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The retrosplenial cortex (RSC) plays a critical role in complex cognitive functions such as contextual fear memory formation and consolidation. Perineuronal nets (PNNs) are specialized structures of the extracellular matrix that modulate synaptic plasticity by enwrapping the soma, proximal neurites and synapsis mainly on fast spiking inhibitory GABAergic interneurons that express parvalbumin (PV). PNNs change after contextual fear conditioning (CFC) in amygdala or hippocampus, yet it is unknown if similar remodeling takes place at RSC. Here, we used Wisteria floribunda agglutinin (WFA), a ubiquitous marker of PNNs, to study the remodeling of PNNs in RSC during the acquisition or retrieval of contextual fear conditioning (CFC). Adult male mice were exposed to paired presentations of a context and footshock, or to either of these stimuli alone (control groups). The mere exposure of animals to the footshock, either alone or paired with the context, evoked a significant expansion of PNNs, both in the number of WFA positive neurons and in the area occupied by WFA staining, across the entire RSC. This was not associated with c-Fos expression in RSC nor correlated with c-Fos expression in individual PNNs-expressing neurons in RSC, suggesting that PNNs remodeling is triggered by inputs external to the RSC. We also found that PNNs remodeling was independent of the level of PV expression. Notably, PNNs in RSC remained expanded long-after CFC. These results suggest that, in male mice, the threatening experience is the main cause of PNNs remodeling in the RSC.

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Pereskia sacharosa Griseb. is a plant used in traditional herbal medicine to treat inflammation. We analyzed the phenolic content of P. sacharosa leaves (EEPs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and investigated the anti-inflammatory properties of EEPs and its flavonoid fraction (F10) in animal models subjected to acute neuroinflammation induced by bacterial lipopolysaccharide (LPS). Coronal brain sections of C57BL/6JN male mice or Wistar male rats administered with EEPs or F10 before LPS were subjected to in situ hybridization to determine c-fos and CD14 mRNA levels in the hypothalamus or GABAA γ2 mRNA levels in the hippocampus. Theta oscillations were recorded every 6 h in the hippocampus of Wistar rats. In total, five flavonoids and eight phenolic acids were identified and quantified in P. sacharosa leaves. Either EEPs or F10 crossed the blood-brain barrier (BBB) into the brain and reduced the mRNA expression of c-fos, CD14, and GABAA γ2. A decrease in theta oscillation was observed in the hippocampus of the LPS group, while the F10 + LPS group overrode the LPS effect on theta activity. We conclude that the bioactive compounds of P. sacharosa reduce the central response to inflammation, allowing the early return of ambulatory activity and well-being of the animal.

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Previous studies from our laboratory have shown sex differences in the behavioral, molecular, and neurochemical manifestations of morphine withdrawal and they were related to an increased sensitivity to morphine effects in males. In addition, we observed an interaction between the GABAergic and opioid systems that could also be sex-dependent. Baclofen, a GABAB receptor agonist, prevented the somatic expression and the molecular and neurochemical changes induced by morphine withdrawal syndrome in mice. On the contrary, little is known about baclofen effects in the rewarding properties of morphine in male and female mice. The present study aimed to explore the effect of baclofen (1, 2 and 3 mg/kg, i.p.) pretreatment in the rewarding effects induced by morphine (7 mg/kg, s.c.) and its effect on c-Fos and brain-derived neurotrophic factor (BDNF) expression induced by the rewarding properties of morphine in prepubertal male and female mice. Baclofen (2 mg/kg) pretreatment prevented the rewarding effects of morphine only in male mice, while baclofen (3 mg/kg) reduced these effects in both sexes. Moreover, the rewarding effects of morphine were associated with a decrease of BDNF and c-Fos expression cingulate cortex, nucleus accumbens shell, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) areas of the hippocampus only in male mice. In addition, baclofen pretreatment prevented these changes in BDNF, but not in c-Fos expression. In conclusion, our results show that GABAB receptors have a regulatory role in the rewarding effects of morphine that could be of interest for a potential future therapeutic application in opioid use disorders.

