26) Anxiolytic-like effect of losartan injected into amygdala of the acutely stressed rats.

LLANO LOPEZ, L.H. ; CAIF, F. ; GARCIA, S. ; FRAILE, M. ; LANDA, A.I. ; BAIARDI, G. ; LAFUENTE, J.V. ; BRASZKO, J. ; BREGONZIO, C. ; GARGIULO, P.A.

PHARMACOLOGICAL REPORTS

POLISH ACAD SCIENCES INST PHARMACOLOGY

Año: 2012 vol. 64 p. 54 - 63

1734-1140

It has been recognized that the stress-related peptides are involved in anxiety states. Angiotensin II receptor blockade by systemic administration of the AT1 receptor antagonists has been proposed as a new treatment possibility for anxiety disorders. For better understanding of the related mechanisms, in this study we evaluated effects of bilateral intraamygdaloid injections of 2 (LOS 2) and 4 (LOS 4) ìg of losartan (LOS), a selective AT1 receptor antagonist, on the behavior of the not stressed and acutely stressed rats in an elevated ?plus? maze. Under non-stress conditions, LOS 4 increased time spent in the open arms (p < 0.01), number of extreme open arm arrivals (p < 0.05), time per entry (p < 0.01), and the number of total arm entries (p < 0.05) showing thus considerable anxiolytic activity. The open arm extreme arrivals were increased by LOS 4 in both not stressed (p < 0.05) and stressed (p < 0.05) rats. When no stressed and stressed LOS 4 animals were compared, time per entry and the number of closed arm entries (p < 0.05, both) were decreased in the latter group. Moreover, the LOS 4 stressed rats had significantly increased open/closed arm quotient (p < 0.05) as compared to the both control and LOS 4 non-stress group (p < 0.05, both). These findings suggest that the AT1 receptor blockade in amygdala is important for the anxiolytic action of LOS (and probably other AT1 receptor blockers) under both non-stress and stress conditions.