Neuronal Hypertrophy Research Articles

TSC2-mTORC1 axis regulates morphogenesis and neurological function of Gli1+ adult-born dentate granule cells.

Aberrant adult hippocampal neurogenesis is implicated in neurological and mood disorders associated with dysregulation of the mechanistic target of rapamycin (mTOR). Understanding how the mTOR pathway shapes the functional development of different subpopulations of adult-born hippocampal neural stem cells will enable insight into potential therapeutic pathways for these disorders. Here we study how loss of TSC2, a regulator of mTOR pathway and a causal gene for Tuberous Sclerosis Complex (TSC), affects dentate gyrus granule cell (dGC) morphogenesis and hippocampal-dependent function. We found that Tsc2KO mice with TSC2 specifically ablated from Gli1+ adult-born neural stem cells showed neuronal hypertrophy, reduced NEUN expression, increased dendritic arborization, premature cellular senescence, and hypervascularization of the dentate gyrus (DG). Neurologically, Tsc2KO mice showed altered exploratory behavior, impaired spatial learning, abnormal contextual recall, and hypersensitivity to kainic acid-induced seizures. Importantly, genetic reduction of Raptor, essential for mTORC1 signaling, rebalanced mTORC1 signaling and mitigated molecular, cellular, and neurological deficits in Tsc2KO mice. This study uncovered functions of TSC2 in Gli1+ adult-born neural stem cells and highlights RAPTOR as a potential therapeutic target for reversing disease features associated with TSC2 mutations.

Hypertension-induced heart failure disrupts cardiac sympathetic innervation.

About 26 million people worldwide live with heart failure (HF), and hypertension is the primary cause in 25% of these cases. Autonomic dysfunction and sympathetic hyperactivity accompany cardiovascular diseases, including HF. However, changes in cardiac sympathetic innervation in HF are not well understood. We hypothesized that cardiac sympathetic innervation is disrupted in hypertension-induced HF. Male and female C57BL6/J mice were infused with Angiotensin II (AngII) for 4 weeks to generate hypertension leading to HF; controls were infused with saline. AngII-treated mice displayed HF phenotype including reduced cardiac function, hypertrophy, and fibrosis. AngII-treated mice also had significantly reduced sympathetic nerve density in the left ventricle, intraventricular septum, and right ventricle. In the left ventricle, the subepicardium remained normally innervated, while the subendocardium was almost devoid of sympathetic nerves. Loss of sympathetic fibers led to loss of norepinephrine content in the left ventricle. Several potential triggers for axon degeneration were tested and ruled out. AngII-treated mice had increased premature ventricular contractions after isoproterenol and caffeine injection. Although HF can induce a cholinergic phenotype and neuronal hypertrophy in stellate ganglia, AngII treatment did not induce a cholinergic phenotype or activation of trophic factors in this study. Cardiac neurons in the left stellate ganglion were significantly smaller in AngII-treated mice, while neurons in the right stellate were unchanged. Our findings show that AngII-induced HF disrupts sympathetic innervation, particularly in the left ventricle. Further investigations are imperative to unveil the mechanisms of denervation in HF and to develop neuromodulatory therapies for patients with autonomic imbalance.

PTEN controls alternative splicing of autism spectrum disorder-associated transcripts in primary neurons.

