Neuropathological alterations in drug abusers : The involvement of neurons, glial, and vascular systems

Multi-omics study reveals associations among neurotransmitter, extracellular vesicle-derived microRNA and psychiatric comorbidities during heroin and methamphetamine withdrawal

Despite decades of research in the field of substance withdrawal, molecular biomarkers and related mechanistic study have generally been lacking. In addition to known neurotransmitters, circulating miRNAs are found in small vesicles known as exosomes within blood that have diagnostic potential and are known to contribute to psychiatric disorders. The aim of this work was to characterize the changes in neurotransmitter and exosomal miRNA profiles during heroin and methamphetamine withdrawal using a cross-sectional study design, and to determine their associations to psychiatric comorbidities in a large group of patients with substance use disorders (SUDs). Using weighted gene co-expression network analysis, a series of known, conserved, and novel exosomal miRNAs were identified as being associated with the severity of anxiety and depression, as well as the concentrations of neurotransmitters GABA, choline, and serotonin. Bioinformatics analyses established that the differences in the miRNA profile target signaling pathways are significantly associated with developmental and intellectual abnormalities. Notably, a set of dysregulated miRNA signatures including hsa-mia-451a and hsa-mir-21a resulted in an AUC of 0.966 and 0.861, respectively, for predicting the patients with SUDs. Furthermore, hsa-miR-744a-5p was positively correlated with serotonin, and its important role in maintaining neuronal development and function was revealed using an in vitro human induced pluripotent stem cells derived neuronal model. Our results suggest that the miRNA content of circulating exosomes represent a biomolecular "fingerprint" of the progression of substance withdrawal and may uncover the putative mechanism of how these exosomal miRNAs contribute to psychiatric symptoms.

6-Monoacetylmorphine-antibody distribution in tissues from heroin-related death cases: An experimental study to investigate the distributive response

Heroin, a semisynthetic opioid drug synthesized from morphine, is the 3,6-diacetyl ester of morphine (diacetylmorphine). The post-mortem diagnosis of heroin-related death could be an issue and usually rely on a combination of investigations, including the autopsy, histological and toxicological analysis. We conducted the present study to evaluate the correlation between the heroin concentration in biological fluids (peripheral blood, bile and urine) and the post-mortem anti-6-MAM antibody expression in various tissues (brain, heart, lung, liver and kidney) using immunohistochemical staining. A quantitative analysis of the immunohistochemical reaction was carried out. 45 cases of heroin-related death investigated at the Forensic Pathology Institutes of the University of Rome, Foggia and Pisa were included. The control group was composed of 15 cases of death due to other causes, without brain lesions and negative toxicological analysis for drugs. We found a positive immunohistochemical reaction in different organs and it was related to the timing of heroin metabolization. No reaction was found in the control group. Our findings show that immunohistochemistry can be a valuable tool for the post-mortem diagnosis of acute heroin abuse. A better understanding of the timing of heroin's metabolism can be useful in the forensic field and for future therapeutic applications.

Is the Neuroimmune System a Therapeutic Target for Opioid Use Disorder? A Systematic Review

Opioid use disorder (OUD) is an epidemic in the United States. In the past 12 months alone, there have been 75,000+ deaths attributed to opioid overdose: more than any other year in American history. Current pharmacotherapies for the treatment of OUD effectively suppress opioid withdrawal symptoms, but long-term relapse rates remain unacceptably high. Novel treatments for OUD are desperately needed to curb this epidemic. One target that has received considerable recent interest is the neuroimmune system. The neuroimmune system is anchored by glial cells, i.e., microglia and astrocytes, but neuroimmune signaling is known to influence neurons, including altering neurotransmission, synapse formation, and ultimately, brain function. Preclinical studies have shown that experimental attenuation of pro-inflammatory neuroimmune signaling modulates opioid addiction processes, including opioid reward, tolerance, and withdrawal symptoms, which suggests potential therapeutic benefit in patients. Whereas the peripheral immune system in OUD patients has been studied for decades and is well-understood, little is known about the neuroimmune system in OUD patients or its viability as a treatment target. Herein, we review the literature describing relationships between opioid administration and the neuroimmune system, the influence of neuroimmune signaling on opioid addiction processes, and the therapeutic potential for targeting the neuroimmune system in OUD subjects using glial modulator medications.

