ATP cooperating with the P2 purinoceptors plays a role of neurotransmitter in the CNS. Both types of these purinoceptors (P2X and P2Y) are present in CNS. These receptors are found in all structures of the brain, but the P2X to P2Y ratio is characteristic for every structure. This ratio might change during the development and maturation of the brain structures. The special role in CNS is played by P2X purinoceptors, which are the ion channels characterized by low selectivity and fast transmission. On the other hand, the action of P2Y purinoceptors is mediated by the G proteins.