Release of some endogenous trace amines from rat striatal slices in the presence and absence of a monoamine oxidase inhibitor.

The basal and 50 mM K+-stimulated release of m-tyramine (mTA), p-tyramine (pTA), tryptamine (TR) and phenylethylamine (PE) from striatal slices obtained from rats pretreated with a monoamine oxidase inhibitor (MAOI) was investigated. A K+-stimulated release of mTA and pTA was observed, but K+ did not stimulate either TR or PE release. The latter two amines, therefore, are unlikely to be conventional neurotransmitters in the rat striatum. The release of endogenous striatal pTA from control rats was also investigated. Veratridine stimulated endogenous pTA release, but 50 mM K+ did not. It is possible, therefore, that endogenous pTA can be released in a transmitter-like fashion.