Purinergic Signalling (2012) 8 (Suppl 1):S61–S79 SY5Y and identified the P2Y6 receptor as a novel potential target in anti-tumoral therapies. This work investigated the role of the P2Y6 receptor using anti-P2Y6 receptor antibody in Western blot analysis and immunofluorescence micros- copy. The in vitro results contribute to expand the general knowledge about the P2Y6 receptor and to possibly identify its manipulation as a strategy for the understanding and potential relapse of neuroblastoma. P2Y receptors in the spinal cord Under normal conditions, pain is associated with electrical activity in small-diameter fibers of dorsal root ganglions (DRG) of the spinal cord. All subtypes of the P2Y receptor family are widely expressed in different parts of the nervous system. The activation of P2Y receptors causes blockade of the N-type calcium channels in DRG cells. This effect may decrease the release of glutamate from DRG terminals in the spinal cord and thereby partly counterbalance the algogenic effect of ATP released from spinal cord nerve terminals upon depolarization and probably from damaged or stressed cells upon pathological conditions [7]. The involvement of P2Y receptors in the modulation of rat spinal neurotransmitters glutamate and noradrenaline release was investigated [7]. The study showed that the inhibitory effect of ATP on glutamate release was mediated by P2Y13 and/or by P2Y1 receptors, whereas the inhibition of noradrenaline release was most likely mediated by P2Y13 and/or by P2Y1 and P2Y12 receptors. In order to explore the cell type-specific distribution of the P2Y1 receptor and to determine whether P2Y1 receptors, involved in the modu- lation of glutamate release, are expressed on primary afferent nerve terminals or interneurons, immunohisto- chemical experiments were performed using anti-P2Y1 receptor antibody. Thus, the results indicated that sensory information processing and its modulation by the descend- ing noradrenergic pathway in the spinal cord could be targeted by distinct subtypes of P2Y receptors, providing novel sites of action for potential analgesic compounds. Microglia in the spinal cord may play an important role in the development and maintenance of neuropathic pain. In spinal microglia, P2Y12 is expressed constitutively and is involved in chemotaxis. The activation of p38 mitogen- activated protein kinase (MAPK) occurs in spinal microglia after nerve injury and may be related to the production of cytokines and other mediators, resulting in neuropathic pain. Anti-P2Y12 receptor antibody in immunohistochemi- cal analysis of the dorsal horn cells 7 days after nerve injury was used in order to demonstrate that the cells expressing increased P2Y12 protein were exclusively microglia [8]. In addition, the data suggested a new mechanism of neuro- S63 pathic pain in which the increased P2Y12 expression works as a gateway in microglia following nerve injury. The activation of this receptor by the released ATP activates the p38 MAPK pathway and thus may play a crucial role in the generation of neuropathic pain. In another study, the expression and function in nociception of P2Y1 and P2Y12 using their respective Alomone Labs antibodies via immunohistochemistry analysis was examined in sensory neurons [9]. The results demonstrated that nociception sensitivity is modulated by the integration and balance of nucleotide signaling through Gq- and Gi-coupled P2Y receptors which are altered in response to inflammatory injury. Gi-coupled P2Y receptors are broadly expressed in peripheral sensory neurons, inhibit nociceptive signaling, and reduce behavioral hyperalgesia in vivo and thus represent potential targets for the development of novel analgesic drugs. On the other hand, P2Y1, a Gq-coupled ADP receptor, is required for the full expression of inflammatory hyperalgesia. P2Y receptors in the ear Purinergic signaling is inherently important to the hearing organ and involves signal transduction via metabotropic G protein-coupled P2Y receptors. Many of the principal elements of the purinergic signaling complex have been well characterized in the cochlea, forming the basis of paracrine and autocrine communication systems in this organ. The results presented below reinforce the signifi- cance of extracellular nucleotide and nucleoside signaling to hearing. Huang et al. [10] used anti-P2Y2 receptor, anti-P2Y4 receptor, anti-P2Y6 receptor, and anti-P2Y12 receptor anti- bodies in order to evaluate their expression during development of the rat cochlea using immunohistochemis- try analysis. The key findings of this study involved the dynamic interplay between the expressions of the closely related P2Y receptors mentioned above within the highly differentiated cochlear tissue. None of the receptors exhibited significant expression at the embryonic period as P2Y receptor expression is pronounced in the developing CNS. In the cochlea, neuronal P2Y receptor expression did not commence until day 18 of the embryonic period. During maturation of the hearing organ, P2Y receptor expression became increasingly compartmentalized even to a subcellular level in the case of the sensory hair cells and some supporting cells. The distribution of NTPDase5 and NTPDase6, two intracellular members of the membrane-bound ectonucleoside triphosphate diphosphohydrolases (E-NTPDase) family, in the inner ear was investigated [11]. Their expression was linked to the regulation of P2 receptor signaling in the adult rat cochlea. By using anti-P2Y6 receptor and anti-P2Y14