Opioid use disorder and the brain: a clinical perspective

Opioid use disorder (OUD) has gained increasing publicity and interest during recent years, with many countries describing problems of epidemic proportions with regard to opioid use and deaths related to opioids. While opioids are not themselves acutely neurotoxic, the chronic relapsing and remitting nature of this disorder means that individuals are often exposed to exogenous opioids for lengthy periods of time (either illicit or prescribed as treatment). We are increasingly characterizing the effect of such long-term opioid exposure on the brain. This narrative review aims to summarize the literature regarding OUD and the brain from a clinical perspective. Alterations of brain structure and function are discussed, as well as neurological and psychiatric disorders in OUD. Finally, we review current and new directions for assessment and treatment.

Quantitative evidence of suppressed TMEM119 microglial immunohistochemistry in fatal morphine intoxications

The aim of this pilot study was to investigate the diagnostic potential of TMEM119 as a useful microglia-specific marker in combination with immunostainings for phagocytic function and infiltrating capacity of monocytes in cases of lethal monosubstance intoxications by morphine (MOR), methamphetamine (METH), and of ethanol-associated death (ETH) respectively. Human brain tissue samples were obtained from forensic autopsies of cases with single substance abuse (MOR, n = 8; ETH, n = 10; METH, n = 9) and then compared to a cohort of cardiovascular fatalities as controls (n = 9). Brain tissue samples of cortex, white matter, and hippocampus were collected and stained immunohistochemically with antibodies against TMEM119, CD68KiM1P, and CCR2. We could document the lowest density of TMEM119-positive cells in MOR deaths with highly significant differences to the control densities in all three regions investigated. In ETH and METH deaths, the expression of TMEM119 was comparable to cell densities in controls. The results indicate that the immunoreaction in brain tissue is different in these groups depending on the drug type used for abuse.

Cocaine Reduces the Neuronal Population While Upregulating Dopamine D2-Receptor-Expressing Neurons in Brain Reward Regions: Sex-Effects

Addiction to cocaine is associated with dysfunction of the dopamine mesocortical system including impaired dopamine-2 receptor (D2r) signaling. However, the effects of chronic cocaine on neuronal adaptations in this system have not been systematically examined and data available is mostly from males. Here, we investigated changes in the total neuronal density and relative concentration of D2r-expressing neurons in the medial prefrontal cortex (mPFC), dorsal striatum (Dstr), nucleus accumbens (NAc), and ventral tegmental area (VTA) in both male and female mice passively exposed to cocaine for two weeks. In parallel experiments, we measured mRNA levels for Drd2 and for opioid peptides (mPenk and mPdyn). Through a combination of large field of view fluorescent imaging with BAC transgenic D2r-eGFP mice and immunostaining, we observed that cocaine exposed mice had a higher density of D2r-positive cells that was most prominent in mPFC and VTA and larger for females than for males. This occurred amidst an overall significant decrease in neuronal density (measured with NeuN) in both sexes. However, increases in Drd2 mRNA levels with cocaine were only observed in mPFC and Dstr in females, which might reflect the limited sensitivity of the method. Our findings, which contrast with previous findings of cocaine-induced downregulation of D2r binding availability, could reflect a phenotypic shift in neurons that did not previously express Drd2 and merits further investigation. Additionally, the neuronal loss particularly in mPFC with chronic cocaine might contribute to the cognitive impairments observed with cocaine use disorder.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV.

