Immunohistochemical increase in cyclooxygenase-2 without apoptosis in different brain areas of subchronic nicotine- and D-amphetamine-treated rats.
Cyclooxygenase-2 (COX-2) upregulation has been related to both neurodegeneration and physiological processes. To clarify whether nicotine-induced upregulation of COX-2 occurs, and to analyse its significance, a comparative immunohistochemical and Western blot study was performed on the frontoparietal cortex, hippocampus and cerebellar cortex of rats treated (14 days) with nicotine, D(+)amphetamine (0.35 and 1.16 mg free base/kg/day, respectively), or both drugs simultaneously. None of these treatments promoted neuronal apoptosis. Lipid peroxidation increased in the hippocampus of the nicotine-treated rats and in all the brain regions examined in the D(+)amphetamine rats, but not in the double-treated animals. Both molecules increased the COX-2 content (as determined by the number of immunopositive neurons and the intensity of their immunodeposits) in an area-, layer- and neuron type-dependent manner, in all brain regions in which a large number of COX-2 immunopositive neurons were observed in controls (the somatosensory cortical areas, CA-1, CA-3, the gyrus dentatus, the ectorhinal/perirhinal areas, and the gyrus cingularis). No increase was seen in the motor cortical areas, while a reduction was recorded in the cerebellar cortex; these regions had only a few immunopositive neurons in controls. Western blot analysis revealed a 50-80% increase in COX-2 in the brain cortex and hippocampus of nicotine-treated rats, and similar increases (150-200%) in the cortex of the D(+)amphetamine- and nicotine + D(+)amphetamine-treated rats. Nicotine-induced upregulation of COX-2 seems to be related to neuronal plasticity rather than neurodegeneration. Nicotine agonists might be useful in the treatment of cognitive disorders.
Toledano
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A
Instituto Cajal, CSIC, Avda. Dr. Arce 37, 28002, Madrid, Spain. atoledano@cajal.csic.es
Alvarez
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MI
Caballero
I
I
Carmona
P
P
De Miguel
E
E
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002525:Cerebellar Cortex / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D003913:Dextroamphetamine / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism; D005625:Frontal Lobe / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D007150:Immunohistochemistry; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D000697:Central Nervous System Stimulants; D005609:Free Radicals; D018722:Nicotinic Agonists; D009538:Nicotine; D051546:Cyclooxygenase 2; D003913:Dextroamphetamine