Cocaine treatment increases expression of a 40 kDa catecholamine-regulated protein in discrete brain regions

The effects of oxidative stress on female reproduction: a review

Oxidative stress (OS), a state characterized by an imbalance between pro-oxidant molecules including reactive oxygen and nitrogen species, and antioxidant defenses, has been identified to play a key role in the pathogenesis of subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between pro-oxidants and antioxidants can lead to a number of reproductive diseases such as endometriosis, polycystic ovary syndrome (PCOS), and unexplained infertility. Pregnancy complications such as spontaneous abortion, recurrent pregnancy loss, and preeclampsia, can also develop in response to OS. Studies have shown that extremes of body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess free radical production, which could affect fertility. Exposures to environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes. Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of antioxidants to treat infertility.

Knockdown of mortalin within the medial prefrontal cortex impairs normal sensorimotor gating

The 70-kDa mitochondrial heat shock protein, mortalin, is a ubiquitously expressed, multifunctional protein that is capable of binding the neurotransmitter, dopamine, within the brain. Dopamine dysregulation has been implicated in many of the abnormal neurological behaviors. Although studies have indicated that mortalin is differentially regulated in response to dopaminergic modulation, research has yet to elucidate the role of mortalin in the regulation of dopaminergic activity. This study seeks to investigate the role of mortalin in the regulation of dopamine-dependent behavior, specifically as it pertains to schizophrenia (SCZ). Mortalin expression was knocked down through the infusion of antisense oligodeoxynucleotide molecules into the medial prefrontal cortex (mPFC). Rats infused with mortalin antisense oligodeoxynucleotide molecules exhibited significant prepulse inhibition deficits, suggestive of defects in normal sensorimotor gating. Furthermore, mortalin misexpression within the mPFC was coupled to a significant increase in mortalin protein expression within the nucleus accumbens at the molecular level. These findings demonstrate that mortalin plays an essential role in the regulation of dopamine-dependent behavior and plays an even greater role in the pathogenesis of SCZ.

Antipsychotic drug use is correlated with CRP40/mortalin mRNA expression in the dorsolateral prefrontal cortex of human postmortem brain specimens

Heat shock proteins act as intracellular chaperones by assisting with proper protein folding in response to various cellular stresses. In doing so, these proteins protect the cell from unwanted protein aggregation, which in turn, plays an important role in the pathogenesis of numerous disorders. Previous reports from our laboratory have described a 40 kDa catecholamine regulated heat shock-like protein (CRP40), an alternate gene product of the 70 kDa mitochondrial heat shock protein, mortalin. CRP40 shares an intimate association with dopaminergic activity, specifically as it pertains to dopamine dysregulation in schizophrenia. This study investigates human CRP40/mortalin mRNA expression within dorsolateral prefrontal cortex postmortem specimens from normal control, schizophrenic and bipolar patients obtained from the Stanley Medical Research Institute. Real-time polymerase chain reaction was carried out for all patient samples (n=105; n=35 per group) in a blinded manner. No significant alterations in CRP40/mortalin mRNA expression levels were observed between control, bipolar and schizophrenic patients. However, multiple regression demonstrated a distinct positive correlation between CRP40/mortalin mRNA expression and lifetime use of antipsychotic drugs within the schizophrenic patient profile, after controlling for important confounding factors. Thus, the data suggest that human CRP40/mortalin is modulated by dopaminergic activity and may act to protect neurons from excess catecholamine activity in regions of the brain associated with psychosis.

