Absence of Gem1 (mammalian Miro/Rhot) mitigates alpha-synuclein toxicity in a yeast model of Parkinson's disease.

Alpha-synuclein aggregation is a hallmark of Parkinson's disease (PD). Mutants A30P and A53T alpha-synuclein are known to exacerbate the toxicity of alpha-synuclein, which includes oxidative stress, mitochondrial and endoplasmic reticulum (ER) dysfunction. Saccharomyces cerevisiae (budding yeast) is a cellular model widely used to investigate mechanisms underlying neurodegenerative disorders, such as PD. In yeast, Gem1 (Miro/Rhot mammalian orthologue) coordinates mitochondrial dynamics and ER homeostasis, which is impaired in the presence of mutant alpha-synuclein and can lead to cell death. In this study, A30P or A53T alpha-synuclein were expressed in wild type or ΔGem (deletion of Gem1 gene) yeast strains. ΔGem cells presented decreased viability and increased mitochondrial H2O2 production and ER stress compared to wild type cells. However, in the presence of mutant alpha-synuclein, ΔGem cells showed increased growth compared to cells that do not express mutant alpha-synuclein. ΔGem cells expressing A53T alpha-synuclein also presented reduced ER stress and increased ability to deal with oxidative stress. Together, our results suggest that deletion of Gem1 activates pathways that strengthen cells against other stressful agents such as the presence of mutant alpha-synuclein.

Mitochondria-ER Tethering in Neurodegenerative Diseases.

Organelles juxtaposition has been detected for decades, although only recently gained importance due to a pivotal role in the regulation of cellular processes dependent on membrane contact sites. Endoplasmic reticulum (ER) and mitochondria interaction is a prime example of organelles contact sites. Mitochondria-associated membranes (MAM) are proposed to harbor ER-mitochondria tether complexes, mainly when these organelles are less than 30 nm apart. Dysfunctions of proteins located at the MAM are associated with neurodegenerative diseases such as Parkinson's, Alzheimer's and amyotrophic lateral sclerosis, as well as neurodevelopmental disorders; hence any malfunction in MAM can potentially trigger cell death. This review will focus on the role of ER-mitochondria contact sites, regarding calcium homeostasis, lipid metabolism, autophagy, morphology and dynamics of mitochondria, mainly in the context of neurodegenerative diseases. Approaches that have been employed so far to study organelles contact sites, as well as methods that were not used in neurosciences yet, but are promising and accurate ways to unveil the functions of MAM during neurodegeneration, is also discussed in the present review.

BAG2 prevents Tau hyperphosphorylation and increases p62/SQSTM1 in cell models of neurodegeneration.

BACKGROUND: Protein aggregates are pathological hallmarks of many neurodegenerative diseases, however the physiopathological role of these aggregates is not fully understood. Protein quality control has a pivotal role for protein homeostasis and depends on specific chaperones. The co-chaperone BAG2 can target phosphorylated Tau for degradation by an ubiquitin-independent pathway, although its possible role in autophagy was not yet elucidated. In view of this, the aim of the present study was to investigate the association among protein aggregation, autophagy and BAG2 levels in cultured cells from hippocampus and locus coeruleus as well as in SH-SY5Y cell line upon different protein aggregation scenarios induced by rotenone, which is a flavonoid used as pesticide and triggers neurodegeneration. METHODS AND RESULTS: The present study showed that rotenone exposure at 0.3 nM for 48 h impaired autophagy prior to Tau phosphorylation at Ser199/202 in hippocampus but not in locus coeruleus cells, suggesting that distinct neuron cells respond differently to rotenone toxicity. Rotenone induced Tau phosphorylation at Ser199/202, together with a decrease in the endogenous BAG2 protein levels in SH-SY5Y and hippocampus cell culture, which indicates that rotenone and Tau hyperphosphorylation can affect this co-chaperone. Finally, it has been shown that BAG2 overexpression, increased p62/SQSTM1 levels in cells from hippocampus and locus coeruleus, stimulated LC3II recycling as well as prevented the raise of phosphorylated Tau at Ser199/202 in hippocampus. CONCLUSIONS: Results demonstrate a possible role for BAG2 in degradation pathways of specific substrates and its importance for the study of cellular aspects of neurodegenerative diseases.

Parkin is downregulated among autophagy-related proteins prior to hyperphosphorylation of Tau in TS65DN mice.