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The immediate early gene exhibits activation markers in the nervous system consisting of ARC, EGR-1, and c-Fos and is related to synaptic plasticity, especially in the hippocampus. Immediate early gene expression is affected by physical exercise, which induces direct ARC, EGR-1, and c-Fos expression. Objective: To assess the impact of exercise, we conducted a literature study to determine the expression levels of immediate early genes (ARC, c-Fos, and EGR-1). Methods: The databases accessed for online literature included PubMed-Medline, Scopus, and ScienceDirect. The original English articles were selected using the following keywords in the title: (Exercise OR physical activity) AND (c-Fos) AND (Hippocampus), (Exercise OR physical activity) AND (ARC) AND (Hippocampus), (Exercise OR physical activity) AND (EGR-1 OR zif268) AND (Hippocampus). Results: Physical exercise can affect the expression of EGR-1, c-Fos, and ARC in the hippocampus, an important part of the brain involved in learning and memory. High-intensity physical exercise can increase c-Fos expression, indicating neural activation. Furthermore, the expression of the ARC gene also increases due to physical exercise. ARC is a gene that plays a role in synaptic plasticity and regulation of learning and memory, changes in synaptic structure and increased synaptic connections, while EGR-1 also plays a role in synaptic plasticity, a genetic change that affects learning and memory. Overall, exercise or regular physical exercise can increase the expression of ARC, c-Fos, and EGR-1 in the hippocampus. This reflects the changes in neuroplasticity and synaptic plasticity that occur in response to physical activity. These changes can improve cognitive function, learning, and memory. Conclusion: c-Fos, EGR-1, and ARC expression increases in hippocampal neurons after exercise, enhancing synaptic plasticity and neurogenesis associated with learning and memory.

O gene precoce imediato (GPI) exibe marcadores de ativação no sistema nervoso constituídos por ARC, EGR-1 e c-Fos e está relacionado à plasticidade sináptica, especialmente no hipocampo. A expressão do GPI é afetada pelo exercício físico, que induz a expressão direta de ARC, EGR-1 e c-Fos. Objetivo: Para avaliar o impacto do exercício físico, realizamos um estudo de literatura para determinar os níveis de expressão dos GPIs (ARC, c-Fos e EGR-1). Métodos: A base de dados utiliza literatura on-line, PubMed-Medline, Scopus e ScienceDirect. O artigo original em inglês usa as seguintes palavras-chave em seu título: (Exercise) AND (c-Fos) AND (Hippocampus), (Exercise) AND (ARC) AND (Hippocampus), (Exercise) AND (EGR-1) AND (Hippocampus). Resultados: O exercício físico pode afetar a expressão de EGR-1, c-fos e ARC no hipocampo, uma parte importante do cérebro envolvida na aprendizagem e na memória. O exercício físico aumenta a expressão do gene c-Fos; sua alta intensidade pode aumentar a expressão de c-Fos, indicando ativação neural. Além disso, a expressão do gene ARC aumentou devido ao exercício físico, onde ARC é um gene que desempenha um papel na plasticidade sináptica e na regulação da aprendizagem e da memória, nas mudanças na estrutura sináptica e no aumento das conexões sinápticas, enquanto o EGR-1 também desempenha um papel na plasticidade sináptica, uma mudança genética que afeta o aprendizado e a memória. De maneira geral, o exercício físico regular pode aumentar a expressão de ARC, c-fos e EGR-1 no hipocampo. Isso reflete as mudanças na neuroplasticidade e na plasticidade sináptica que ocorrem em resposta à atividade física. Essas mudanças podem melhorar a função cognitiva, o aprendizado e a memória. Conclusão: A expressão de c-Fos, EGR-1 e ARC aumenta após o exercício físico nos neurônios do hipocampo, para aumentar a plasticidade sináptica, a neurogênese associada ao aprendizado e à memória.