Graphical Abstract

Neuropathological Findings in Ephedrone Encephalopathy

BACKGROUND

A number of cases of severe parkinsonism-dystonia have been recognized and reported following the illicit use of ephedrone prepared from pseudoephedrine and potassium permanganate. The pathology associated with ephedrone neurotoxicity has not been described yet in the scientific literature.

OBJECTIVES

To report the first neuropathological study of ephedrone toxicity.

METHODS

The brain of a 33-year-old Ukrainian female ex-ephedrone addict with a long history of l-dopa-unresponsive parkinsonism with dysarthria, dystonia, profound postural instability, cock-gait, and frequent falls, and on antiretroviral treatment, was examined using routine stains and immunohistochemistry.

RESULTS

Neuropathological findings included diffuse pallidal astrogliosis without neuronal depletion. There was also widespread vascular pathology with small vessels occluded by foreign material, associated with giant cell response without any evidence of consequent focal infarction and a cerebellar abscess.

CONCLUSIONS

Clinical findings of l-dopa-unresponsive parkinsonism with dystonia, caused by illicit use of ephedrone, are fully consistent with neuropathological changes in the pallidum, lack of change in the SN, and preserved tyrosine hydroxylase activity. The findings in the basal ganglia are compatible with manganese toxicity. The vascular pathology is likely a joint effect of infection and the ephedrone toxicity on the vessels. © 2020 International Parkinson and Movement Disorder Society.

Fatal intoxication of a regular drug user following N-ethyl-hexedrone and ADB-FUBINACA consumption

In Hungary, N-ethyl-hexedrone (NEH) was the most frequently seized stimulant designer drug in 2017, while among synthetic cannabinoids ADB-FUBINACA and AB-FUBINACA were the most popular. Symptoms of intoxication by these substances are well known but less is known about the pathology of overdose-related death. NEH-induced fatal intoxication has not been described in the literature and knowledge surrounding the particular circumstances of death could be useful better public education of risk and more adequate treatment of overdose patients. In this report, we characterize the case of a 23-year-old male regular drug user who died a few hours after NEH and ADB-FUBINACA consumption. His medical history showed arrhythmia in childhood, and some seizures. Autopsy found he had a BMI of 42.9, a hypertrophic and dilated heart, severe atherosclerosis of the valves, coronaries and the arteries, and edema of the internal organs. Histology confirmed those findings. Postmortem blood levels of NEH were 285 ng/ml, along with 0.08 ng/ml ADB-FUBINACA and five ADB-FUBINACA metabolites. Based on the blood concentrations measured in suspected drug users (≤83.9 ng/ml) we hypothesize that NEH intoxication was the cause of death in this case, with heart disease being a co-factor and that the synthetic cannabinoid effect might have been accompaniment. This case also offered the opportunity to identify the metabolites of ADB-FUBINACA in the blood. We identified metabolites in the post-mortem blood by comparing them to human liver microsomal enzyme metabolites in vitro. Three major and two minor metabolites were found in the blood, of which two could only be derived from ADB-FUBINACA, as opposed to other cannabinoids. The case highlights the importance of the complex analysis of drug related deaths by medico-legal autopsy, histopathology and toxicology.

Regional elevations in microglial activation and cerebral glucose utilization in frontal white matter tracts of rhesus monkeys following prolonged cocaine self-administration

