The Hidden Dangers of Sedentary Living: Insights into Molecular, Cellular, and Systemic Mechanisms.

With the aging of the global population, neurodegenerative diseases are emerging as a major public health issue. The adoption of a less sedentary lifestyle has been shown to have a beneficial effect on cognitive decline, but the molecular mechanisms responsible are less clear. Here we provide a detailed analysis of the complex molecular, cellular, and systemic mechanisms underlying age-related cognitive decline and how lifestyle choices influence these processes. A review of the evidence from animal models, human studies, and postmortem analyses emphasizes the importance of integrating physical exercise with cognitive, multisensory, and motor stimulation as part of a multifaceted approach to mitigating cognitive decline. We highlight the potential of these non-pharmacological interventions to address key aging hallmarks, such as genomic instability, telomere attrition, and neuroinflammation, and underscore the need for comprehensive and personalized strategies to promote cognitive resilience and healthy aging.

Unraveling the Influence of Litter Size, Maternal Care, Exercise, and Aging on Neurobehavioral Plasticity and Dentate Gyrus Microglia Dynamics in Male Rats.

This study explores the multifaceted influence of litter size, maternal care, exercise, and aging on rats' neurobehavioral plasticity and dentate gyrus microglia dynamics. Body weight evolution revealed a progressive increase until maturity, followed by a decline during aging, with larger litters exhibiting lower weights initially. Notably, exercised rats from smaller litters displayed higher body weights during the mature and aged stages. The dentate gyrus volumes showed no significant differences among groups, except for aged sedentary rats from smaller litters, which exhibited a reduction. Maternal care varied significantly based on litter size, with large litter dams showing lower frequencies of caregiving behaviors. Behavioral assays highlighted the detrimental impact of a sedentary lifestyle and reduced maternal care/large litters on spatial memory, mitigated by exercise in aged rats from smaller litters. The microglial dynamics in the layers of dentate gyrus revealed age-related changes modulated by litter size and exercise. Exercise interventions mitigated microgliosis associated with aging, particularly in aged rats. These findings underscore the complex interplay between early-life experiences, exercise, microglial dynamics, and neurobehavioral outcomes during aging.

Genes, inflammatory response, tolerance, and resistance to virus infections in migratory birds, bats, and rodents.

Normally, the host immunological response to viral infection is coordinated to restore homeostasis and protect the individual from possible tissue damage. The two major approaches are adopted by the host to deal with the pathogen: resistance or tolerance. The nature of the responses often differs between species and between individuals of the same species. Resistance includes innate and adaptive immune responses to control virus replication. Disease tolerance relies on the immune response allowing the coexistence of infections in the host with minimal or no clinical signs, while maintaining sufficient viral replication for transmission. Here, we compared the virome of bats, rodents and migratory birds and the molecular mechanisms underlying symptomatic and asymptomatic disease progression. We also explore the influence of the host physiology and environmental influences on RNA virus expression and how it impacts on the whole brain transcriptome of seemingly healthy semipalmated sandpiper (Calidris pusilla) and spotted sandpiper (Actitis macularius). Three time points throughout the year were selected to understand the importance of longitudinal surveys in the characterization of the virome. We finally revisited evidence that upstream and downstream regulation of the inflammatory response is, respectively, associated with resistance and tolerance to viral infections.

Molecular Changes in the Brain of the Wintering Calidris pusilla in the Mangroves of the Amazon River Estuary.

