GABA level and GAD activity in human and mouse normal and neoplastic mammary gland.

Our studies have demonstrated that GABA (gamma-aminobutyric acid) is detectable both in mouse and in human normal mammary gland and in neoplastic alterations. We have also shown that GABA content in tumor was significantly higher than in normal tissue. The statistically significant difference in GAD (glutamine acid decarboxylase) activity between tumor and normal mammary tissue was also detected. The positive correlation between GABA content and GAD activity in tumor cells was observed both in human and in mice materials. The observed increase in GABA level and GAD activity in tumor tissue could reflect an eventual local antitumor immune response, however, a hypoxia of tumor cells could also be considered. The role of GABA, GAD and GABA-ergic receptors in cancerogenesis and in cancer progression is still to be clarified and requires further studies; however, it may indicate that the known agonists of GABA-ergic system (e.g. baclofen) can potentially modulate the tumor growth.