Autophagy as a gateway for the effects of methamphetamine: From neurotransmitter release and synaptic plasticity to psychiatric and neurodegenerative disorders.

As a major eukaryotic cell clearing machinery, autophagy grants cell proteostasis, which is key for neurotransmitter release, synaptic plasticity, and neuronal survival. In line with this, besides neuropathological events, autophagy dysfunctions are bound to synaptic alterations that occur in mental disorders, and early on, in neurodegenerative diseases. This is also the case of methamphetamine (METH) abuse, which leads to psychiatric disturbances and neurotoxicity. While consistently altering the autophagy machinery, METH produces behavioral and neurotoxic effects through molecular and biochemical events that can be recapitulated by autophagy blockade. These consist of altered physiological dopamine (DA) release, abnormal stimulation of DA and glutamate receptors, as well as oxidative, excitotoxic, and neuroinflammatory events. Recent molecular insights suggest that METH early impairs the autophagy machinery, though its functional significance remains to be investigated. Here we discuss evidence suggesting that alterations of DA transmission and autophagy are intermingled within a chain of events underlying behavioral alterations and neurodegenerative phenomena produced by METH. Understanding how METH alters the autophagy machinery is expected to provide novel insights into the neurobiology of METH addiction sharing some features with psychiatric disorders and parkinsonism

The effects of proteasome on baseline and methamphetamine-dependent dopamine transmission.

Abstract The Ubiquitin Proteasome System (UPS) is a major multi-catalytic machinery, which guarantees cellular proteolysis and turnover. Beyond cytosolic and nuclear cell compartments, the UPS operates at the synapse to modulate neurotransmission and plasticity. In fact, dysregulations of the UPS are linked with early synaptic alterations occurring in a variety of dopamine (DA)-related brain disorders. This is the case of psychiatric conditions such as methamphetamine (METH) addiction. While being an extremely powerful DA releaser, METH impairs UPS activity, which is largely due to DA itself. In turn, pre- and post- synaptic neurons of the DA circuitry show a high vulnerability to UPS inhibition. Thus, alterations of DA transmission and UPS activity are intermingled within a chain of events underlying behavioral alterations produced by METH. These findings, which allow escaping the view of a mere implication of the UPS in protein toxicity-related mechanisms, indicate a more physiological role for the UPS in modulating DA-related behavior. This is seminal for those plasticity mechanisms which underlie overlapping psychiatric disorders such as METH addiction and schizophrenia

The Neuroanatomy of the Reticular Nucleus Locus Coeruleus in Alzheimer's Disease.

Alzheimer's Disease (AD) features the accumulation of β-amyloid and Tau aggregates, which deposit as extracellular plaques and intracellular neurofibrillary tangles (NFTs), respectively. Neuronal Tau aggregates may appear early in life, in the absence of clinical symptoms. This occurs in the brainstem reticular formation and mostly within Locus Coeruleus (LC), which is consistently affected during AD. LC is the main source of forebrain norepinephrine (NE) and it modulates a variety of functions including sleep-waking cycle, alertness, synaptic plasticity, and memory. The iso-dendritic nature of LC neurons allows their axons to spread NE throughout the whole forebrain. Likewise, a prion-like hypothesis suggests that Tau aggregates may travel along LC axons to reach out cortical neurons. Despite this timing is compatible with cross-sectional studies, there is no actual evidence for a causal relationship between these events. In the present mini-review, we dedicate special emphasis to those various mechanisms that may link degeneration of LC neurons to the onset of AD pathology. This includes the hypothesis that a damage to LC neurons contributes to the onset of dementia due to a loss of neuroprotective effects or, even the chance that, LC degenerates independently from cortical pathology. At the same time, since LC neurons are lost in a variety of neuropsychiatric disorders we considered which molecular mechanism may render these brainstem neurons so vulnerable

A Sentinel in the Crosstalk Between the Nervous and Immune System: The (Immuno)-Proteasome

