ALTERATION OF DOPAMINE D-2 RECEPTORS IN HUMAN-MALIGNANT STOMACH TISSUE

Dopamine is an important enteric neurotransmitter with a wide spectrum of physiological actions on the gastrointestinal tract. In addition, it showed inhibition of malignant cell proliferation as well as a prot ective influence on experimental carcinogenesis in the gastrointestina l tract of murine hosts. It is well established that dopamine acts on target cells through specific receptors. Therefore the status of dopam ine receptors in malignant tumors of the stomach has been evaluated, N ormal, benign, and malignant stomach tissue showed the presence of hig h-affinity D-2 dopamine receptors. The concentration (B-max) and affin ity (k(d)) of dopamine binding sites in normal and benign tumor tissue s were similar. In malignant stomach tissue B-max showed a significant decrease compared to normal and benign controls; however, K-d was sim ilar. This alteration of dopamine receptors may be of significance in understanding the etiopathogenesis of gastric cancer at the level of p eripheral neurotransmitters. Rational use of dopamine receptor antagon ists for various stomach diseases may be suggested.