It has been shown that exposure to cocaine can result in neuroinflammatory responses. Microglia, the resident CNS immune cells, undergo a transition to an activated state when challenged. In rodents, and possibly humans, cocaine exposure activates microglia. The goal of this study was to assess the extent and magnitude of microglial activation in rhesus monkeys with an extensive history of cocaine self-administration. Male rhesus monkeys (N = 4/group) were trained to respond on a fixed-interval 3-min schedule of food or 0.3 mg/kg/injection cocaine presentation (30 reinforcers/session) for 300 sessions. At the end of the final session, monkeys were administered 2-[¹⁴C]deoxyglucose intravenously and 45 min later euthanized. Brain sections were used for autoradiographic assessments of glucose utilization and for microglia activation with [³H]PK11195, a marker for the microglial 18-kDa translocator protein. There were no group differences in gray matter [³H]PK11195 binding, while binding was significantly greater in cocaine self-administration animals as compared to food controls in 8 of the 11 white matter tracts measured at the striatal level. Binding did not differ from control at other levels. There were also significant increases in white matter local cerebral glucose utilization at the striatal level, which were positively correlated with [³H]PK11195 binding. The present findings demonstrate an elevation in [³H]PK11195 binding in forebrain white matter tracts of nonhuman primates with a prolonged history of cocaine self-administration. These elevations were also associated with greater cerebral metabolic rates. These data suggest that white matter deficits may contribute to behavioral, motivational, and cognitive impairments observed in cocaine abusers.

Systemic Complications and Radiographic Findings of Opioid Use and Misuse: An Overview for Orthopedic Surgeons

Amid growing concern about the misuse of prescribed opioids, the rising rates of opioid use disorder, and the use of illicit opioids, clinicians in ambulatory, inpatient, and operative environments are encountering opioid-related complications in their patients. These complications can affect multiple organ systems including cardiovascular, pulmonary, gastrointestinal, and neurologic and are related to excess opioid levels in the body or contamination from non-sterile injection. It is important for the orthopedic surgeon to have a general understanding of the pathologies associated with opioid use disorder and their appearance on diagnostic imaging. This article reviews image findings of several complications, organized in a systems-based approach, for the orthopedic surgeon.

General Pathophysiology of Astroglia

Astroglial cells are involved in most if not in all pathologies of the brain. These cells can change the morpho-functional properties in response to pathology or innate changes of these cells can lead to pathologies. Overall pathological changes in astroglia are complex and diverse and often vary with different disease stages. We classify astrogliopathologies into reactive astrogliosis, astrodegeneration with astroglial atrophy and loss of function, and pathological remodelling of astrocytes. Such changes can occur in neurological, neurodevelopmental, metabolic and psychiatric disorders as well as in infection and toxic insults. Mutation in astrocyte-specific genes leads to specific pathologies, such as Alexander disease, which is a leukodystrophy. We discuss changes in astroglia in the pathological context and identify some molecular entities underlying pathology. These entities within astroglia may repent targets for novel therapeutic intervention in the management of brain pathologies.

Transient Hypothyroidism During Lactation Arrests Myelination in the Anterior Commissure of Rats. A Magnetic Resonance Image and Electron Microscope Study

Thyroid hormone deficiency at early postnatal ages affects the cytoarchitecture and function of neocortical and telencephalic limbic areas, leading to impaired associative memory and in a wide spectrum of neurological and mental diseases. Neocortical areas project interhemispheric axons mostly through the corpus callosum and to a lesser extent through the anterior commissure (AC), while limbic areas mostly project through the AC and hippocampal commissures. Functional magnetic resonance data from children with late diagnosed congenital hypothyroidism and abnormal verbal memory processing, suggest altered ipsilateral and contralateral telencephalic connections. Gestational hypothyroidism affects AC development but the possible effect of transient and chronic postnatal hypothyroidism, as occurs in late diagnosed neonates with congenital hypothyroidism and in children growing up in iodine deficient areas, still remains unknown. We studied AC development using in vivo magnetic resonance imaging and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated rats were studied. One group was MMI-treated from postnatal day (P) 0 to P21; some of these rats were also treated with L-thyroxine (T4) from P15 to P21, as a model for early transient hypothyroidism. Other rats were MMI-treated from P0 to P150 and from embryonic day (E) 10 to P170, as a chronic hypothyroidism group. The results were compared with age paired control rats. The normalized T2 signal using magnetic resonance image was higher in MMI-treated rats and correlated with the number and percentage of myelinated axons. Using electron microscopy, we observed decreased myelinated axon number and density in transient and chronic hypothyroid rats at P150, unmyelinated axon number increased slightly in chronic hypothyroid rats. In MMI-treated rats, the myelinated axon g-ratio and conduction velocity was similar to control rats, but with a decrease in conduction delays. These data show that early postnatal transient and chronic hypothyroidism alters AC maturation that may affect the transfer of information through the AC. The alterations cannot be recovered after delayed T4-treatment. Our data support the neurocognitive delay found in late T4-treated children with congenital hypothyroidism.

