[Activation of the diffuse thalamic projection system by GABA-ergic stimulation]

Since Hess's first conclusive experiment of a sleep-inducing effect by median thalamic low-frequency stimulation, many studies have shown that this is due to the activity of the thalamic diffuse projection system. Activation of this system results in an augmentation of thalamo-cortical IPSP. Benzodiazepines, generally considered as GABAergic mediators, increase the system's activity. Therefore it seemed reasonable to postulate a GABAergic transmission within this system. In support of this hypothesis, micro-injections of SL 75.102 (a specific GABAergic agonist) in the rabbit thalamus increase the spindle-rich slow wave sleep, producing a sleep graph similar to those induced by anesthetics. When injected intravenously to rabbits, at doses between 80 and 300 mk/kg, SL 75.102 shows potent anesthetic qualities.