Developmental changes in heteromeric P2X(2/3) receptor expression in rat sympathetic ganglion neurons

We have used whole cell patch clamp recording and immunohistochemistry to investigate the expression of P2X(2/3) receptors in rat superior cervical ganglion neurons during late embryonic and early post-natal development. Neurons from E18 and P1 animals responded to the nicotinic agonist dimethylphenylpiperazinium (DMPP), and the purinoceptor agonists ATP and alpha,beta-meATP with sustained inward currents. Responsiveness to DMPP was maintained at P 17, while that to ATP declined dramatically, and responses to alpha,beta-meATP were rarely detected. Immunohistochemistry for the P2X(3) subunit revealed widespread staining in superior cervical ganglia from P1 rats, but little immunoreactivity in ganglia from P17 animals. In neurons from P1 animals, the response to alpha,beta-meATP exhibited pharmacological properties of the heteromeric P2X(2/3) receptor. In conclusion, sympathetic neurons of the rat superior cervical ganglion are more responsive to ATP and alpha,beta-meATP at birth and during the early post-natal period, due largely to the expression of the P2X(3) subunit, but these responses are much reduced in mature rats.