Proposals for best-quality immunohistochemical staining of paraffin-embedded brain tissue slides in forensics

Immunohistochemistry (IHC) has become an integral part in forensic histopathology over the last decades. However, the underlying methods for IHC vary greatly depending on the institution, creating a lack of comparability. The aim of this study was to assess the optimal approach for different technical aspects of IHC, in order to improve and standardize this procedure. Therefore, qualitative results from manual and automatic IHC staining of brain samples were compared, as well as potential differences in suitability of common IHC glass slides. Further, possibilities of image digitalization and connected issues were investigated. In our study, automatic staining showed more consistent staining results, compared to manual staining procedures. Digitalization and digital post-processing facilitated direct analysis and analysis for reproducibility considerably. No differences were found for different commercially available microscopic glass slides regarding suitability of IHC brain researches, but a certain rate of tissue loss should be expected during the staining process.

Neurotoxicology and drug-related disorders

Neuropsychiatric disorders caused by toxic substances pose a great diagnostic challenge due to the large variety of changes caused in the central and peripheral nervous system. The pathogenetic mechanisms at work are multifaceted and partly not solved. In human drug abusers (cannabis, opiates, cocaine, amphetamines, methamphetamine and "designer drugs"), a broad spectrum of central nervous system alterations are observed including infarction, intracerebral and subarachnoidal hemorrhage, hypoxic-ischemic leukoencephalopathy, infections, neuronal loss, specific astroglial and microglial reaction patterns, and vascular changes, including the endothelial cell as well as the basal lamina.

Translational potential of astrocytes in brain disorders

Fundamentally, all brain disorders can be broadly defined as the homeostatic failure of this organ. As the brain is composed of many different cells types, including but not limited to neurons and glia, it is only logical that all the cell types/constituents could play a role in health and disease. Yet, for a long time the sole conceptualization of brain pathology was focused on the well-being of neurons. Here, we challenge this neuron-centric view and present neuroglia as a key element in neuropathology, a process that has a toll on astrocytes, which undergo complex morpho-functional changes that can in turn affect the course of the disorder. Such changes can be grossly identified as reactivity, atrophy with loss of function and pathological remodeling. We outline the pathogenic potential of astrocytes in variety of disorders, ranging from neurotrauma, infection, toxic damage, stroke, epilepsy, neurodevelopmental, neurodegenerative and psychiatric disorders, Alexander disease to neoplastic changes seen in gliomas. We hope that in near future we would witness glial-based translational medicine with generation of deliverables for the containment and cure of disorders. We point out that such as a task will require a holistic and multi-disciplinary approach that will take in consideration the concerted operation of all the cell types in the brain.

Astroglia, Glutamatergic Transmission and Psychiatric Diseases

Astrocytes are primary homeostatic cells of the central nervous system. They regulate glutamatergic transmission through the removal of glutamate from the extracellular space and by supplying neurons with glutamine. Glutamatergic transmission is generally believed to be significantly impaired in the contexts of all major neuropsychiatric diseases. In most of these neuropsychiatric diseases, astrocytes show signs of degeneration and atrophy, which is likely to be translated into reduced homeostatic capabilities. Astroglial glutamate uptake/release and glutamate homeostasis are affected in all forms of major psychiatric disorders and represent a common mechanism underlying neurotransmission disbalance, aberrant connectome and overall failure on information processing by neuronal networks, which underlie pathogenesis of neuropsychiatric diseases.

