HOW DOES THE DISTENSION OF URINARY-BLADDER CAUSE AROUSAL

Under urethane anesthesia, the urinary bladder of male rats was disten ded by 0.3-0.5 mL of saline. When the animals displayed large amplitud e delta waves, the distention caused tonic excitation in 76% (19/25) o f the noradrenergic neurons in the locus coeruleus and in 53% (16/30) of the cholinergic neurons in the laterodorsal GRAPHICS tegmental nucl eus. The response was followed by a shift of electroencephalogram (EEG ) pattern to faster waves of smaller amplitude. When EEG amplitude was faster and smaller, the same stimuli caused no response. Neurons in B arrington's nucleus were excited by a small amount of bladder distenti on independent of EEG patterns. These results suggest that the transit ion of state, caused by bladder distention, from deep sleep to light s leep is mediated by noradrenergic and cholinergic neurons in the brain stem.