MC4R expression in pedunculopontine nucleus involved in the modulation of midbrain dopamine system.

BACKGROUND AND OBJECTIVE Separate studies have implicated the pedunculopontine tegmental nucleus (PPTg) in processing aversive stimuli to dopamine systems, and melanocortin-4 receptor (MC4R) are broadly expressed by the neurons in the PPTg, but the exact neurosubstrate underlying the regulation of dopamine systems by the central melanocortin pathway is poorly understood. METHODS In this study, the PPTg of 6 adult mice expressing green fluorescent protein (GFP) under the control of the MC4R promoter was detected by fluorescence immunohistochemistry. RESULTS A large number of GFP-positive neurons in the dissipated parts of PPTg (dpPPTg) were found, and approximately 50% of MC4R-GFP- positive neurons in the dpPPTg coexpressed tyrosine hydroxylase, a marker of dopamine neurons, indicating that they were dopaminergic. CONCLUSIONS Our findings support the hypothesis that MC4R signaling in the dpPPTg may involve in the modulation of midbrain dopamine systems.