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Circular RNAs (circRNAs) are non­coding single­stranded covalently closed RNA molecules that are considered important as regulators of gene expression at the transcriptional and post­transcriptional levels. These molecules have been implicated in the initiation and progression of multiple human diseases, ranging from cancer to inflammatory and metabolic diseases, including diabetes mellitus and its vascular complications. The present article aimed to review the current knowledge on the biogenesis and functions of circRNAs, as well as their role in cell processes associated with diabetic nephropathy. In addition, novel potential interactions between circRNAs expressed in renal cells exposed to high­glucose concentrations and the transcription factors c­Jun and c­Fos are reported.

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The menopause transition is a vulnerable period for developing both psychiatric and metabolic disorders, and both can be enhanced by stressful events worsening their effects. The present study aimed to evaluate whether a cafeteria diet (CAF) combined with chronic variable stress (CVS) exacerbates anxious- or depressive-like behavior and neuronal activation, cell proliferation and survival, and microglia activation in middle-aged ovariectomized (OVX) rats. In addition, body weight, lipid profile, insulin resistance, and corticosterone as an index of metabolic changes or hypothalamus-pituitary-adrenal (HPA) axis activation, and the serum pro-inflammatory cytokines IL-6, IL-ß, and TNFα were measured. A CAF diet increased body weight, lipid profile, and insulin resistance. CVS increased corticosterone and reduced HDL. A CAF produced anxiety-like behaviors, whereas CVS induced depressive-like behaviors. CVS increased serum TNFα independently of diet. A CAF and CVS separately enhanced the percentage of Iba-positive cells in the hippocampus; the combination of factors further increased Iba-positive cells in the ventral hippocampus. A CAF and CVS increased the c-fos-positive cells in the hippocampus; the combination of factors increased the number of positive cells expressing c-fos in the ventral hippocampus even more. The combination of a CAF and CVS generates a slight neuroinflammation process and neuronal activation in a hippocampal region-specific manner and differentially affects the behavior.

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Abstract During oral surgery and temporomandibular joint repositioning, pain hypersensitivity often occurs due to irritation or inflammation of the nerve endings in the orofacial region. Objective: This study aimed to investigate the effects of ECa 233, a Centella asiatica-standardized extract, on the development of mechanical hyperalgesia and allodynia induced by chronic constriction injury of the infraorbital nerve in mice. Methodology: The right infraorbital nerves of the mice were ligated. Oral carbamazepine (20 mg/kg) or ECa 233 (30, 100, or 300 mg/kg) was administered daily for 21 days. Von Frey and air-puff tests were performed on both sides of the whisker pad on days 0, 7, 14, and 21. Thereafter, the expression of purinergic receptor subtype 3 (P2X3) and voltage-gated sodium channel 1.7 (NaV1.7), a transmembrane protein, in the trigeminal ganglion and c-fos immunoreactivity-positive neurons in the trigeminal nucleus caudalis was assessed. Results: After 21 days of infraorbital nerve ligation, the mice showed allodynia- and hyperalgesia-like behavior, P2X3 and NaV1.7 were upregulated in the trigeminal ganglion, and nociceptive activity increased in the trigeminal nucleus caudalis. However, the oral administration of carbamazepine (20 mg/kg), ECa 233 (100 mg/kg), or ECa 233 (300 mg/kg) mitigated these effects. Nevertheless, ECa 233 failed to affect NaV1.7 protein expression. Conclusion: Carbamazepine and ECa 233 can prevent pain hypersensitivity in mice. Considering the side effects of the long-term use of carbamazepine, ECa 233 monotherapy or combined ECa 233 and carbamazepine therapy can be used as an alternative for regulating the development of hypersensitivity in trigeminal pain. However, further detailed clinical studies should be conducted to provide comprehensive information on the use of ECa 233.

