Pontine tegmentum lesions increase anxiety-like behavior in rats: A comparison with anxiety produced by beta-CCE

Electrolytic lesions of the pedunculopontine tegmental nucleus (PPTg) have been previously reported to increase anxiety-like behavior in rats. The aim of the present study was to compare these behavioral changes with those pr oduced by an anxiogenic compound,the partial inverse agonist at benzodiazep ine receptors, beta-CCE. Three groups of rats, sham-lesioned treated with v ehicle, sham-lesioned treated with 10 mg/kg of beta-CCE, and PPTg-lesioned rats treated with vehicle, were tested in the elevated plus-maze, the socia l-interaction test, and for spontaneous locomotion. Histology showed that l esions were concentrated on the caudal half of the PPTg. Measures of both t he PPTg-lesioned and beta-CCE-treated rats indicated increased anxiety-like behavior in the elevated plus-maze and in the social-interaction test. Spo ntaneous locomotion, measured in the open- field arena, did not differ betw een sham controls and PPTg-lesioned rats, but was decreased in rats treated with beta-CCE. Our results confirmed that electrolytic lesions of the caud al PPTg produce increased anxiety-like behavior. This behavior is quantitat ively and qualitatively similar to that produced by 10 mg/kg of beta-CCE. ( C) 2000 Elsevier Science Inc.