Autophagy is a pathway through which cells execute a plethora of functions, such as macromolecules and organelles quality control, recycling of building blocks and apoptosis. Numerous studies have shown in the past that autophagy is an important mechanism associated with the pathology of various neurodegenerative diseases, whose impairment may lead to several disease-characteristic phenotypes (e.g. misfolded protein and defective organelles accumulation). With this in mind, we aimed to investigate whether alterations in expression of autophagy-related proteins would show before hyperphosphorylation of Tau, a hallmark of Alzheimer's disease (AD). After analyzing 7 different proteins, we observed that, while Pink1 and p62 show an age-related reduction in the Ts65Dn mice respectively in the locus coeruleus and hippocampus, Parkin shows an age-genotype interaction-associated reduction in both brain areas. This suggests potential outcomes in pathways associated with Parkin that could relate to later stages of the disease development.

Alpha-Synuclein Toxicity on Protein Quality Control, Mitochondria and Endoplasmic Reticulum.

Parkinson's disease (PD) is characterized by the presence of insoluble protein clusters containing α-synuclein. Impairment of mitochondria, endoplasmic reticulum, autophagy and intracellular trafficking proper function has been suggested to be caused by α-synuclein toxicity, which is also associated with the higher levels of ROS found in the aged brain and in PD. Oxidative stress leads to protein oligomerization and aggregation that impair autophagy and mitochondrial dynamics leading to a vicious cycle of organelles damage and neurodegeneration. In this review we focused on the role of α-synuclein dysfunction as a cellular stressor that impairs mitochondria, endoplasmic reticulum, autophagy and cellular dynamics culminating with dopaminergic depletion and the pathogenesis of PD.

Effects of mild running on substantia nigra during early neurodegeneration.

Moderate physical exercise acts at molecular and behavioural levels, such as interfering in neuroplasticity, cell death, neurogenesis, cognition and motor functions. Therefore, the aim of this study is to analyse the cellular effects of moderate treadmill running upon substantia nigra during early neurodegeneration. Aged male Lewis rats (9-month-old) were exposed to rotenone 1mg/kg/day (8 weeks) and 6 weeks of moderate treadmill running, beginning 4 weeks after rotenone exposure. Substantia nigra was extracted and submitted to proteasome and antioxidant enzymes activities, hydrogen peroxide levels and Western blot to evaluate tyrosine hydroxylase (TH), alpha-synuclein, Tom-20, PINK1, TrkB, SLP1, CRMP-2, Rab-27b, LC3II and Beclin-1 level. It was demonstrated that moderate treadmill running, practiced during early neurodegeneration, prevented the increase of alpha-synuclein and maintained the levels of TH unaltered in substantia nigra of aged rats. Physical exercise also stimulated autophagy and prevented impairment of mitophagy, but decreased proteasome activity in rotenone-exposed aged rats. Physical activity also prevented H2O2 increase during early neurodegeneration, although the involved mechanism remains to be elucidated. TrkB levels and its anterograde trafficking seem not to be influenced by moderate treadmill running. In conclusion, moderate physical training could prevent early neurodegeneration in substantia nigra through the improvement of autophagy and mitophagy.

Rotenone-dependent changes of anterograde motor protein expression and mitochondrial mobility in brain areas related to neurodegenerative diseases.

The presence of protein aggregates is common in neurodegenerative disorders; however, the real cause and effect of these aggregates during neurodegeneration is still a matter of investigation. We hypothesize that impairment of intracellular traffic may appear in the absence of protein inclusions and might trigger protein aggregation. In the present study, we aimed to evaluate mitochondria mobility as well as protein and messenger RNA expression of KIF1B and KIF5 that are molecular motors for neuronal anterograde traffic, in hippocampus, substantia nigra, and locus coeruleus of 10-month-old Lewis rats and cultured cells, from these same areas, following exposure to low doses of rotenone that do not lead to protein inclusions. The present study showed alteration in KIF1B and KIF5 expression, as well as in mitochondria mobility prior to protein aggregation involved in neurodegenerative disorders. These findings suggest that change in intracellular trafficking might be critical and one of the primary events for impairment of cell physiology during neurodegeneration associated with protein inclusions.

Effects of Magnetite Nanoparticles and Static Magnetic Field on Neural Differentiation of Pluripotent Stem Cells.

