Intraventricular administration of D-Ala2-Met5-enkephalinamide induces rapid recovery of responding for electrical brain stimulation from the ventral tegmental area following uncontrollable footshock.
The effects of uncontrollable footshock were assessed in CD-1 mice responding for electrical brain stimulation (ICSS) from the dorsal aspects of the ventral tegmental area (VTA). Uncontrollable footshock provoked a marked reduction of responding for ICSS immediately, 24 h and 168 h following initial stressor exposure. Intraventricular administration of the neuropeptide, D-Ala2-Met5-enkephalinamide (DALA) (1 microgram/microliter delivered in a 1-microliter volume) following induction of reward alterations from the dorsal VTA provoked a rapid recovery of responding for ICSS in the immediate poststressor interval. This ameliorative effect of the neuropeptide deteriorated 24 h after initial exposure to uncontrollable footshock and was absent 1 week later. These data are discussed with respect to stressor-induced anhedonia in the mesocorticolimbic system.
Maddeaux
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Psychology Department, Carleton University, Ottawa, Ontario, Canada.
Zacharko
R M
RM
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004597:Electroshock; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D005528:Foot / Q000294:innervation; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013681:Tegmentum Mesencephali / Q000502:physiology*; D013997:Time Factors
D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-