Effects of Adrenoceptor Agonists and Antagonists on the Firing, of Neurons in the Rat Al Noradrenergic Region

抄録

Noradrenaline (NA), but not clonidine applied microiontophoretically, inhibited the firing of neurons in the rat Al noradrenergic region, whereas intravenous clonidine dose-dependently inhibited their firing (ED₅₀=18.3μg/kg). The NA-induced inhibition was blocked by the β-antagonist timolol, but not by the α-antagonists phentolamine or piperoxane. These results suggest that neurons in the Al region possess β- adrenoceptors rather than α-adrenoceptors near their cell bodies, and that systemically administered clonidine acts indirectly on these cells.