Migrant birds prepare differently to fly north for breeding in the spring and for the flight to lower latitudes during autumn, avoiding the cold and food shortages of the Northern Hemisphere's harsh winter. The molecular events associated with these fundamental stages in the life history of migrants include the differential gene expression in different tissues. Semipalmated sandpipers (Calidris pusilla) are Arctic-breeding shorebirds that migrate to the coast of South America during the non-breeding season. In a previous study, we demonstrated that between the beginning and the end of the wintering period, substantial glial changes and neurogenesis occur in the brain of C. pusilla. These changes follow the epic journey of the autumn migration when a 5-day non-stop transatlantic flight towards the coast of South America and the subsequent preparation for the long-distance flight of the spring migration takes place. Here, we tested the hypothesis that the differential gene expressions observed in the brains of individuals captured in the autumn and spring windows are consistent with the previously described cellular changes. We searched for differential gene expressions in the brain of the semipalmated sandpiper, of recently arrived birds (RA) from the autumnal migration, and that of individuals in the premigratory period (PM) in the spring. All individuals were collected in the tropical coastal of northern Brazil in the mangrove region of the Amazon River estuary. We generated a de novo neurotranscriptome for C. pusilla individuals and compared the gene expressions across libraries. To that end, we mapped an RNA-Seq that reads to the C. pusilla neurotranscriptome in four brain samples of each group and found that the differential gene expressions in newly arrived and premigratory birds were related with neurogenesis, metabolic pathways (ketone body biosynthetic and the catabolic and lipid biosynthetic processes), and glial changes (astrocyte-dopaminergic neuron signaling, astrocyte differentiation, astrocyte cell migration, and astrocyte activation involved in immune response), as well as genes related to the immune response to virus infections (Type I Interferons), inflammatory cytokines (IL-6, IL-1ß, TNF, and NF-κB), NLRP3 inflammasome, anti-inflammatory cytokines (IL-10), and cell death pathways (pyroptosis- and caspase-related changes).

Behavioral and Neuropathological Changes After Toxoplasma gondii Ocular Conjunctival Infection in BALB/c Mice.

Ocular infection with Toxoplasma gondii causes toxoplasmosis in mice. However, following ocular infection with tachyzoites, the cause of the accompanying progressive changes in hippocampal-dependent tasks, and their relationship with the morphology and number of microglia, is less well understood. Here, in 6-month-old, female BALB/c mice, 5 µl of a suspension containing 48.5 × 106 tachyzoites/ml was introduced into the conjunctival sac; control received an equal volume of saline. Before and after instillation, all mice were subject to an olfactory discrimination (OD) test, using predator (cat) feces, and to an open-field (OF) task. After the behavioral tests, the animals were culled at either 22 or 44 days post-instillation (dpi), and the brains and retinas were dissected and processed for immunohistochemistry. The total number of Iba-1-immunolabeled microglia in the molecular layer of the dentate gyrus was estimated, and three-dimensional reconstructions of the cells were evaluated. Immobility was increased in the infected group at 12, 22, and 43 dpi, but the greatest immobility was observed at 22 dpi and was associated with reduced line crossing in the OF and distance traveled. In the OD test, infected animals spent more time in the compartment with feline fecal material at 14 and at 43 dpi. No OD changes were observed in the control group. The number of microglia was increased at 22 dpi but returned to control levels by 44 dpi. These changes were associated with the differentiation of T. gondii tachyzoites into bradyzoite-enclosed cysts within the brain and retina. Thus, infection of mice with T. gondii alters exploratory behavior, gives rise to a loss in predator's odor avoidance from 2 weeks after infection, increased microglia number, and altered their morphology in the molecular layer of the dentate gyrus.

Acquired acoria and iris pearls in leprosy: Case report.

PURPOSE: To describe a case of a patient presenting with acquired acoria and iris pearls, a rare eye manifestation and pathognomonic finding for leprosy; to reinforce clinical, histopathological, and therapeutic aspects of ocular involvement in leprosy. METHODS: Case report. CASE DESCRIPTION: A 62-year-old male presenting with acquired acoria and iris pearls in both eyes due to leprosy also had anterior uveitis and cataract. Histopathological diagnosis of iris pearls was confirmed by the presence of Hansen's bacilli. Ophthalmological examination revealed improvement of the visual acuity after iridectomy and extracapsular cataract extraction. CONCLUSIONS: To our knowledge, this is the first reported case of acquired acoria in a leprosy patient. It led to impaired vision and reversible blindness. Proper diagnosis and ophthalmological treatment of patients with these conditions are essential for the maintenance of a good quality of life.

Plasticity in the hippocampal formation of shorebirds during the wintering period: Stereological analysis of parvalbumin neurons in Actitis macularius.

