RESUMO
ABSTRACTObjectives: The aim of this study was thus to evaluate the effect of Cr supplementation on morphological changes and expression of pro-inflammatory cytokines in the hippocampus and on developmental parameters. Methods: Male Wistar rat pups were submitted to an experimental model of CP. Cr was administered via gavage from the 21st to the 28th postnatal day, and in water after the 28th, until the end of the experiment. Body weight (BW), food consumption (FC), muscle strength, and locomotion were evaluated. Expression of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) were assessed in the hippocampus by quantitative real-time polymerase chain reaction. Iba1 immunoreactivity was assessed by immunocytochemistry in the hippocampal hilus. Results: Experimental CP caused increased density and activation of microglial cells, and overexpression of IL-6. The rats with CP also presented abnormal BW development and impairment of strength and locomotion. Cr supplementation was able to reverse the overexpression of IL-6 in the hippocampus and mitigate the impairments observed in BW, strength, and locomotion. Discussion: Future studies should evaluate other neurobiological characteristics, including changes in neural precursor cells and other cytokines, both pro- and anti-inflammatory.
Assuntos
Paralisia Cerebral , Células-Tronco Neurais , Ratos , Animais , Masculino , Interleucina-6/genética , Interleucina-6/metabolismo , Creatina/metabolismo , Ratos Wistar , Hipocampo/metabolismo , Citocinas/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Microglia/metabolismo , Modelos Teóricos , Suplementos NutricionaisRESUMO
Early life stress induced by maternal separation (MS) causes neuroendocrine, behavioral, and metabolic alterations that are related to gut dysbiosis. MS also increases microglial activation and decreases neurogenesis. Whether these long-term alterations are maintained or worsened in the absence of gut microbiota remains unknown. Hence, this study evaluated the effect of MS symptomatology after antibiotic-induced microbiota depletion (AIMD) in adult rats. Control and maternally separated (3 h per day from postnatal day one to 14, MS180) rats were subjected to AIMD for one month, then assessed for behavioral, metabolic, and neuroendocrine responses. Effects of MS180 and AIMD on gut microbiota were confirmed by qPCR. The data indicate that MS180 caused a passive coping strategy in the forced swimming test and decreased hippocampal neurogenesis. In addition, fasting glucose, cholesterol, and corticosterone levels increased, which correlated with a decrease in Lactobacillus spp counts in the caecum. AIMD also increased immobility in the forced swimming test, decreased hippocampal neurogenesis, and augmented corticosterone levels. However, it had no effects on glucose homeostasis or plasma lipid levels. Furthermore, the MS180-induced long-term effects on behavior and neurogenesis were not affected by microbiota depletion. Meanwhile, the metabolic imbalance was partially reversed in MS180 + AIMD rats. These results show that AIMD mimics the behavioral consequences of MS180 but may prevent metabolic imbalance, suggesting that gut dysbiosis could be part of the mechanisms involved in the maintenance of the long-term consequences of early life stress.
Assuntos
Microbiota , Estresse Psicológico , Animais , Ratos , Antibacterianos/farmacologia , Comportamento Animal/fisiologia , Corticosterona , Disbiose , Glucose/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Privação Materna , Sistema Hipófise-Suprarrenal/metabolismoRESUMO
Axon initial segments (AIS) of dentate granule cells in the hippocampus exhibit prominent spines (AISS) during early development that are associated with microglial contacts. In the present study, we investigated whether developmental changes in AISS could be modified by early-life stress (ELS), specifically neonatal maternal separation (MS), through stress hormones and microglial activation and examined the potential behavioural consequences. We examined AISS at postnatal day (PND)5, 15 and 50, using Golgi-Cox staining and anatomical analysis. Neurone-microglial interaction was assessed using antibodies against ankyrin-G, PSD-95 and Iba1, for AIS, AISS and microglia visualisation, respectively, in normally reared and neonatal maternally separated male and female rats. We observed a higher density of AISS in ELS rats at both PND15 and PND50 compared to controls. Effects were more pronounced in females than males. AIS-associated microglia in ELS rats showed a hyper-ramified morphology and less co-localisation with PSD-95 compared to controls at PND15. ELS-associated alteration in microglial morphology and synaptic pruning was mimicked by treatment of acute hippocampal slices of normally reared rats with vasopressin. ELS rats exhibited increased freezing behaviour during auditory fear memory testing, which was more pronounced in female subjects and corresponded with increased Fos expression in dorsal and ventral dentate granule cells. Thus, microglial synaptic pruning in dentate AIS of hippocampus is influenced by ELS, with demonstrable sex bias regarding its anatomical characteristics and subsequent fear-induced defensive behaviours.