Astrogliopathology in neurological, neurodevelopmental and psychiatric disorders

Astroglial cells represent a main element in the maintenance of homeostasis and providing defense to the brain. Consequently, their dysfunction underlies many, if not all, neurological, neurodevelopmental and neuropsychiatric disorders. General astrogliopathy is evident in diametrically opposing morpho-functional changes in astrocytes, i.e. their hypertrophy along with reactivity or atrophy with asthenia. Neurological disorders with astroglial participation can be genetic, of which Alexander disease is a primary sporadic astrogliopathy, environmentally caused, such as heavy metal encephalopathies, or neurodevelopmental in origin. Astroglia contribute to neurodegenerative processes seen in amyotrophic lateral sclerosis, Alzheimer's and Huntington's diseases. Furthermore, astroglia also play a role in major neuropsychiatric disorders, ranging from schizophrenia to depression, as well as in addictive disorders.

Alterations of neuronal precursor cells in stages of human adult neurogenesis in heroin addicts

BACKGROUND

Adult neurogenesis has been shown to occur throughout life and different brain pathologies were demonstrated to be associated with altered neurogenesis. Here, an impact of heroin addiction on neurogenesis in humans is hypothesised.

METHODS

Post mortem hippocampal specimens of drug addicts with known heroin abuse and a group of non-addictive control subjects were analysed, using antibodies indicating different stages of neurogenesis. The subgranular zone of the dentate gyrus was examined qualitatively and quantitatively.

RESULTS

The data indicate (i) a decreased number of neural precursor cells, (ii) accompanied by low rates of proliferation and (iii) a marked loss of dendritic trees in targeting cells in heroin fatalities. (iv) The age-dependent increase of differentiating cells in the healthy controls was not observed in the addicts. Additionally, double immunofluorescence labelling indicated the precursor nature of Musashi-1 positive cells in the human subgranular zone of the dentate gyrus.

CONCLUSIONS

Present data firstly demonstrate the influence of drug addiction with known heroin abuse on different developmental stages of progenitors in the dentate gyrus. The patterns of antibody staining suggest a distinct inhibition of neurogenesis at the stage of neural precursor cells and revealed morphological changes in targeting cells in cases of heroin addicts as compared to healthy controls. These alterations could be considerable for memory and cognitive deficits as well as addictive behaviour in chronic drug abusers and may give rise to specific pro-neurogenic therapies.

Amphetamine-related drugs neurotoxicity in humans and in experimental animals: Main mechanisms

Amphetamine-related drugs, such as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH), are popular recreational psychostimulants. Several preclinical studies have demonstrated that, besides having the potential for abuse, amphetamine-related drugs may also elicit neurotoxic and neuroinflammatory effects. The neurotoxic potentials of MDMA and METH to dopaminergic and serotonergic neurons have been clearly demonstrated in both rodents and non-human primates. This review summarizes the species-specific cellular and molecular mechanisms involved in MDMA and METH-mediated neurotoxic and neuroinflammatory effects, along with the most important behavioral changes elicited by these substances in experimental animals and humans. Emphasis is placed on the neuropsychological and neurological consequences associated with the neuronal damage. Moreover, we point out the gap in our knowledge and the need for developing appropriate therapeutic strategies to manage the neurological problems associated with amphetamine-related drug abuse.