The number of parvalbumin neurons can be modified by social, multisensory, and cognitive stimuli in both mammals and birds, but nothing is known about their plasticity in long-distance migratory shorebirds. Here, in the spotted sandpiper (Actitis macularius), we investigated the plasticity of parvalbumin neurons of two brain areas during this species' wintering period at a lower latitude. We compared individuals in a nonmigratory rest period (November-January) and premigration (May-July) period. We used parvalbumin as a marker for counting a subpopulation of inhibitory neurons in the hippocampal formation (HF), with the magnocellular nucleus of the tectal isthmus (IMC) as a control area. Because the HF is involved in learning and memory and social interaction and the IMC is essential for control of head, neck, and eye movements, we hypothesized that parvalbumin neurons would increase in the HF and remain unchanged in the IMC. We used an optical fractionator to estimate cell numbers. Compared with the nonmigratory rest birds, parvalbumin neuron count estimates in the premigration birds increased significantly in the HF but remained unchanged in IMC. We suggest that the greater number of parvalbuminergic neurons in the HF of A. macularius in the premigration period represents adaptive circuitry changes involved in the migration back to reproductive niches in the northern hemisphere.

Unwanted Exacerbation of the Immune Response in Neurodegenerative Disease: A Time to Review the Impact.

The COVID-19 pandemic imposed a series of behavioral changes that resulted in increased social isolation and a more sedentary life for many across all age groups, but, above all, for the elderly population who are the most vulnerable to infections and chronic neurodegenerative diseases. Systemic inflammatory responses are known to accelerate neurodegenerative disease progression, which leads to permanent damage, loss of brain function, and the loss of autonomy for many aged people. During the COVID-19 pandemic, a spectrum of inflammatory responses was generated in affected individuals, and it is expected that the elderly patients with chronic neurodegenerative diseases who survived SARSCoV-2 infection, it will be found, sooner or later, that there is a worsening of their neurodegenerative conditions. Using mouse prion disease as a model for chronic neurodegeneration, we review the effects of social isolation, sedentary living, and viral infection on the disease progression with a focus on sickness behavior and on the responses of microglia and astrocytes. Focusing on aging, we discuss the cellular and molecular mechanisms related to immunosenescence in chronic neurodegenerative diseases and how infections may accelerate their progression.

Microglial Metamorphosis in Three Dimensions in Virus Limbic Encephalitis: An Unbiased Pictorial Representation Based on a Stereological Sampling Approach of Surveillant and Reactive Microglia.

Microglia influence pathological progression in neurological diseases, reacting to insults by expressing multiple morphofunctional phenotypes. However, the complete morphological spectrum of reactive microglia, as revealed by three-dimensional microscopic reconstruction, has not been detailed in virus limbic encephalitis. Here, using an anatomical series of brain sections, we expanded on an earlier Piry arbovirus encephalitis study to include CA1/CA2 and assessed the morphological response of homeostatic and reactive microglia at eight days post-infection. Hierarchical cluster and linear discriminant function analyses of multimodal morphometric features distinguished microglial morphology between infected animals and controls. For a broad representation of the spectrum of microglial morphology in each defined cluster, we chose representative cells of homeostatic and reactive microglia, using the sum of the distances of each cell in relation to all the others. Based on multivariate analysis, reactive microglia of infected animals showed more complex trees and thicker branches, covering a larger volume of tissue than in control animals. This approach offers a reliable representation of microglia dispersion in the Euclidean space, revealing the morphological kaleidoscope of surveillant and reactive microglia morphotypes. Because form precedes function in nature, our findings offer a starting point for research using integrative methods to understand microglia form and function.

Microglial Morphology Across Distantly Related Species: Phylogenetic, Environmental and Age Influences on Microglia Reactivity and Surveillance States.

Microglial immunosurveillance of the brain parenchyma to detect local perturbations in homeostasis, in all species, results in the adoption of a spectrum of morphological changes that reflect functional adaptations. Here, we review the contribution of these changes in microglia morphology in distantly related species, in homeostatic and non-homeostatic conditions, with three principal goals (1): to review the phylogenetic influences on the morphological diversity of microglia during homeostasis (2); to explore the impact of homeostatic perturbations (Dengue virus challenge) in distantly related species (Mus musculus and Callithrix penicillata) as a proxy for the differential immune response in small and large brains; and (3) to examine the influences of environmental enrichment and aging on the plasticity of the microglial morphological response following an immunological challenge (neurotropic arbovirus infection). Our findings reveal that the differences in microglia morphology across distantly related species under homeostatic condition cannot be attributed to the phylogenetic origin of the species. However, large and small brains, under similar non-homeostatic conditions, display differential microglial morphological responses, and we argue that age and environment interact to affect the microglia morphology after an immunological challenge; in particular, mice living in an enriched environment exhibit a more efficient immune response to the virus resulting in earlier removal of the virus and earlier return to the homeostatic morphological phenotype of microglia than it is observed in sedentary mice.

