Intra-amygdaloid microinjection of neuropeptide glutamic acid-isoleucine induces anxiety-like behaviour.

GASTÓN, S.; GARGIULO, P.A.; BREGONZIO, C.; BAIARDI, G.

NEUROREPORT

LIPPINCOTT WILLIAMS & WILKINS

Año: 2010

0959-4965

The amygdaloid complex is involved in anxiety or fear responses to stressful stimuli. The aim of the present work was to study the effect of Neuropeptide-EI on anxiety-like behavior and its influence on adrenocortical function. For this purpose, male Wistar rats were injected bilaterally in the basolateral amygdala with Neuropeptide-EI (1ìg/1ìl) or artificial cerebrospinal fluid and placed on the plus-maze for 5 min. Trunk blood was collected 2-5 min after behavioral testing and plasma corticosterone levels were analyzed by competitive protein-binding assay. Microinjection of Neuropeptide-EI in the basolateral amygdala significantly decreased the time spent in open arms but had no effect on locomotor activity, showing an anxiogenic effect. However, neuropeptide administration did not change serum corticosterone levels compared to vehicle controls. This data suggests that Neuropeptide-EI did not modify the release of adrenal gland corticosterone induced by the behavioral test, and the anxiogenic effect observed could be independent of the hypothalamic-pituitary-adrenocortical system response. Thus, Neuropeptide-EI may be involved as a factor modulating anxiety state through activation of the basolateral amygdala. Publisehd on line. 2010 Dec 15. [Epub ahead of print].