Central GABA activation and behaviors evoked by tail-pinch stress in the rat

Experiments were conducted to evaluate the possibility that central GABAA r eceptors are involved in the stress response of rats. Separate groups of an imals were implanted bilaterally with cannulae in the lateral cerebral vent ricle, substantia nigra, and anterior to the rostral margin of the substant ia nigra. Microinjections of the GABA, agonist muscimol into each of these areas augmented the stress response evoked by moderate tail pinch. Although consistent changes in the amount of food eaten in response to stress were not observed, stress-evoked gnawing was significantly increased by muscimol at all three sites. Additionally, intraventricular muscimol resulted in an enhancement of stress-evoked oral stereotypy, revolution (escape behavior) , and vocalization. The data suggest that a GABAergic component exists in t he central mediation of stress. The results are discussed in regard to poss ible interactions between GABA and central dopamine systems. (C) 1999 Elsev ier Science Inc.