Cloning, characterization, and functional studies of a human 40-kDa catecholamine-regulated protein: implications in central nervous system disorders

Catecholamine-regulated proteins (CRPs) have been shown to bind dopamine and other structurally related catecholamines; in particular, the 40-kDa CRP (CRP40) protein has been previously cloned and functionally characterized. To determine putative human homologs, BLAST analysis using the bovine CRP40 sequence identified a human established sequence tag (EST) with significant homology (accession #BQ224193). Using this EST, we cloned a recombinant human brain CRP40-like protein, which possessed chaperone activity. Radiolabeled dopamine binding studies with recombinant human CRP40 protein demonstrated the ability of this protein to bind dopamine with low affinity and high capacity. The full-length human CRP40 nucleotide sequence was elucidated (accession #DQ480334) with RNA ligase-mediated rapid amplification of complementary DNA ends polymerase chain reaction, while Northern blot hybridization suggested that human CRP40 is an alternative splice variant of the 70-kDa mitochondrial heat shock protein, mortalin. Human SH-SY5Y neuroblastoma cells treated with the antipsychotic drug, haloperidol, exhibited a significant increase in CRP40 messenger RNA expression compared to untreated control cells, while other dopamine agonists/antagonists also altered CRP40 expression and immunolocalization. In conclusion, these results show that we have cloned a splice variant of mortalin with a novel catecholamine binding function and that this chaperone-like protein may be neuroprotective in dopamine-related central nervous system disorders.

Alterations in tryptophan and purine metabolism in cocaine addiction: a metabolomic study

BACKGROUND

Mapping metabolic "signatures" can provide new insights into addictive mechanisms and potentially identify biomarkers and therapeutic targets.

OBJECTIVE

We examined the differences in metabolites related to the tyrosine, tryptophan, purine, and oxidative stress pathways between cocaine-dependent subjects and healthy controls. Several of these metabolites serve as biological indices underlying the mechanisms of reinforcement, toxicity, and oxidative stress.

METHODS

Metabolomic analysis was performed in 18 DSM-IV-diagnosed cocaine-dependent individuals with at least 2 weeks of abstinence and ten drug-free controls. Plasma concentrations of 37 known metabolites were analyzed and compared using a liquid chromatography electrochemical array platform. Multivariate analyses were used to study the relationship between severity of drug use [Addiction Severity Index (ASI) scores] and biological measures.

RESULTS

Cocaine subjects showed significantly higher levels of n-methylserotonin (p < 0.0017) and guanine (p < 0.0031) and lower concentrations of hypoxanthine (p < 0.0002), anthranilate (p < 0.0024), and xanthine (p < 0.012), compared to controls. Multivariate analyses showed that a combination of n-methylserotonin and xanthine contributed to 73% of the variance in predicting the ASI scores (p < 0.0001). Logistic regression showed that a model combining n-methylserotonin, xanthine, xanthosine, and guanine differentiated cocaine and control groups with no overlap.

CONCLUSIONS

Alterations in the methylation processes in the serotonin pathways and purine metabolism seem to be associated with chronic exposure to cocaine. Given the preliminary nature and cross-sectional design of the study, the findings need to be confirmed in larger samples of cocaine-dependent subjects, preferably in a longitudinal design.

Differential modulation of a 40 kDa catecholamine regulated protein in the core and shell subcompartments of the nucleus accumbens following chronic quinpirole and haloperidol administration in the rat

Past reports have shown dopamine (DA) D2/D3 receptor agonist quinpirole (QNP) and the DA D2 receptor antagonist, haloperidol (HAL) display a significant increase in expression of catecholamine regulated protein (CRP40) in the nucleus accumbens (NAcc) and the striatum, respectively. The present study investigated the in vivo effects of QNP and HAL on CRP40 protein levels within the core and shell subcompartments of the NAcc. As significant homology exists between CRP40 and Hsp70/Hsc70, parallel studies with inducible Hsp70 and constitutive Hsc70 were conducted to establish the specificity with respect to QNP on Hsp70 and CRP40. Results demonstrated that CRP40 protein was significantly expressed in the shell relative to the core region of NAcc following chronic QNP (+16.28%+/-0.42%, P<0.05) and CRP40 protein was significantly expressed in the core vs. the shell following chronic HAL (+36.02%+/-0.75%, P<0.05). There was no significant change in Hsp70 protein levels following chronic QNP or HAL administration. The results demonstrated selective modulation of CRP40 within NAcc by QNP and HAL treatment, without affecting Hsp70.

