Brain Hyperglycemia Induced by Heroin: Association with Metabolic Neural Activation

Analysis of heroin effects on calcium channels in rat cardiomyocytes based on transcriptomics and metabolomics

Heroin can cause damage to many human organs, possibly leading to different types of arrhythmias and abnormal electrophysiological function of the heart muscle and the steady state of calcium-ion channels. We explored cardiomyocytes treated with heroin and the effect on calcium-ion channels. Transcriptomics and metabolomics were used to screen for differential genes and metabolite alterations after heroin administration to jointly analyze the effect of heroin on calcium channels in cardiomyocytes. Cardiomyocytes from primary neonatal rats were cultured in vitro and were treated with different concentrations of heroin to observe the changes in morphology and spontaneous beat frequency and rhythm by a patch clamp technique. Transcriptomic studies selected a total of 1,432 differentially expressed genes, 941 upregulated and 491 downregulated genes in rat cardiomyocytes from the control and drug intervention groups. Gene Ontology functional enrichment showed that 1,432 differential genes selected by the two groups were mainly involved in the regulation of the multicellular organismal process, response to external stimulus, myofibril, inflammatory response, muscle system process, cardiac muscle contraction, etc. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these genes were mainly concentrated in cardiac muscle contraction, osteoclast differentiation, adrenergic signaling in cardiomyocytes, dilated cardiomyopathy, hypertrophic cardiomyopathy, and other important pathways. Metabolomic testing further suggested that cardiomyocyte metabolism was severely affected after heroin intervention. After the treatment with heroin, the L-type calcium channel current I-V curve was up-shifted, the peak value was significantly lower than that of the control group, action potential duration 90 was significantly increased in the action potential, resting potential negative value was lowered, and action potential amplitude was significantly decreased in cardiomyocytes. In this study, heroin could cause morphological changes in primary cardiomyocytes of neonatal rats and electrophysiological function. Heroin can cause myocardial contraction and calcium channel abnormalities, damage the myocardium, and change the action potential and L-type calcium channel.

Dose-Dependent Molecular Responses of Labeo rohita to Triphenyl Phosphate

Triphenyl phosphate (TPhP) is a broad-spectrum organophosphate compound widely used as an additive in several products to prevent ignition. However, its utilization produces a hazardous impact on various organisms. So far, very few studies have investigated the acute toxicity of TPhP at environmentally relevant concentrations in nontarget aquatic species. This study aimed to assess whether the short-term exposure of TPhP (4, 20, and 100 μg L^-1) affects the oxidative stress, antioxidant activity, biomolecule metabolism, DNA stability, chromosomal integrity, apoptosis, and pathological changes in various organs of Labeo rohita fingerlings. The results illustrated that the reactive oxygen species (ROS) production and lipid peroxidation (LPO) rates were significantly higher in tissues (brain, liver, and kidney) of TPhP-treated groups. Interestingly, superoxide dismutase (SOD) and catalase (CAT) activities were remarkably decreased in tissues following TPhP exposure. The levels of protein, glucose, total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) in various tissues were also found to be significantly altered in TPhP-exposed fish fingerlings. These significant alterations in the antioxidant system and biochemical profile induced genotoxic responses such as DNA and chromosomal damage in the fish fingerlings. Furthermore, the incidence of the observed genotoxic responses was also found to be dose-dependent. Likewise, the apoptotic responses were also significantly altered following TPhP acute exposure in L. rohita fingerlings. The subsequent effects on oxidative stress, antioxidant inhibition, dysregulated biomolecule metabolism, and genotoxicity might be the possible reason for the observed pathological changes in various tissues of L. rohita. Taken together, the present findings showed that the toxicity of TPhP is principally associated with exposure concentrations. Therefore, this study illustrates the toxicity risks of TPhP to vertebrate organisms at real-world concentrations.

The Critical Role of Peripheral Targets in Triggering Rapid Neural Effects of Intravenous Cocaine

Direct interaction of cocaine with centrally located monoamine transporters is the primary mechanism underlying its reinforcing properties. It is also often assumed that this drug action is responsible for all the physiological and behavioral effects of this drug. The goal of this review is to challenge this basic mechanism and demonstrate the importance of peripheral actions of cocaine in inducing its initial, rapid neural effects. The use of high-resolution electrophysiological, neurochemical and physiological techniques revealed that the effects of intravenous cocaine at behaviorally relevant doses are exceptionally rapid and transient correlating with strong, quick, and transient increases in blood cocaine levels. Some of these effects are mimicked by cocaine-methiodide, a cocaine analog that cannot cross the blood-brain barrier and they are resistant to dopamine (DA) receptor blockade. Therefore, it appears that rapid neural effects of cocaine result from its direct interaction with receptive sites on afferents of sensory nerves densely innervating blood vessels. This interaction creates a rapid neural signal to the CNS that results in generalized neural activation and subsequent changes in different physiological parameters. This drug's action appears to be independent from cocaine's action on central neurons, which requires a definite time to occur and induce neural and physiological effects with longer latencies and durations. The co-existence in the same drug on two timely distinct actions with their subsequent interaction in the CNS could explain consistent changes in physiological and behavioral effects of cocaine following their repeated use, playing a role in the development of drug-seeking and drug-taking behavior.

