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Single or multiple injections of methamphetamine increased dopamine turnover but did not decrease tyrosine
Frederico Costa Pereira1, Elita Santos Lourenço, Fernanda Borges
1Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
Synapse (New York, N.Y.)
|June 2, 2006
Summary
Methamphetamine causes dopamine depletion and increased turnover in rat striatum, but does not induce significant apoptosis markers within 24 hours. This suggests methamphetamine toxicity is independent of caspase-3 driven cascades in this timeframe.
Area of Science:
- Neuroscience
- Toxicology
- Biochemistry
Background:
- Methamphetamine (METH) is known to cause dopamine (DA) nerve terminal toxicity.
- Previous studies suggest METH may induce apoptosis in striatal neurons.
Purpose of the Study:
- To investigate the acute effects of single versus multiple METH injections on dopaminergic toxicity markers.
- To determine if METH induces apoptotic cascades in the rat striatum.
Main Methods:
- Rats received either multiple METH injections (4 x 5 mg/kg) or a single injection (20 mg/kg).
- Dopamine levels, turnover, and tyrosine hydroxylase (TH) immunoreactivity were measured.
- Western blot analysis assessed Bax and caspase-3 expression.
Main Results:
- Both METH paradigms depleted striatal DA and increased DA turnover.
- TH expression remained unchanged by either treatment.
- Multiple METH doses increased Bax expression but did not activate caspase-3.
Conclusions:
- Acute METH administration alters striatal dopaminergic markers independently of terminal degeneration within 24 hours.
- METH-induced striatal toxicity in this acute model does not involve the mitochondria-dependent caspase-3 apoptotic pathway.