[Experimental hepatic encephalopathy. Central nervous system excitability in rats following portacaval anastomosis]

The excitability of reticulo-thalamo-cortical and reticulo-cortical system (RtCS) was studied by electrical stimulation of reticular formation during waking, slow wave sleep and paradoxical sleep during five weeks in control rats and in rats with portocaval shunt. In control rats, no modification of the excitability of RtCS was observed during the experimentation. In rats with portocaval shunt and from the fourteenth post-operative day, the excitability of RtCS was decreased during waking. All along the post-operative period, the excitability of RtCS was increased during slow wave sleep. No modification of the excitability of RtCS was observed postoperatively during paradoxical sleep. These modifications of the excitability of RtCS during waking and slow wave sleep could be related to quantitative variation of the waking-sleep cycle that have been described in rat with portocaval shunt. Their responsability in the disorganization of the waking-sleep states during the experimental hepatic encephalopathy may be hypothetized.