Assuntos
Giro Denteado/fisiologia , Medo/psicologia , Microglia/fisiologia , Plasticidade Neuronal/fisiologia , Estresse Psicológico , Envelhecimento/psicologia , Animais , Animais Recém-Nascidos , Segmento Inicial do Axônio/fisiologia , Espinhas Dendríticas/fisiologia , Giro Denteado/citologia , Feminino , Masculino , Privação Materna , Microglia/citologia , Gravidez , Ratos , Ratos Wistar , Caracteres Sexuais , Estresse Psicológico/fisiopatologia , Estresse Psicológico/psicologiaRESUMO
In rodents, daily maternal separation for 180â¯min (MS180) during the first weeks of life affects hippocampal granule cell neurogenesis. Development of the cerebellum granule cell layer also occurs during the first weeks of life. However, whether MS180 affects this neurogenic niche remains unknown. To study this, we evaluated the immediate and long term effect of MS180 on granule cell survival within the cerebellum. Pups were injected twice at an 8-hour interval at PND (postnatal day) 5 with bromodeoxyuridine (BrdU, 50â¯mg/kg) and were sacrificed ten days later (PND15) or allowed to survive into adulthood (PND60). We observed a higher density of BrdU-positive cells in the cerebellar foliae (pâ¯<â¯0.05) of MS180 pups at PND15. This increase was also observed in both, cerebellar foliae and fissures (pâ¯<â¯0.05) at PND60. Triple immunofluorescence staining against BrdU, NeuN (a marker of mature neurons), and GFAP (a marker of mature glia), revealed that BrdUâ¯+â¯cells labeled at PND5 co-localized with NeuN but not with GFAP, indicating that they were mature neurons. MS180 did not affect baseline corticosterone levels at PND15 but significantly increased adult corticosterone levels (pâ¯<â¯0.05). In conclusion, MS180 increased cell survival in the granular layer of cerebellar foliae and fissures and resulted in further integration of the cells into adult circuits. These effects occurred without early alterations of basal corticosterone by MS180. Our results indicate that early-life stress induces a permanent increase in cerebellar neurogenesis.
Assuntos
Cerebelo/fisiologia , Grânulos Citoplasmáticos/efeitos dos fármacos , Estresse Psicológico/fisiopatologia , Acetatos/farmacologia , Animais , Animais Recém-Nascidos , Bromodesoxiuridina/farmacologia , Contagem de Células , Corticosterona/metabolismo , Grânulos Citoplasmáticos/patologia , Feminino , Hipocampo/metabolismo , Sistema Hipotálamo-Hipofisário , Masculino , Privação Materna , Morfolinas/farmacologia , Neurogênese/fisiologia , Neurônios/efeitos dos fármacos , Sistema Hipófise-Suprarrenal , Ratos , Ratos Sprague-DawleyRESUMO
Early life stress (ELS) affects hippocampal neurogenesis, increases depressive-like behavior, and causes mild metabolic imbalance in early adulthood (2 months). However, whether these effects worsen in mid life remains unclear. To test whether age-dependent effects of ELS on hippocampal neurogenesis are related to deficient hypothalamic-pituitary-adrenal (HPA) axis feedback that causes increased comorbidity of depression and metabolic risk, we evaluated the effects of periodic maternal separation (MS180) in young (4-months-old) and middle-aged (10-months-old) adult rats. MS180 caused more severe depressive-like behavior in middle-aged adults than in young animals. There were no behavioral phenotypic differences between young MS180 and control middle-aged groups. MS180 similarly affected glucose tolerance, increased fasting corticosterone, insulin, and the quantitative insulin sensitivity check index (QUICKI) at both ages. However, middle-aged adult MS180 rats showed more severe age-induced obesity (>40% BW) than controls (>22% BW). MS180 differentially affected dorsal and ventral neurogenesis. In young adults, MS180 animals only showed a decrease in dorsal hippocampal neurogenesis as compared to their age-matched counterparts. In contrast, at 10 months of age, MS180 caused a similar decrease in both dorsal and ventral hippocampal neurogenesis as compared to age-matched controls, and a more severe decrease as compared to young animals. Taken together, our data indicate that MS180 animals show an early onset of age-induced alterations on depression and metabolic risk, and these effects relate to alterations in hippocampal neurogenesis.