N-acetyl cysteine mitigates the acute effects of cocaine-induced toxicity in astroglia-like cells

Cocaine has a short half-life of only about an hour but its effects, predominantly on the central nervous system (CNS), are fairly long-lasting. Of all cells within the CNS, astrocytes may be the first to display cocaine toxicity owing to their relative abundance in the brain. Cocaine entry could trigger several early response changes that adversely affect their survival, and inhibiting these changes could conversely increase their rate of survival. In order to identify these changes and the minimal concentrations of cocaine that can elicit them in vitro, rat C6 astroglia-like cells were treated with cocaine (2–4 mM for 1h) and assayed for alterations in gross cell morphology, cytoplasmic vacuolation, viability, reactive oxygen species (ROS) generation, glutathione (GSH) levels, cell membrane integrity, F-actin cytoskeleton, and histone methylation. We report here that all of the above identified features are significantly altered by cocaine, and may collectively represent the key pathology underlying acute toxicity-mediated death of astroglia-like cells. Pretreatment of the cells with the clinically available antioxidant N-acetyl cysteine (NAC, 5 mM for 30 min) inhibited these changes during subsequent application of cocaine and mitigated cocaine-induced toxicity. Despite repeated cocaine exposure, NAC pretreated cells remained highly viable and post NAC treatment also increased viability of cocaine treated cells to a smaller yet significant level. We show further that this alleviation by NAC is mediated through an increase in GSH levels in the cells. These findings, coupled with the fact that astrocytes maintain neuronal integrity, suggest that compounds which target and mitigate these early toxic changes in astrocytes could have a potentially broad therapeutic role in cocaine-induced CNS damage.

Methamphetamine causes degeneration of dopamine cell bodies and terminals of the nigrostriatal pathway evidenced by silver staining

Methamphetamine is a widely abused illicit drug. Recent epidemiological studies showed that methamphetamine increases the risk for developing Parkinson's disease (PD) in agreement with animal studies showing dopaminergic neurotoxicity. We examined the effect of repeated low and medium doses vs single high dose of methamphetamine on degeneration of dopaminergic terminals and cell bodies. Mice were given methamphetamine in one of the following paradigms: three injections of 5 or 10 mg/kg at 3 h intervals or a single 30 mg/kg injection. The integrity of dopaminergic fibers and cell bodies was assessed at different time points after methamphetamine by tyrosine hydroxylase immunohistochemistry and silver staining. The 3 × 10 protocol yielded the highest loss of striatal dopaminergic terminals, followed by the 3 × 5 and 1 × 30. Some degenerating axons could be followed from the striatum to the substantia nigra pars compacta (SNpc). All protocols induced similar significant degeneration of dopaminergic neurons in the SNpc, evidenced by amino-cupric-silver-stained dopaminergic neurons. These neurons died by necrosis and apoptosis. Methamphetamine also killed striatal neurons. By using D1-Tmt/D2-GFP BAC transgenic mice, we observed that degenerating striatal neurons were equally distributed between direct and indirect medium spiny neurons. Despite the reduced number of dopaminergic neurons in the SNpc at 30 days after treatment, there was a partial time-dependent recovery of dopamine terminals beginning 3 days after treatment. Locomotor activity and motor coordination were robustly decreased 1-3 days after treatment, but recovered at later times along with dopaminergic terminals. These data provide direct evidence that methamphetamine causes long-lasting loss/degeneration of dopaminergic cell bodies in the SNpc, along with destruction of dopaminergic terminals in the striatum.

Astrogliopathology: a central element of neuropsychiatric diseases?

Astroglia are the homoeostatic cells of the central nervous system that control a normal function of synaptically connected neuronal networks and contribute to brain defense. Recent advances in comprehension of pathological potential of astroglia indicate that astrocytes are fundamental for most (if not all) neurological diseases. Neuropathological and neuroimaging studies demonstrate prominent astroglial atrophy and astroglial asthenia occurring in most of neuropsychiatric illnesses. In chronic diseases such as schizophrenia and major depression, decrease in astroglial numbers and functional capabilities are, arguably, fundamental for pathological developments being responsible for neurotransmitter disbalance and failures in connectivity within neural networks. In neurodegenerative diseases atrophic changes in astrocytes are complemented by astrogliosis triggered by specific lesions such as senile plaques or dying neurons, these two processes contributing to cognitive decline and ultimately neuronal death. It is therefore possible to hypothesize that neuropsychiatric diseases represent a chronic astrogliopathology, which compromises glial homeostatic and defensive capabilities, and the degree and the alacrity of gliodegenerative changes define the progression and outcome of these disorders.

