The Role of AGRP in Regulating Dopaminergic Neurons in the Brain

Immunoreactive processes containing agouti-regulated protein (AGRP) were detected in various dopaminergic structures in the brains of rats and mice. Double immunolabeling demonstrated the presence of AGRP-immunoreactive processes around the bodies of dopaminergic neurons. In in vitro experiments, incubation of brain tissue from the ventral tegmental area and hypothalamus with AGRP(83-132) identified significant reductions in the optical density of tyrosine hydroxylase. These data provide evidence of the possible direct inhibitory effect of AGRP on the level of tyrosine hydroxylase in dopaminergic neurons and of its role as a modulator of the functional activity of dopaminergic neurons.