Electrophysiological manifestations of supraspinal actions of baclofen

Abstract Microiontophoretically applied baclofen (B) potently depressed the majority of thalamic and neocortical neurons. A structure-activity study on the cell and reflex depressant action of a variety of B-derivatives was performed. Even small structural changes of the GABA-moiety were accompanied by significant reductions of the cell and reflex reducing action. These findings suggest that the activity of B does not reside only within the phenylethylamine moiety of B alone as suggested previously. In doses of 10 mg/kg IP B did not attenuate the cortically evoked excitations of striatal cells which are thought to be mediated through glutaminergic fibers. After systemic application we could demonstrate central effects at the single cellular level as well as by means of electroencephalographic investigations. In doses of 3–10 mg/kg IP B inhibits the spontaneous discharge rate of neurons in the dorsal raphe nucleus. In the freely moving cat 3.0 mg/kg PO B changed the sleep-waking pattern and high delta waves appeared on the EEG.