Linopirdine is an enhancer of the stimulus-evoked but not basal release of several neurotransmitters, including acetylcholine, dopamine, serotonin, and glutamate. It increases acetylcholine release in rat hippocampal CA1 neurons by blocking voltage-gated, calcium-activated and leak (M-type; Kv7.2/7.3; KCNQ2/3) K+ current with an IC50 value of 2.4 μM. Inhibition of M-channels is reported to result in the depolarization of CA3 pyramidal neurons and activated presynaptic voltage-gated P/Q- and N-type calcium channels, which leads to Ca2+ influx and increased neurotransmitter release. Linopirdine has been shown to produce a number of effects including EEG patterns of enhanced vigilance, induction of c-fos expression in cerebral cortex, reduction of the increase of cerebral glucose utilization induced by hypoxia, and improved performance in animal models of learning and memory. Linopirdine has also been identified as an agonist of transient receptor potential vanilloid type 1 (EC50 = 115 μM in HEK293 cells voltage clamped at -60 mV).
Blocker of KCNQ voltage-gated potassium channels; blocks KCNQ2+3/M-currents (IC 50 = 4-7 μ M) and KCNQ1 homomeric channels (IC 50 = 8.9 μ M). Augments hippocampal ACh release and is a cognitive enhancer following oral administration in vivo .
