P2Y13 receptor is one of the most recently identified nucleotide receptor on neurons.303 Like P2Y1 and P2Y12, P2Y13 receptor belongs to a group of P2Y receptors responding to endogenous nucleotides ADP.304 P2Y13Rs are specifically present in cerebellar astrocytes, microglia, and granule neurons where they, and not the P2Y1 receptors, participate in the ADP-evoked calcium responses with P2Y13 expression higher in microglia than in the astrocytes.305 In granule neurons, P2Y13 receptors have been coupled to PI3K/Akt pathway that prevents neuronal death.304 Additionally, P2Y13-mediated ERK1/2 signaling has shown to trigger activation of CREB, suggesting an antiapoptotic act of the P2Y13 receptor against glutamate neurotransmitter toxicity.304 P2Y13 receptors are implicated in the release of acetylcholine from synapses and play key roles in neuronal cell differentiation and axonal elongation.305,306
