title: Anxiolytic-like effect of losartan injected into amygdala of the acutely stressed rats.
abstract: It has been recognized that the stress-related peptides are involved in anxiety states. Angiotensin II receptor blockade by systemic administration of the AT(1) 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) μg of losartan (LOS), a selective AT(1) 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 AT(1) receptor blockade in amygdala is important for the anxiolytic action of LOS (and probably other AT(1) receptor blockers) under both non-stress and stress conditions.
authors.affiliation: Laboratory of Neurosciences and Experimental Psychology, IMBECU-CONICET, Department of Pathology, Faculty of Medical Sciences, National University of Cuyo, Mendoza (5500), Argentina.
authors.forename: Luis H
authors.initials: LH
authors.lastname: Llano López
authors.forename: Fernando
authors.initials: F
authors.lastname: Caif
authors.forename: Sebastián
authors.initials: S
authors.lastname: García
authors.forename: Miriam
authors.initials: M
authors.lastname: Fraile
authors.forename: Adriana I
authors.initials: AI
authors.lastname: Landa
authors.forename: Gustavo
authors.initials: G
authors.lastname: Baiardi
authors.forename: José V
authors.initials: JV
authors.lastname: Lafuente
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Braszko
authors.forename: Claudia
authors.initials: C
authors.lastname: Bregonzio
authors.forename: Pascual A
authors.initials: PA
authors.lastname: Gargiulo
mesh_terms: D000679:Amygdala / Q000187:drug effects* / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001007:Anxiety / Q000188:drug therapy / Q000378:metabolism; D001522:Behavior, Animal / Q000187:drug effects*; D019808:Losartan / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D051381:Rats; D013315:Stress, Psychological / Q000188:drug therapy / Q000378:metabolism
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D014151:Anti-Anxiety Agents; D019808:Losartan