Phosphatase and tensin homologue (PTEN) is the main antagonist of the phosphatidylinositol-3-kinase (PI3K)/AKT/mTOR signalling pathway and mutated in 10-20% of individuals with autism spectrum disorder (ASD) exhibiting macrocephaly. Hyperactive mTOR signalling is responsible for some aspects during PTEN-ASD progression, e.g. neuronal hypertrophy and -excitability, but PI3K/mTOR-independent processes have additionally been described. There is emerging evidence that PTEN regulates gene transcription, spliceosome formation and pre-mRNA splicing independently of PI3K/mTOR. Altered splicing is a hallmark of brains from individuals with idiopathic and PTEN-ASD, however, molecular mechanisms are yet to be identified. We performed RNA-Seq followed by analysis of altered transcript splicing in Pten-deficient primary cortical mouse neurons, which we compared with published data from PTEN-deficient human neuronal stem cells. This analysis identified that transcripts were globally mis-spliced in a developmentally regulated fashion and cluster in synaptic and gene expression regulatory processes. Strikingly, splicing defects following Pten-deficiency represent a significant number of other known ASD-susceptibility genes. Furthermore, we show that exons with strong 3' splice sites are more frequently mis-spliced under Pten-deficient conditions. Our study indicates that PTEN-ASD is a multifactorial condition involving the dysregulation of other known ASD-susceptibility genes.

PTEN DELETION IN THE ADULT DENTATE GYRUS INDUCES EPILEPSY.

Embryonic and early postnatal promotor-driven deletion of the phosphatase and tensin homolog (PTEN) gene results in neuronal hypertrophy, hyperexcitable circuitry and development of spontaneous seizures in adulthood. We previously documented that focal, vector-mediated PTEN deletion in mature granule cells of adult dentate gyrus triggers dramatic growth of cell bodies, dendrites, and axons, similar to that seen with early postnatal PTEN deletion. Here, we assess the functional consequences of focal, adult PTEN deletion, focusing on its pro-epileptogenic potential. PTEN deletion was accomplished by injecting AAV-Cre either bilaterally or unilaterally into the dentate gyrus of double transgenic PTEN-floxed, ROSA-reporter mice. Hippocampal recording electrodes were implanted for continuous digital EEG with concurrent video recordings in the home cage. Electrographic seizures and epileptiform spikes were assessed manually by two investigators, and corelated with concurrent videos. Spontaneous electrographic and behavioral seizures appeared after focal PTEN deletion in adult dentate granule cells, commencing around 2 months post-AAV-Cre injection. Seizures occurred in the majority of mice with unilateral or bilateral PTEN deletion and led to death in several cases. PTEN-deletion provoked epilepsy was not associated with apparent hippocampal neuron death; supra-granular mossy fiber sprouting was observed in a few mice. In summary, focal, unilateral deletion of PTEN in the adult dentate gyrus suffices to provoke time-dependent emergence of a hyperexcitable circuit generating hippocampus-origin, generalizing spontaneous seizures, providing a novel model for studies of adult-onset epileptogenesis.

Cytoplasmic vacuolization and ectopic formation of perineuronal nets are characteristic pathologies of cytomegalic neurons in tuberous sclerosis.

Cytomegalic neurons, characterized by increased size and a hyperactive mechanistic target of rapamycin complex 1 (mTORC1), are pathognomonic for tuberous sclerosis complex (TSC). To model these neurons, we recently generated a murine Tsc1 conditional knockout model in which Tsc1 deletion in late embryonic radial glia results in neuronal hypertrophy of a subset of isocortical pyramidal neurons. In the current study, we compared the cellular pathology of these cytomegalic neurons to those of the enlarged neurons in human cortical tubers. Neurons from the mice showed unique features, such as cytoplasmic vacuoles associated with Golgi complexes and the ectopic formation of perineuronal nets (PNNs), a feature of inhibitory neurons, rarely present in excitatory cortical neurons. The membranes of these vacuoles were enriched for the plasma membrane proteins CD44, KCC2, and Na+/K+ ATPase, suggesting deficits in Golgi membrane trafficking. These aberrant features in the mouse appeared only after the onset of seizures, probably due to the prolonged seizure activity in the context of constitutive mTORC1 activation. Similar PNNs and cytoplasmic vacuoles were present in the cytomegalic neurons of human cortical tubers. Our findings reveal novel pathological features of Golgi complexes and PNNs in the cytomegalic neurons in TSC.

Reelin differentially shapes dendrite morphology of medial entorhinal cortical ocean and island cells.

