Inhibition of stimulated cyclic AMP production by multiple neuropeptide Y receptors in the rat brainstem

Abstract

Neuropeptide Y (NPY) has been shown to modulate blood pressure, heart rate and to inhibit the baroreceptor reflex at the level of nucleus tractus solitarius (NTS). The aim of this study was to examine effects of NPY and its related peptides on forskolin (1 μM)-stimulated cyclic AMP production in slices of the rat NTS. Each peptide was present at 0.3 μM. Pretreatment with NPY inhibited the stimulated increase in cyclic AMP levels in slices of rat NTS. Also [Pro 34]NPY, an analog, which activates Y1, Y3 (and Y5) receptors inhibited the stimulated increase in cyclic AMP levels. However, pretreatment with the Y1 receptor-selective antagonist BIBP3226 (3 μM) did not affect the [Pro 34]NPY-evoked inhibition of cyclic AMP levels. In addition, [Leu 31,Pro 34]NPY, an Y1 (and PP1/Y4 and Y5) receptor agonist did not inhibit the stimulated increase in cyclic AMP production. Also the Y2 receptor-selective agonist C2-NPY inhibited the stimulated elevation of cyclic AMP levels, while peptide YY, which does not recognize Y3 receptors did not significantly affect the stimulated cyclic AMP production. In conclusion, it seems that Y2 and Y3 receptors are coupled to inhibition of adenylate cyclase activity in the rat NTS.