Withdrawal from chronic morphine administration causes prolonged enhancement of immobility in rat forced swimming test.
BACKGROUND
Opiate-dependent subjects experience severe depression as one of the subjective symptoms during withdrawal. No experimental work, however, has focused on the ability of opiate-withdrawal to produce depression-like behavior in dependent animal. OBJECTIVES. We therefore investigated whether withdrawal from chronic morphine treatment affects immobility in forced swimming test in rats.


METHODS
Morphine was administered in a dose escalation fashion using doses ranging from 20 to 140 mg/kg twice daily for 14 days, followed by 1-6 days of withdrawal, and their duration of immobility was assessed.


RESULTS
After the last morphine treatment. an increase in immobility occurred late on day 3 and persisted to at least day 6 of withdrawal without any change in ambulatory activity.


CONCLUSIONS
The results suggest that the morphine withdrawal resulted in prolonged enhancement of depression-like behavior in drug-dependent laboratory animals.
Anraku
T
T
Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Japan.
Ikegaya
Y
Y
Matsuki
N
N
Nishiyama
N
N
D000818:Animals; D003863:Depression / Q000523:psychology; D004334:Drug Administration Schedule; D007103:Immobilization / Q000502:physiology; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009294:Narcotics / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000523:psychology; D013550:Swimming / Q000523:psychology
D009294:Narcotics; D009020:Morphine