Acute effects of cocaine, morphine and their combination on bioenergetic function and susceptibility to oxidative stress of rat liver mitochondria

Morphine self-administration is inhibited by the antioxidant N-acetylcysteine and the anti-inflammatory ibudilast; an effect enhanced by their co-administration

BACKGROUND

The treatment of opioid addiction mainly involves the medical administration of methadone or other opioids, aimed at gradually reducing dependence and, consequently, the need for illicit opioid procurement. Thus, initiating opioid maintenance therapy with a lower level of dependence would be advantageous. There is compelling evidence indicating that opioids induce brain oxidative stress and associated glial activation, resulting in the dysregulation of glutamatergic homeostasis, which perpetuates drug intake. The present study aimed to determine whether inhibiting oxidative stress and/or neuroinflammation reduces morphine self-administration in an animal model of opioid dependence.

METHODS

Morphine dependence, assessed as voluntary morphine self-administration, was evaluated in Wistar-derived UChB rats. Following an extended period of morphine self-administration, animals were administered either the antioxidant N-acetylcysteine (NAC; 40 mg/kg/day), the anti-inflammatory ibudilast (7.5 mg/kg/day) or the combination of both agents. Oxidative stress and neuroinflammation were evaluated in the hippocampus, a region involved in drug recall that feeds into the nucleus accumbens, where the levels of the glutamate transporters GLT-1 and xCT were further assessed.

RESULTS

Daily administration of either NAC or ibudilast led to a mild reduction in voluntary morphine intake, while the co-administration of both therapeutic agents resulted in a marked inhibition (-57%) of morphine self-administration. The administration of NAC or ibudilast markedly reduced both the oxidative stress induced by chronic morphine intake and the activation of microglia and astrocytes in the hippocampus. However, only the combined administration of NAC + ibudilast was able to restore the normal levels of the glutamate transporter GLT-1 in the nucleus accumbens.

CONCLUSION

Separate or joint administration of an antioxidant and anti-inflammatory agent reduced voluntary opioid intake, which could have translational value for the treatment of opioid use disorders, particularly in settings where the continued maintenance of oral opioids is a therapeutic option.

Impact of Opioids on Cellular Metabolism: Implications for Metabolic Pathways Involved in Cancer

Opioid utilization for pain management is prevalent among cancer patients. There is significant evidence describing the many effects of opioids on cancer development. Despite the pivotal role of metabolic reprogramming in facilitating cancer growth and metastasis, the specific impact of opioids on crucial oncogenic metabolic pathways remains inadequately investigated. This review provides an understanding of the current research on opioid-mediated changes to cellular metabolic pathways crucial for oncogenesis, including glycolysis, the tricarboxylic acid cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS). The existing literature suggests that opioids affect energy production pathways via increasing intracellular glucose levels, increasing the production of lactic acid, and reducing ATP levels through impediment of OXPHOS. Opioids modulate pathways involved in redox balance which may allow cancer cells to overcome ROS-mediated apoptotic signaling. The majority of studies have been conducted in healthy tissue with a predominant focus on neuronal cells. To comprehensively understand the impact of opioids on metabolic pathways critical to cancer progression, research must extend beyond healthy tissue and encompass patient-derived cancer tissue, allowing for a better understanding in the context of the metabolic reprogramming already undergone by cancer cells. The current literature is limited by a lack of direct experimentation exploring opioid-induced changes to cancer metabolism as they relate to tumor growth and patient outcome.

Cocaine perturbs mitovesicle biology in the brain

Cocaine, an addictive psychostimulant, has a broad mechanism of action, including the induction of a wide range of alterations in brain metabolism and mitochondrial homeostasis. Our group recently identified a subpopulation of non-microvesicular, non-exosomal extracellular vesicles of mitochondrial origin (mitovesicles) and developed a method to isolate mitovesicles from brain parenchyma. We hypothesised that the generation and secretion of mitovesicles is affected by mitochondrial abnormalities induced by chronic cocaine exposure. Mitovesicles from the brain extracellular space of cocaine-administered mice were enlarged and more numerous when compared to controls, supporting a model in which mitovesicle biogenesis is enhanced in the presence of mitochondrial alterations. This interrelationship was confirmed in vitro. Moreover, cocaine affected mitovesicle protein composition, causing a functional alteration in mitovesicle ATP production capacity. These data suggest that mitovesicles are previously unidentified players in the biology of cocaine addiction and that target therapies to fine-tune brain mitovesicle functionality may be beneficial to mitigate the effects of chronic cocaine exposure.