The wealth of recent evidence about a bi-directional communication between nerve- and immune- cells revolutionized the traditional concept about the brain as an “immune-privileged” organ while opening novel avenues in the pathophysiology of CNS disorders. In fact, altered communication between the immune and nervous system is emerging as a common hallmark in neuro-developmental, neurodegenerative, and neuro-immunological diseases. At molecular level, the ubiquitin proteasome machinery operates as a sentinel at the crossroad between the immune system and brain. In fact, the standard proteasome and its alternative/inducible counterpart, the immunoproteasome, operate dynamically and coordinately in both nerve- and immune- cells to modulate neurotransmission, oxidative/inflammatory stress response, and immunity. When dysregulations of the proteasome system occur, altered amounts of standard- vs. immune-proteasome subtypes translate into altered communication between neurons, glia, and immune cells. This contributes to neuro-inflammatory pathology in a variety of neurological disorders encompassing Parkinson's, Alzheimer's, and Huntingtin's diseases, brain trauma, epilepsy, and Multiple Sclerosis. In the present review, we analyze those proteasome-dependent molecular interactions which sustain communication between neurons, glia, and brain circulating T-lymphocytes both in baseline and pathological conditions. The evidence here discussed converges in that upregulation of immunoproteasome to the detriment of the standard proteasome, is commonly implicated in the inflammatory- and immune- biology of neurodegeneration. These concepts may foster additional studies investigating the role of immunoproteasome as a potential target in neurodegenerative and neuro-immunological disorders

The Effects of Amphetamine and Methamphetamine on the Release of Norepinephrine, Dopamine and Acetylcholine From the Brainstem Reticular Formation

Amphetamine (AMPH) and methamphetamine (METH) are widely abused psychostimulants, which produce a variety of psychomotor, autonomic and neurotoxic effects. The behavioral and neurotoxic effects of both compounds (from now on defined as AMPHs) stem from a fair molecular and anatomical specificity for catecholamine-containing neurons, which are placed in the brainstem reticular formation (RF). In fact, the structural cross-affinity joined with the presence of shared molecular targets between AMPHs and catecholamine provides the basis for a quite selective recruitment of brainstem catecholamine neurons following AMPHs administration. A great amount of investigations, commentary manuscripts and books reported a pivotal role of mesencephalic dopamine (DA)-containing neurons in producing behavioral and neurotoxic effects of AMPHs. Instead, the present review article focuses on catecholamine reticular neurons of the low brainstem. In fact, these nuclei add on DA mesencephalic cells to mediate the effects of AMPHs. Among these, we also include two pontine cholinergic nuclei. Finally, we discuss the conundrum of a mixed neuronal population, which extends from the pons to the periaqueductal gray (PAG). In this way, a number of reticular nuclei beyond classic DA mesencephalic cells are considered to extend the scenario underlying the neurobiology of AMPHs abuse. The mechanistic approach followed here to describe the action of AMPHs within the RF is rooted on the fine anatomy of this region of the brainstem. This is exemplified by a few medullary catecholamine neurons, which play a pivotal role compared with the bulk of peripheral sympathetic neurons in sustaining most of the cardiovascular effects induced by AMPHs

The Role of Cellular Prion Protein in Promoting Stemness and Differentiation in Cancer

Cellular prion protein (PrPC) is seminal to modulate a variety of baseline cell functions to grant homeostasis. The classic role of such a protein was defined as a chaperone-like molecule being able to rescue cell survival. Nonetheless, PrPC also represents the precursor of the deleterious misfolded variant known as scrapie prion protein (PrPSc). This variant is detrimental in a variety of prion disorders. This multi-faceted role of PrP is greatly increased by recent findings showing how PrPC in its folded conformation may foster tumor progression by acting at multiple levels. The present review focuses on such a cancer-promoting effect. The manuscript analyzes recent findings on the occurrence of PrPC in various cancers and discusses the multiple effects, which sustain cancer progression. Within this frame, the effects of PrPC on stemness and differentiation are discussed. A special emphasis is provided on the spreading of PrPC and the epigenetic effects, which are induced in neighboring cells to activate cancer-related genes. These detrimental effects are further discussed in relation to the aberrancy of its physiological and beneficial role on cell homeostasis. A specific paragraph is dedicated to the role of PrPC beyond its effects in the biology of cancer to represent a potential biomarker in the follow up of patients following surgical resection

Persistent paradoxical eff ects on striatal and limbic a-synuclein and tyrosine hydroxylase following methamphetamine withdrawal

