Uric acid is released in the zona incerta of the subthalamic region of the sheep during rumination and in response to feeding and drinking stimuli.

The technique of intracranial dialysis was used to sample changes in monoamine metabolite and uric acid concentrations in the zona incerta (ZI) of the subthalamic region of conscious sheep during rumination and in response to the presentation of feeding and drinking stimuli. Sequential 10-min dialysis samples were taken over a 5-h period with stimuli presented at hourly intervals. For each animal, sampling was carried out weekly for 2-3 months. Results from HPLC analysis showed that concentrations of uric acid rose significantly in the ZI, but not in the cortex or peripheral plasma, during rumination, eating, drinking or exposure to the sight or smell of food. No response to control stimuli--loud noise, smell of amyl acetate or sight of a syringe--was found. Concentrations of 5-hydroxyindol-3-yl-acetic acid in the ZI were unaffected.