Relationship between social capital and heroin use behaviors among patients in methadone maintenance treatment in Sichuan Province, China: A cross-sectional study

Covertly using heroin during methadone maintenance treatment (MMT) is very common among heroin-dependent patients, which has posed threats to the physical health of heroin-dependent patients and social safety. Covertly using heroin may be influenced by many factors, especially social capital. Therefore, we aimed to investigate the relationship between behaviors of covertly using heroin during MMT and social capital heroin-dependent patients in Sichuan Province, China. A cross-sectional study was conducted between October and November 2018, with a total of 581 heroin-dependent patients participating in the study. In addition to socio-demographic characteristics and heroin use related behaviors, the questionnaire also included the measures of social capital: social network (SN), social support (SP), community participation (CP) and social trust (ST). Multivariate logistic regression analyses were used to estimate the association between different measures of social capital and heroin use. The prevalence of covertly using heroin of heroin during MMT was 31.0% among our participants in the 6 months before the study. After adjusting for socio-demographic factors and heroin-use related variables, SN (OR = 0.85, 95% CI: 0.76-0.95), SP (OR = 0.89, 95% CI: 0.83-0.95), and ST (OR = 0.88, 95% CI: 0.81-0.95) were significantly associated with heroin use. Results suggest that social capital may have a protective effect on behavior of covertly using heroin during MMT, which should be consider in the interventions for heroin-dependent patients, in order to reduce the incidence of heroin use during MMT as well as improve the compliance of MMT.

Changes in brain oxygen and glucose induced by oxycodone: Relationships with brain temperature and peripheral vascular tone

Oxycodone is a semi-synthetic opioid drug that is used to alleviate acute and chronic pain. However, oxycodone is often abused and, when taken at high doses, can induce powerful CNS depression that manifests in respiratory abnormalities, hypotension, coma, and death. Here, we employed several techniques to examine the effects of intravenous oxycodone at a wide range of doses on various metabolism-related parameters in awake, freely-moving rats. High-speed amperometry was used to assess how oxycodone affects oxygen and glucose levels in the nucleus accumbens (NAc). These measurements were supplemented by recordings of locomotor activity and temperature in the NAc, temporal muscle, and skin. At low doses, which are known to maintain self-administration behavior (0.15-0.3 mg/kg), oxycodone transiently decreased locomotor activity, induced modest brain and body hyperthermia, and monotonically increased NAc oxygen and glucose levels. While locomotor inhibition became stronger with higher oxycodone doses (0.6-1.2 mg/kg), NAc oxygen and glucose transiently decreased and subsequently increased. High-dose oxycodone induced similar biphasic down-up changes in brain and body temperature, with the initial decreases followed by increases. While cerebral vasodilation induced by neural activation appears to be the underlying mechanism for the correlative increases in brain oxygen and glucose levels, respiratory depression and the subsequent drop in blood oxygen likely mediate the brain hypoxia induced by large-dose oxycodone injections. The initial inhibitory effects induced by large-dose oxycodone injections could be attributed to rapid and profound CNS depression-the most dangerous health complication linked to opioid overdose in humans.

Intravenous Heroin Induces Rapid Brain Hypoxia and Hyperglycemia that Precede Brain Metabolic Response

Heroin use and overdose have increased in recent years as people transition from abusing prescription opiates to using the cheaper street drug. Despite a long history of research, many physiological effects of heroin and their underlying mechanisms remain unknown. Here, we used high-speed amperometry to examine the effects of intravenous heroin on oxygen and glucose levels in the nucleus accumbens (NAc) in freely-moving rats. Heroin within the dose range of human drug use and rat self-administration (100–200 μg/kg) induced a rapid, strong, but transient drop in NAc oxygen that was followed by a slower and more prolonged rise in glucose. Using oxygen recordings in the subcutaneous space, a densely-vascularized site with no metabolic activity, we confirmed that heroin-induced brain hypoxia results from decreased blood oxygen, presumably due to drug-induced respiratory depression. Respiratory depression and the associated rise in CO₂ levels appear to drive tonic increases in NAc glucose via local vasodilation. Heroin-induced changes in oxygen and glucose were rapid and preceded the slow and prolonged increase in brain temperature and were independent of enhanced intra-brain heat production, an index of metabolic activation. A very high heroin dose (3.2 mg/kg), corresponding to doses used by experienced drug users in overdose conditions, caused strong and prolonged brain hypoxia and hyperglycemia coupled with robust initial hypothermia that preceded an extended hyperthermic response. Our data suggest heroin-induced respiratory depression as a trigger for brain hypoxia, which leads to hyperglycemia, both of which appear independent of subsequent changes in brain temperature and metabolic neural activity.