Could Alcohol Abuse and Dependence on Junk Foods Inducing Obesity and/or Illicit Drug Use Represent Danger to Liver in Young People with Altered Psychological/Relational Spheres or Emotional Problems?

Recent data show that young people, mainly due to the pressure of some risk factors or due to disrupted interpersonal relationships, utilise greater reward value and display greater sensitivity to the reinforcing properties of “pleasurable stimuli”, specifically in those situations in which an enhanced dopamine release is present. Alcoholic beverages, foods rich in sugar and fat, and illicit drug use are pleasurable feelings associated with rewards. Research shows that there is a link between substance abuse and obesity in brain functioning. Still, alcohol excess is central in leading to obesity and obesity-related morbidities, such as hepatic steatosis, mainly when associated with illicit drug dependence and negative eating behaviours in young people. It is ascertained that long-term drinking causes mental damage, similarly to drug abuse, but also affects liver function. Indeed, beyond the pharmacokinetic interactions of alcohol with drugs, occurring in the liver due to the same metabolic enzymes, there are also pharmacodynamic interactions of both substances in the CNS. To complicate matters, an important noxious effect of junk foods consists of inducing obesity and obesity-related NAFLD. In this review, we focus on some key mechanisms underlying the impact of these addictions on the liver, as well as those on the CNS.

Environmentally realistic concentrations of cocaine in seawater disturbed neuroendrocrine parameters and energy status in the marine mussel Perna perna

Cocaine (COC) is a powerful illicit drug frequently detected in the aquatic environment. COC acts by inhibiting the reuptake of dopamine (DOPA) and 5-hydroxytryptamine (5-HT - serotonin) and causes endocrine disturbances in mammals. This study investigated similar effects from cocaine exposure in the marine mussel Perna perna, as well as neurotoxicity and energy imbalances. Mussels were exposed to COC (0.2 μg.L^-1 and 2 μg.L^-1) for periods of 48, 96, and 168 h. Acetylcholinesterase (AChE) was measured in adductor muscle tissue to determine neurotoxicity, and neurotransmitter levels (DOPA and 5-HT), monoamine oxidase (MAO) and cyclooxygenase (COX) activity, and energy status (mitrochondrial electron transport, MET, and total lipids, TLP) were evaluated in the mussels' gonads. COC decreased AChE activity in the mussels exposed to 0.2 μg.L^-1 and 2 μg.L -1 after 168 h, and all concentrations of COC increased neurotransmitter levels. Increases in MET (0.2 μg.L -1, for all exposure periods) and TLP (0.2 μg.L 1 after 48 h, and 2 μg.L -1 after 96 h and 168 h) were also observed. No significant change was detected in MAO activity. COC also decreased COX activity in the mussels exposed to 0.2 μg.L -1 (48 h and 96 h) and 2 μg.L -1 (96 h). These results suggest that COC may compromise neurotransmitter levels and COX activity. Furthermore, the changes in MET and LPT suggest that COC affects the energy balance of the mussels, and could negatively affect physiological processes such as metabolism, hormone production, and embryonic development.

The role of mitochondria in cocaine addiction

The incidence of cocaine abuse is increasing especially in the U.K. where the rates are among the highest in Europe. In addition to its role as a psychostimulant, cocaine has profound effect on brain metabolism, impacting glycolysis and impairing oxidative phosphorylation. Cocaine exposure alters metabolic gene expression and protein networks in brain regions including the prefrontal cortex, the ventral tegmental area and the nucleus accumbens, the principal nuclei of the brain reward system. Here, we focus on how cocaine impacts mitochondrial function, in particular through alterations in electron transport chain function, reactive oxygen species (ROS) production and oxidative stress (OS), mitochondrial dynamics and mitophagy. Finally, we describe the impact of cocaine on brain energy metabolism in the developing brain following prenatal exposure. The plethora of mitochondrial functions altered following cocaine exposure suggest that therapies maintaining mitochondrial functional integrity may hold promise in mitigating cocaine pathology and addiction.

