Drugs and PGO waves in the lateral geniculate body of the curarized cat. I. PGO wave activity induced by Ro 43284 and by p-chlorophenylalanine (PCPA) as a basis for neuropharmacological studies.

Depletion, either predominantly of brain noradrenaline (NA) or preferentially of brain 5-hydroxytryptamine (5-HI), was achieved in cats by a single i.p. dose of 20 mg kg(-1) of Ro 4-1284, a benzoquinolizine derivative reducing the storage capacity of monoamine neurones, or by two i.p. injections of 300 mg kg(-1) of p-chlorophenylalanine (PCPA), an inhibitor of tryptophan hydroxylase. The ponto-geniculo-occipital (PGO) waves induced by these drugs (abbreviated PGO1284 and PGOPCPA, respectively) were continuously recorded from both lateral geniculate bodies of the unanaesthetized animals immobilized by gallamine. The present paper describes the characteristic qualitative and quantitative features of PGO1284 and PGOPCPA recorded under our standard experimental conditions; it provides the basis required for the following investigations of this series on the modulating effects of various drugs on this phasic brain activity. The density (number hr(-1) or number 0.5 hr(-1)) of PGO waves was inversely correlated with the levels of brain NA and 5-HT. At the peak of activity, during the second hr following the injection of Ro 4-1284, the density of PGO1284 was 630 hr(-1); it slightly declined during the following 5 hr. The highest activity of PGOPCPA (395 hr(-1)) appeared around the 74th hr after the first of 2 injections of PCPA; it remained constant for 3 hr and thereafter gradually declined. In constrst to the regular appearance of PGO1284, the PGOPCPA occurred in highly variable bursts. This difference was probably due to the different levels of NA and 5-HT in the brain.