A critical role for beta-endorphin in cocaine-seeking behavior.
Endogenous beta-endorphin levels in the brain are elevated in response to cocaine and are downstream of the mesolimbic dopaminergic system. However, beta-endorphin's direct involvement in cocaine reinforcement has not been demonstrated. In the present study, a single bilateral microinjection of anti-beta-endorphin antibodies (4 microg) to the nucleus accumbens during the maintenance phase of cocaine self-administration (1 mg/kg/infusion) significantly increased the number of active and inactive lever responses. The increase in lever responses is reminiscent of rat behavior during extinction of cocaine self-administration. Further, a cocaine dose-response demonstrates that the increased lever presses in anti-beta-endorphin antibody-injected rats was still present after substitution with a lower dose of cocaine. These findings support a critical role for beta-endorphin in the cocaine brain reward system.
Roth-Deri
I
I
Neuropharmacology Section, Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel.
Schindler
C J
CJ
Yadid
G
G
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D003042:Cocaine / Q000494:pharmacology; D019970:Cocaine-Related Disorders / Q000523:psychology*; D003216:Conditioning, Operant / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D008297:Male; D008845:Microinjections; D009714:Nucleus Accumbens; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012646:Self Administration; D001615:beta-Endorphin / Q000037:antagonists & inhibitors / Q000502:physiology*
D019138:Antibodies, Blocking; D001615:beta-Endorphin; D003042:Cocaine