The function of medial entorhinal cortex layer II (MECII) excitatory neurons has been recently explored. MECII dysfunction underlies deficits in spatial navigation and working memory. MECII neurons comprise two major excitatory neuronal populations, pyramidal island and stellate ocean cells, in addition to the inhibitory interneurons. Ocean cells express reelin and surround clusters of island cells that lack reelin expression. The influence of reelin expression by ocean cells and interneurons on their own morphological differentiation and that of MECII island cells has remained unknown. To address this, we used a conditional reelin knockout (RelncKO) mouse to induce reelin deficiency postnatally in vitro and in vivo. Reelin deficiency caused dendritic hypertrophy of ocean cells, interneurons and only proximal dendritic compartments of island cells. Ca2+ recording showed that both cell types exhibited an elevation of calcium frequencies in RelncKO, indicating that the hypertrophic effect is related to excessive Ca2+ signalling. Moreover, pharmacological receptor blockade in RelncKO mouse revealed malfunctioning of GABAB, NMDA and AMPA receptors. Collectively, this study emphasizes the significance of reelin in neuronal growth, and its absence results in dendrite hypertrophy of MECII neurons.

Neuroanatomical Signature of the Transition from Normal Cognition to MCI in Parkinson's Disease.

The progression of Parkinson's disease (PD) is often accompanied by cognitive decline. We had previously developed a brain age estimation program utilizing structural MRI data of 949 healthy individuals from publicly available sources. Structural MRI data of 244 PD patients who were cognitively normal at baseline was acquired from the Parkinson Progression Markers Initiative (PPMI). 192 of these showed stable normal cognitive function from baseline out to 5 years (PD-SNC), and the remaining 52 had unstable normal cognition and developed mild cognitive impairment within 5 years (PD-UNC). 105 healthy controls were also included in the analysis as a reference. First, we examined if there were any baseline differences in regional brain structure between PD-UNC and PD-SNC cohorts utilizing the three most widely used atrophy estimation pipelines, i.e., voxel-based morphometry (VBM), deformation-based morphometry and cortical thickness analyses. We then investigated if accelerated brain age estimation with our multivariate regressive machine learning algorithm was different across these groups (HC, PD-SNC, and PD-UNC). As per the VBM analysis, PD-UNC patients demonstrated a noticeable increase in GM volume in the posterior and anterior lobes of the cerebellum, sub-lobar, extra-nuclear, thalamus, and pulvinar regions when compared to PD-SNC at baseline. PD-UNC patients were observed to have significantly older brain age compared to both PD-SNC patients (p=0.009) and healthy controls (p<0.009). The increase in GM volume in the PD-UNC group could potentially indicate an inflammatory or neuronal hypertrophy response, which could serve as a biomarker for future cognitive decline among this population.

Comparative Brain Microanatomical and Neurochemical Alterations Following the Administration of Seven Oral Artemisinin-Based Combination Therapies in Swiss Mice