Sedentary Life and Reduced Mastication Impair Spatial Learning and Memory and Differentially Affect Dentate Gyrus Astrocyte Subtypes in the Aged Mice.

To explore the impact of reduced mastication and a sedentary lifestyle on spatial learning and memory in the aged mice, as well as on the morphology of astrocytes in the molecular layer of dentate gyrus (MolDG), different masticatory regimens were imposed. Control mice received a pellet-type hard diet, while the reduced masticatory activity group received a pellet diet followed by a powdered diet, and the masticatory rehabilitation group received a pellet diet, followed by powder diet and then a pellet again. To mimic sedentary or active lifestyles, mice were housed in an impoverished environment of standard cages or in an enriched environment. The Morris Water Maze (MWM) test showed that masticatory-deprived group, regardless of environment, was not able to learn and remember the hidden platform location, but masticatory rehabilitation combined with enriched environment recovered such disabilities. Microscopic three-dimensional reconstructions of 1,800 glial fibrillary acidic protein (GFAP)-immunolabeled astrocytes from the external third of the MolDG were generated using a stereological systematic and random sampling approach. Hierarchical cluster analysis allowed the characterization into two main groups of astrocytes with greater and lower morphological complexities, respectively, AST1 and AST2. When compared to compared to the hard diet group subjected to impoverished environment, deprived animals maintained in the same environment for 6 months showed remarkable shrinkage of astrocyte branches. However, the long-term environmental enrichment (18-month-old) applied to the deprived group reversed the shrinkage effect, with significant increase in the morphological complexity of AST1 and AST2, when in an impoverished or enriched environment. During housing under enriched environment, complexity of branches of AST1 and AST2 was reduced by the powder diet (pellet followed by powder regimes) in young but not in old mice, where it was reversed by pellet diet (pellet followed by powder and pellet regime again). The same was not true for mice housed under impoverished environment. Interestingly, we were unable to find any correlation between MWM data and astrocyte morphological changes. Our findings indicate that both young and aged mice subjected to environmental enrichment, and under normal or rehabilitated masticatory activity, preserve spatial learning and memory. Nonetheless, data suggest that an impoverished environment and reduced mastication synergize to aggravate age-related cognitive decline; however, the association with morphological diversity of AST1 and AST2 at the MolDG requires further investigation.

Shorebirds' Longer Migratory Distances Are Associated With Larger ADCYAP1 Microsatellites and Greater Morphological Complexity of Hippocampal Astrocytes.

For the epic journey of autumn migration, long-distance migratory birds use innate and learned information and follow strict schedules imposed by genetic and epigenetic mechanisms, the details of which remain largely unknown. In addition, bird migration requires integrated action of different multisensory systems for learning and memory, and the hippocampus appears to be the integration center for this task. In previous studies we found that contrasting long-distance migratory flights differentially affected the morphological complexity of two types of hippocampus astrocytes. Recently, a significant association was found between the latitude of the reproductive site and the size of the ADCYAP1 allele in long distance migratory birds. We tested for correlations between astrocyte morphological complexity, migratory distances, and size of the ADCYAP1 allele in three long-distance migrant species of shorebird and one non-migrant. Significant differences among species were found in the number and morphological complexity of the astrocytes, as well as in the size of the microsatellites of the ADCYAP1 gene. We found significant associations between the size of the ADCYAP1 microsatellites, the migratory distances, and the degree of morphological complexity of the astrocytes. We suggest that associations between astrocyte number and morphological complexity, ADCYAP1 microsatellite size, and migratory behavior may be part of the adaptive response to the migratory process of shorebirds.

BALB/c female subjected to valproic acid during gestational period exhibited greater microglial and behavioral changes than male mice: A significant contra intuitive result.

