Effects of brain extracts on activity of the trigeminal motor and hypoglossal nuclei

¹ Department of Physiology, Dental School Osaka University, Joancho, Kitaku, Osaka, Japan

Alterations in trigeminal motor and hypoglossal nuclei discharges were noted following microinjections of ethanol and saline brain tissue extracts, ACh and -aminobutyric acid (GABA). Background activities of these nuclei were not affected by microinjection of 0.9% saline solution or tris buffer [tris (hydroxymethyl) amino methane] of pH 7.2. Solutions of pH 8.5 (tris buffer) or pH 5.8 (glycine buffer) gradually inhibited these discharges. Spontaneous discharges of the trigeminal motor nuclei were accelerated by the saline extract of the brain tissue and ACh, and they were inhibited by the ethanol extract of the brain tissue and GABA. Discharge of this nucleus accelerated by lower jaw depression was also inhibited by the ethanol brain extract and GABA. Background activity of the hypoglossal nuclei was mildly accelerated by the saline brain extracts and ACh, greatly accelerated by the ethanol brain extracts, and strongly inhibited by GABA. The saline extract of the brain tissue extracted from brain stem had a stronger activator than that extracted from cortical tissue.