Over a decade after artemisinin-based combination therapy (ACT) approval as the most preferred anti-malarial drug. Seven ACTs can be sourced as over-the-counter medications in most African pharmacies without prescription. A comparative neurotoxicity of these ACTs was investigated in an in vivo experimental model. Swiss mice numbering 40, weighing 18 - 26 g were allotted to eight groups (n = 5). Group 1 (normal control [NC]), received distilled water 10 mL, while groups 2 to 8 were administered (5.71 mg artesunate+amodiaquine [AA]); (19.29 mg artesunate+mefloquine [AM]); (10.36 mg artesunate+sulfadoxine+pyrimethamine [ASP]); (19.29 mg artesunate+pyronaridine [APy]); (12.5 mg artemisinin+piperaquine [AP]); (15.42 mg dihydroartemisinin+piperaquine [DP]); and (8 mg artemether+lumefantrine [AL]) per kg body weights, respectively orally for 3 days, but for 2 days in group 6. Animals were sacrificed 24 hrs after last administration under ketamine anaesthesia (100 mg/kg, i.p), and excised brains were evaluated for neurochemical and neurohistological alterations. Oxidative stress markers: malondialdehyde and reduced glutathione significantly (p &lt; 0.05) increased as well as antioxidant enzymes glutathione peroxidase, catalase, superoxide dismutase in ACT-administered groups compared to NC. Neurohistology of hippocampal cornu ammonis 1 (CA1) and cerebellum demonstrated vacuolations, neuronal hypertrophy and atrophy pyramidal, and Purkinje neurons. Immunohistochemistry with glial fibrillary acidic protein antibody demonstrated mild to mostly severe astrogliosis in the ACT-administered groups. In conclusion, oxidative stress markers and antioxidants were elevated in the order DP&gt;APy&gt;AP&gt;ASP&gt;AA&gt;AL&gt;AM. Together with the neurohistology, neurotoxicity were in the order DP&gt;ASP&gt;APy&gt;AP&gt;AL&gt;AA&gt;AM particularly in the hippocampus compared to the cerebellum. KEYWORDS: Artemisinin-based combination therapies, Cerebellum, CA1 region of the hippocampus, Neurodegeneration, Oxidative stress.

Impact of Early Life Stress on Neurobiological Vulnerability to Obsessive-Compulsive Disorder: Early Life Stress &amp; Neurobiological OCD Risk

The impact of early life stress on neurobiological vulnerability to obsessive-compulsive disorder (OCD) is a major focus of psychiatric research. Individuals with OCD frequently report that psychosocial stress exacerbates their symptoms, with many attributing the onset of symptoms to stressful life events. However, the exact pathophysiological relationship between stress and OCD is not well understood. Stress has been shown in preclinical studies to have significant effects on cortico-striatal and limbic circuitry, including neuronal atrophy in the frontal cortices, dorsomedial striatum, and hippocampus, as well as neuronal hypertrophy in the dorsolateral striatum and amygdala. These neurobiological effects may contribute to an imbalance between goal-directed and habitual behaviour, which is associated with OCD symptoms. Furthermore, genetic and environmental factors, including early life stress, play an essential role in the advancement of OCD. Understanding gene-environment interactions and pathogenic mechanisms is critical to advancing precision medicine and improving treatment outcomes for OCD and related disorders. This review emphasises the need for additional research into how early life stress interacts with genetic factors to cause the behavioural, cellular, and molecular changes seen in OCD. Integrating global mental health and translational neuroscience approaches shows potential for enhancing our understanding and treatment of OCD and related disorders.

4E-BP1 expression in embryonic postmitotic neurons mitigates mTORC1-induced cortical malformations and behavioral seizure severity but does not prevent epilepsy in mice.

Hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway during neurodevelopment leads to focal cortical malformations associated with intractable seizures. Recent evidence suggests that dysregulated cap-dependent translation downstream of mTORC1 contributes to cytoarchitectural abnormalities and seizure activity. Here, we examined whether reducing cap-dependent translation by expressing a constitutively active form of the translational repressor, 4E-BP1, downstream of mTORC1 would prevent the development of cortical malformations and seizures. 4E-BP1CA was expressed embryonically either in radial glia (neural progenitor cells) that generate cortical layer 2/3 pyramidal neurons or in migrating neurons destined to layer 2/3 using a conditional expression system. In both conditions, 4E-BP1CA expression reduced mTORC1-induced neuronal hypertrophy and alleviated cortical mislamination, but a subset of ectopic neurons persisted in the deep layers and the white matter. Despite the above improvements, 4E-BP1CA expression in radial glia had no effects on seizure frequency and further exacerbated behavioral seizure severity associated with mTORC1 hyperactivation. In contrast, conditional 4E-BP1CA expression in migratory neurons mitigated the severity of behavioral seizures but the seizure frequency remained unchanged. These findings advise against targeting 4E-BPs by 4E-BP1CA expression during embryonic development for seizure prevention and suggest the presence of a development-dependent role for 4E-BPs in mTORC1-induced epilepsy.

