Disturbances in the CNS cholinergicsystem have been implicated in the pathophysiology of Alzheimer’sand Parkinson’s disease, schizophrenia, depression, or epilepsy.7−10 H3R treatment has also been found to modulate cholinergictransmission in the peripheral nervous system.11 H3R activation reduces the release of [3H]-ACh induced by electrical stimulation in the longitudinalsmooth muscle/myenteric plexus preparations.12,13. This evidence concerns the gene HRH3 and major depressive disorder.