Role of oxidative stress in methamphetamine-induced dopaminergic toxicity mediated by protein kinase Cδ

Abstract

This study examined the role of protein kinase C (PKC) isozymes in methamphetamine (MA)-induced dopaminergic toxicity. Multiple-dose administration of MA did not significantly alter PKCα, PKCβI, PKCβII, or PKCζ expression in the striatum, but did significantly increase PKCδ expression. Gö6976 (a co-inhibitor of PKCα and -β), hispidin (PKCβ inhibitor), and PKCζ pseudosubstrate inhibitor (PKCζ inhibitor) did not significantly alter MA-induced behavioral impairments. However, rottlerin (PKCδ inhibitor) significantly attenuated behavioral impairments in a dose-dependent manner. In addition, MA-induced behavioral impairments were not apparent in PKCδ knockout (–/–) mice. MA-induced oxidative stress (i.e., lipid peroxidation and protein oxidation) was significantly attenuated in rottlerin-treated mice and was not apparent in PKCδ (–/–) mice. Consistent with this, MA-induced apoptosis (i.e., terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive apoptotic cells) was significantly attenuated in rottlerin-treated mice. Furthermore, MA-induced increases in the dopamine (DA) turnover rate and decreases in tyrosine hydroxylase (TH) activity and the expression of TH, dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT2) were not significantly observed in rottlerin-treated or PKCδ (–/–) mice. Our results suggest that PKCδ gene expression is a key mediator of oxidative stress and dopaminergic damage induced by MA. Thus, inhibition of PKCδ may be a useful target for protection against MA-induced neurotoxicity.

Histone Hyperacetylation Up-regulates Protein Kinase Cδ in Dopaminergic Neurons to Induce Cell Death

“…Consistent with these studies, we demonstrated in an in vivo study that administering rottlerin, a PKC␦-specific inhibitor, protected against MPTP-induced loss of tyrosine hydroxylase-positive neurons in the nigrostriatum and the depletion of striatal dopamine and its metabolites, as well as MPTP-induced locomotor deficits (16). In a methamphetamine-intoxicated animal model, PKC␦ deficiency and rottlerin effectively attenuated methamphetamine-induced dopaminergic damage and behavioral deficits, further supporting that PKC␦ could represent a valid pharmacological target for the treatment of dopaminergic neuronal degeneration (17,18). Interestingly, we also showed that PKC␦ negatively modulates dopamine synthesis by inhibiting the rate-limiting enzyme, tyrosine hydroxylase (3).…”

“…We then proceeded to analyze the 6-OHDA-induced oxidative toxicity by MTS viability and dopamine reuptake assays. To determine the effects of PKC␦, we applied the PKC␦ inhibitor rottlerin, which has been shown to protect against MPTP and methamphetamine dopaminergic neurotoxicity and alleviate LPS-induced neuroinflammation both in vitro and in vivo (16,18,85). Our preliminary analyses indicate 0.3 M rottlerin for a 24-h treatment would be optimal for differentiated LUHMES cells (data not shown).…”

Neuroimmune Basis of Methamphetamine Toxicity

“…Likewise, protein kinase Cδ knock-out animals have reduced lipid peroxidation, protein oxidation, and behavioral deficits in response to methamphetamine. These studies were corroborated using pharmacological interventions, which also indicate increased tyrosine hydroxylase phosphorylation in response to methamphetamine (Shin et al, 2011, 2012). …”

Liposomal melatonin rescues methamphetamine‐elicited mitochondrial burdens, pro‐apoptosis, and dopaminergic degeneration through the inhibition PKCδ gene

“…We failed to observe MA‐induced TUNEL‐positive cells in the striatum of WT mice 12 hr, 1 day, or 3 days after the final MA administration (i.e., four injections of 8 mg/kg MA, intraperitoneally at 2‐hr intervals or a single injection of MA 20–40 mg/kg), suggesting that the C57BL/6 background is not sensitive to TUNEL staining . Thus, according to the previous reports , we used 10‐wk‐old male Taconic ICR mice. Because apoptotic cell death was detectable at 20 mg/kg MA and reached a significant level at 35 mg/kg in our previous study, a 35 mg/kg dose of MA was chosen for the present study.…”