Stress-induced changes in brain Met-enkephalin, Leu-enkephalin and dynorphin concentrations.
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 concentration 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.
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
T
T
Nabeshima
A
A
Katoh
M
M
Wada
T
T
Kameyama
D000818:Animals; D001921:Brain / Q000378:metabolism*; D004399:Dynorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism*; D008297:Male; D051379:Mice; D011863:Radioimmunoassay; D013312:Stress, Physiological / Q000378:metabolism*
D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D004399:Dynorphins