Pertussis toxin treatment counteracts intramembrane interactions between neuropeptide Y receptors and alpha 2-adrenoceptors.
The effect of intracerebroventricular injections of pertussis toxin were investigated on the neuropeptide Y-induced modulation of alpha 2-adrenoceptor binding in membranes from the dorsomedial medulla oblongata of the rat. Concentration-response experiments showed that neuropeptide Y reduced the binding affinity of the alpha 2-agonist, p-[3H]aminoclonidine, with a maximal effect of 30% at 3-30 nM. Pertussis toxin treatment (10 micrograms, 24 h) counteracted this modulation, without reducing the binding of neuropeptide Y to its own receptor. The results indicate that pertussis toxin-sensitive G-proteins are essential for the mediation of the intramembrane interaction between neuropeptide Y receptors and alpha 2-adrenoceptors.