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.
Nabeshima
T
T
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
Katoh
A
A
Wada
M
M
Kameyama
T
T
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