Neuropathology and morphometry of dentate nucleus neurons in DYT1 brains: Cerebellar abnormalities in isolated dystonia.

Brain lesions exclusive to dystonia, or specific forms of it, such as isolated dystonia, have been rarely described. While the identification of distinctive intra- or extraneuronal abnormalities in childhood-onset generalized dystonia (DYT1) brains remains lacking, recent stereology-based findings demonstrated hypertrophy of neurons in the substantia nigra (SN) of DYT1-carriers manifesting dystonia (DYT1-manif) versus DYT1-carriers nonmanifesting dystonia (DYT1-nonmanif), and age-matched control subjects (C). Because other brain regions including the cerebellum (CRB) have been implicated in the pathomechanisms of dystonia, we investigated neurons of the dentate nucleus (DN), the "door-out" nucleus of the CRB. We performed systematic neuropathologic assessments and stereology-based measurements of 7 DN from DYT1-carriers (DYT1-DN; 4 DYT1-manif and 3 DYT1-nonmanif), and 5 age-matched control (C-DN) subjects. Data demonstrated larger cell body (+14.1%), nuclear (+10.6%), and nucleolar (+48.3%) volumes of DYT1-DN versus C-DN neurons. No differences in intra- and extracellular pathological indicators (β-amyloid, pTau, α-synuclein, Torsin1A, Negri, Bunina, Hirano, Marinesco, Nissl bodies, Buscaino bodies, granulovacuolar degeneration, or cerebrovascular lesions) were detected in DYT1-DN versus C-DN. Astroglial reactivity (GFAP) and microglial activation (IBA1) were observed in some DYT1-DNs. These novel findings confirm involvement of the DN and CRB in the pathogenesis of DYT1 and perhaps of other forms of isolated dystonia.

Vector-mediated PTEN deletion in the adult dentate gyrus initiates new growth of granule cell bodies and dendrites and expansion of mossy fiber terminal fields that continues for months

Embryonic and early postnatal deletion of the gene phosphatase and tensin homolog (PTEN) results in neuronal hypertrophy, formation of aberrant neural networks and spontaneous seizures. Our previous studies document that deletion of PTEN in mature neurons also causes growth of cortical neuron cell bodies and dendrites, but it is unknown how this growth alters connectivity in mature circuits. Here, we explore consequences of deleting PTEN in a focal area of the dentate gyrus in adult male and female mice. PTEN deletion was accomplished by injecting AAV-Cre unilaterally into the dentate gyrus of double transgenic mice with lox-P sites flanking exon 5 of the PTEN gene and stop/flox tdTomato in the Rosa locus (PTENf/f/RosatdTomato). Focal deletion led to progressive increases in the size of the dentate gyrus at the injection site, enlargement of granule cell bodies, and increases in dendritic length and caliber. Quantitative analysis of dendrites by Golgi staining revealed dramatic increases in spine numbers throughout the proximo-distal extent of the dendritic tree, suggesting that dendritic growth is sufficient to induce new synapse formation by input neurons with intact PTEN expression. Tract tracing of input pathways to the dentate gyrus from the ipsilateral entorhinal cortex and commissural/associational system revealed that laminar specificity of termination of inputs is maintained. Mossy fiber axons from PTEN-deleted granule cells expanded their terminal field in CA3 where PTEN expression was intact and supra-granular mossy fibers developed in some mice. These findings document that persistent activation of mTOR via PTEN deletion in fully mature neurons re-initiates a state of robust cell-intrinsic growth, upending connectional homeostasis in fully mature hippocampal circuits.

Axon terminal hypertrophy of striatal projection neurons with levodopa-induced dyskinesia priming.