Sex differences and Tat expression affect dopaminergic receptor expression and response to antioxidant treatment in methamphetamine-sensitized HIV Tat transgenic mice

Methamphetamine (Meth) abuse is a common HIV comorbidity. Males and females differ in their patterns of Meth use, associated behaviors, and responses, but the underlying mechanisms and impact of HIV infection are unclear. Transgenic mice with inducible HIV-1 Tat protein in the brain (iTat) replicate many neurological aspects of HIV infection in humans. We previously showed that Tat induction enhances the Meth sensitization response associated with perturbation of the dopaminergic system, in male iTat mice. Here, we used the iTat mouse model to investigate sex differences in individual and interactive effects of Tat and Meth challenge on locomotor sensitization, brain expression of dopamine receptors (DRDs) and regulatory adenosine receptors (ADORAs). Because Meth administration increases the production of reactive oxygen species (ROS), we also determined whether the effects of Meth could be rescued by concomitant treatment with the ROS scavenger N-acetyl cysteine (NAC). After Meth sensitization and a 7-day abstinence period, groups of Tat+ and Tat-male and female mice were challenged with Meth in combination with NAC. We confirmed that Tat expression and Meth challenge suppressed DRD mRNA and protein in males and females' brains, and showed that females were particularly susceptible to the effects of Meth on D1-like and D2-like DRD subtypes and ADORAs. The expression of these markers differed strikingly between males and females, and between females in different phases of the estrous cycle, in a Tat -dependent manner. NAC attenuated Meth-induced locomotor sensitization and preserved DRD expression in all groups except for Tat + females. These data identify complex interactions between sex, Meth use, and HIV infection on addiction responses, with potential implications for the treatment of male and female Meth users in the context of HIV, especially those with cognitive disorders.

Sobriety and Satiety: Is NAD+ the Answer?

Nicotinamide adenine dinucleotide (NAD+) is an essential pyridine nucleotide that has garnered considerable interest in the last century due to its critical role in cellular processes associated with energy production, cellular protection against stress and longevity. Research in NAD+ has been reinvigorated by recent findings that components of NAD+ metabolism and NAD-dependent enzymes can influence major signalling processes associated with the neurobiology of addiction. These studies implicate raising intracellular NAD+ levels as a potential target for managing and treating addictive behaviour and reducing cravings and withdrawal symptoms in patients with food addiction and/or substance abuse. Since clinical studies showing the use of NAD+ for the treatment of addiction are limited, this review provides literature evidence that NAD+ can influence the neurobiology of addiction and may have benefits as an anti-addiction intervention.

Oxidative Stress Parameters after Abdominal Hysterectomy and Their Relationships with Quality of Recovery

Study aimed to investigate relationship between oxidative stress markers and postoperative recovery in woman after abdominal hysterectomy, as well as to test the hypothesis that different analgesics differently influence redox status.

The quality of recovery was evaluated with a QoR-40 questionnaire in fifty-one patients who underwent abdominal hysterectomy, preoperatively and on the 1st, 2nd, 3rd postoperative days (POD1,2,3). Blood samples were collected at baseline (T0), 3 (T1), 24 (T2), 48 (T3) and 72 (T4) hours after surgery. Oxidative stress markers concentrations (TBARS, NO2 −, H2O2, O2 − ) as well as antioxidative enzymes (SOD, CAT, and GSH) were analyzed.

QoR-40 total score significantly declined on POD1 and POD2 and returned to baseline levels on POD3 (p<0.001). H2O2 levels significantly decreased from T0 to T3 and then, increased at T4 (p=0,011). Changes of TBARS and H2O2 from T0 to T3 showed significant and negative correlation (r=−0.303, p=0.046). There was no significant correlation between QoR-40 total score and any parameter of oxidative stress response (p>0.05). Changes in TBARS levels from T0 to T3 were statistically significant between the study subgroups primarily due to increase of the concentrations in patients receiving paracetamol (p=0.031). Patients age, duration of surgery and cigarette smoking status showed significant influcences on and association with some oxidative stress response markers (TBARS, O2 −, CAT) (p<0.05).

