Trace amines reduce GABAB receptor-mediated presynaptic inhibition at GABAergic synapses of the rat substantia nigra pars compacta

Trace amines (TAs) act in the mammalian brain through amphetamine-like effects and as endogenous agonists of specific receptors. We now show that tyramine and β-phenylethylamine, in the presence of specific dopamine (DA) receptor antagonists, inhibit the GABAB-dependent presynaptic inhibition of GABAergic inputs to midbrain DA neurons. Our results further extend the role of TAs as neuromodulators and propose a novel mechanism by which they modulate DA neurons.