Gamma-aminobutyric acid concentrations in benign parotid tumours and unstimulated parotid saliva.

OBJECTIVE

Apart from its role as an inhibitory neurotransmitter, γ-aminobutyric acid is also thought to regulate various stages of cell proliferation and differentiation in the brain and periphery. The present study aimed to assess the levels of γ-aminobutyric acid and its biochemical precursor glutamic acid (glutamate) in benign parotid tumours and in unstimulated parotid saliva.

METHOD: Unstimulated parotid saliva was collected bilaterally, using the swab method, in 20 patients with unilateral pleomorphic adenoma or Warthin's tumour. Samples of tumour and adjacent salivary tissue were collected during tumour resection.

RESULTS

Concentrations of γ-aminobutyric acid and glutamate, but not aspartate, were significantly higher in the tumour tissue than in the non-tumour tissue. There was no significant difference in salivary concentrations of γ-aminobutyric acid, glutamate or aspartate, comparing the involved and non-involved side.

CONCLUSION

The present results provide preliminary evidence that γ-aminobutyric acid may be involved in the growth of benign parotid tumours.