title: Dynorphin a (1-13) alleviated stress-induced behavioral impairments in mice.
abstract: In this study we investigated whether κ-opioid receptor stimulation by dynorphin A (1-13), a potent fragment of endogenous peptide, attenuated repeated stress-induced behavioral impairments in mice. In order to reduce the motivation to escape, mice were preexposed to inescapable electric footshock (day 0), and then dynorphin A (1-13) was administered to mice prior to the stress from the next day for 4 d (days 1-4). Dynorphin A (1-13) (1500 pmol/5 µL intracerebroventricular (i.c.v.)) attenuated the repeated stress-induced escape failures from the shock, and this improvement was inhibited by the pretreatment of nor-binaltorphimine (4.9 nmol/kg subcutaneously (s.c.)), a κ-opioid receptor antagonist. In the neurochemical experiments, we detected an increase in 5-hydroxyindoleacetic acid (5-HIAA) content, but not in serotonin (5-HT) content, and an increase in the 5-HIAA/5-HT ratio was observed in the amygdala of the group with footshock compared with the group without shock. Additionally, the changes in 5-HIAA content and the ratio were reversed by dynorphin A (1-13). However, there were no differences in 5-HT or 5-HIAA content or their ratios in the hippocampus among the three groups. These results suggest that dynorphin might alleviate the stress-induced behavioral impairments accompanied by regulation of the 5-HTergic system in the brain.
authors.affiliation: Department of Chemical Pharmacology, Faculty of Pharmacy, Meijo University.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Mamiya
authors.forename: Yuya
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hiramatsu
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood; D004399:Dynorphins / Q000494:pharmacology*; D004597:Electroshock; D004924:Escape Reaction / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology*; D017473:Receptors, Opioid, kappa / Q000819:agonists*; D012701:Serotonin / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects* / Q000502:physiology
chemical_list: D010446:Peptide Fragments; D017473:Receptors, Opioid, kappa; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; C026843:dynorphin (1-13); D004399:Dynorphins; D003345:Corticosterone