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PRODUCTION OF TOLERANCE AND PHYSICAL DEPENDENCE IN THE RAT BY SIMPLE ADMINISTRATION OF MORPHINE IN DRINKING WATER
Author(s) -
BADAWY A.A.B.,
EVANS C.M.,
EVANS M.
Publication year - 1982
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1982.tb09165.x
Subject(s) - morphine , physical dependence , body weight , pharmacology , drug , weight loss , analgesic , drug tolerance , (+) naloxone , medicine , drug administration , anesthesia , opioid , obesity , receptor
1 Rats are capable of consuming solutions of morphine sulphate in drinking water ad libitum in the absence of taste‐masking chemicals and without the need for scheduled provision or prior parenteral administration of the drug. 2 The success of this method depends on the initial provision of a 0.1 mg/ml solution of morphine sulphate. 3 When the drug concentration is increased to 0.4 mg/ml, the rats achieve an average daily intake of 50 mg/kg body wt. each. 4 Daily intake of morphine may be increased by at least about three fold by increasing the drug concentration to 1.2 mg/ml. 5 Oral morphine administration causes only a moderate loss in body weight. 6 Rats whose daily intake of the drug is 50 mg/kg exhibit tolerance to the analgesic action of morphine and show a drastic loss in body weight at 24 h after withdrawal and most of the behavioural symptoms of the naloxone‐precipitated withdrawal syndrome. 7 It is suggested that this simple method of morphine administration is suitable for further biochemical and behavioural studies of the actions of the drug.