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ABSTRACT. The immediate early gene exhibits activation markers in the nervous system consisting of ARC, EGR-1, and c-Fos and is related to synaptic plasticity, especially in the hippocampus. Immediate early gene expression is affected by physical exercise, which induces direct ARC, EGR-1, and c-Fos expression. Objective: To assess the impact of exercise, we conducted a literature study to determine the expression levels of immediate early genes (ARC, c-Fos, and EGR-1). Methods: The databases accessed for online literature included PubMed-Medline, Scopus, and ScienceDirect. The original English articles were selected using the following keywords in the title: (Exercise OR physical activity) AND (c-Fos) AND (Hippocampus), (Exercise OR physical activity) AND (ARC) AND (Hippocampus), (Exercise OR physical activity) AND (EGR-1 OR zif268) AND (Hippocampus). Results: Physical exercise can affect the expression of EGR-1, c-Fos, and ARC in the hippocampus, an important part of the brain involved in learning and memory. High-intensity physical exercise can increase c-Fos expression, indicating neural activation. Furthermore, the expression of the ARC gene also increases due to physical exercise. ARC is a gene that plays a role in synaptic plasticity and regulation of learning and memory, changes in synaptic structure and increased synaptic connections, while EGR-1 also plays a role in synaptic plasticity, a genetic change that affects learning and memory. Overall, exercise or regular physical exercise can increase the expression of ARC, c-Fos, and EGR-1 in the hippocampus. This reflects the changes in neuroplasticity and synaptic plasticity that occur in response to physical activity. These changes can improve cognitive function, learning, and memory. Conclusion: c-Fos, EGR-1, and ARC expression increases in hippocampal neurons after exercise, enhancing synaptic plasticity and neurogenesis associated with learning and memory.

RESUMO. O gene precoce imediato (GPI) exibe marcadores de ativação no sistema nervoso constituídos por ARC, EGR-1 e c-Fos e está relacionado à plasticidade sináptica, especialmente no hipocampo. A expressão do GPI é afetada pelo exercício físico, que induz a expressão direta de ARC, EGR-1 e c-Fos. Objetivo: Para avaliar o impacto do exercício físico, realizamos um estudo de literatura para determinar os níveis de expressão dos GPIs (ARC, c-Fos e EGR-1). Métodos: A base de dados utiliza literatura on-line, PubMed-Medline, Scopus e ScienceDirect. O artigo original em inglês usa as seguintes palavras-chave em seu título: (Exercise) AND (c-Fos) AND (Hippocampus), (Exercise) AND (ARC) AND (Hippocampus), (Exercise) AND (EGR-1) AND (Hippocampus). Resultados: O exercício físico pode afetar a expressão de EGR-1, c-fos e ARC no hipocampo, uma parte importante do cérebro envolvida na aprendizagem e na memória. O exercício físico aumenta a expressão do gene c-Fos; sua alta intensidade pode aumentar a expressão de c-Fos, indicando ativação neural. Além disso, a expressão do gene ARC aumentou devido ao exercício físico, onde ARC é um gene que desempenha um papel na plasticidade sináptica e na regulação da aprendizagem e da memória, nas mudanças na estrutura sináptica e no aumento das conexões sinápticas, enquanto o EGR-1 também desempenha um papel na plasticidade sináptica, uma mudança genética que afeta o aprendizado e a memória. De maneira geral, o exercício físico regular pode aumentar a expressão de ARC, c-fos e EGR-1 no hipocampo. Isso reflete as mudanças na neuroplasticidade e na plasticidade sináptica que ocorrem em resposta à atividade física. Essas mudanças podem melhorar a função cognitiva, o aprendizado e a memória. Conclusão: A expressão de c-Fos, EGR-1 e ARC aumenta após o exercício físico nos neurônios do hipocampo, para aumentar a plasticidade sináptica, a neurogênese associada ao aprendizado e à memória.

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The cognitive effects of nicotine are linked to persistent modifications in extended neural systems that regulate cognitive and emotional processes, and these changes occur during development. Additionally, acute stress has modulatory effects on cognition that involve broad neural systems and can be influenced by prior environmental challenges. The effects of nicotine and stress may be interconnected, leading to modifications in a network of shared brain substrates. Here, we explored the interaction between nicotine and stress by evaluating the effects of acute stress exposure in spatial memory retrieval for animals pretreated with nicotine during adolescence or adulthood. Adolescent (35 days old) and adult (70 days old) male Wistar rats were treated for 21 days with one daily subcutaneous injection of nicotine 0.14 mg/ml (free base). 30 days after the last injection, rats were trained in the Barnes maze and tested 24 h later, half the rats were tested under regular conditions, and half of them were exposed to 1 h of restraining stress before the retrieval test, and brain samples were collected and c-Fos immunopositive cells were stained. Prolonged nicotine withdrawal or acute stress improved spatial memory retrieval. Acute stress in nicotine pretreated adults impaired spatial memory retrieval. Nicotine exposure during early adulthood resulted in long-lasting brain adaptations that amplified emotional responses to acute stress after prolonged drug withdrawal.

