![]() |
|
|
A Katoh, T Nabeshima and T Kameyama
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
Effects of opioid peptides on behavioral changes induced by stressful situations were investigated. [D-Ala2,Met5]-enkephalinamide and [D- Ala2,D-Leu5]-enkephalin, degrading-enzyme-resistant derivatives of methionine-enkephalin and leucine-enkephalin, respectively, significantly attenuated both environment-induced conditioned suppression of motility and forced swimming-induced immobility in a dose-dependent manner. The [D-Ala2,Met5]-enkephalinamide- and [D-Ala2,D- Leu5]-enkephalin-induced attenuations were antagonized by naloxone at different doses. In contrast, dynorphin A(1-17) and [N-methyl-Tyr1,N- methyl-Arg7,D-Leu8]-dynorphin A(1-8) ethylamide (E 2078), a degrading- enzyme-resistant derivative of dynorphin, significantly potentiated both behavioral changes. The dynorphin- and E 2078-induced potentiations were inhibited by Mr 2266. [D-Ala2,Met5]-enkephalinamide- induced attenuation of environment-induced conditioned suppression of motility and forced swimming-induced immobility was prevented by treatment with dynorphin and E 2078 at the doses that did not affect the behavioral changes. This antagonism by both dynorphin and E 2078 was inhibited by Mr 2266. However, [D-Ala2,D-Leu5]-enkephalin-induced attenuation of both behavioral changes was not affected by either dynorphin or E 2078. These results indicated that activation of the methionine- or leucine-enkephalinergic system attenuates behavioral changes induced by stress, whereas activation of the dynorphinergic system potentiates those changes. Furthermore, the dynorphinergic system may interact with the methionine-enkephalinergic system, but not with the leucine-enkephalinergic system.
This article has been cited by other articles:
![]() |
J. P. McLaughlin, M. Marton-Popovici, and C. Chavkin {kappa} Opioid Receptor Antagonism and Prodynorphin Gene Disruption Block Stress-Induced Behavioral Responses J. Neurosci., July 2, 2003; 23(13): 5674 - 5683. [Abstract] [Full Text] [PDF] |
||||