Effect of subchronic administration of metrifonate, rivastigmine and donepezil on brain acetylcholine in aged F344 rats.
The changes in extracellular acetylcholine levels were investigated by microdialysis in the cortex and hippocampus of aging rats after administration of metrifonate (80 mg/kg), rivastigmine (0.75 mg/kg), donepezil (1.5 mg/kg) or vehicle for 21 days (twice daily p.o.). Eighteen h after the last administration, cholinesterase inhibition was 85, 52 and 39% after metrifonate, rivastigmine and donepezil, respectively, and was accompanied by 988, 590 and 75% increase in cortical acetylcholine level. In the hippocampus, metrifonate and rivastigmine brought about a 169 and 108% increase in acetylcholine levels. A challenge dose of metrifonate, rivastigmine and donepezil was followed by a further increase in cortical and hippocampal acetylcholine levels. The retrograde perfusion of the M(2)-M(4) receptor antagonist AFDX-384 (10 microM) induced a 500 and 300% increase in cortical and hippocampal acetylcholine release, in control and rivastigmine-treated rats, respectively, no increase in metrifonate-treated rats, and a 210% increase in donepezil-treated rats. In conclusion, chronic treatment of aging rats with metrifonate, rivastigmine and donepezil induces a long-lasting increase in acetylcholine levels, and reveals marked differences between the three drugs.
Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, I-50139 Florence, Italy.
C
C
Scali
F
F
Casamenti
A
A
Bellucci
C
C
Costagli
B
B
Schmidt
G
G
Pepeu
D000109:Acetylcholine / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002219:Carbamates / Q000008:administration & dosage* / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage* / Q000494:pharmacology; D002802:Cholinesterases / Q000378:metabolism; D000077265:Donepezil; D004334:Drug Administration Schedule; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007189:Indans / Q000008:administration & dosage* / Q000494:pharmacology; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D048448:Phenylcarbamates; D010880:Piperidines / Q000008:administration & dosage* / Q000494:pharmacology; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D000068836:Rivastigmine; D014236:Trichlorfon / Q000008:administration & dosage* / Q000494:pharmacology
D002219:Carbamates; D002800:Cholinesterase Inhibitors; D007189:Indans; D018727:Muscarinic Antagonists; D048448:Phenylcarbamates; D010880:Piperidines; C065959:AFDX 384; D010890:Pirenzepine; D000077265:Donepezil; D014236:Trichlorfon; D002802:Cholinesterases; D000109:Acetylcholine; D000068836:Rivastigmine