Most animal model studies of autism spectrum disorders (ASD) were performed in males. Thus, little is known about the mechanisms underlying disease progression in females. Here, we searched for potential influences of sex and environment on gestational valproic acid-induced behavioral abnormalities using hippocampal-dependent tasks, and on number and morphometry of microglia of the molecular layer of the dentate gyrus (Mol-DG). We compared male and females BALB/c control mice with BALB/c mice gestationally exposed to VPA with regards to exploratory activity and risk assessment in novel environments. Pregnant females and males on gestational day 12.5 received VPA in saline (600 mg/kg body weight) or an equal volume of saline by gavage. After weaning, female and male offspring were housed separately either in standard laboratory cages (SE) or enriched cages (EE). At 5 months of age, these mice underwent behavioral testing and had their brains processed for microglia IBA1 immunolabeling. Compared with control mice, VPA-exposed mice exhibited abnormal behavior in exploring novel environments and assessing risk, and these effects were significantly greater in females than in males and less intense among mice from enriched cages. Three-way ANOVA revealed that environment, sex and valproic acid conditions interacted and altered the behavior results. Microglia number and volume of the Mol-DG were significantly higher in VPA-exposed groups raised in standard cages. The results of counting the intersects of microglia branching on Sholl's circles analyzed with permutational MANOVA, demonstrated that in comparison with males, there was a greater reduction in the number of intersections in females raised in standard cages. These findings suggest that the increased microglia and morphological changes might be associated with behavioral dysfunction in ASD. Moreover, the somatomotor and cognitive stimulation of environmental enrichment started at weaning may be beneficial for reducing behavioral abnormalities and reduction of microglia response in adulthood.

Contrasting migratory journeys and changes in hippocampal astrocyte morphology in shorebirds.

Semipalmated sandpiper (Calidris pusilla) migration to the Southern Hemisphere includes a 5-day non-stop flight over the Atlantic Ocean, whereas semipalmated plover (Charadrius semipalmatus) migration, to the same area, is largely over land, with stopovers for feeding and rest. We compared the number and 3D morphology of hippocampal astrocytes of Ch. semipalmatus before and after autumnal migration with those of C. pusilla to test the hypothesis that the contrasting migratory flights of these species could differentially shape hippocampal astrocyte number and morphology. We captured individuals from both species in the Bay of Fundy (Canada) and in the coastal region of Bragança (Brazil) and processed their brains for selective GFAP immunolabeling of astrocytes. Hierarchical cluster analysis of astrocyte morphological features distinguished two families of morphological phenotypes, named type I and type II, which were differentially affected after migratory flights. Stereological counts of hippocampal astrocytes demonstrated that the number of astrocytes decreased significantly in C. pusilla, but did not change in Ch. semipalmatus. In addition, C. pusilla and Ch. semipalmatus hippocampal astrocyte morphological features were differentially affected after autumnal migration. We evaluated whether astrocyte morphometric variables were influenced by phylogenetic differences between C. pusilla and Ch. semipalmatus, using phylogenetically independent contrast approach, and phylogenetic trees generated by nuclear and mitochondrial markers. Our findings suggest that phylogenetic differences do not explain the results and that contrasting long-distance migratory flights shape plasticity of type I and type II astrocytes in different ways, which may imply distinct physiological roles for these cells.

Lateral septum microglial changes and behavioral abnormalities of mice exposed to valproic acid during the prenatal period.

Most animal model studies of autism spectrum disorder (ASD) have been performed in males, which may be a reflex of the 3-times higher prevalence in boys than in girls. For this reason, little is known about the mechanisms underlying disease progression in females, and nothing is known about potential associations between microglial changes in the lateral septum (LS) and adult female cognition. Prenatal exposure to valproic acid (VPA) in mice has been widely used as an experimental model of autism-like behaviors associated with cellular changes. However, no study has reported the influence of VPA exposure in utero and its consequences on limbic system-dependent tasks or the microglial response in the LS in adult female mice. We compared the exploratory activity and risk assessment in novel environments of BALB/c control mice to mice exposed in utero to VPA and estimated the total number of microglia in the LS using an optical fractionator. On day 12.5 of pregnancy, females received diluted VPA or saline by gavage. After weaning, VPA exposed or control pups were separately housed in standard laboratory cages. At 5 months of age, all mice underwent behavioral testing and their brain sections were immunolabelled using IBA-1 antibody. In the open field test, VPA group showed a greater distance traveled, which was accompanied by less immobility, less time spent on the periphery and a greater number, crossed lines. Similar findings were found in the elevated plus maze test, where VPA mice traveled greater distances, immobility was significantly higher than that of control and VPA group spent less time on the closed arms of apparatus. Stereological analysis demonstrated higher microglial total number and density in the LS of VPA mice, as the cell count was greater, but the volume was similar. Therefore, we suggest that an increase in microglia in the LS may be part of the cellular changes associated with behavioral dysfunction in the VPA model of ASD.

