Effects of a cold environment or age on methamphetamine-induced dopamine release in the caudate putamen of female rats

• Published in: Pharmacology, biochemistry and behavior Vol. 44; no. 1; pp. 87 - 98
• Main Authors: Bowyer, J.F., Gough, B., Slikker, W., Lipe, G.W., Newport, G.D., Holson, R.R.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1993; Elsevier Science
• Subjects: 3,4-Dihydroxyphenylacetic Acid - metabolism; Aging; Aging - metabolism; Amino Acids; Animals; Biogenic Monoamines - metabolism; Biological and medical sciences; Caudate Nucleus - drug effects; Caudate Nucleus - metabolism; Caudate putamen; Chromatography, High Pressure Liquid; Cold Temperature; Dialysis; Dopamine; Dopamine - metabolism; Drug addictions; Female; Glutamates - metabolism; Glutamic Acid; Hippocampus - drug effects; Hippocampus - metabolism; Medical sciences; Methampethamine; Methamphetamine - pharmacology; Microdialysis; Neurotoxicity; Putamen - drug effects; Putamen - metabolism; Rats; Rats, Sprague-Dawley; Serotonin - metabolism; Taurine - metabolism; Toxicology; Methampethamine; Neurotoxicity; Microdialysis; Dopamine; Aging; Caudate putamen; Amino Acids; Amphetamine derivatives; Nervous system diseases; Intraperitoneal administration; Cold; Rat; CNS stimulant; Psychotropic; Toxicity; Rodentia; Catecholamine; Vertebrata; Mammalia; Animal; Drug of abuse; Age; Room temperature
• ISSN: 0091-3057; 1873-5177
• DOI: 10.1016/0091-3057(93)90284-Z

Extracellular levels of dopamine (DA) and metabolites as well as serotonin [5-hydroxytryptamine (5-HT)] and 5-hydroxyindoleacetic acid (5-HIAA) were determined in the caudate putamen (CPU) of either 6- or 12-month-old female rats using microdialysis and high-performance liquid chromatography with electrochemical detection (HPLC-ED) before, during, and after four consecutive injections (given at 2-h intervals) of methampetamine (METH). In 6-month-old rats administered 4 × 5 mg/kg METH at an environmental temperature (ET) of 23°C, peak extracellular DA levels (between 50 and 150 ϱg/10 μl) were attained 30–45 min after each dose of METH while dihydroxyphenylacetic acid (DOPAC) decreased steadily after the first doses of METH until it reached a plateau at 50% of control (550−700 pg/10 μl) levels. Increase in 5-HT levles during METH administrations paralleled DA increases while 5-HIAA decreases paralleled DOPAC decreases. The total CPU DA and 5-HT content of these rats was about 65% of control at 3 days post-METH. Reducing the ET to 4°C during dosing decreased the peak and average DA levels attained during the 4 × 5 mg/kg METH administration to about 50% of that observed at a 23°C ET. Increasing the dose to 4 × 10 mg/kg METH (4°C ET) increased peak and average CPU DA levels to 200% that observed during 4 × 5 mg/kg METH at a 23°C ET. However, no significant decreases in total CPU DA content of any rats dosed with METH at a 4°C ET were observed 3 days post-METH. In 12-month-old rats dosed with 4 × 5 mg/kg METH (23°C ET), the peak and average extracellular DA levels were only 30−60% that of 6-month-old rats. However, the CPU DA content of older rats was significantly decreased both 3 (30% control) and 14 (60% control) days post-METH. In summary, METH toxicity may not be predicted solely by the extracellular levels of DA attained during METH administration; age and ET also greatly influence METH neurotoxicity.