PKCδ knockout mice are protected from para-methoxymethamphetamine-induced mitochondrial stress and associated neurotoxicity in the striatum of mice.
Para-methoxymethamphetamine (PMMA) is a para-ring-substituted amphetamine derivative sold worldwide as an illegal psychotropic drug. Although PMMA use has been reported to lead to severe intoxication and even death, little is known about the mechanism(s) by which PMMA exerts its neurotoxic effects. Here we found that PMMA treatment resulted in phosphorylation of protein kinase Cδ (PKCδ) and subsequent mitochondrial translocation of cleaved PKCδ. PMMA-induced oxidative stress was more pronounced in mitochondria than in the cytosol. Moreover, treatment with PMMA consistently resulted in significant reductions in mitochondrial membrane potential, mitochondrial complex I activity, and mitochondrial Mn superoxide dismutase-immunoreactivity. In contrast, PMMA treatment led to a significant increase in intramitochondrial Ca2+level. Treatment with PMMA also significantly increased ionized calcium binding adaptor molecule 1 (Iba-1)-labeled microglial activation and upregulated tumor necrosis factor alpha (TNF-α) gene expression. PKCδ knockout attenuated these mitochondrial effects and dampened the neurotoxic effects of PMMA. Importantly, TNF-α knockout mice were significantly protected from PMMA-induced increases in phospho-PKCδ expression, mitochondrial translocation of cleaved PKCδ, and Iba-1-labeled microgliosis. Both rottlerin, a pharmacological inhibitor of PKCδ, and etanercept, a pharmacological inhibitor of TNF-α, significantly protected against PMMA-mediated induction of apoptosis, as assessed by terminal deoxynucleotidyl transferase dUDP nick end labeling (TUNEL) assays. In addition, PKCδ knockout and TNF-α knockout both resulted in decreased PMMA-mediated induction of dopaminergic loss. Therefore, our results suggest that PKCδ mediates PMMA-induced neurotoxicity by facilitating oxidative stress (mitochondria > cytosol), mitochondrial dysfunction, microglial activation, and pro-apoptotic signaling. Our results also indicate that PMMA-induced PKCδ activation requires the proinflammatory cytokine TNF-α.
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
Eun-Joo
EJ
Shin
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
Duy-Khanh
DK
Dang
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
Hai-Quyen
HQ
Tran
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
Yunsung
Y
Nam
Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea.
Ji Hoon
JH
Jeong
Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea.
Young Hun
YH
Lee
Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea.
Kyung Tae
KT
Park
Department of Life and Nanopharmaceutical Sciences, Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea.
Yong Sup
YS
Lee
Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Choon-Gon
CG
Jang
Neuropharmacology Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA.
Jau-Shyong
JS
Hong
Nabeshima Laboratory, Graduate School of Pharmaceutical Sciences, Meijo University, Nagoya, 468-8503, Japan.
Toshitaka
T
Nabeshima
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea. Electronic address: kimhc@kangwon.ac.kr.
Hyoung-Chun
HC
Kim
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008694:Methamphetamine / Q000494:pharmacology*; D018345:Mice, Knockout; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D020258:Neurotoxicity Syndromes / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000172:deficiency / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects*
D008694:Methamphetamine; D051745:Protein Kinase C-delta; D004298:Dopamine
Microglia; Mitochondria; Oxidative stress; Para-methoxymethamphetamine; Protein kinase Cδ; Tumor necrosis factor-α