Long-term environmental enrichment reduces microglia morphological diversity of the molecular layer of dentate gyrus.

We investigated long-term environmental influences on morphology of microglia from the outer and middle thirds of molecular layer of the dentate gyrus (MolDG), and on microglia from dorsal and ventral dentate gyrus molecular layer. We also estimated the total number of MolDG microglia using stereology. For this purpose, microglia of the molecular layer of the dentate gyrus of 20-month-old female Swiss albino mice, housed from 21st postnatal day onwards, in the impoverished environment of the standard laboratory cages (SEA), or in a cage with an enriched environment (EEA), were reconstructed microscopically in three dimensions and compared with each other and with microglia of 6-month-old female Swiss albino mice, also housed from weaning onwards in an enriched cage (EEY). All mice had their brains sectioned and processed for immunolabeling for IBA-1, a selective microglia marker. Random and systematic microglia samples were reconstructed in three dimensions and classified morphologically using hierarchical cluster analysis, followed by discriminant function analysis. SEA and EEY showed two morphological phenotypes of microglia in both the outer and middle thirds of MolDG. EEA mice showed such a reduction in the morphological diversity of microglia that essentially a single morphotype was found. EEA mouse microglia showed an intermediate morphological complexity between types I and II SE microglia. We suggest that type I and type II microglia in SE mice may have different physiological roles and that long-term EE may be associated with adaptive responses of microglial phenotypes to somatomotor and cognitive stimuli.

Changes in hippocampal astrocyte morphology of Ruddy turnstone (Arenaria interpres) during the wintering period at the mangroves of Amazon River estuary.

Astrocytes are essential for lipid neuronal metabolism in long-distance uninterrupted migratory flights, when glucose is not available as the main source of energy. We previously demonstrated in Calidris pusilla that after uninterrupted 5 days transatlantic flight, astrocytes shrink and reduce its number in the hippocampal formation. Here we shifted our attention to the wintering period and tested the hypothesis that hippocampal astrocyte morphology of A interpres will change as the wintering period progresses towards the premigration window. To that end we used Arenaria interpres, which also crosses the Atlantic Ocean and reaches the mangroves of the Amazon River estuary for wintering. Birds were captured in September/October (closer to the arrival in the coast of Bragança, Para, Brazil for wintering) and in April/May (closer to the departure towards the breeding sites) and had their brains processed for selective GFAP-astrocyte immunolabeling. Three-dimensional reconstructions of the immunostained astrocytes were performed and morphological classification was done based on hierarchical cluster and discriminant analysis of multimodal morphometric features. We found two morphological phenotypes of astrocytes in the newcomers which differentially increased its morphological complexities as wintering period progresses towards the pre-migration window. Taken together, our findings demonstrate that the long-distance non-stop flight and wintering period differentially affected the two astrocytes morphotypes, suggesting distinct physiological roles for these cells. We suggest that morphological changes during the wintering period, may be part of the adaptive plasticity of the local hippocampal circuits of A. interpres in preparation for the long journey back to their breeding sites in the north hemisphere.

Environmental Enrichment Improved Learning and Memory, Increased Telencephalic Cell Proliferation, and Induced Differential Gene Expression in Colossoma macropomum.

