Brief early handling increases morphine dependence in adult rats.
Short early manipulations of rodent postnatal environment may trigger long-term effects on neurobiological and behavioural phenotypes in adulthood. However, little is known about such effects of handling on the vulnerability to develop drug dependence. The present study aimed to analyze the long-term effects of a brief handling (1 min) on morphine and ethanol dependence and on the preproenkephalin (PPE) mRNA and mu opioid receptor levels. Handled rats showed a significant increase in morphine (25mg/l) but not ethanol (10%) consumption and preference after 7 weeks and no difference in morphine (2 and 5mg/kg) conditioned place preference. No difference of preproenkephalin mRNA and mu opioid receptor levels was detected in the mesolimbic system between both groups. These data emphasize that human brief handling, which can lead to morphine dependence development, constitutes in itself an experimental treatment and not a control condition.
INSERM, U513, Créteil, F-94010 France; Université Paris XII, Créteil, F-94010 France.
Vincent
V
Vazquez
Jacqueline
J
Penit-Soria
Claudette
C
Durand
Marie-Jo
MJ
Besson
Bruno
B
Giros
Valérie
V
Daugé
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography / Q000379:methods; D001522:Behavior, Animal; D002492:Central Nervous System Depressants / Q000009:adverse effects; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000009:adverse effects; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006234:Handling, Psychological; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D009020:Morphine / Q000009:adverse effects*; D009021:Morphine Dependence / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D009294:Narcotics / Q000009:adverse effects*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism
D002492:Central Nervous System Depressants; D019332:Endothelin-1; D009294:Narcotics; D012333:RNA, Messenger; D017450:Receptors, Opioid, mu; D000431:Ethanol; D009020:Morphine