A rat model of levodopa-induced dyskinesia (LID) showed enlarged axon terminals of striatal direct pathway neurons in the internal segment of the globus pallidus (GPi) with excessive gamma-aminobutyric acid (GABA) storage in them. Massive GABA release to GPi upon levodopa administration determines the emergence of LID. We examined whether LID and axon terminal hypertrophy gradually develop with repeated levodopa treatment in Parkinsonian rats to examine if the hypertrophy reflects dyskinesia priming. 6-hydroxydopamine-lesioned hemiparkinsonian rats were randomly allocated to receive saline injections (placebo group, 14 days; n = 4), injections of 6 mg/kg levodopa methyl ester combined with 12.5 mg/kg benserazide (levodopa-treated groups, 3-day-treatment; n = 4, 7-day-treatment; n = 4, 14-day-treatment; n = 4), or injections of 6 mg/kg levodopa methyl ester with 12.5 mg/kg benserazide and 1 mg/kg 8-hydroxy-2-(di-n-propylamino)tetralin for 14 days (8-OH-DPAT-treated group; n = 4). We evaluated abnormal involuntary movement (AIM) scores and axon terminals in the GPi. The AIM score increased with levodopa treatment, as did the hypertrophy of axon terminals in the GPi, showing an increased number of synaptic vesicles in hypertrophied terminals. Increased GABA storage in axon terminals of the direct pathway neurons represents the priming process of LID.

Huntingtin Decreases Susceptibility to a Spontaneous Seizure Disorder in FVN/B Mice.

Huntington disease (HD) is an adult-onset neurodegenerative disorder that is caused by a trinucleotide CAG repeat expansion in the HTT gene that codes for the protein huntingtin (HTT in humans or Htt in mice). HTT is a multi-functional, ubiquitously expressed protein that is essential for embryonic survival, normal neurodevelopment, and adult brain function. The ability of wild-type HTT to protect neurons against various forms of death raises the possibility that loss of normal HTT function may worsen disease progression in HD. Huntingtin-lowering therapeutics are being evaluated in clinical trials for HD, but concerns have been raised that decreasing wild-type HTT levels may have adverse effects. Here we show that Htt levels modulate the occurrence of an idiopathic seizure disorder that spontaneously occurs in approximately 28% of FVB/N mice, which we have called FVB/N Seizure Disorder with SUDEP (FSDS). These abnormal FVB/N mice demonstrate the cardinal features of mouse models of epilepsy including spontaneous seizures, astrocytosis, neuronal hypertrophy, upregulation of brain-derived neurotrophic factor (BDNF), and sudden seizure-related death. Interestingly, mice heterozygous for the targeted inactivation of Htt (Htt+/- mice) exhibit an increased frequency of this disorder (71% FSDS phenotype), while over-expression of either full length wild-type HTT in YAC18 mice or full length mutant HTT in YAC128 mice completely prevents it (0% FSDS phenotype). Examination of the mechanism underlying huntingtin's ability to modulate the frequency of this seizure disorder indicated that over-expression of full length HTT can promote neuronal survival following seizures. Overall, our results demonstrate a protective role for huntingtin in this form of epilepsy and provide a plausible explanation for the observation of seizures in the juvenile form of HD, Lopes-Maciel-Rodan syndrome, and Wolf-Hirschhorn syndrome. Adverse effects caused by decreasing huntingtin levels have ramifications for huntingtin-lowering therapies that are being developed to treat HD.

Role of Irvingia gabonensis Seed Extract in Streptozotocin- Induced Hyperglycemia Memory Deficit in Rodents