Fish use spatial cognition based on allocentric cues to navigate, but little is known about how environmental enrichment (EE) affects learning and memory in correlation with hematological changes or gene expression in the fish brain. Here we investigated these questions in Colossoma macropomum (Teleostei). Fish were housed for 192 days in either EE or in an impoverished environment (IE) aquarium. EE contained toys, natural plants, and a 12-h/day water stream for voluntary exercise, whereas IE had no toys, plants, or water stream. A third plus maze aquarium was used for spatial and object recognition tests. Compared with IE, the EE fish showed greater learning rates, body length, and body weight. After behavioral tests, whole brain tissue was taken, stored in RNA-later, and then homogenized for DNA sequencing after conversion of isolated RNA. To compare read mapping and gene expression profiles across libraries for neurotranscriptome differential expression, we mapped back RNA-seq reads to the C. macropomum de novo assembled transcriptome. The results showed significant differential behavior, cell counts and gene expression in EE and IE individuals. As compared with IE, we found a greater number of cells in the telencephalon of individuals maintained in EE but no significant difference in the tectum opticum, suggesting differential plasticity in these areas. A total of 107,669 transcripts were found that ultimately yielded 64 differentially expressed transcripts between IE and EE brains. Another group of adult fish growing in aquaculture conditions were either subjected to exercise using running water flow or maintained sedentary. Flow cytometry analysis of peripheral blood showed a significantly higher density of lymphocytes, and platelets but no significant differences in erythrocytes and granulocytes. Thus, under the influence of contrasting environments, our findings showed differential changes at the behavioral, cellular, and molecular levels. We propose that the differential expression of selected transcripts, number of telencephalic cell counts, learning and memory performance, and selective hematological cell changes may be part of Teleostei adaptive physiological responses triggered by EE visuospatial and somatomotor stimulation. Our findings suggest abundant differential gene expression changes depending on environment and provide a basis for exploring gene regulation mechanisms under EE in C. macropomum.

Limbic Encephalitis Brain Damage Induced by Cocal Virus in Adult Mice Is Reduced by Environmental Enrichment: Neuropathological and Behavioral Studies.

We previously demonstrated, using the Piry virus model, that environmental enrichment promotes higher T-cell infiltration, fewer microglial changes, and faster central nervous system (CNS) virus clearance in adult mice. However, little is known about disease progression, behavioral changes, CNS cytokine concentration, and neuropathology in limbic encephalitis in experimental models. Using Cocal virus, we infected C57Bl6 adult mice and studied the neuroanatomical distribution of viral antigens in correlation with the microglial morphological response, measured the CNS cytokine concentration, and assessed behavioral changes. C57Bl6 adult mice were maintained in an impoverished environment (IE) or enriched environment (EE) for four months and then subjected to the open field test. Afterwards, an equal volume of normal or virus-infected brain homogenate was nasally instilled. The brains were processed to detect viral antigens and microglial morphological changes using selective immunolabeling. We demonstrated earlier significant weight loss and higher mortality in IE mice. Additionally, behavioral analysis revealed a significant influence of the environment on locomotor and exploratory activity that was associated with less neuroinvasion and a reduced microglial response. Thus, environmental enrichment was associated with a more effective immune response in a mouse model of limbic encephalitis, allowing faster viral clearance/decreased viral dissemination, reduced disease progression, and less CNS damage.

Stereological Analysis of Early Gene Expression Using Egr-1 Immunolabeling After Spreading Depression in the Rat Somatosensory Cortex.

Early growth response-1 (Egr-1), defined as a zinc finger transcription factor, is an upstream master switch of the inflammatory response, and its expression can be used to investigate the spatial and temporal extent of inflammatory changes in the brain. Cortical spreading depression (CSD) is characterized as a slowly propagating (2-5 mm/min) depolarization wave through neurons and astrocytes in humans that contributes to migraines and possibly to other brain pathologies. In rodents, CSD can be induced experimentally, which involves unilateral depolarization that is associated with microglial and astrocyte responses. The impact of CSD on structures beyond the affected hemisphere has not been explored. Here, we used an optical fractionator method to investigate potential correlations between the number of and period of the eletrophysiologic record of CSD phenomena and Egr-1 expression in ipsilateral and contralateral hemispheres. CSD was elicited by the restricted application of a 2% KCl solution over the left premotor cortex. Electrophysiological events were recorded using a pair of Ag/AgCl agar-Ringer electrodes for 2 or 6 h. An optical fractionator was applied to count the Egr-1 positive cells. We found that CSD increased Egr-1 expression in a time- and event-dependent manner in the ipsilateral/left hemisphere. Although CSD did not cross the midline, multiple CSD inductions were associated with an increased number of Egr-1 positive cells in the contralateral/right hemisphere. Thus, repeated CSD waves may have far reaching effects that are more global than previously considered possible. The mechanism of contralateral expression is unknown, but we speculate that callosal projections from the depolarized hemisphere may be related to this phenomenon.