Oral self-administration of morphine in rats.

Abstract

The operant behavior method has been utilized to ascertain whether certain drugs have the power to reinforce the animal's operant behavior and also whether the animal can self-administer the drug by means of automatic intravenous or intragastric injections (1-5).Using operant behavior the oral self-administration of morphine has been little studied though the preference for morphine has been reported (6-8). In our present work, the operant discrimination behavior was used with the drug-admixed food method (9, 10) to examine the oral self-administration of morphine.A Skinner discrimination box (25 x 20 x 30 cm) was used; two sets of levers, food trays and small lights were attached to the inside of the box. Two food dispensers outside the box were connected to the food trays by tubes (developed by our department and Charles River Japan, Inc., Kanagawa). Ordinary pellet food, weighing approx. 45 mg, was from the CLEA Japan, Inc. and the same type of pellet food which was produced by mixing morphine hydrochloride (1 mg/g food) into normal food was prepared in our department

The neurocircuitry of addiction: an overview

“…Similar to humans, animals will readily self‐administer most drugs of abuse (for reviews, see Schuster and Thompson, 1969 ; Spealman and Goldberg, 1978 ; Balster and Lukas, 1985 ; Young and Herling, 1986 ), including opiates ( Weeks, 1962 ; Blakesley et al ., 1972 ), cannabinoids ( Takahashi and Singer, 1979 ; Justinova et al ., 2003 ), alcohol ( Woods et al ., 1971 ; Anderson and Thompson, 1974 ), nicotine ( Hanson et al ., 1979 ; Ator and Griffiths, 1983 ), amphetamines ( Pickens et al ., 1967 ; Pickens and Harris, 1968 ; Balster et al ., 1976 ) and cocaine ( Pickens and Thompson, 1968 ; Goldberg and Kelleher, 1976 ), with studies almost universally demonstrating that animals will preferentially respond on a reinforced (that is, active), rather than a non‐reinforced (that is, inactive) operandum. Although a variety of species and routes of drug administration can be used, most studies involve the use of rodents ( Weeks, 1972 ; Smith and Davis, 1975 ) or non‐human primates ( Deneau et al ., 1969 ; Stretch and Gerber, 1970 ) self‐administering drugs orally ( Anderson and Thompson, 1974 ; Yanaura et al ., 1980 ), intracranially ( Bozarth and Wise, 1981 ; Phillips et al ., 1981 ) or intravenously via a chronic indwelling catheter ( Griffiths et al ., 1978 ; Spealman and Goldberg, 1978 ). The abuse potential of a drug in humans can be predicted from animal intravenous self‐administration models ( Collins et al ., 1984 ), which clearly models the clinical abuse of drugs far better than repeated experimenter‐delivered drug via intraperitoneal or subcutaneous administration ( Markou et al ., 1993 ).…”

Female rats consume and prefer oxycodone more than males in a chronic two-bottle oral voluntary choice paradigm

“…To understand these factors, preclinical researchers would benefit from animal models of prescription opioid abuse liability that recapitulate key aspects of long-term use, such as voluntary and escalating intake that results in tolerance. Prescribed oxycodone is typically taken orally, and animal models of oral opioid intake have been in use for many years (Cappell and LeBlanc, 1971;Enga et al, 2016;Heyne, 1996;Klein, 1995;Nichols et al, 1956;Risner and Khavari, 1973;Shaham et al, 1992;Stolerman and Kumar, 1972;Wikler et al, 1963;Yanaura et al, 1980) . Some oral intake paradigms predispose the rodent to opioid drinking via intraperitoneal injection of opioids (Nichols, 1963;Seevers and Deneau, 1963) , or force opioid drinking by restricting access to non-drugged water (Cappell and LeBlanc, 1971;Kumar et al, 1968;McMillan et al, 1976;Thompson and Ostlund, 1965) .…”