The study evaluated the role of Irvingia gabonensis as an antidote for memory loss in streptozotocin (STZ) hyperglycemia. Forty-two rats were grouped into six groups of seven rats. A single dose of STZ (60mg/kg) given intraperitoneally was used to induce hyperglycemia and confirmed after 72 hours with over 200mg/dL of fasting blood glucose. Three doses of extract (100, 200, and 300mg/kg) were used to treat groups C, D, and E, while F received 500mg/kg of the standard drug (metformin). Spatial memory was evaluated using Morris Water Maze, while blood was used to estimate biomarkers. The result showed that hyperglycemia significantly reduced memory with decreased latency compared to control (β) in both the acquisition and reversal memory phases (p≤0.05). The extract improved memory in C, D, and E compared to B (ϒ) and in the standard drug (α) at p≤0.05. Group A showed distinct hippocampal layers with CA 1-4 vital for spatial memory, while group B showed cell vacuolations and hypertrophied neurons with large nuclei. Groups C, D, E, and F showed healthier cells than B. A significant reduction was observed in GST, GOT, and GPX in B compared to the treated groups ((P≤0.05). In conclusion, Irvingia gabonensis seed extract may ameliorate hippocampal alterations and improve learning and memory.

Disruption of mTORC1 rescues neuronal overgrowth and synapse function dysregulated by Pten loss.

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of AKT/mTOR signaling pathway. Mutations in PTEN are found in patients with autism, epilepsy, or macrocephaly. In mouse models, Pten loss results in neuronal hypertrophy, hyperexcitability, seizures, and ASD-like behaviors. The underlying molecular mechanisms of these phenotypes are not well delineated. We determined which of the Pten loss-driven aberrations in neuronal form and function are orchestrated by downstream mTOR complex 1 (mTORC1). Rapamycin-mediated inhibition of mTORC1 prevented increase in soma size, migration, spine density, and dendritic overgrowth in Pten knockout dentate gyrus granule neurons. Genetic knockout of Raptor to disrupt mTORC1 complex formation blocked Pten loss-mediated neuronal hypertrophy. Electrophysiological recordings revealed that genetic disruption of mTORC1 rescued Pten loss-mediated increase in excitatory synaptic transmission. We have identified an essential role for mTORC1 in orchestrating Pten loss-driven neuronal hypertrophy and synapse formation.

Probiotics in Experimental Ulcerative Colitis: Mast Cell Density and Neuronal Hypertrophy.

Probiotics such as Lactobacillus and Bifidobacterium are among the supportive treatment methods to achieve effective results in ulcerative colitis. This study was established to investigate the effect of probiotics in experimental ulcerative colitis and to detect changes in mast cell and neuronal structures in this treatment method. A total of 48 adult male rats were used to study the effects of probiotics on ulcerative colitis. The animals were divided into 6 groups as control, experimental colitis, and four probiotic protective groups. Three different bacterial strains were administered to the protective groups individually and in combination by gavage. PGP 9.5 antibody and mast cell tryptase were used for the detection of neuronal structures and mast cells. The number of Schwann cells and ganglia, size measurements of ganglia, and density of mast cells were evaluated. Compared to the control, an increase in the number of mast cells was detected in all groups. Especially the increase in the num- ber of mast cells was found to be statistically significant in combined probiotic administration. In the detection of neuronal structures, a significant increase in the number of Schwann cells and ganglia was detected in groups where probiotics were administered combined and individually. These results suggest that probiotics may play a role in the supporting effect of increasing the number of mast cells and neuronal structures, protecting the intestinal wall. We think that more specific and detailed studies should be conducted to evaluate the protective/therapeutic effect of probiotics in future studies.

Raptor downregulation rescues neuronal phenotypes in mouse models of Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is a neurodevelopmental disorder caused by mutations in the TSC1 or TSC2 genes, which encode proteins that negatively regulate mTOR complex 1 (mTORC1) signaling. Current treatment strategies focus on mTOR inhibition with rapamycin and its derivatives. While effective at improving some aspects of TSC, chronic rapamycin inhibits both mTORC1 and mTORC2 and is associated with systemic side-effects. It is currently unknown which mTOR complex is most relevant for TSC-related brain phenotypes. Here we used genetic strategies to selectively reduce neuronal mTORC1 or mTORC2 activity in mouse models of TSC. We find that reduction of the mTORC1 component Raptor, but not the mTORC2 component Rictor, rebalanced mTOR signaling in Tsc1 knock-out neurons. Raptor reduction was sufficient to improve several TSC-related phenotypes including neuronal hypertrophy, macrocephaly, impaired myelination, network hyperactivity, and premature mortality. Raptor downregulation represents a promising potential therapeutic intervention for the neurological manifestations of TSC.

