NOVELTY-INDUCED INCREASE IN DOPAMINE RELEASE IN THE RAT PREFRONTAL CORTEX IN-VIVO - INHIBITION BY DIAZEPAM

The effects of graded stressful conditions on extracellular concentrat ions of dopamine (DA) in the medial prefrontal cortex of rats were mea sured in vivo using microdialysis. Picking up the rat twice with a 20- min interval increased extracellular DA to 120%, exposure to a novel e nvironment by placement in a clean cage for 20 min to 150% and holding the rat in the hands for 20 min to over 200%. Diazepam (5 mg/kg) decr eased DA to about 75% and attenuated the novelty- and handling-induced increases. Exposure to novelty or handling are easy and simple method s to obtain graded increases of in vivo cortical DA release.