Long-lasting change in brain dynamics induced by methamphetamine: enhancement of protein kinase C-dependent astrocytic response and behavioral sensitization.
It is well known that long-term exposure to psychostimulants induces neuronal plasticity. Recently, accumulating evidence suggests that astrocytes may actively participate in synaptic plasticity. In this study, we found that in vitro treatment of cortical neuron/glia co-cultures with either methamphetamine (METH) or morphine (MRP) caused the activation of astrocytes via protein kinase C (PKC). Purified astrocytes were markedly activated by METH, whereas MRP had no such effect. METH, but not MRP, caused a long-lasting astrocytic activation in cortical neuron/glia co-cultures. Furthermore, MRP-induced behavioral sensitization to hyper-locomotion was reversed by 2 months of withdrawal following intermitted MRP administration, whereas behavioral sensitization to METH-induced hyper-locomotion was maintained even after 2 months of withdrawal. Consistent with this cell culture study, in vivo treatment with METH, which was associated with behavioral sensitization, caused a PKC-dependent astrocytic activation in the cingulate cortex and nucleus accumbens of mice. These findings provide direct evidence that METH induces a long-lasting astrocytic activation and behavioral sensitization through the stimulation of PKC in the rodent brain. In contrast, MRP produced a reversible activation of astrocytes via neuronal PKC and a reversibility of behavioral sensitization. This information can break through the definition of drugs of abuse and the misleading of concept that morphine produces a long-lasting neurotoxicity.
Narita
Minoru
M
Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Ebara, Tokyo, Japan. narita@hoshi.ac.jp
Miyatake
Mayumi
M
Shibasaki
Masahiro
M
Tsuda
Makoto
M
Koizumi
Schuichi
S
Narita
Michiko
M
Yajima
Yoshinori
Y
Inoue
Kazuhide
K
Suzuki
Tsutomu
T
D019969:Amphetamine-Related Disorders / Q000201:enzymology* / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002478:Cells, Cultured; D000697:Central Nervous System Stimulants / Q000633:toxicity; D018920:Coculture Techniques; D004195:Disease Models, Animal; D006179:Gyrus Cinguli / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D006948:Hyperkinesis / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D008297:Male; D008694:Methamphetamine / Q000633:toxicity*; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000633:toxicity; D009294:Narcotics / Q000633:toxicity; D009410:Nerve Degeneration / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D011493:Protein Kinase C / Q000187:drug effects* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D000697:Central Nervous System Stimulants; D009294:Narcotics; D008694:Methamphetamine; D009020:Morphine; D011493:Protein Kinase C