Xiaolin Deng

Speed kills: cellular and molecular bases of methamphetamine-induced nerve terminal degeneration and neuronal apoptosis

Methamphetamine (METH) is a drug of abuse that has long been known to damage monoaminergic systems in the mammalian brain. Recent reports have provided conclusive evidence that METH can cause neuropathological changes in the rodent brain via apoptotic mechanisms akin to those reported in various models of neuronal death. The purpose of this review is to provide an interim account for a role of oxygen‐based radicals and the participation of transcription factors and the involvement of cell death genes in METH‐induced neurodegeneration. We discuss data suggesting the participation of endoplasmic reticulum and mitochondria‐mediated activation of caspase‐dependent and ‐independent cascades in the manifestation of METH‐induced apoptosis. Studies that use more comprehensive approaches to gene expression profiling should allow us to draw more instructive molecular portraits of the complex plastic and degenerative effects of this drug.—Cadet, J. L., Jayanthi, S., Deng, X. Speed kills: cellular and molecular bases of methamphetamine‐induced nerve terminal degeneration and neuronal apoptosis. FASEB J. 17, 1775–1788 (2003)

Methamphetamine induces neuronal apoptosis via cross-talks between endoplasmic reticulum and mitochondria-dependent death cascades

Methamphetamine (METH) is an illicit drug that causes neurodegenerative effects in humans. In rodents, METH induces apoptosis of striatal glutamic acid decarboxylase (GAD) ‐containing neurons. This paper provides evidence that METH‐induced cell death occurs consequent to interactions of ER stress and mitochondrial death pathways. Specifically, injec¬tions of METH are followed by an almost immediate activation of proteases calpain and caspase‐12, events consistent with drug‐induced ER stress. Involvement of ER stress was further supported by observations of increases in the expression of GRP78/BiP and CHOP. Participation of the mitochondrial pathway was demon¬strated by the transition of AIF, smac/DIABLO, and cytochrome c from mitochondrial into cytoplasmic frac¬tions. These changes occur before the apoptosome‐associated pro‐caspase‐9 cleavage. Effector caspases‐3 and ‐6, but not ‐7, were cleaved with the initial time of caspase‐3 activation occurring before caspase 9 cleav¬age; this suggests possible earlier cleavage of caspase‐3 by caspase‐12. These events preceded proteolysis of the caspase substrates DFF‐45, lamin A, and PARP in nuclear fractions. These findings indicate that METH causes neuronal apoptosis in part via cross‐talks be¬tween ER‐ and mitochondria‐generated processes, which cause activation of both caspase‐dependent and ‐independent pathways.—Jayanthi, S., Deng, X., Noailles, P.‐A. H., Ladenheim, B., Cadet, J. L. Methamphetamine induces neuronal apoptosis via cross‐talks between endoplasmic reticulum and mitochondria‐de¬pendent death cascades. FASEB J. 18, 238–251 (2004)

Methamphetamine causes widespread apoptosis in the mouse brain: evidence from using an improved TUNEL histochemical method

Terminal deoxynucleotidyl transferase (TdT)-mediated dNTP nick end labeling (TUNEL) histochemistry is a sensitive method to expose DNA strand breaks in apoptotic cells, but it is difficult to conduct on slide-mounted sections. By using a 80 degrees C/0.5% Triton X-100 pretreatment, we have developed a TUNEL histochemical approach with high specificity and sensitivity using sections from ischemic rat brains. Thereafter, methamphetamine (METH)-induced neuronal death was investigated in mice brains. The results showed that a single injection of 40 mg/kg METH caused neuronal death in several brain areas including the striatum, cortex (frontal, parietal, and piriform), indusium griseum, medial habenular nucleus, and hippocampus. These results further confirmed the presence of METH-induced deleterious effects in nondopaminergic neurons. The significance of these findings is also discussed.

