Neuropeptide Y inhibits Ca2+ influx into cultured dorsal root ganglion neurones of the rat via a Y2 receptor

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Abstract
1 The identity of the neuropeptide Y (NPY) receptor associated with the observed inhibition of neuronal Ca2+ currents (ICa) in rat dorsal root ganglion (DRG) cells has been established on the basis of agonist responses to analogues and carboxy terminal (C-terminal) fragments of the NPY molecule. 2 Whole cell barium currents (IBa) in DRG cells were reversibly inhibited by 100 nm NPY, 100 nm PYY and C-terminal fragments of NPY in a manner that correlated with the length of the NPY fragments (for inhibition of the IBa NPY = PYY > NPY2–36 > NPY13–36 > NPY16–36 > NPY18–36 ≫ NPY25–36). 3 C-terminal fragments of NPY were also effective in reversibly reducing the ICa, the associated increase in the intracellular Ca2+ concentration ([Ca2+]i) and the increased [Ca2+]i produced by evoked action potentials in the DRG cells. In addition, a Ca2+-activated Cl− conductance was also reversibly reduced by NPY fragments only when accompanied by a reduction in Ca2+ entry. 4 We conclude that the Y2 receptor for neuropeptide Y is coupled to inhibition of Ca2+ influx via voltage-sensitive calcium channels in DRG cells.

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