Cocaine alters catalase activity in prefrontal cortex and striatum of mice

Catalase is one of the enzymes that convert hydrogen peroxide (H2O2) to H2O presenting a protective role against free radicals. In this study, catalase activity was determined in homogenates of striatum (ST) and prefrontal cortex (PFC) in order to examine the participation of oxidative stress (OS) on cocaine actions in mice brain. Male Swiss mice were injected (i.p.) with cocaine at low (10 and 30 mg/kg) and high doses (90 mg/kg), and observed for 1 h. After cocaine overdose (90 mg/kg) some animals presented only status epilepticus (SE) while others died after seizures. These animals were dissected and divided in two groups, SE and death. Catalase activity was also determined after pretreatment with the anticonvulsant drug, diazepam, alone or injected before cocaine 90 mg/kg, and after seizures induced by a high dose of bupropion, a known inhibitor of NE and DA reuptake used for comparison. Results showed a decrease in catalase activity of the PFC and ST after SE and death induced by cocaine and bupropion overdoses. Cocaine at low doses decreased the enzyme activity only in ST. Diazepam treatment alone and before cocaine overdose did not interfere with catalase activity. This reduction in catalase activity may reflect an increase in H2O2 content in PFC and ST. Previous data reports that H2O2 inhibits dopamine transporter activity, suggesting that the decrease in catalase activity may potentiate the toxic mechanism of drugs that inhibit monoamines reuptake. As far as we know, this is the first report showing an involvement of OS in the cocaine's central mechanism of action.

Role of oxidative metabolites of cocaine in toxicity and addiction: oxidative stress and electron transfer

Cocaine is one of the principal drugs of abuse. Although impressive advances have been made, unanswered questions remain concerning mechanism of toxicity and addiction. Discussion of action mode usually centers on receptor binding and enzyme inhibition, with limited attention to events at the molecular level. This review provides extensive evidence in support of the hypothesis that oxidative metabolites play important roles comprising oxidative stress (OS), reactive oxygen species (ROS), and electron transfer (ET). The metabolites include norcocaine and norcocaine derivatives: nitroxide radical, N-hydroxy, nitrosonium, plus cocaine iminium and formaldehyde. Observed formation of ROS is rationalized by redox cycling involving several possible ET agents. Three potential ones are present in the form of oxidative metabolites, namely, nitroxide, nitrosonium, and iminium. Most attention has been devoted to the nitroxide-hydroxylamine couple which has been designated by various investigators as the principal source of ROS. The proximate ester substituent is deemed important for intramolecular stabilization of reactive intermediates. Reduction potential of nitroxide is in accord with plausibility of ET in the biological milieu. Toxicity by cocaine, with evidence for participation of OS, is demonstrated for many body components, including liver, central nervous system, cardiovascular system, reproductive system, kidney, mitochondria, urine, and immune system. Other adverse effects associated with ROS comprise teratogenesis and apoptosis. Examples of ROS generated are lipid peroxides and hydroxyl radical. Often observed were depletion of antioxidant defenses, and protection by added antioxidants, such as, thiol, salicylate, and deferoxamine. Considerable evidence supports the contention that oxidative ET metabolites of cocaine are responsible for much of the observed OS. Quite significantly, the pro-oxidant, toxic effects, including generation of superoxide and lipid peroxyl radicals, plus depletion of glutathione, elicited by nitroxide or the hydroxylamine derivative, were greater than for the parent drug. The formaldehyde metabolite also appears to play a role. Mechanistic similarity to the action of neurotoxin 3,3'-iminodipropionitrile is pointed out. A number of literature strategies for treatment of addiction are addressed. However, no effective interventions are currently available. An hypothesis for addiction is offered based on ET and ROS at low concentrations. Radicals may aid in cell signaling entailing redox processes which influence ion transport, neuromodulation, and transcription. Ideas are suggested for future work dealing with health promotion. These include use of AOs, both dietary and supplemental, trapping of the norcocaine metabolite by non-toxic complexing agents, and use of nitrones for capturing harmful radical species.

