Orexin–Corticotropin-Releasing Factor Receptor Heteromers in the Ventral Tegmental Area as Targets for Cocaine

Abstract

Release of the neuropeptides corticotropin-releasing factor (CRF) and orexin-A in the ventral tegmental area (VTA) play an important role in stress-induced cocaine-seeking behavior. We provide evidence for pharmacologically significant interactions between CRF and orexin-A that depend on oligomerization of CRF₁ receptor (CRF₁R) and orexin OX₁ receptors (OX₁R). CRF₁R–OX₁R heteromers are the conduits of a negative crosstalk between orexin-A and CRF as demonstrated in transfected cells and rat VTA, in which they significantly modulate dendritic dopamine release. The cocaine target σ₁ receptor (σ₁R) also associates with the CRF₁R–OX₁R heteromer. Cocaine binding to the σ₁R–CRF₁R–OX₁R complex promotes a long-term disruption of the orexin-A–CRF negative crosstalk. Through this mechanism, cocaine sensitizes VTA cells to the excitatory effects of both CRF and orexin-A, thus providing a mechanism by which stress induces cocaine seeking.