Neurodevelopmental processes of pluripotent cells, such as proliferation and differentiation, are influenced by external natural forces. Despite the presence of biogenic magnetite nanoparticles in the central nervous system and constant exposure to the Earth's magnetic fields and other sources, there is scant knowledge regarding the role of electromagnetic stimuli in neurogenesis. Moreover, emerging applications of electrical and magnetic stimulation to treat neurological disorders emphasize the relevance of understanding the impact and mechanisms behind these stimuli. Here, the effects of magnetic nanoparticles (MNPs) in polymeric coatings and the static external magnetic field (EMF) were investigated on neural induction of murine embryonic stem cells (mESCs) and human induced pluripotent stem cells (hiPSCs). The results show that the presence of 0.5% MNPs in collagen-based coatings facilitates the migration and neuronal maturation of mESCs and hiPSCs in vitro. Furthermore, the application of 0.4 Tesla EMF perpendicularly to the cell culture plane, discernibly stimulates proliferation and guide fate decisions of the pluripotent stem cells, depending on the origin of stem cells and their developmental stage. Mechanistic analysis reveals that modulation of ionic homeostasis and the expression of proteins involved in cytostructural, liposomal and cell cycle checkpoint functions provide a principal underpinning for the impact of electromagnetic stimuli on neural lineage specification and proliferation. These findings not only explore the potential of the magnetic stimuli as neural differentiation and function modulator but also highlight the risks that immoderate magnetic stimulation may affect more susceptible neurons, such as dopaminergic neurons.

Epigenetic regulation of retinal development.

In the developing vertebrate retina, retinal progenitor cells (RPCs) proliferate and give rise to terminally differentiated neurons with exquisite spatio-temporal precision. Lineage commitment, fate determination and terminal differentiation are controlled by intricate crosstalk between the genome and epigenome. Indeed, epigenetic regulation plays pivotal roles in numerous cell fate specification and differentiation events in the retina. Moreover, aberrant chromatin structure can contribute to developmental disorders and retinal pathologies. In this review, we highlight recent advances in our understanding of epigenetic regulation in the retina. We also provide insight into several aspects of epigenetic-related regulation that should be investigated in future studies of retinal development and disease. Importantly, focusing on these mechanisms could contribute to the development of novel treatment strategies targeting a variety of retinal disorders.

Protein aggregation containing ß-amyloid, α-synuclein and hyperphosphorylated τ in cultured cells of hippocampus, substantia nigra and locus coeruleus after rotenone exposure.

BACKGROUND: Protein aggregates containing alpha-synuclein, beta-amyloid and hyperphosphorylated tau are commonly found during neurodegenerative processes which is often accompanied by the impairment of mitochondrial complex I respiratory chain and dysfunction of cellular systems of protein degradation. In view of this, we aimed to develop an in vitro model to study protein aggregation associated to neurodegenerative diseases using cultured cells from hippocampus, locus coeruleus and substantia nigra of newborn Lewis rats exposed to 0.5, 1, 10 and 25 nM of rotenone, which is an agricultural pesticide, for 48 hours. RESULTS: We demonstrated that the proportion of cells in culture is approximately the same as found in the brain nuclei they were extracted from. Rotenone at 0.5 nM was able to induce alpha-synuclein and beta amyloid aggregation, as well as increased hyperphosphorylation of tau, although high concentrations of this pesticide (over 1 nM) lead cells to death before protein aggregation. We also demonstrated that the 14 kDa isoform of alpha-synuclein is not present in newborn Lewis rats. CONCLUSION: Rotenone exposure may lead to constitutive protein aggregation in vitro, which may be of relevance to study the mechanisms involved in idiopathic neurodegeneration.

microRNAs expression correlates with levels of APP, DYRK1A, hyperphosphorylated Tau and BDNF in the hippocampus of a mouse model for Down syndrome during ageing.

Down syndrome (DS) patients are more susceptible to Alzheimer's disease (AD) due to the presence of three copies of genes on chromosome 21 such as DYRK1A, which encodes a broad acting kinase, and APP (amyloid precursor protein), leading to formation of amyloid beta (Aß) peptide and hyperphosphorylation of Tau. In this study, we investigated the association among miRNAs miR-17, -20a, -101, -106b, -199b, -26a, 26b and some of their target mRNAs such as APP, DYRK1A and BDNF, as well as the levels of hyperphosphorylated Tau in the hippocampus of a 2 and 5 months old mice model of trisomy 21 (Ts65Dn). Results indicated that increased APP expression in the hippocampus of 5 months old DS mice might be correlated with decrease in miR-17, -20a, -101 and -106b. Whereas at 2 months of age normal levels of APP expression in the hippocampus was correlated with increased levels of miR-17, -101 and -106b in DS mice. DYRK1A mRNA also increased in the hippocampus of 5 months old DS mice and it is associated with decreased levels of miR-199b. Increased levels of DYRK1A in 5-month old mice are associated with increased phosphorylation of Tau at Thr212 residue but not at Ser199-202. Tau pathology is accompanied by decreased expression of BDNF and increased miR-26a/b in mice of 5 months of age. Taken together, data indicate that miR-17, -20a, -26a/b, -101, -106b and -199b might be interesting targets to mitigate Tau and Aß pathology in DS.