Methamphetamine (METH) produces a variety of epigenetic eff ects in the brain, which are seminal to establish long-lasting alterations in neuronal activity. A number of studies were car ried out aimed at rough assessment of the amount of either histone acetylation and methyla tion or direct DNA methylation, without a selective analysis of specifi c genes. In the present study we wish to assess whether METH-induced epigenetic alterations may specifi cally engage the expression of a-synuclein, which is a key protein in neurodegeneration and synaptic plastic ity. In this way, a potential long-term alteration of brain circuitries may produce a variation in the threshold for neurotoxicity, sensitization, addiction and neurodegeneration. Thus, the occur rence of long-term changes in the expression of the protein were analyzed in parallel with per sistent changes in a specifi c marker of integrity of meso-striatal/meso-limbic pathway, which is the expression of tyrosine hydroxylase (TH) both in the mesencephalon and within dorsal striatum. The integrity of dopamine (DA) projection was assessed at the level of the olfactory tubercle, the nucleus accumbens and fundus striati. Prolonged exposure to small doses of METH, produces nigro-striatal toxicity, when assessed at short time intervals following prolonged exposure. However, at prolonged time intervals a paradoxical increase progressively occurred in TH immunostaining within limbic regions. Such an increase exceeds at large the amount of TH expressed in controls. This occurs concomitantly with an overexpression of the primary transcript as well as the protein alpha synuclein within the same brain regions and dorsal striatum. This increase is persistent at prolonged time inter val of METH withdrawal.The increase in the primary a-synuclein transcript is due to hypomethylation of specifi c CPG islands placed in the SNCA gene promoter which ranged roughly ten-fold of controls, it was steady, and it persisted at least 21 days following METH withdrawal. Thus, such an appar ent synucleinopathy induced by METH indeed was associated with increased mesolimbic DA innervation, which equally surpasses several folds the amount which was measured in controls and persists at least for three weeks. The increase in SNCA is not associated with an increase of SNCA copy number. Nonetheless, the amount of the native protein, which is detected by ultra structural stoichiometry, exceeds the increase reported following genetic SNCA multiplications (ten-fold of controls). These fi ndings are discussed in the light of METH-induced phenotype changes which accompany toxicity, sensitization, addiction and neurodegeneration

mTOR Modulates Methamphetamine-Induced Toxicity through Cell Clearing Systems

Methamphetamine (METH) is abused worldwide, and it represents a threat for public health. METH exposure induces a variety of detrimental effects. In fact, METH produces a number of oxidative species, which lead to lipid peroxidation, protein misfolding, and nuclear damage. Cell clearing pathways such as ubiquitin-proteasome (UP) and autophagy (ATG) are involved in METH-induced oxidative damage. Although these pathways were traditionally considered to operate as separate metabolic systems, recent studies demonstrate their interconnection at the functional and biochemical level. Very recently, the convergence between UP and ATG was evidenced within a single organelle named autophagoproteasome (APP), which is suppressed by mTOR activation. In the present research study, the occurrence of APP during METH toxicity was analyzed. In fact, coimmunoprecipitation indicates a binding between LC3 and P20S particles, which also recruit p62 and alpha-synuclein. The amount of METH-induced toxicity correlates with APP levels. Specific markers for ATG and UP, such as LC3 and P20S in the cytosol, and within METH-induced vacuoles, were measured at different doses and time intervals following METH administration either alone or combined with mTOR modulators. Western blotting, coimmunoprecipitation, light microscopy, confocal microscopy, plain transmission electron microscopy, and immunogold staining were used to document the effects of mTOR modulation on METH toxicity and the merging of UP with ATG markers within APPs. METH-induced cell death is prevented by mTOR inhibition, while it is worsened by mTOR activation, which correlates with the amount of autophagoproteasomes. The present data, which apply to METH toxicity, are also relevant to provide a novel insight into cell clearing pathways to counteract several kinds of oxidative damage

Procedure di record linkage in epidemiologia: uno studio multicentrico italiano, Record-linkage procedures in epidemiology: an italian multicentre study

Abstract Objective: to compare record linkage (RL) procedures adopted in several Italian settings and a standard probabilistic RL procedure for matching data from electronic health care databases. Design: two health care archives are matched: the hospital discharges (HD) archive and the population registry of four Italian areas. Exact deterministic, stepwise deterministic techniques and a standard probabilistic RL procedure are applied to match HD for acute myocardial infarction (AMI) and diabetes mellitus. Sensitivity and specificity for RL procedures are estimated after manual review. Age and gender standardized annual hospitalization rates for AMI and diabetes are computed using different RL procedures and compared