Women who underwent hysterectomy had significant changes of H2O2 and TBARS activity however, those changes were not associated with changes of QoR-40 total scores during recovery.

Protective Effect of Morphine Against the Oxidant-Induced Injury in H9c2 Cells

There are some indications that morphine may exert myocardial protective effects under certain conditions. The aim of the present study was to investigate the effect of morphine on viability and oxidative state of H9c2 cells (rat cardiomyoblasts) influenced by oxidative stress that was elicited by exposure to tert-butyl hydroperoxide (t-BHP). Our experiments showed that pretreatment with morphine before the addition of t-BHP markedly improved cell viability. Morphine was able to increase total antioxidant capacity of H9c2 cells and to reduce the production of reactive oxygen species, protein carbonylation, and lipid peroxidation. Cellular damage caused by t-BHP was associated with low levels of p38 MAPK and GSK-3β phosphorylation. Pretreatment with morphine augmented p38 phosphorylation, and the increased phospho-p38/p38 ratio was preserved even in the presence of t-BHP. Morphine did not change the level of GSK-3β phosphorylation, but interestingly, the phospho-GSK-3β/GSK-3β ratio significantly increased after subsequent incubation with t-BHP. Furthermore, morphine exposure resulted in upregulation of the antioxidant enzyme catalase. The protective effect of morphine was abrogated by the addition of the PI3K inhibitor wortmannin and/or p38 MAPK inhibitor SB203580. It can be concluded that morphine may protect H9c2 cells against oxidative stress and that this protection is at least partially mediated through activation of the p38 MAPK and PI3K/GSK-3β pathways.

The Effects of Fentanyl on Hepatic Mitochondrial Function

BACKGROUND

Remifentanil interferes with hepatic mitochondrial function. The aim of the present study was to evaluate whether hepatic mitochondrial function is affected by fentanyl, a more widely used opioid than remifentanil.

METHODS

Human hepatoma HepG2 cells were exposed to fentanyl or pretreated with naloxone (an opioid receptor antagonist) or 5-hydroxydecanoate (5-HD, an inhibitor of mitochondrial adenosine triphosphate (ATP)-sensitive potassium [mitoKATP] channels), followed by incubation with fentanyl. Mitochondrial function and metabolism were then analyzed.

RESULTS

Fentanyl marginally reduced maximal mitochondrial complex-specific respiration rates using exogenous substrates (decrease in medians: 11%-18%; P = 0.003-0.001) but did not affect basal cellular respiration rates (P = 0.834). The effect on stimulated respiration was prevented by preincubation with naloxone or 5-HD. Fentanyl reduced cellular ATP content in a dose-dependent manner (P < 0.001), an effect that was not significantly prevented by 5-HD and not explained by increased total ATPase concentration. However, in vitro ATPase activity of recombinant human permeability glycoprotein (an ATP-dependent drug efflux transporter) was significantly stimulated by fentanyl (P = 0.004).

CONCLUSIONS

Our data suggest that fentanyl reduces stimulated mitochondrial respiration of cultured human hepatocytes by a mechanism that is blocked by a mitoKATP channel antagonist. Increased energy requirements for fentanyl efflux transport may offer an explanation for the substantial decrease in cellular ATP concentration.

Specific behavioral and cellular adaptations induced by chronic morphine are reduced by dietary omega-3 polyunsaturated fatty acids