Assuntos
Depressão , Neurogênese , Estresse Psicológico , Animais , Feminino , Masculino , Gravidez , Ratos , Fatores Etários , Comportamento Animal/fisiologia , Corticosterona/análise , Depressão/metabolismo , Depressão/fisiopatologia , Modelos Animais de Doenças , Proteína Duplacortina , Glucocorticoides/análise , Hipocampo/metabolismo , Sistema Hipotálamo-Hipofisário , Privação Materna , Neurogênese/fisiologia , Sistema Hipófise-Suprarrenal , Ratos Sprague-Dawley , Estresse Psicológico/fisiopatologiaRESUMO
Adult animals subjected to chronic stress show an inflammatory response in the hippocampus which has been related to cognitive dysfunction and psychopathology. However the immediate consequences of early life stress on hippocampal glial cells have not been studied. Here we analyzed the effects of maternal separation (MS) on astrocyte and microglial cell morphology in the hippocampal hilus, compared the expression of cytokines in the hippocampus and hypothalamus, and the peripheral response of cytokines, on postnatal day (PD) 15. Male rat pups of MS (3h/day, PD1-PD14) and Control (CONT) pups showed similar microglial cell densities in the hilus, but MS pups presented more activated microglia. MS decreased astrocyte density and the number of processes in the hilus. Cytokine mRNA expression (qPCR) was analyzed in MS and CONT groups, sacrificed (i) under basal (B) conditions or (ii) after a single stress event (SS) at PN15. In hippocampal extracts, MS increased IL-1ß mRNA, under B and SS conditions while IL-6 and TNF-α did not change. In hypothalamic tissue, MS increased TNF-α and IL-6 mRNA, but not IL-1b, after SS. Peripheral concentrations of IL-1ß were decreased under B and SS conditions in MS; IL-6 concentration increased after SS in MS pups, and TNF-α concentration was unchanged. In conclusion, MS activates microglial cells and decreases astrocyte density in the hippocampus. A differential cytokine expression is observed in the hippocampus and the hypothalamus after MS, and after SS. Also, MS triggers an independent response of peripheral cytokines. These specific responses together could contribute to decrease hippocampal neurogenesis and alter the neuroendocrine axis.
Assuntos
Astrócitos , Hipocampo/metabolismo , Inflamação/imunologia , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Privação Materna , Microglia , Estresse Psicológico/imunologia , Animais , Astrócitos/citologia , Contagem de Células , Giro Denteado/metabolismo , Modelos Animais de Doenças , Hipotálamo/metabolismo , Interleucina-1beta/sangue , Interleucina-6/sangue , Masculino , Microglia/citologia , Ratos , Ratos Sprague-DawleyRESUMO
Tight regulation of hormone and neurochemical milieu during developmental periods is critical for adequate physiological functions. For instance, activation of peptide systems during early life stress induces morphological changes in the brain resulting in depression and anxiety disorders. Prolactin (PRL) exerts different actions within the brain; it regulates neurogenesis and modulates neuroendocrine functions in the adult. However, PRL effects during early postnatal life are hardly known. Therefore, we examined whether neonatal administration of PRL influences cell survival in the hippocampal dentate gyrus (DG) and in the olfactory bulb (OB) and whether such influence results in behavioral consequences in adulthood. PRL-treated rat pups (13 mg/kg; PND1 to PND14), injected with BrdU at postnatal day 5 (PND5), showed a decrease in the density of DG BrdU/DCX and BrdU/NeuN-positive cells that survive at PND15. Similarly, PRL treatment decreased the density of BrdU+ cells in the OB compared with VEH. Fluorojade B analysis showed no significant changes in the amount of cell death in the DG between the groups. Postnatal PRL administration induced a passive coping strategy in the forced swimming test in male and female adult rats when compared with control and vehicle groups. Corticosterone endogenous levels at PND12 were not affected by PRL or VEH treatment. Altogether, these results suggest that opposed to its effects in the adult, postnatal PRL treatment affects neurogenesis and results in psychopathology later in life. High PRL levels, as observed in neonates under several pathological states, might contribute to detrimental effects on the developing brain.
Assuntos
Depressão/induzido quimicamente , Hipocampo/efeitos dos fármacos , Neurogênese/efeitos dos fármacos , Bulbo Olfatório/efeitos dos fármacos , Prolactina/farmacologia , Envelhecimento/efeitos dos fármacos , Envelhecimento/psicologia , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Proteína Duplacortina , Feminino , Hipocampo/fisiologia , Masculino , Bulbo Olfatório/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
Although not directly evaluated, the early rise of glucocorticoid (GC) levels, as occur after exposure to adverse early life experience, are assumed to affect hippocampal ontogeny by altering the hippocampus negative feedback on adult HPA axis. To test whether hippocampal ontogeny is affected by early exposure to stress we estimated the survival of recently formed hippocampal granule cells in rat pups subjected to periodic maternal separation (180 min/day; MS180) from postnatal days (PND) 1 to 14. Accordingly, MS180 pups injected with bromodeoxyuridine (BrdU, 50 mg/kg, ip) at PND 5 showed decreased density of doublecortin (DCX) positive BrdU-labeled cells at PND 15. MS180 and AFR pups showed similar corticosterone (CORT) basal levels between PND 3 and 12, whereas adult MS180 rats presented with higher CORT levels than AFR adults. Nonetheless, both AFR and MS180 pups and adults showed similar transient increments of CORT levels in response to stress. In addition, MS180 had no effect on the adult anxiety-like behavior evaluated in the elevated plus maze, but evoked a passive coping strategy in the forced swimming test. The data show that the decrease in hippocampal neurogenesis is an early onset phenomenon, and suggests that adverse experiences alter hippocampal ontogeny without chronic elevation of GC levels.