? ? This Stage 1 Cebra application seeks to test the feasibility of simultaneous functional down-regulation of two ATP gated ion channels present in the subset of nociceptive sensory neurons. The P2X2 and P2X3 purinergic receptors arechosen for investigation because recent studies suggest that many sensory neurons behave as if they express these two receptors in a heteromultimeric configuration (P2X2/3), and because antisense oligonucleotide knockdown of P2X3 alone results in modest attenuation of some nociceptive behaviors. The underlying hypotheses of this proposal is that simultaneous knockdown of P2X2 and P2X3 purinergic receptors is an effective approach to interfere with nociceptive processing, and that it is a more efficient way to target heteromeric receptor configurations than approaches targeting either P2X2 or P2X3 receptors alone. An antisense oligonucleotide approach combined with immunohistochemical, behavioral, and electrophysiological measures will be used to determine whether simultaneous delivery of antisense oligonucleotides for P2X2 and P2X3 will decrease the expression of P2X2 and P2X3 in sensory neurons and reduce nociceptive behaviors. In addition, these studies will determine for the first time whether antisense treatment will alter the response properties of functionally identified sensory neurons with intact receptive fields. In making this proposal, existing methodologies will be integrated and applied as a new paradigm. Findings from these experiments could contribute to the development of viable therapeutic alternatives to the use of analgesic agents such as opiate compounds that have high potential for tolerance and dependence. ? ?