Cocaine induces apoptosis in primary cultured rat aortic vascular smooth muscle cells: possible relationship to aortic dissection, atherosclerosis, and hypertension

Cocaine abuse is known to induce many adverse cardiovascular effects, including hypertension, atherosclerosis, and aortic dissection. A major physiological event leading to these pathophysiological actions of cocaine could be apoptosis. This study was designed to investigate if primary cultured rat aortic vascular smooth muscle cells (VSMCs) can undergo apoptosis when treated with cocaine. After treatment with cocaine (10(-6) to 10(-4) M), morphological analysis of aortic VSMCs using confocal fluoresence microscopy showed that the percentage of apoptotic aortic VSMCs increased after cocaine (10(-6) to 10(-4) M) treatment for 12, 24, and 48 h. These results demonstrate that aortic VSMCs can undergo rapid apoptosis in response to cocaine in a concentration-dependent manner. Cocaine-induced apoptosis may thus play a major role in cocaine abuse-induced aortic dissection, atherosclerosis, and hypertension.

Electron spin resonance spectroscopy reveals alpha-phenyl-N-tert-butylnitrone spin-traps free radicals in rat striatum and prevents haloperidol-induced vacuous chewing movements in the rat model of human tardive dyskinesia

The typical antipsychotic drug haloperidol causes vacuous chewing movements (VCM) in rats, which are representative of early-Parkinsonian symptoms or later-onset extrapyramidal side effects of tardive dyskinesia (TD) in humans. Haloperidol (HP) has been hypothesized to potentiate increases in oxidative stress or free radical-mediated levels of toxic metabolites in rat striatum while simultaneous upregulating dopamine (DA)-D2 receptors leading to presumed DA supersensitivity. Alpha(alpha)-Phenyl-N-tert-butylnitrone (PBN) is an antioxidant used to combat oxidative stress and measure increases in PBN spin-adduct activity. Thus, the aim of this study was to investigate whether VCMs are related to upregulation of DA-D2 receptors or to increased levels of free radicals produced during oxidative stress, and whether PBN had any protective effects. Rats received daily chronic (28 day) i.p. injections of saline, haloperidol (2 mg/kg), PBN (150 mg/kg), or haloperidol + PBN. The VCM model was used to measure extrapyramidal side effects of drug treatments. Electron spin resonance (ESR) spectroscopy was performed to compare concentrations of free radical species in rats receiving injections of HP + PBN. To examine the upregulation of DA-D2 receptors, binding assays were carried out to assess the increase in DA-D(2) receptor numbers with respect to VCMs following treatment of rats injected with HP, PBN, and HP + PBN. Results of these experiments show that HP-induced VCMs in rats results from increases in oxidative cellular events and may not be related to increases in striatal DA-D(2) receptors.

Cocaine induces apoptosis in cerebral vascular muscle cells: potential roles in strokes and brain damage

Cocaine abuse is known to induce different types of brain-microvascular damage and many adverse cerebrovascular effects, including cerebral vasculitis, intracranial hemorrhage, cerebral infarction and stroke. A major physiological event leading to these pathophysiological actions of cocaine could be apoptosis. Whether cocaine can cause brain-microvascular pathology and vascular toxicity by inducing apoptosis of cerebral vascular smooth muscle cells is not known. This study, using several different methods to discern apoptosis, was designed to investigate if primary cultured canine cerebral vascular smooth muscle cells can undergo apoptosis when treated with cocaine. After treatment with cocaine (10(-6)-10(-3) M) for 12-24 h, the death rates of cerebral vascular smooth muscle cells increased in a concentration-dependent manner compared with controls. Morphological analysis of cerebral vascular smooth muscle cells using confocal fluoresence microscopy showed that the percentage of apoptotic cerebral vascular smooth muscle cells increased after cocaine (10(-6)-10(-3) M) treatment in a concentration-dependent manner. TUNEL assays also showed positive results for cerebral vascular smooth muscle cells treated with cocaine. These results clearly demonstrate that cerebral vascular smooth muscle cells can undergo rapid apoptosis in response to cocaine in a concentration-dependent manner. Cocaine-induced apoptosis may thus play a major role in brain-microvascular damage, cerebral vascular toxicity and strokes.