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Nutritional status during critical windows in early development can challenge metabolic functions and physiological responses to immune stress in adulthood, such as the systemic inflammation induced by lipopolysaccharide (LPS). The aim of this study was to investigate the long-term effects of post-natal over- and undernutrition on the anorexigenic effect of LPS and its association with neuronal activation in the brainstem and hypothalamus of male rats. Animals were raised in litters of 3 (small - SL), 10 (normal - NL), or 16 (large - LL) pups per dam. On post-natal day 60, male rats were treated with LPS (500 µg/Kg) or vehicle for the evaluation of food intake and c-Fos expression in the area postrema (AP), nucleus of solitary tract (NTS), and paraventricular (PVN), arcuate (ARC), ventromedial (VMH), and dorsomedial (DMH) nuclei of the hypothalamus. SL, NL, and LL animals showed a decreased food consumption after LPS treatment. In under- and normonourished animals, peripheral LPS induced an increase in neuronal activation in the brainstem, PaV, PaMP, and ARC and a decrease in the number of c-Fos-ir neurons in the DMH. Overnourished rats showed a reduced hypophagic response, lower neuron activation in the NTS and PaMP, and no response in the DMH induced by LPS. These results indicate that early nutritional programming displays different responses to LPS, by means of neonatal overnutrition decreasing LPS-mediated anorexigenic effect and neuronal activation in the NTS and hypothalamic nuclei.

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Pain is a common symptom associated with disorders involving the orofacial structures. Most acute orofacial painful conditions are easily recognized, but the pharmacological treatment may be limited by the adverse events of current available drugs and/or patients' characteristics. In addition, chronic orofacial pain conditions represent clinical challenges both, in terms of diagnostic and treatment. There is growing evidence that specialized pro-resolution lipid mediators (SPMs) present potent analgesic effects, in addition to their well characterized role in the resolution of inflammation. Maresins (MaR-1 and MaR-2) were the last described members of this family, and MaR-2 analgesic action has not yet been reported. Herein the effect of MaR-2 in different orofacial pain models was investigated. MaR-2 (1 or 10 ng) was always delivered via medullary subarachnoid injection, which corresponds to the intrathecal treatment. A single injection of MaR-2 caused a significant reduction of phases I and II of the orofacial formalin test in rats. Repeated injections of MaR-2 prevented the development of facial heat and mechanical hyperalgesia in a model of post-operative pain in rats. In a model of trigeminal neuropathic pain (CCI-ION), repeated MaR-2 injections reversed facial heat and mechanical hyperalgesia in rats and mice. CCI-ION increased c-Fos positive neurons and CGRP+ activated (nuclear pNFkB) neurons in the trigeminal ganglion (TG), which were restored to sham levels by MaR-2 repeated treatment. In conclusion, MaR-2 showed potent and long-lasting analgesic effects in inflammatory and neuropathic pain of orofacial origin and the inhibition of CGRP-positive neurons in the TG may account for MaR-2 action.

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The present study aimed to characterize the phenomenon of behavioral sensitization to cocaine and to identify neuroanatomical structures involved in the induction and expression phases of this phenomenon. For this, in experiment 1 (induction phase), mice were treated with saline or cocaine every second day for 15 days (conditioning period), in the open-field or in their home-cages. In experiment 2 (expression phase), the same protocol was followed, except that after the conditioning period the animals were not manipulated for 10 days, and after this interval, animals were challenged with cocaine. Neuroanatomical structures involved in the induction and expression phases were identified by stereological quantification of c-Fos staining in the dorsomedial prefrontal cortex (dmPFC), nucleus accumbens core (NAc core and shell (NAc shell), basolateral amygdala (BLA), and ventral tegmental area (VTA). Neuroanatomical analysis indicated that in the induction phase, cocaine-conditioned animals had higher expression of c-Fos in the dmPFC, NAc core, BLA, and VTA, whereas in the expression phase, almost all areas had higher expression except for the VTA. Therefore, environmental context plays a major role in the induction and expression of behavioral sensitization, although not all structures that compose the mesolimbic system contribute to this phenomenon.