Altered in vitro muscle differentiation in X-linked myopathy with excessive autophagy.

X-linked myopathy with excessive autophagy (XMEA) is a genetic disease associated with weakness of the proximal muscles. It is caused by mutations in the VMA21 gene, coding for a chaperone that functions in the vacuolar ATPase (v-ATPase) assembly. Mutations associated with lower content of assembled v-ATPases lead to an increase in lysosomal pH, culminating in partial blockage of macroautophagy, with accumulation of vacuoles of undigested content. Here, we studied a 5-year-old boy affected by XMEA, caused by a small indel in the VMA21 gene. Detection of sarcoplasmic Lc3 (also known as MAP1LC3B)-positive vacuoles in his muscle biopsy confirmed an autophagy defect. To understand how autophagy is regulated in XMEA myogenesis, we used patient-derived muscle cells to evaluate autophagy during in vitro muscle differentiation. An increase in lysosomal pH was observed in the patient's cells, compatible with predicted functional defect of his mutation. Additionally, there was an increase in autophagic flux in XMEA myotubes. Interestingly, we observed that differentiation of XMEA myoblasts was altered, with increased myotube formation observed through a higher fusion index, which was not dependent on lysosomal acidification. Moreover, no variation in the expression of myogenic factors nor the presence of regenerating fibers in the patient's muscle were observed. Myoblast fusion is a tightly regulated process; therefore, the uncontrolled fusion of XMEA myoblasts might generate cells that are not as functional as normal muscle cells. Our data provide new evidence on the reason for predominant muscle involvement in the context of the XMEA phenotype.This article has an associated First Person interview with the first author of the paper.

Gene expression profiling of cultured cells from brainstem of newborn spontaneously hypertensive and Wistar Kyoto rats.

The spontaneously hypertensive rat (SHR) is a good model to study several diseases such as the attention-deficit hyperactivity disorder, cardiopulmonary impairment, nephropathy, as well as hypertension, which is a multifactor disease that possibly involves alterations in gene expression in hypertensive relative to normotensive subjects. In this study, we used high-density oligoarrays to compare gene expression profiles in cultured neurons and glia from brainstem of newborn normotensive Wistar Kyoto (WKY) and SHR rats. We found 376 genes differentially expressed between SHR and WKY brainstem cells that preferentially map to 17 metabolic/signaling pathways. Some of the pathways and regulated genes identified herein are obviously related to cardiovascular regulation; in addition there are several genes differentially expressed in SHR not yet associated to hypertension, which may be attributed to other differences between SHR and WKY strains. This constitute a rich resource for the identification and characterization of novel genes associated to phenotypic differences observed in SHR relative to WKY, including hypertension. In conclusion, this study describes for the first time the gene profiling pattern of brainstem cells from SHR and WKY rats, which opens up new possibilities and strategies of investigation and possible therapeutics to hypertension, as well as for the understanding of the brain contribution to phenotypic differences between SHR and WKY rats.

Restoration of Rab1 Levels Prevents Endoplasmic Reticulum Stress in Hippocampal Cells during Protein Aggregation Triggered by Rotenone.

Disrupted neuronal intracellular trafficking is often related with protein aggregates present in the brain during neurodegenerative diseases such as Alzheimer's. Impairment of intracellular transport may be related to Rab proteins, a class of small GTPases responsible for trafficking of organelles and vesicles. Deficit in trafficking between the endoplasmic reticulum (ER) and Golgi apparatus mediated by Rab1 and 6 may lead to increased unfolded protein response (UPR) and ER stress and remodeling. Thus, the objective of this study is to analyze the levels of Rabs 1 and 6 in the hippocampus of aged rats and in vitro during protein aggregation promoted by exposure to rotenone. Levels of Rabs 1 and 6, ATF6 and CHOP were measured by western blotting. PDI immunolabeling and ER-Tracker were employed to study ER morphology. MTT was used to analyze cell metabolism. Rab1 levels and cell viability decreased, whereas Rab6, UPR proteins and ER remodeling increased during protein aggregation, which were restored to normal levels after exogenous expression of Rab1.These results suggest that decrease of Rab1 levels contributes to ER stress and remodeling, while maintaining the elevated expression of Rab1 prevented impairment of cell viability during protein aggregation. In conclusion, Rab1 is a significant player to maintain intracellular homeostasis and its expression may mitigate ER dysfunction in the context of neurodegeneration-related protein inclusions.

