Amitriptyline modulates calcium currents and intracellular calcium concentration in mouse trigeminal ganglion neurons

Migraine is increasingly recognized as a channelopathy, and abnormalities of voltage-activated ionic channels could represent the molecular basis for the altered neuronal functioning. The high-voltage-activated (HVA) Ca(2+) channels in the trigeminovascular system play a role in the pathophysiology of migraine. In the present study, effects of amitriptyline (AMT), a commonly used migraine prophylactic drug, on the HVA calcium currents (I(Ca)) were examined in mouse trigeminal ganglion neurons using whole-cell patch clamp technique. AMT produced concentration- and use-dependent inhibition of HVA I(Ca). Bath application of GÖ-6983 (a selective protein kinase C inhibitor) or H89 (a protein kinase A inhibitor) did not reduce the AMT-induced inhibition of HVA I(Ca). A similar inhibition was observed when calcium imaging was used to directly monitor the effects of AMT on KCl-induced increments of intracellular Ca(2+) concentration ([Ca(2+)](i)). By blocking HVA Ca(2+) channels and Ca(2+) entry into cells, AMT could prevent the release of neurotransmitters and help restore the neuronal threshold for excitation. Our findings suggest interesting therapeutic mechanisms for AMT in migraine prevention.