Cytokines, chaperones and neuroinflammatory responses in heroin-related death: what can we learn from different patterns of cellular expression?

Heroin (3,6-diacetylmorphine) has various effects on the central nervous system with several neuropathological alterations including hypoxic-ischemic brain damage from respiratory depressing effects and neuroinflammatory response. Both of these mechanisms induce the release of cytokines, chemokines and other inflammatory mediators by the activation of many cell types such as leucocytes and endothelial and glial cells, especially microglia, the predominant immunocompetent cell type within the central nervous system. The aim of this study is to clarify the correlation between intravenous heroin administration in heroin related death and the neuroinflammatory response. We selected 45 cases among autopsies executed for heroin-related death (358 total cases); immunohistochemical studies and Western blotting analyses were used to investigate the expression of brain markers such as tumor necrosis factor-α, oxygen-regulated protein 150, (interleukins) IL-1β, IL-6, IL-8, IL-10, IL-15, cyclooxygenase-2, heat shock protein 70, and CD68 (MAC387). Findings demonstrated that morphine induces inflammatory response and cytokine release. In particular, oxygen-regulated protein 150, cyclooxygenase-2, heat shock protein 70, IL-6 and IL-15 cytokines were over-expressed with different patterns of cellular expression.

Quantitative analysis of astrogliosis in drug-dependent humans

Drug addiction is a chronic, relapsing disease caused by neurochemical and molecular changes in the brain. In this human autopsy study qualitative and quantitative changes of glial fibrillary acidic protein (GFAP)-positive astrocytes in the hippocampus of 26 lethally intoxicated drug addicts and 35 matched controls are described. The morphological characterization of these cells reflected alterations representative for astrogliosis. But, neither quantification of GFAP-positive cells nor the Western blot analysis indicated statistical significant differences between drug fatalities versus controls. However, by semi-quantitative scoring a significant shift towards higher numbers of activated astrocytes in the drug group was detected. To assess morphological changes quantitatively, graph-based representations of astrocyte morphology were obtained from single cell images captured by confocal laser scanning microscopy. Their underlying structures were used to quantify changes in astroglial fibers in an automated fashion. This morphometric analysis yielded significant differences between the investigated groups for four different measures of fiber characteristics (Euclidean distance, graph distance, number of graph elements, fiber skeleton distance), indicating that, e.g., astrocytes in drug addicts on average exhibit significant elongation of fiber structures as well as two-fold increase in GFAP-positive fibers as compared with those in controls. In conclusion, the present data show characteristic differences in morphology of hippocampal astrocytes in drug addicts versus controls and further supports the involvement of astrocytes in human pathophysiology of drug addiction. The automated quantification of astrocyte morphologies provides a novel, testable way to assess the fiber structures in a quantitative manner as opposed to standard, qualitative descriptions.

Neuropathological Alterations in Illicit Drug Abuse

A variety of neuropathological findings has been described in illicit drug abusers. The majority of these alterations result from the consequences of hypoxia-ischemia and from cerebrovascular diseases. Within the last few years, widespread morphological alterations of the cellular elements of the brain have been detected. These changes consist of neuronal loss, a numerical reduction of astrocytes, widespread axonal damage with concomitant microglial activation and reactive and degenerative changes of the cerebral microvessels. Based on various studies there is also concern that drug abusers develop neurodegeneration or Parkinsonism as they age. However, whether or to what extent neurodegeneration occurs in human drug abusers remains to be established. In the present paper a brief overview on the neuropathological changes in drug abuse is presented for the forensic pathologist/toxi-cologist with reference to the most pertinent literature.