Prenatal morphine enhances morphine-conditioned place preference in adult rats.
Conditioned place preference (CPP) is a commonly used method for assessing the rewarding qualities of drugs, including opiates. In the present study, we examined long-term effects of prenatal morphine on morphine-associated place preference. Pregnant Fischer 344 rats were given increasing doses of morphine (0.75-12.0 mg/day) in slow-release emulsion during gestational days 12-18. Control rats were injected with vehicle and were fed either with morphine rats or ad libitum. At birth, all litters were culled to 8 pups and fostered to naive dams. Testing began when rats were 10-12 weeks old. Rats prenatally exposed to morphine exhibited a significantly higher preference for the morphine-paired compartment, suggesting that prenatal morphine induces a long-lasting enhancement of its reinforcing effect. Thus, prenatal morphine may result in enhanced activity and/or sensitivity of the endogenous opiate system, thereby placing the organism at higher risk for opiate drug abuse.
Gagin
R
R
Department of Psychology, The Hebrew University, Mount Scopus, Jerusalem, Israel.
Kook
N
N
Cohen
E
E
Shavit
Y
Y
D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects*; D005260:Female; D018811:Maternal Exposure; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*; D009293:Opioid-Related Disorders; D011247:Pregnancy; D051381:Rats; D011916:Rats, Inbred F344; D012201:Reward; D013647:Task Performance and Analysis
D009294:Narcotics; D009020:Morphine