2-Aminoethanol as a possible neuromodulator in the pigeon optic tectum

A mass fragmentographic method was used for determination of low molecular weight compounds in perfusates collected in vivo in the pigeon optic tectum by a push-pull cannula technique. 2-Aminoethanol (ethanolamine) could be collected under resting conditions (5.6 +/- 0.09 pmol/min). Electrical stimulation of optic nerve induced a 2.3-fold increase of the tectal ethanolamine outflow whereas that of GABA was not affected. Ethanolamine applied iontophoretically to tectal neurons did not influence their spontaneous discharge; however, their glutamate-induced excitation as well as the GABA-induced depression were enhanced if ethanolamine was applied simultaneously. It is suggested that optic nerve stimulation exerts a neuromodulatory effect on tectal neurons.