Dopamine-induced death of PC12 cells is prevented by a substituted tetrahydronaphthalene

The ability of dopamine to induce apoptosis in a variety of cell types, including PC12 cells and neurons, has been well documented. Under non-reducing conditions, dopamine can be oxidized to semi-quinone and quinone species, which have the ability to arylate proteins and lead to the formation of covalent adducts. Potentially, it is the arylation of substrates critical to cell survival and/or the formation of toxic adducts which leads to the death observed after dopamine treatment. We have previously described the ability of a substituted monohydroxy-tetra-hydronaphthalene (DATN) to bind proteins that are susceptible to arylation by dopamine and related catecholamines. As DATN can prevent the covalent incorporation of dopamine into substrate molecules, we hypothesized that this compound could have a protective effect on cells that undergo apoptotic death in response to dopamine exposure. We report here that DATN prevents the dopamine-induced apoptotic death of PC12 cells in a dose-dependent manner. DATN did not prevent the oxidative stress associated with dopamine treatment, as lipid peroxide production was not influenced by DATN treatment. The ability of DATN to prevent dopamine-induced cell death was selective for this insult, as this compound did not influence the death of PC12 cells induced by hydrogen peroxide (H(2)O(2)). Consistent with this finding, DATN did not alter lipid peroxidation, nor oxidation of intracellular dichlorodihydrofluorescein subsequent to H(2)O(2) treatment. Consistent with a reduction in apoptotic death, the increase in caspase-3 activity associated with dopamine treatment was also prevented by DATN. These observations suggest that DATN may act to prevent one of the pathways linking dopamine and oxidative stress to caspase-3 activation. We propose that the inhibition of substrate arylation by the products of dopamine oxidation may provide a useful strategy for the prevention of dopamine-induced cell death.

Asymmetric modulation of a catecholamine-regulated protein in the rat brain, following quinpirole administration

We previously reported a brain-specific 40 kDa catecholamine-regulated protein (CRP40) that binds dopamine (DA) and related catecholamines. CPR40 shares significant sequence homology with human heat shock protein (Hsp70), GRP78/BIP, and human #BQ24193 protein. Recent studies with the DA D(2) receptor antagonist, haloperidol, demonstrated a significant increase in expression of CRP40 in the striatum (STR). The objective of the present study was to investigate CRP40 expression in various brain regions following treatments with the DA D(2)/D(3) receptor agonist quinpirole (QNP) in rats and examine possible relationships between neurochemical parameters and locomotor activity. Rats received injections of either QNP (0.5 mg/kg, for 27 days every third day) or saline (SAL) and their locomotor activities were measured for 90 min after each injection. At injection 9, QNP-treated rats showed locomotor activity that was significantly greater than SAL controls (F(2,28) = 3.88, P < 0.05, Duncan's multiple range test, P < 0.05). Neurochemically, acute QNP-treated rats demonstrated significant differential expression of CRP40 in the left/right prefrontal cortex (PFC) relative to SAL-treated rats (-17.76 +/- 2.10%, -10.35 +/- 1.23%, P < 0.001). Chronic QNP significantly decreased CRP40 expression in the STR, ventral tegmental area (VTA), and left/right PFC (-24.85+/- 2.10%, -18.15 +/- 5.64%, -49.13 +/- 7.05%, -25 +/- 3.63%, P < 0.001). Finally, chronic QNP treatment resulted in a significant increase in CRP40 levels in the nucleus accumbens (NA) (+39.32 +/- 7.00%, P < 0.001). Heat shock protein (i.e., Hsp70 or Hsc70) expression remained unaltered following QNP treatment. Since QNP is a DA D(2)/D(3) agonist, alterations in CRP40 expression following QNP treatment suggest the protein's function in dopaminergic neurotransmission.