ANIMAL models have revealed that psychoactive cannabinoids induce both anxiolytic and anxiety-like reactions which are dose- and context-dependent. In the present study we examined the acute actions of the CB1 cannabinoid receptor antagonist SR 141716A in both the defensive withdrawal test and the elevated plus-maze in rats. Acute administration of SR 141716A (0.1, 1 and 3 mg kg−1) induced defensive responses in both anxiety tests, at a dose of 3 mg kg−1. This dose had no effect on horizontal locomotor activity and did not activate the hypothalamus–pituitary–adrenal axis, although several cannabinoid withdrawal-like behavioural symptoms were observed. These results demonstrate that blockade of the endogenous cannabinoid tone might induce anxiety-like responses in rats.
1Departamento de Psicobiología, Facultad de Psicología Instituto Complutense de Drogodependencias
2Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28223-Madrid, Spain
3Department of Neuropharmacology, The Scripps Research Institute, La Jolla, California, USA
4Corresponding Author: Miguel Navarro.
ACKNOWLEDGEMENTS: This work has been supported by Comisión Interministerial de Ciencia y Tecnología (CICYT, grant SAF-94/0465)). The authors thank the expert assistance of Leticia Escuredo, Olivia Maestre and Yolanda Martin. They acknowledge Sanofi Recherche for providing SR 141716A. Dr. F.R.F. is a research fellow of the Fundución Jaime del Amo, Universidad Complutense de Madrid.
Received 27 September 1996; accepted 17 October 1996