Opiates, one of the oldest known drugs, are the benchmark for treating pain. Regular opioid exposure also induces euphoria making these compounds addictive and often misused, as shown by the current epidemic of opioid abuse and overdose mortalities. In addition to the effect of opioids on their cognate receptors and signaling cascades, these compounds also induce multiple adaptations at cellular and behavioral levels. As omega-3 polyunsaturated fatty acids (n-3 PUFAs) play a ubiquitous role in behavioral and cellular processes, we proposed that supplemental n-3 PUFAs, enriched in docosahexanoic acid (DHA), could offset these adaptations following chronic opioid exposure. We used an 8 week regimen of n-3 PUFA supplementation followed by 8 days of morphine in the presence of this diet. We first assessed the effect of morphine in different behavioral measures and found that morphine increased anxiety and reduced wheel-running behavior. These effects were reduced by dietary n-3 PUFAs without affecting morphine-induced analgesia or hyperlocomotion, known effects of this opiate acting at mu opioid receptors. At the cellular level we found that morphine reduced striatal DHA content and that this was reversed by supplemental n-3 PUFAs. Chronic morphine also increased glutamatergic plasticity and the proportion of Grin2B-NMDARs in striatal projection neurons. This effect was similarly reversed by supplemental n-3 PUFAs. Gene analysis showed that supplemental PUFAs offset the effect of morphine on genes found in neurons of the dopamine receptor 2 (D2)-enriched indirect pathway but not of genes found in dopamine receptor 1(D1)-enriched direct-pathway neurons. Analysis of the D2 striatal connectome by a retrogradely transported pseudorabies virus showed that n-3 PUFA supplementation reversed the effect of chronic morphine on the innervation of D2 neurons by the dorsomedial prefontal and piriform cortices. Together these changes outline specific behavioral and cellular effects of morphine that can be reduced or reversed by dietary n-3 PUFAs.

Cocaine/crack use is not associated with fibrosis progression measured by AST-to-Platelet Ratio Index in HIV-HCV co-infected patients: a cohort study

Background

Cocaine and crack use has been associated with HIV and HCV infections, but its consequences on HCV progression have not been well established. We analyzed the impact of cocaine/crack use on liver fibrosis progression in a cohort of HIV-HCV co-infected patients.

Methods

A Canadian multicenter prospective cohort study followed 1238 HIV-HCV co-infected persons every 6 months between 2003 and 2013. Data were analyzed from 573 patients with positive HCV RNA, not on HCV treatment, without significant liver fibrosis (AST-to-Platelet Ratio Index (APRI) <1.5) or history of end-stage liver disease at baseline, and having at least two study visits. Recent cocaine/crack use was defined as use within 6 months of cohort entry. Incidence rates of progression to significant fibrosis (APRI ≥ 1.5) were determined according to recent cocaine/crack use. Cox Proportional Hazards models were used to assess the association between time-updated cocaine/crack use and progression to APRI ≥ 1.5 adjusting for age, sex, HCV duration, baseline ln(APRI), and time-updated alcohol abuse, history of other drug use and CD4+ cell count.

Results

At baseline, 211 persons (37%) were recent cocaine/crack users and 501 (87%) ever used cocaine/crack. Recent users did not differ from non-recent users on gender, age, and CD4+ T-cell count. Over 1599 person-years of follow up (522 PY in recent users, 887 PY in previous users and 190 PY in never users),158 (28%) persons developed significant fibrosis (9.9/100 PY; 95% CI, 8.3–11.4); 56 (27%) recent users (10.7/100 PY; 7.9–13.5), 81 (28%) previous users (9.1/100 PY; 7.1–11.1), and 21 (29%) never users (11.1/100 PY; 6.3–15.8). There was no association between ever having used or time-updated cocaine/crack use and progression to APRI ≥ 1.5 (adjusted HR (95%CI): 0.96 (0.58, 1.57) and 0.88;(0.63–1.25), respectively).

Conclusions

We could not find evidence that cocaine/crack use is associated with progression to advanced liver fibrosis in our prospective study of HIV-HCV co-infected patients.

