The P2X3 receptor blocker AF-353 (Ro-4) reduces bioenergetic index of a primary mixed culture of hippocampal neurons.

In clinical studies, the purinergic receptor P2X3 is considered as a molecular target for pain correction in spinal sensory neurons by highly selective antagonists based on diaminopyrimidine derivatives. In the CNS, P2X3 receptors are involved in synaptic plasticity underlying memory and learning. Currently, potent and selective allosteric modulators of P2X3 and P2X2/3 receptors have been recognized among diaminopyrimidine derivatives. These include 5-(5-iodo-2-isopropyl-4-methoxyphenoxy)pyrimidine-2,4-diamine (Ro-4 or AF-353), gefapixant, which have a good pharmacokinetic profile and are less active with respect to a wide range of kinases, receptors, and ion channels. Although the therapeutic value of P2X3 receptor blockade in CNS neurons has not been studied, however, certain evidence exists in the literature that this receptor could represent a new target in the search for antiepileptic drugs, as well as drugs that reduce anxiety and stress. The aim of the work was to study the effect of the P2X3 receptor antagonist AF-353 (Ro-4) on the neuronal bioenergetic health index (BHI) in a primary mixed hippocampal culture. The P2X3 receptor blockade in embryonic and postnatal mouse hippocampal neuron cultures increased non-mitochondrial respiration by 27.5% and 15.8%, respectively, proton loss by 31.0% and 61.4%, and decreased basal respiration by 89% and 39% compared to the control. The neuronal BHI decrease in the postnatal culture was 68% compared to the control. The obtained results indicate the effect of AF-353 on mitochondrial respiration of a primary mixed culture of hippocampal neurons; this reveals the potential of the P2X3 receptor as a pharmacological target in hypoxic conditions of the brain.