Axodendritic fibres of mouse cerebellar granule neurons exhibit a diversity of functional P2X receptors

Distribution and functional expression of P2X receptors were analyzed in mouse cerebellum axodendritic fibres, using different experimental approaches such as RT-PCR, western blot, immunochemistry, microfluorimetric experiments and exocytotic studies.RT-PCR and western blot demonstrated the presence of P2X1–4,7 subunits in both whole cerebellum and mouse cerebellar granule cultured neurons. Immunochemistry analysis of tissular and cellular location of P2X1–4,7 receptors confirmed their presence and unequal distribution between somas and axodendritic prolongations. Microfluorimetric experiments using a variety of modulators of the P2X subunits revealed the presence of different functional P2X receptors in the axodendritic fibres. The use of the synthetic agonist α,β-meATP and the antagonist Ip5I revealed the activation of functional P2X1 and P2X3 receptors. Responses mediated by P2X1 subunits were also confirmed by using ZnSO4. Activation of functional P2X4 receptors is observed when stimulated in the presence of ivermectin. Exocytotic studies confirmed the role of most P2X subunits in the activation of neurotransmitter release in axodendritic fibres from mouse cerebellar granule neurons.