treatment groups received mPES therapy for three consecutive days. Following the intervention, swallowing function was re-evaluated using videofluoroscopic swallowing studies (VFSS), and western blotting analysis was conducted to assess the excitability of sensorimotor cortex. Compared to the model group, all mPES groups exhibited improvements in swallowing function. Among them, the group receiving treatment 72 h post-modeling demonstrated the most significant enhancements (P < 0.05). In addition, The expressions of N-methyl-D-aspartic acid receptor (NMDAR1) and Vesicular glutamate transporter 2 (Vglut2) were higher in the 72-hour group compared to the 7 day group (P < 0.05). This study concluded that mPES treatment was effective when initiated at any of the tested time points-24 h, 72 h, 5 days, or 7 days post-modeling. However, initiating treatment 72-hour post-modeling yielded the greatest improvement in swallowing function in PSD rats.