Dietary supplementation with blueberries, spinach, or spirulina reduces ischemic brain damage

Free radicals are involved in neurodegenerative disorders, such as ischemia and aging. We have previously demonstrated that treatment with diets enriched with blueberry, spinach, or spirulina have been shown to reduce neurodegenerative changes in aged animals. The purpose of this study was to determine if these diets have neuroprotective effects in focal ischemic brain. Adult male Sprague-Dawley rats were fed with equal amounts of diets (blueberry, spinach, and spirulina) or with control diet. After 4 weeks of feeding, all animals were anesthetized with chloral hydrate. The right middle cerebral artery was ligated with a 10-O suture for 60 min. The ligature was later removed to allow reperfusional injury. Animals were sacrificed and brains were removed for caspase-3 enzymatic assays and triphenyltetrazolium chloride staining at 8 and 48 h after the onset of reperfusion. A subgroup of animals was used for locomotor behavior and biochemical assays. We found that animals which received blueberry, spinach, or spirulina enriched diets had a significant reduction in the volume of infarction in the cerebral cortex and an increase in post-stroke locomotor activity. There was no difference in blood biochemistry, blood CO2, and electrolyte levels among all groups, suggesting that the protection was not indirectly mediated through the changes in physiological functions. Animals treated with blueberry, spinach, or spirulina had significantly lower caspase-3 activity in the ischemic hemisphere. In conclusion, our data suggest that chronic treatment with blueberry, spinach, or spirulina reduces ischemia/reperfusion-induced apoptosis and cerebral infarction.

Methamphetamine induces apoptosis in an immortalized rat striatal cell line by activating the mitochondrial cell death pathway

Methamphetamine is a neurotoxic drug of abuse known to cause cell death both in vitro and in vivo. Nevertheless, the molecular and cellular mechanisms involved in this process remain to be clarified. Herein, we show that methamphetamine-induced apoptosis is associated with early (2 h) overexpression of bax, decreases of mitochondrial membrane potential and oxygen consumption as well as release of cytochrome c from mitochondria. In addition, activated caspase-9 was detected at 4 h post-METH exposure. Cell death was detectable by annexin V and propidium iodide staining after 8 h of methamphetamine exposure. At that time, the majority of the cells were stained by annexin V alone, with some cells being stained for both annexin V and propidium iodide. Moreover, cleavage of caspase-3, poly (ADP-ribose) polymerase and DNA fragmentation-related factor 45 was detected at 8 h post drug treatment. These results indicate that methamphetamine-induced apoptotic cell death results from early overexpression of bax, reduction of mitochondrial respiration and membrane potential and release of mitochondrial cytochrome c with subsequent activation of the caspase cascade.

Methamphetamine-induced neuronal apoptosis involves the activation of multiple death pathways. Review.

The abuse of the illicit drug methamphetamine (METH) is a major concern because it can cause terminal degeneration and neuronal cell death in the brain. METH-induced cell death occurs via processes that resemble apoptosis. In the present review, we discuss the role of various apoptotic events in the causation of METH-induced neuronal apoptosisin vitro andin vivo. Studies using comprehensive approaches to gene expression profiling have allowed for the identification of several genes that are up-regulated or down-regulated after an apoptosis-inducing dose of the drug. Further experiments have also documented the fact that the drug can cause demise of striatal enkephalinergic neurons by cross-talks between mitochondria-, endo-plasmic reticulum- and receptor-mediated apoptotic events. These neuropathological observations have also been reported in models of drug-induced neuroplastic alterations used to mimic drug addiction (Nestler, 2001).