Cysteine Metabolism and Oxidative Processes in the Rat Liver and Kidney after Acute and Repeated Cocaine Treatment

The role of cocaine in modulating the metabolism of sulfur-containing compounds in the peripheral tissues is poorly understood. In the present study we addressed the question about the effects of acute and repeated (5 days) cocaine (10 mg/kg i.p.) administration on the total cysteine (Cys) metabolism and on the oxidative processes in the rat liver and kidney. The whole pool of sulfane sulfur, its bound fraction and hydrogen sulfide (H₂S) were considered as markers of anaerobic Cys metabolism while the sulfate as a measure of its aerobic metabolism. The total-, non-protein- and protein- SH group levels were assayed as indicators of the redox status of thiols. Additionally, the activities of enzymes involved in H₂S formation (cystathionine γ-lyase, CSE; 3-mercaptopyruvate sulfurtransferase, 3-MST) and GSH metabolism (γ-glutamyl transpeptidase, γ-GT; glutathione S-transferase, GST) were determined. Finally, we assayed the concentrations of reactive oxygen species (ROS) and malondialdehyde (MDA) as markers of oxidative stress and lipid peroxidation, respectively. In the liver, acute cocaine treatment, did not change concentrations of the whole pool of sulfane sulfur, its bound fraction, H₂S or sulfate but markedly decreased levels of non-protein SH groups (NPSH), ROS and GST activity while γ-GT was unaffected. In the kidney, acute cocaine significantly increased concentration of the whole pool of sulfane sulfur, reduced the content of its bound fraction but H₂S, sulfate and NPSH levels were unchanged while ROS and activities of GST and γ-GT were reduced. Acute cocaine enhanced activity of the CSE and 3-MST in the liver and kidney, respectively. Repeatedly administered cocaine enhanced the whole pool of sulfane sulfur and reduced H₂S level simultaneously increasing sulfate content both in the liver and kidney. After repeated cocaine, a significant decrease in ROS was still observed in the liver while in the kidney, despite unchanged ROS content, a marked increase in MDA level was visible. The repeated cocaine decreased 3-MST and increased γ-GT activities in both organs but reduced GST in the kidney. Our results show that cocaine administered at a relatively low dose shifts Cys metabolism towards the formation of sulfane sulfur compounds which possess antioxidant and redox regulatory properties and are a source of H₂S which can support mitochondrial bioenergetics.

Cardiovascular and Hepatic Toxicity of Cocaine: Potential Beneficial Effects of Modulators of Oxidative Stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy.

Drugs of abuse and addiction: A slippery slope toward liver injury

Substances of abuse induce alteration in neurobehavioral symptoms, which can lead to simultaneous exacerbation of liver injury. The biochemical changes of liver are significantly observed in the abused group of people using illicit drugs or drugs that are abused. A huge amount of work has been carried out by scientists for validation experiments using animal models to assess hepatotoxicity in cases of drugs of abuse. The risk of hepatotoxicity from these psychostimulants has been determined by different research groups. Hepatotoxicity of these drugs has been recently highlighted and isolated case reports always have been documented in relation to misuse of the drugs. These drugs induce liver toxicity on acute or chronic dose dependent process, which ultimately lead to liver damage, acute fatty infiltration, cholestatic jaundice, liver granulomas, hepatitis, liver cirrhosis etc. Considering the importance of drug-induced hepatotoxicity as a major cause of liver damage, this review emphasizes on various drugs of abuse and addiction which induce hepatotoxicity along with their mechanism of liver damage in clinical aspect as well as in vitro and in vivo approach. However, the mechanisms of drug-induced hepatotoxicity is dependent on reactive metabolite formation via metabolism, modification of covalent bonding between cellular components with drug and its metabolites, reactive oxygen species generation inside and outside of hepatocytes, activation of signal transduction pathways that alter cell death or survival mechanism, and cellular mitochondrial damage, which leads to alteration in ATP generation have been notified here. Moreover, how the cytokines are modulated by these drugs has been mentioned here.

Measuring Mitochondrial Membrane Potential with a Tetraphenylphosphonium-Selective Electrode

Mitochondrial bioenergetics is based on the generation of the protonmotive force by the electron transport chain. The protonmotive force is used by mitochondria for different critical aspects of its normal function, ranging from calcium accumulation to the synthesis of ATP. The transmembrane electric potential (ΔΨ) is the major component of the protonmotive force and is also the main responsible for ATP synthesis by mitochondrial ATP synthase. Although several methods can be used to measure the ΔΨ, the use of the tetraphenylphosphonium cation (TPP(+))-selective electrode is still a method of election due to its sensitivity. The method is based on the accumulation of TPP(+) by energized mitochondria, which develop a negative charge in the matrix due to the ejection of protons. This unit describes how to build a custom-made TPP(+)-selective electrode and how to establish the necessary set-up to follow ΔΨ fluctuations in isolated mitochondrial fractions.

