Expression of receptors for insulin and leptin in the ventral tegmental area/substantia nigra (VTA/SN) of the rat: Historical perspective

Since the publication of the observation that dopaminergic neurons in the ventral tegmental area/substantia nigra of the rat express receptors for insulin and leptin, numerous studies have extended and validated these findings. Thus, these major metabolic hormones have effects on synaptic and cell signaling function of the midbrain dopamine neurons, across a range of concentrations that reflect physiologic (fasting vs. fed) and pathophysiologic (diabetes) circumstances. The capacity of metabolic hormones to alter reward behaviors, including palatability-related food intake; motivation for food; and the conditioning of place preference by food, is now appreciated as an integral part of the larger actions of these hormones to regulate caloric homeostasis. Finally, the delineation of metabolic hormone effects on the CNS reward circuitry of normal animals provides the rationale and experimental basis for evaluating dysfunction of reward circuitry in obesity and diabetes. This article is part-of a Special Issue entitled SI:50th Anniversary Issue. Published by Elsevier B.V.