Ethanol-induced changes in proenkephalin mRNA expression in the rat nigrostriatal pathway.
Endogenous opioid systems have been suggested to play a key role in ethanol reinforcement mechanisms and alcohol-drinking behavior. Ethanol induces differential alterations in opioid peptide expression in brain areas of the reward circuits, which may be linked to the reinforcing effects of ethanol. In addition, ethanol-induced alterations in opioidergic nigrostriatal transmission could be involved in brain sensitivity to ethanol and play a role in addictive processes. The aim of this work was to study the effects of acute ethanol administration on proenkephalin (proenk) mRNA expression in the rat substantia nigra and caudate-putamen (CP) for up to 24 h post treatment. Male Wistar rats received ethanol (2.5 g/kg) or distilled water by intragastric administration, and proenk mRNA expression was studied by in situ hybridization and densitometry. Ethanol transiently increased proenk mRNA expression in the CP 1 h after drug administration. Proenk mRNA levels remained elevated 2 h post treatment in the anterior-medial and medial-posterior regions of the CP. In contrast, ethanol decreased proenk mRNA expression in the substantia nigra pars compacta and pars reticulata 2 h after drug exposure. Alterations in enkephalin expression in the substantia nigra and CP in response to ethanol exposure could be involved in the mechanisms underlying brain sensitivity to the drug.
Méndez
Milagros
M
Departamento de Neuroquímica, Calzada México Xochimilco 101, Col. San Lorenzo Huipulco, 14370, México D.F., México. ubach@imp.edu.mx
Morales-Mulia
Marcela
M
Pérez-Luna
José Manuel
JM
D020268:Alcohol-Induced Disorders, Nervous System / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D000437:Alcoholism / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D002492:Central Nervous System Depressants / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004745:Enkephalins / Q000235:genetics*; D000431:Ethanol / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D019966:Substance-Related Disorders / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D013378:Substantia Nigra / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D002492:Central Nervous System Depressants; D004745:Enkephalins; D011498:Protein Precursors; D012333:RNA, Messenger; C029992:proenkephalin; D000431:Ethanol; D004298:Dopamine