Elsevier

Life Sciences

Volume 51, Issue 3, 1992, Pages 211-217
Life Sciences

Stress-induced changes in brain Met-enkephalin, Leu-enkephalin and dynorphin concentrations

https://doi.org/10.1016/0024-3205(92)90077-3Get rights and content

Abstract

Methionine-enkephalin (Met-enkephalin), leucine-enkephalin (Leu-enkephalin) and dynorphin A (1–17) (dynorphin A) concentrations in discrete brain areas were determined in the mice showing behavioral changes induced by stress using radioimmunoassay (RIA). In the present experiment, we used environment-induced conditioned suppression of motility and forced swimming-induced immobility. In the environment-induced conditioned suppression of motility, Met-enkephalin concentration in the striatum and hypothalamus significantly decreased. Leu-enkephalin concentration in the hypothalamus also decreased. Dynorphin A concentraion in the striatum decreased, but significantly increased in the hypothalamus and pituitary. In the forced swimming-induced immobility, Met-enkephalin concentration in the striatum significantly decreased. Leu-enkephalin concentration in the hypothalamus and pituitary significantly decreased. Dynorphin A concentration in the pituitary decreased, but significantly increased in the hypothalamus. Our results indicated that the concentrations of Met-enkephalin, Leu-enkephalin and dynorphin A in the discrete brain areas changed in two different stressful situations. These findings suggested that these peptides might modulate the behavioral changes induced by stressors.

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