Abstract: The experiments were carried out on conscious albino rats immobilized by tubocurarine. The spontaneous firings of nucleus locus coeruleus (LC), which is the major nucleus of noradrenergic perikarya in the brain, were recorded with glass microelectrode autofilled. Spontaneous firings of LC with a frequency mostly at 4 spikes/s were observed. The firing rate LC was significantly decreased by intraventricular injection of scopolamine(250μg,3μl)Cells in the LC gave an excitatory response to noxious stimulus. This response was not depressed by scopolamine.The results obtained may demonstrate that the anesthetic action induced by scopolamine injected intraventricularly seems to be related to noradrenergic system in the brain.