Cortical neuronal hypertrophy and mTOR pathway activation in CAN regions in SUDEP.

Dysfunctional connectivity and preexisting structural abnormalities of central autonomic network (CAN) regions have been shown on magnetic resonance imaging (MRI) in sudden unexpected death in epilepsy (SUDEP) and may be mechanistically relevant. In a previous postmortem study we reported increased microglia in CAN regions, including the superior temporal gyrus (STG) in SUDEP. In this current study we investigated mammalian target of rapamycin (mTOR) pathway activation and neuronal c-Fos activation in CAN regions in SUDEP compared to control groups. In a series of 59 postmortem cases (SUDEP, n=26; epilepsy controls [EPCs], n=14; and nonepilepsy controls [NECs], n=19), we quantified pS6-240/4, pS6-235/6 (markers of mTOR activation) and c-Fos neuronal densities and labeling index in the STG, anterior cingulate, insula, frontobasal, and pulvinar regions using immunohistochemistry with whole-slide automated image analysis. Significantly more pS6-positive neurons were present in the STG in cases with a history of recent seizures prior to death and also in SUDEP compared to other cause of death groups. No differences were noted for c-Fos neuronal labeling in any region between cause of death groups. Cortical neuronal hypertrophy in the STG was observed in some SUDEP cases and associated with pS6-240/4 expression. pS6-235/6 highlighted neuronal intranuclear inclusions, mainly in SUDEP cases and in the STG region. Neuronal labeling for pS6 in the STG correlated with both seizure activity in the period prior to death and SUDEP. Further investigations are required to explore the significance of this region in terms of autonomic network dysfunction that may increase the vulnerability for SUDEP.

The Duration of Stress Determines Sex Specificities in the Vulnerability to Depression and in the Morphologic Remodeling of Neurons and Microglia.

Stress exposure has been shown to induce a variety of molecular and functional alterations associated with anxiety and depression. Some studies suggest that microglia, the immune cells of the brain, play a significant role in determining neuronal and behavioral responses to chronic stress and also contribute to the development of stress-related psychopathologies. However, little is known about the impact of the duration of stress exposure upon microglia and neurons morphology, particularly considering sex differences. This issue deserves particular investigation, considering that the process of morphologic remodeling of neurons and microglia is usually accompanied by functional changes with behavioral expression. Here, we examine the effects of short and long unpredictable chronic mild stress (uCMS) protocols on behavior, evaluating in parallel microglia and neurons morphology in the dorsal hippocampus (dHIP) and in the nucleus accumbens (NAc), two brain regions involved in the etiology of depression. We report that long-term uCMS induced more behavioral alterations in males, which present anxiety and depression-like phenotypes (anhedonia and helplessness behavior), while females only display anxiety-like behavior. After short-term uCMS, both sexes presented anxiety-like behavior. Microglia cells undergo a process of morphologic adaptation to short-term uCMS, dependent on sex, in the NAc: we observed a hypertrophy in males and an atrophy in females, transient effects that do not persist after long-term uCMS. In the dHIP, the morphologic adaptation of microglia is only observed in females (hypertrophy) and after the protocol of long uCMS. Interestingly, males are more vulnerable to neuronal morphological alterations in a region-specific manner: dendritic atrophy in granule neurons of the dHIP and hypertrophy in the medium spiny neurons of the NAc, both after short- or long-term uCMS. The morphology of neurons in these brain regions were not affected in females. These findings raise the possibility that, by differentially affecting neurons and microglia in dHIP and NAc, chronic stress may contribute for differences in the clinical presentation of stress-related disorders under the control of sex-specific mechanisms.