Sofia Baptista

Methamphetamine‐induced neuroinflammation and neuronal dysfunction in the mice hippocampus: preventive effect of indomethacin

Methamphetamine (METH) causes irreversible damage to brain cells leading to neurological and psychiatric abnormalities. However, the mechanisms underlying life‐threatening effects of acute METH intoxication remain unclear. Indeed, most of the hypotheses focused on intra‐neuronal events, such as dopamine oxidation, oxidative stress and excitotoxicity. Yet, recent reports suggested that glia may contribute to METH‐induced neuropathology. In the present study, we investigated the hippocampal dysfunction induced by an acute high dose of METH (30 mg/kg; intraperitoneal injection), focusing on the inflammatory process and changes in several neuronal structural proteins. For that, 3‐month‐old male wild‐type C57BL/6J mice were killed at different time‐points post‐METH. We observed that METH caused an inflammatory response characterized by astrocytic and microglia reactivity, and tumor necrosis factor (TNF) system alterations. Indeed, glial fibrillary acidic protein (GFAP) and CD11b immunoreactivity were upregulated, likewise TNF‐α and TNF receptor 1 protein levels. Furthermore, the effect of METH on hippocampal neurons was also investigated, and we observed a downregulation in beta III tubulin expression. To clarify the possible neuronal dysfunction induced by METH, several neuronal proteins were analysed. Syntaxin‐1, calbindin D28k and tau protein levels were downregulated, whereas synaptophysin was upregulated. We also evaluated whether an anti‐inflammatory drug could prevent or diminish METH‐induced neuroinflammation, and we concluded that indomethacin (10 mg/kg; i.p.) prevented METH‐induced glia activation and both TNF system and beta III tubulin alterations. In conclusion, we demonstrated that METH triggers an inflammatory process and leads to neuronal dysfunction in the hippocampus, which can be prevented by an anti‐inflammatory treatment.

Exercise training decreases proinflammatory profile in Zucker diabetic (type 2) fatty rats

OBJECTIVE In the present study we evaluated the effect of exercise on the plasma levels of proinflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), and the anti-inflammatory molecule uric acid in the Zucker diabetic fatty (ZDF) rats that are more prone to develop type 2 diabetes mellitus. METHODS Sixteen obese ZDF (Gmi fa/fa) rats (8 wk old, 228.40 +/- 4.05 g) were randomly assigned to one of two groups (n = 8 each): an exercise-trained group and a sedentary one. In addition, 16 lean ZDF (Gmi +/+) rats (8 wk old, 199.00 +/- 3.50 g) were subjected to identical sedentary and exercise conditioning (n = 8 each). Initially, rats swam 15 min/d (5 d/wk) in a 36 degrees C bath. The exercise protocol was gradually increased by 15 min/d until a swimming period of 1 h/d (1 wk) was attained. Thereafter, rats swam 1 h/d, 3 d/wk, for an additional period of 11 wk. Rats were sacrificed 48 h after the last training period and the blood and pancreas were collected. Circulating levels of glucose, glycosylated hemoglobin, total cholesterol, triglycerides, insulin, uric acid, IL-6, and TNF-alpha were assessed. The concentrations of proinflammatory cytokines in the pancreas were also evaluated. RESULTS In the diabetic ZDF (fa/fa) rats, exercise decreased hyperuricemia (-37.3%) and IL-6 and TNF-alpha levels (-16.9% and -12.7% respectively) and maintained the weight of the pancreas at near normal. Immunohistochemistry revealed a marked decrease in the expression of TNF-alpha and IL-6 in the pancreatic islet cells of ZDF (fa/fa) rats. CONCLUSION These results indicate that aerobic exercise is anti-inflammatory in nature.

