Acquisition of a fixed ratio schedule in adult male rats neonatally exposed to ethanol and/or cocaine.
Acquisition of an operant learning task for sucrose reinforcement was examined in rats after neonatal exposure to ethanol and/or cocaine. Subjects were raised using an artificial rearing procedure from postnatal days 4 to 11 and were intragastrically fed a milk diet containing either ethanol (6 g/kg/day), cocaine (60 mg/kg/day), the combination (6 g/kg/day + 60 mg/kg/day), or an isocaloric control diet. There was also a suckled sham control. Adult male offspring (postnatal day 65 to postnatal day 68) were shaped to lever press for sucrose reinforcement and then began daily 15-min sessions of fixed ratio (FR) training. The number of days to acquire an FR 20 was measured. Neonatal exposure to the ethanol/cocaine combination significantly increased the number of days to reach the FR 20. There was also a trend for fewer of these subjects to reach the FR 20, although this difference was not statistically significant. These results suggest that subjects neonatally exposed to the ethanol/cocaine combination have difficulty learning an operant task. This impairment was unique to the ethanol/cocaine combination group and suggests that polydrug exposure during development may have a more adverse outcome than exposure to ethanol or cocaine alone.
Department of Psychology, University of Kentucky, Lexington 40506-0044, USA.
T M
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Segar
J E
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Klebaur
M T
MT
Bardo
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Barron
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002492:Central Nervous System Depressants / Q000008:administration & dosage*; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects*; D004347:Drug Interactions; D000431:Ethanol / Q000008:administration & dosage*; D005260:Female; D008297:Male; D009294:Narcotics / Q000008:administration & dosage*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D002492:Central Nervous System Depressants; D009294:Narcotics; D000431:Ethanol; D003042:Cocaine