Mild Exercise Differently Affects Proteostasis and Oxidative Stress on Motor Areas During Neurodegeneration: A Comparative Study of Three Treadmill Running Protocols.

Proteostasis and oxidative stress were evaluated in motor cortex and spinal cord of aged Lewis rats exposed to 1 mg/kg/day of rotenone during 4 or 8 weeks, prior or after practicing three protocols of mild treadmill running. Results demonstrated that exercise done after the beginning of neurodegeneration reverted the increased oxidative stress (measured by H2O2 levels and SOD activity), increased neuron strength, and improved proteostasis in motor cortex. Spinal cord was not affected. Treadmill running practiced before neurodegeneration protected cortical motor neurons of the rotenone-exposed rats; but in this case, oxidative stress was not altered, whereas proteasome activity was increased and autophagy decreased. Spinal cord was not protected when exercise was practiced before neurodegeneration. Prolonged treadmill running (10 weeks) increased oxidative stress, autophagy, and proteasome activity, whereas neuron viability was decreased in motor cortex. In spinal cord, this protocol decreased oxidative stress and increased proteasome activity. Major conclusions were that treadmill running practiced before or after the beginning of neurodegeneration may protect motor cortex neurons, whereas prolonged mild running seems to be beneficial for spinal cord.

Midbrain Dopaminergic Neurons Differentiated from Human-Induced Pluripotent Stem Cells.

The work with midbrain dopaminergic neurons (mDAN) differentiation might seem to be hard. There are about 40 different published protocols for mDAN differentiation, which are eventually modified according to the respective laboratory. In many cases, protocols are not fully described, failing to provide essential tips for researchers starting in the field. Considering that commercial kits produce low mDAN percentages (20-50%), we chose to follow a mix of four main protocols based on Kriks and colleagues' protocol, from which the resulting mDAN were engrafted with success in three different animal models of Parkinson's disease. We present a differential step-by-step methodology for generating mDAN directly from human-induced pluripotent stem cells cultured with E8 medium on Geltrex, without culture on primary mouse embryonic fibroblasts prior to mDAN differentiation, and subsequent exposure of neurons to rock inhibitor during passages for improving cell viability. The protocol described here allows obtaining mDAN with phenotypical and functional characteristics suitable for in vitro modeling, cell transplantation, and drug screening.

Differential regulation of the renin-angiotensin system by nicotine in WKY and SHR glia.

Given that (1) the renin-angiotensin system (RAS) is compartmentalized within the central nervous system in neurons and glia (2) the major source of brain angiotensinogen is the glial cells, (3) the importance of RAS in the central control of blood pressure, and (4) nicotine increases the probability of development of hypertension associated to genetic predisposition; the objective of the present study was to evaluate the effects of nicotine on the RAS in cultured glial cells from the brainstem and hypothalamus of Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Ligand binding, real-time PCR and western blotting assays were used to compare the expression of angiotensinogen, angiotensin converting enzyme, angiotensin converting enzyme 2 and angiotensin II type1 receptors. We demonstrate, for the first time, that there are significant differences in the basal levels of RAS components between WKY and SHR rats in glia from 1-day-old rats. We also observed that nicotine is able to modulate the renin-angiotensin system in glial cells from the brainstem and hypothalamus and that the SHR responses were more pronounced than WKY ones. The present data suggest that nicotine effects on the RAS might collaborate to the development of neurogenic hypertension in SHR through modulation of glial cells.

Effects of bilateral adrenalectomy on systemic kainate-induced activation of the nucleus of the solitary tract. Regulation of blood pressure and local neurotransmitters.