Neuropeptide Y Protects against Methamphetamine-Induced Neuronal Apoptosis in the Mouse Striatum

Methamphetamine (METH) is an illicit drug that causes neuronal apoptosis in the mouse striatum, in a manner similar to the neuronal loss observed in neurodegenerative diseases. In the present study, injections of METH to mice were found to cause the death of enkephalin-positive projection neurons but not the death of neuropeptide Y (NPY)/nitric oxide synthase-positive striatal interneurons. In addition, these METH injections were associated with increased expression of neuropeptide Y mRNA and changes in the expression of the NPY receptors Y1 and Y2. Administration of NPY in the cerebral ventricles blocked METH-induced apoptosis, an effect that was mediated mainly by stimulation of NPY Y2 receptors and, to a lesser extent, of NPY Y1 receptors. Finally, we also found that neuropeptide Y knock-out mice were more sensitive than wild-type mice to METH-induced neuronal apoptosis of both enkephalin- and nitric oxide synthase-containing neurons, suggesting that NPY plays a general neuroprotective role within the striatum. Together, our results demonstrate that neuropeptide Y belongs to the class of factors that maintain neuronal integrity during cellular stresses. Given the similarity between the cell death patterns induced by METH and by disorders such as Huntingtons disease, our results suggest that NPY analogs might be useful therapeutic agents against some neurodegenerative processes.

Methamphetamine-induced apoptosis is attenuated in the striata of copper-zinc superoxide dismutase transgenic mice.

Administration of methamphetamine caused significant increases in terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells, in poly (ADP-ribose) polymerase (PARP) cleavage, as well as in caspase-3 activity in the striata of C57BL/6J mice. In contrast, all these effects were markedly suppressed in the copper-zinc superoxide dismutase transgenic mice. These results indicate that superoxide radicals might be important factors in METH-induced cell death.

Methamphetamine administration causes death of dopaminergic neurons in the mouse olfactory bulb.

BACKGROUND Methamphetamine (METH) is an addictive drug that can cause neurological and psychiatric disorders. In the rodent brain, toxic doses of METH cause damage of dopaminergic terminals and apoptosis of nondopaminergic neurons. The olfactory bulb (OB) is a brain region that is rich with dopaminergic neurons and terminals. METHODS Rats were given a single injection of METH (40 mg/kg) and sacrificed at various time points afterward. The toxic effects of this injection on the OB were assessed by measuring monoamine levels, tyrosine hydroxylase (TH) immunocytochemistry, terminal deoxynucleotidyl transferase-mediated deoxyribonucleotide triphosphate (dNTP) nick end labeling (TUNEL) histochemistry, and caspase-3 immunochemistry. RESULTS Methamphetamine administration caused marked decreases in dopamine (DA) levels and TH-like immunostaining in the mouse OB. The drug also caused increases in TUNEL-labeled OB neurons, some of which were also positive for TH expression. Moreover, there was METH-induced expression of activated caspase-3 in TH-positive cells. Finally, the METH injection was associated with increased expression of the proapoptotic proteins, Bax and Bid, but with decreased expression of the antideath protein, Bcl2. CONCLUSIONS These observations show, for the first time, that METH can cause loss of OB DA terminals and death of DA neurons, in part, via mechanisms that are akin to an apoptotic process.

9-Cis-retinoic acid reduces ischemic brain injury in rodents via bone morphogenetic protein.

Retinoic acid (RA), a biologically active derivative of vitamin A, has protective effects against damage caused by H2O2 or oxygen‐glucose deprivation in mesangial and PC12 cells. In cultured human osteosarcoma cells, RA enhances the expression of bone morphogenetic protein‐7 (BMP7), a trophic factor that reduces ischemia‐ or neurotoxin‐mediated neurodegeneration in vivo. The purpose of this study is to examine whether RA reduces ischemic brain injury through a BMP7 mechanism. We found that intracerebroventricular administration of 9‐cis‐retinoic acid (9cRA) enhanced BMP7 mRNA expression, detected by RT‐PCR, in rat cerebral cortex at 24 hr after injection. Rats were also subjected to transient focal ischemia induced by ligation of the middle cerebral artery (MCA) at 1 day after 9cRA injection. Pretreatment with 9cRA increased locomotor activity and attenuated neurological deficits 2 days after MCA ligation. 9cRA also reduced cerebral infarction and TUNEL labeling. These protective responses were antagonized by the BMP antagonist noggin given 1 day after 9cRA injection. Taken together, our data suggest that 9cRA has protective effects against ischemia‐induced injury, and these effects involve BMPs.