Multifaces of neuropeptide Y in the brain – Neuroprotection, neurogenesis and neuroinflammation

Neuropeptide Y (NPY) has been implicated in the modulation of important features of neuronal physiology, including calcium homeostasis, neurotransmitter release and excitability. Moreover, NPY has been involved as an important modulator of hippocampal and thalamic circuits, receiving particular attention as an endogenous antiepileptic peptide and as a potential master regulator of feeding behavior. NPY not only inhibits excessive glutamate release (decreasing circuitry hyperexcitability) but also protects neurons from excitotoxic cell death. Furthermore, NPY has been involved in the modulation of the dynamics of dentate gyrus and subventricular zone neural stem cell niches. In both regions, NPY is part of the chemical resource of the neurogenic niche and acts through NPY Y1 receptors to promote neuronal differentiation. Interestingly, NPY is also considered a neuroimmune messenger. In this review, we highlight recent evidences concerning paracrine/autocrine actions of NPY involved in neuroprotection, neurogenesis and neuroinflammation. In summary, the three faces of NPY, discussed in the present review, may contribute to better understand the dynamics and cell fate decision in the brain parenchyma and in restricted areas of neurogenic niches, in health and disease.

Methamphetamine transiently increases the blood–brain barrier permeability in the hippocampus: Role of tight junction proteins and matrix metalloproteinase-9

Methamphetamine (METH) is a powerful stimulant drug of abuse that has steadily gained popularity worldwide. It is known that METH is highly neurotoxic and causes irreversible damage of brain cells leading to neurological and psychiatric abnormalities. Recent studies suggested that METH-induced neurotoxicity might also result from its ability to compromise blood-brain barrier (BBB) function. Due to the crucial role of BBB in the maintenance of brain homeostasis and protection against toxic molecules and pathogenic organisms, its dysfunction could have severe consequences. In this study, we investigated the effect of an acute high dose of METH (30mg/kg) on BBB permeability after different time points and in different brain regions. For that, young adult mice were sacrificed 1h, 24h or 72h post-METH administration. METH increased BBB permeability, but this effect was detected only at 24h after administration, being therefore a transitory effect. Interestingly, we also found that the hippocampus was the most susceptible brain region to METH, comparing to frontal cortex and striatum. Moreover, in an attempt to identify the key players in METH-induced BBB dysfunction we further investigated potential alterations in tight junction (TJ) proteins and matrix metalloproteinase-9 (MMP-9). METH was able to decrease the protein levels of zonula occludens (ZO)-1, claudin-5 and occludin in the hippocampus 24h post-injection, and increased the activity and immunoreactivity of MMP-9. The pre-treatment with BB-94 (30mg/kg), a matrix metalloproteinase inhibitor, prevented the METH-induced increase in MMP-9 immunoreactivity in the hippocampus. Overall, the present data demonstrate that METH transiently increases the BBB permeability in the hippocampus, which can be explained by alterations on TJ proteins and MMP-9.

Brain Injury Associated with Widely Abused Amphetamines: Neuroinflammation, Neurogenesis and Blood-Brain Barrier

Over the course of the 20(th) century, it became increasingly clear that amphetamine-like psychostimulants carried serious abuse liability that has resulted in sociological use patterns that have been described as epidemics. In fact, drug addiction is a brain disease with a high worldwide prevalence, and is considered the most expensive of the neuropsychiatric disorders. This review goes beyond the previously well-documented evidence demonstrating that amphetamines cause neuronal injury. Cellular and molecular mechanisms involved in the neurotoxicity of psychostimulants drugs have been extensively described giving particular attention to the role of oxidative stress and metabolic compromise. Recently, it was shown that the amphetamine class of drugs of abuse triggers an inflammatory process, emerging as a critical concept to understand the toxic effects of these drugs. Moreover, it has been suggested that psychostimulants compromise the capacity of the brain to generate new neurons (neurogenesis), and can also lead to blood-brain barrier (BBB) dysfunction. Together, these effects may contribute to brain damage, allowing the entry of pathogens into the brain parenchyma and thus decreasing the endogenous brain repair resources. The overall objective of this review is to highlight experimental evidence in an attempt to clarify the role of neuroinflammation in amphetamines-induced brain dysfunction and the effect of these drugs on both neurogenesis and BBB integrity.

