P 2 purinergic receptors for diadenosine polyphosphates in the nervous system

Abstract

1. 1. The actions of diadenosine polyphosphates, diadenosine tetraphosphate (Ap 4A), diadenosine pentaphosphate (Ap 5A) and diadenosine hexaphosphate (Ap 6A) in the nervous system have been reviewed. 2. 2. In the peripheral nervous system, diadenosine polyphosphates bind to P 2Y-purinergic receptors such as the P 2Y in chromaffin cells and Torpedo synaptosomes, P 2X in vas deferens and urinary bladder and also Torpedo synaptosomes and P 2U in endothelial chromaffin cells. 3. 3. In the central nervous system Ap nA compounds can act through P 2X-purinoceptors opening cation channels in nodose ganglion neurones. Diadenosine polyphosphates bind to a P 2d-purinergic receptor in rat brain synaptic terminals and hippocampus, linked to protein kinase C (PKC) activation. 4. 4. P 4-purinoceptors are specific receptors for diadenosine polyphosphates, coupled to the Ca 2+ influx, in the central synapses. This purinoceptor is not activated by ATP and synthetic analogs. The P 4-purinoceptor could act as a positive modulator of the synaptic transmission, giving even more importance to diadenosine polyphosphates as neurotransmitters.