Glutamatergic transmission through metabotropic and ionotropic receptors, including kainate receptors, plays an important role in the nucleus of the solitary tract (NTS) functions. Glutamate system may interact with several other neurotransmitter systems which might also be influenced by steroid hormones. In the present study we analyzed the ability of systemic kainate to stimulate rat NTS neurons, which was evaluated by c-Fos as a marker of neuronal activation, and also to change the levels of NTS neurotransmitters such as GABA, NPY, CGRP, GAL, NT and NO by means of quantitative immunohistichemistry combined with image analysis. The analysis was also performed in adrenalectomized and kainate stimulated rats in order to evaluate a possible role of adrenal hormones on NTS neurotransmission. Male Wistar rats (3 month-old) were used in the present study. A group of 15 rats was submitted either to bilateral adrenalectomy or sham operation. Forty-eight hours after the surgeries, adrenalectomized rats received a single intraperitoneal injection of kainate (12 mg/kg) and the sham-operated rats were injected either with saline or kainate and sacrificed 8 hours later. The same experimental design was applied in a group of rats in order to register the arterial blood pressure. Systemic kainate decreased the basal values of mean arterial blood pressure (35%) and heart rate (22%) of sham-operated rats, reduction that were maintained in adrenalectomized rats. Kainate triggered a marked elevation of c-Fos positive neurons in the NTS which was 54% counteracted by adrenalectomy. The kainate activated NTS showed changes in the immunoreactive levels of GABA (143% of elevation) and NPY (36% of decrease), which were not modified by previous ablation of adrenal glands. Modulation in the levels of CGRP, GAL and NT immunoreactivities were only observed after kainate in the adrenalectomized rats. Treatments did not alter NOS labeling. It is possible that modulatory function among neurotransmitter systems in the NTS might be influenced by steroid hormones and the implications for central regulation of blood pressure or other visceral regulatory mechanisms control should be further investigated.

Nicotine modulates the renin-angiotensin system of cultured neurons and glial cells from cardiovascular brain areas of Wistar Kyoto and spontaneously hypertensive rats.

Considering the importance of the renin-angiotensin system (RAS) for the central control of blood pressure and that nicotine increases the probability of development of hypertension associated to genetic predisposition, our aims are (1) to determine RAS in cultured neurons and glia from the brainstem and hypothalamus of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats; (2) to analyze the possibility of nicotine to interact with brain RAS; and (3) to hypothesize any contribution of nicotine and RAS to the development of neurogenic hypertension. This study demonstrated physiological differences in RAS between cultured neuronal and glial cells from the brainstem and hypothalamus of SHR and WKY neonate rats. Our study also featured evidences of direct modulation of the RAS by nicotine in neurons and glia of brainstem and hypothalamus, which seems to be differential between the two rat strains. Such modulation gives us a clue about the mechanisms possibly involved in the genesis of neurogenic hypertension in vivo, for example, increase in angiotensin II type 1 receptor binding and decrease in angiotensin-converting enzyme 2. In conclusion, we demonstrated that neuronal and glial RAS from the brainstem and hypothalamus of SHR differ from WKY rats and nicotine differentially modulates the brain RAS in SHR and WKY.

Chronic nicotine administration. Analysis of the development of hypertension and glutamatergic neurotransmission.

Among numerous neurotransmitters involved in central cardiovascular control, glutamate is one of the most studied transmitters that are related to nicotine considering its release and its postsynaptic regulation. However, there are no conclusive studies about nicotine effects on glutamatergic system and its relevance on hypertension development, which can help to understand the role of these two systems in that pathology. In this context, the objective of the present study is to evaluate the effects of systemic chronic nicotine exposure on hypertension development as well as the interaction between nicotine and the glutamatergic system in normotensive and neurogenic hypertensive rats. By means of high performance liquid chromatograph, immunohistochemistry, in situ hybridization and binding techniques, glutamatergic system was evaluated in SHR and Wistar Kyoto (WKY) rats treated with nicotine, delivered subcutaneously through nicotine pellets, for 8 weeks. The most important findings in this study were that (1) moderate doses of nicotine accelerated the onset and increased blood pressure in SHR but not in WKY rats, (2) the nicotine dosage and time of treatment employed did not affect body weight, (3) chronic nicotine treatment differentially affected glutamatergic system in normotensive and hypertensive rats, and (4) spontaneously hypertensive rats seem to be more sensitive to peripherally administered nicotine than Wistar Kyoto rats considering blood pressure and glutamatergic neurotransmission changes. In conclusion, we have demonstrated that a moderate dose of nicotine accelerates the onset and exacerbates hypertension in the SHR and that might be, at least in part, related to the modulation of glutamatergic neurotransmission.