Neuropeptide Y promotes neurogenesis and protection against methamphetamine-induced toxicity in mouse dentate gyrus-derived neurosphere cultures

Methamphetamine (METH) is a psychostimulant drug of abuse that causes severe brain damage. However, the mechanisms responsible for these effects are poorly understood, particularly regarding the impact of METH on hippocampal neurogenesis. Moreover, neuropeptide Y (NPY) is known to be neuroprotective under several pathological conditions. Here, we investigated the effect of METH on dentate gyrus (DG) neurogenesis, regarding cell death, proliferation and differentiation, as well as the role of NPY by itself and against METH-induced toxicity. DG-derived neurosphere cultures were used to evaluate the effect of METH or NPY on cell death, proliferation or neuronal differentiation. Moreover, the role of NPY and its receptors (Y(1), Y(2) and Y(5)) was investigated under conditions of METH-induced DG cell death. METH-induced cell death by both apoptosis and necrosis at concentrations above 10 nM, without affecting cell proliferation. Furthermore, at a non-toxic concentration (1 nM), METH decreased neuronal differentiation. NPYs protective effect was mainly due to the reduction of glutamate release, and it also increased DG cell proliferation and neuronal differentiation via Y(1) receptors. In addition, while the activation of Y(1) or Y(2) receptors was able to prevent METH-induced cell death, the Y(1) subtype alone was responsible for blocking the decrease in neuronal differentiation induced by the drug. Taken together, METH negatively affects DG cell viability and neurogenesis, and NPY is revealed to be a promising protective tool against the deleterious effects of METH on hippocampal neurogenesis.

Hypertension induced by immunosuppressive drugs: a comparative analysis between sirolimus and cyclosporine

The purpose of this study was to compare the effects of sirolimus (SRL) vs cyclosporine (CsA) concerning the cardiovascular mechanisms hypothetically contributing to hypertension development. Three rat groups were studied: control (vehicle), CsA (5 mg/kg/d), and SRL (1 mg/kg/d). The following parameters were evaluated after 7 weeks of treatment: blood pressured (BP) and heart rate (HR; tail cuff), lipid profile, hematology, plasma and platelet 5-HT and catecholamines (HPLC-ECD), and oxidative equilibrium (serum malondialdehyde [MDA] and total antioxidant status [TAS]). Systolic (SBP) and diastolic blood pressure (DBP) values were higher (P < .001) in both the CsA (146.2 +/- 4.5 and 124.9 +/- 4.5 mm Hg) and SRL (148.9 +/- 4.8 and 126.4 +/- 6.0 mm Hg) groups vs the controls (115.9 +/- 3.3 and 99.1 +/- 2.0 mm Hg). However, HR values were elevated in CsA but not SRL animals. The dyslipidemic pattern of CsA was even more enhanced in the SRL group, with significantly higher low-density lipoprotein cholesterol (LDL-c) and triglyceride (TG) levels vs CsA (P < .05); red blood cells, hematocrit, hemoglobin concentration, mean platelet volume, and platelet distribution width were significantly (P < .05) higher in the SRL vs CsA group. The pro-oxidative profile (increased MDA/TAS) in the CsA group was not reproduced in the SRL cohort. While plasma and platelet 5-HT were elevated in SRL rats, catecholamine content was higher in CsA animals. In conclusion, this study demonstrated that CsA and SRL produce identical hypertensive effects. However, while CsA promotes oxidative stress and sympathetic activation, SRL mainly interferes with lipid profile and hematological parameters. Thus, the hypertensive effects of CsA, a calcineurin inhibitor, and of SRL, an mTOR inhibitor, are associated with impairment of distinct cardiovascular pathways.