Cannabidiol rescues acute hepatic toxicity and seizure induced by cocaine

Cocaine is a commonly abused illicit drug that causes significant morbidity and mortality. The most severe and common complications are seizures, ischemic strokes, myocardial infarction, and acute liver injury. Here, we demonstrated that acute cocaine intoxication promoted seizure along with acute liver damage in mice, with intense inflammatory infiltrate. Considering the protective role of the endocannabinoid system against cell toxicity, we hypothesized that treatment with an anandamide hydrolysis inhibitor, URB597, or with a phytocannabinoid, cannabidiol (CBD), protects against cocaine toxicity. URB597 (1.0 mg/kg) abolished cocaine-induced seizure, yet it did not protect against acute liver injury. Using confocal liver intravital microscopy, we observed that CBD (30 mg/kg) reduced acute liver inflammation and damage induced by cocaine and prevented associated seizure. Additionally, we showed that previous liver damage induced by another hepatotoxic drug (acetaminophen) increased seizure and lethality induced by cocaine intoxication, linking hepatotoxicity to seizure dynamics. These findings suggest that activation of cannabinoid system may have protective actions on both liver and brain induced by cocaine, minimizing inflammatory injury promoted by cocaine, supporting its further clinical application in the treatment of cocaine abuse.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Xylazine as a drug of abuse and its effects on the generation of reactive species and DNA damage on human umbilical vein endothelial cells

Human xylazine (XYL) abuse among addicts has received great interest due to its potential toxic effects upon addicts and the need to understand the mechanism of action associated with the potential health effects. XYL is an alpha-2 agonist restricted to veterinarian applications, without human medical applications. Our previous work demonstrated that XYL and its combination with cocaine (COC) and/or 6-monoacetylmorphine (6-MAM) induce cell death through an apoptotic mechanism. The aim of this study was to determine the effect of xylazine on the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as DNA damage on endothelial cell. Human umbilical vein endothelial cells (HUVEC) were treated with XYL (60 μM), COC (160 μM), 6-MAM (160 μM), camptothecin (positive control, 50 μM), XYL/COC (50 μM), XYL/6-MAM (50 μM), and XYL/COC/6-MAM (40 μM) for a period of 24 hours. Generation of intracellular ROS, RNS, and DNA fragmentation were analyzed using a fluorometric assay. Results reveal that XYL and 6-MAM increase levels of ROS; no induction of RNS production was observed. The combination of these drugs shows significant increase in DNA fragmentation in G2/M phase, while XYL, COC, and 6-MAM, without combination, present higher DNA fragmentation in G0/G1 phase. These findings support that these drugs and their combination alter important biochemical events aligned with an apoptotic mechanism of action in HUVEC.

Toxic effects of xylazine on endothelial cells in combination with cocaine and 6-monoacetylmorphine

The use of xylazine as a drug of abuse has emerged worldwide in the last 7 years, including Puerto Rico. Clinical findings reported that xylazine users present greater physiological deterioration, than heroin users. The aim of this study was to assess the xylazine toxicity on endothelial cells, as this is one of the first tissues impact upon administration. Human umbilical vein endothelial cells in culture were treated with xylazine, cocaine, 6-monoacetylmorphine (heroin metabolite) and its combinations, at concentrations of 0.10-400 μM, for periods of 24, 48 and 72 h. IC50 were calculated and the Annexin V assay implemented to determine the cell death mechanism. Results indicated IC50 values at 24h as follow: xylazine 62 μM, cocaine 210 μM, 6-monoacetylmorphine 300 μM. When these drugs were combined the IC50 value was 57 μM. Annexin V results indicated cell death by an apoptosis mechanism in cells treated with xylazine or in combination. Results demonstrated that xylazine use inhibits the endothelial cell proliferation, at lower concentrations than cocaine and 6-monoacetylmorphine. These findings contribute to the understanding of the toxicity mechanisms induced by xylazine on endothelial cells.