Elucidating the Mechanism of Action of Pregabalin

This review provides a brief summary of what is known about the anxiolytic mechanism of action of pregabalin, a highly selective, high-affinity ligand of the P/Q type of voltage-gated calcium channel (CaV). Evidence from in vivo models of neuronal hyperexcitability suggests that pregabalin reduces synaptic release of neurotransmitters in selected CNS regions including the cortex, olfactory bulb, hypothalamus, amygdala, hippocampus, cerebellum and dorsal horn of the spinal cord. Release of neurotransmitters from the synaptic vesicle, and propagation of neurotransmission, requires the vesicle to fuse with the presynaptic membrane. Pregabalin binding to the α₂δ type 1 protein of the P/Q type CaV reduces the availability of Ca²⁺ required for membrane fusion and exocytosis of neurotransmitters. Evidence that the anxiolytic mechanism of action of pregabalin is mediated by binding to the α₂δ type 1 protein comes from animal models, which have demonstrated a structure-activity relationship between the affinity of ligands for the α₂δ type 1 protein and their potency in models of anxiety such as the Vogel conflict test. Furthermore, the anxiolytic activity of pregabalin is lost in transgenic mice with specific point mutations in the CaV α₂δ type 1 protein. Pregabalin-mediated reduction in calcium currents has also been shown to result in a significant inhibition of the release of neurotransmitters implicated in pa-thological anxiety such as glutamate and monoamine neurotransmitters. However, further research is needed to confirm that these effects contribute to the anxiolytic mechanism of action of pregabalin. Finally, pregabalin may also act by inhibiting synaptogenesis of excitatory neurons formed in response to chronic stress or anxiety, or more acutely inhibit the trafficking of CaV to the plasma membrane.