Decreased dopamine receptor expression and its second-messenger cAMP in malignant human colon tissue

As an important enteric neurotransmitter, the role of dopamine as a mitotic inhibitor as well as a protective factor of epithelial cells of stomach an d colon indicates its significance in malignant growth of gastrointestinal tract. Our previous results have shown significant alteration of dopamine r eceptors in human malignant stomach tissues. The present experiments, there fore, evaluate DA content, its receptor expression, and its second-messenge r cAMP in human malignant colon tissues to evaluate its role. Results demon strate a significant decrease of dopamine content, its receptor expression, and its second-messenger cAMP in malignant tissues of human colon. These r esults may provide insight into the role of dopamine as an enteric neurotra nsmitter on malignant growth of human colon and may also suggest a therapeu tic approach targeting dopamine receptors and its signal transduction.