Comparative Neuropharmacological Effects of Antiseizure Drugs on Cultured Myenteric and Dorsal Root Ganglion Neurons.

Background/Objectives: Antiseizure drugs (ASDs) are the primary therapeutic approach for epilepsy in small animals. Although ASDs are primarily used to modulate central neuronal excitability, they are commonly administered systemically, most often by the oral route, and may therefore influence neuronal populations outside the central nervous system. Nevertheless, their functional effects on peripheral neuronal populations, including enteric and dorsal root ganglion (DRG) neurons, remain incompletely characterized at a comparative pharmacological level. This study aimed to perform a comparative functional neuropharmacological profiling of commonly used ASDs in primary cultured myenteric and DRG neurons. Methods: Changes in neuronal activity were assessed in primary cultured guinea pig myenteric and DRG neurons using voltage-sensitive dye imaging with Di-8-ANEPPS following direct ASD application under standardized in vitro conditions. Results: ASDs exerted distinct drug- and neuron-type-specific effects on peripheral neuronal excitability. Topiramate induced the most pronounced reduction in neuronal excitability in myenteric neurons, whereas phenobarbital and levetiracetam produced only minor changes compared with buffer control. Potassium bromide induced mainly excitatory effects in both enteric and DRG neurons. Overall, most ASDs predominantly increased neuronal excitability in DRG neurons. Conclusions: These findings demonstrate distinct functional response profiles of ASDs in enteric and sensory neuronal populations. This comparative in vitro approach may provide a basis for future studies investigating peripheral neuronal drug effects and may help relate experimental pharmacological profiling to clinically relevant challenges associated with ASD treatment across different disorders.