Effect of Diazepam on Dopamine Release from Prefrontal Cortex in Rats with Occlusal Interferences

Abstract

Purpose: We measured dopamine release from the prefrontal cortex of rats with occlusal interferences in order to clarify the relation between the occlusal interferences and psychiatric stress. Changes in the activity of the dopaminergic neuron system of the prefrontal cortex have been found to be an index of stress responses involved in anxiety and so on. Since it is difficult to measure anxiety in animal experiments, we used benzodiazepine (diazepam) in this experiment to determine whether increased dopamine release was caused by psychiatric stress.
Methods: Dopamine release was measured using microdialysis in three experiments. In each experiment, the control group comprised 6 rats and the occlusal interference group comprised 6 rats. The level of dopamine release was measured for each experiment: We measured it before and after feeding pellets in experiment 1. Diazepam was intraperitoneally administered before the rats were fed pellets in experiment 2. Physiological saline was given to the rats before they were fed pellets in experiment 3.
Results: Experiment 1: In the occlusal interference group only, the amount of dopamine release significantly increased after feeding. Experiment 2: The amount of dopamine release did not significantly increase in either group. Experiment 3: In the occlusal interference group only, the amount of dopamine release significantly increased after feeding.
Conclusions: The amount of dopamine release increased by occlusal interference i the rats that had been fed. Diazepam suppressed this increase, but physiological saline did not. These results proved statistically that occlusal interferences related to psychiatric stress involving anxiety.