Treadmill running and swimming imposes distinct cardiovascular physiological adaptations in the rat: Focus on serotonergic and sympathetic nervous systems modulation

Physical exercise may improve the metabolic and haemodynamic responses, but the beneficial effects seem to depend on intensity, duration and muscular mass recruitment, which may vary between different types of protocols. This study was performed to evaluate the effects of two distinct moderate/long-term aerobic training protocols in the normal Wistar rat, the treadmill running and the swimming, on several important parameters related to cardiovascular (CV) physiological adaptations, namely: lipid profile, haemorheological measures, lipid peroxidation, peripheral serotonergic system (SS) modulation and sympathetic nervous system (SNS) activation. In both groups under training an HDL-c increment versus the sedentary control was demonstrated. There was a noticeable increase in ADP-induced platelet aggregation in the exercised rats, together with higher PDW and MPV values. The RBC patterns were altered in both groups under training; in the swimming one, however, significantly higher RBC and HCT and lower MCH and MCHC values were found, suggesting renovation of the RBCs. Plasma and platelet SS measures were generally higher in both groups under training, being noticeably relevant the 5-HT and 5-HIAA increment in the treadmill. In opposition, concerning the plasma and platelet NE and E concentrations, the rise was remarkably higher in the rats under a swimming protocol. In conclusion, this study demonstrates that, despite the similar beneficial effects on lipid profile, different aerobic exercise protocols may produce distinct CV physiological adaptations. Therefore, treadmill running was more influent than swimming concerning peripheral SS modulation while swimming was more important on SNS activation, thus recommending a judicious choice of the protocol to be tested in works which make use of rat models of exercise to study physiological or pathophysiological conditions.

Methamphetamine-induced changes in the mice hippocampal neuropeptide Y system: implications for memory impairment.

Methamphetamine (METH) is a psychostimulant drug that causes irreversible brain damage leading to several neurological and psychiatric abnormalities, including cognitive deficits. Neuropeptide Y (NPY) is abundant in the mammalian central nervous system (CNS) and has several important functions, being involved in learning and memory processing. It has been demonstrated that METH induces significant alteration in mice striatal NPY, Y1 and Y2 receptor mRNA levels. However, the impact of this drug on the hippocampal NPY system and its consequences remain unknown. Thus, in this study, we investigated the effect of METH intoxication on mouse hippocampal NPY levels, NPY receptors function, and memory performance. Results show that METH increased NPY, Y2 and Y5 receptor mRNA levels, as well as total NPY binding accounted by opposite up‐ and down‐regulation of Y2 and Y1 functional binding, respectively. Moreover, METH‐induced impairment in memory performance and AKT/mammalian target of rapamycin pathway were both prevented by the Y2 receptor antagonist, BIIE0246. These findings demonstrate that METH interferes with the hippocampal NPY system, which seems to be associated with memory failure. Overall, we concluded that Y2 receptors are involved in memory deficits induced by METH intoxication.

Methamphetamine Exerts Toxic Effects on Subventricular Zone Stem/Progenitor Cells and Inhibits Neuronal Differentiation

Methamphetamine (METH) is a potent and widely consumed psychostimulant drug that causes brain functional and structural abnormalities. However, there is little information regarding METH impact on adult neurogenic niches and, indeed, nothing is known about its consequences on the subventricular zone (SVZ). Thus, this work aims to clarify the effect of METH on SVZ stem/progenitor cells dynamics and neurogenesis. For that purpose, SVZ neurospheres were obtained from early postnatal mice and treated with increasing concentrations of METH (1  μM to 500  μM). Exposure to 100, 250, or 500  μM METH for 24  h triggered cell death both by necrosis and apoptosis, as assessed by propidium iodide uptake, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and quantification of the proapoptotic caspase-3 activity. Furthermore, we showed that METH inhibited SVZ progenitor cells proliferation as it decreased BrdU incorporation. Interestingly, at non-toxic concentrations (1 and 10  μM), METH decreased neuronal differentiation and maturation, which were evaluated by quantification of the number of neuronal nuclei-positive neurons and measurements of phospho-c-Jun-NH(2)-terminal kinase signal in growing axons, respectively. Altogether, our data demonstrate that METH has a negative impact on SVZ stem/progenitor cells, inducing cell death and inhibiting neurogenesis, effects that in vivo may challenge the cell replacement capacities displayed by endogenous populations of brain stem/progenitor cells.