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INTRODUCTION: Worldwide, breast cancer is the most common cancer in women and is the main cause of death among all neoplasia in this group. Luminal A breast cancer represents approximately 70% of all breast cancers and is treated with hormone therapies targeting estrogen receptor alpha (ERα). Unfortunately, patients develop drug resistance leading to recurrence of neoplasia due to estrogen-independent ERα reactivation. Therefore, it is crucial to identify new molecular targets downstream ERα signaling pathway that allows the implementation of better treatments to improve the outcome of breast cancer patients. Overexpression of c-Fos, an ERα gene target, has been associated with increased cell motility, malignancy, metastasis, and invasion while its neutralization results in decreased breast cancer tumorigenesis. The aryl hydrocarbon receptor (AHR) ligands halogenated and polycyclic aromatic hydrocarbons, highly toxic compounds, down regulate c-Fos and ERα levels. The present study aimed to evaluate whether 6-formylindolo(3,2-b)carbazole (FICZ), a no toxic AHR agonist, modifies c-Fos levels in MCF-7 mammary carcinoma cells as well as to determine its effects on cell proliferation and migration. In addition, the possible mechanism through which FICZ mediates c-Fos levels in MCF-7 cells was investigated. METHODS: Initially, the effect of FICZ on c-Fos mRNA and protein levels in MCF-7 cells, untreated or treated with estradiol, was evaluated by qPCR and Western blot. 2,3,7,8-Tetrachloro-dibenzo-p-dioxin, an AHR prototype agonist, was used as a positive control. Next, we examined the effect of FICZ on MCF-7 cell proliferation and migration by cell counting, MTT, 3H-thymidine incorporation, and scratch-wound assays. Finally, the involvement of proteasome 26S on ERα and c-Fos protein degradation was investigated by the use of MG132 and Western blot. RESULTS: The data show that FICZ treatment downregulates c-Fos mRNA and protein levels, most likely by promoting ERα proteasome degradation, blocking MCF-7 cell proliferation and migration. The results also demonstrate that liganded ERα was required for FICZ-mediated ERα degradation. CONCLUSIONS: Activation of AHR results in a decreased MCF-7 cell proliferation and migration by ERα and c-Fos down regulation. Targeting AHR might be a promising therapy for breast cancer treatment, particularly when estrogen-independent ERα reactivation presents.

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The interest in studying the neural circuits related to mating behavior and mate choice in monogamous species lies in the parallels found between human social structure and sexual behavior and that of other mammals that exhibit social monogamy, potentially expanding our understanding of human neurobiology and its underlying mechanisms. Extensive research has suggested that social monogamy, as opposed to non-monogamy in mammals, is a consequence of the neural encoding of sociosensory information from the sexual partner with an increased reward value. Thus, the reinforced value of the mate outweighs the reward value of mating with any other potential sexual partners. This mechanism reinforces the social relationship of a breeding pair, commonly defined as a pair bond. In addition to accentuated prosocial behaviors toward the partner, other characteristic behaviors may appear, such as territorial and partner guarding, selective aggression toward unfamiliar conspecifics, and biparental care. Concomitantly, social buffering and distress upon partner separation are also observed. The following work intends to overview and compare known neural and functional circuits that are related to mating and sexual behavior in monogamous mammals. We will particularly discuss reports on Cricetid rodents of the Microtus and Peromyscus genus, and New World primates (NWP), such as the Callicebinae subfamily of the titi monkey and the marmoset (Callithrix spp.). In addition, we will mention the main factors that modulate the neural circuits related to social monogamy and how that modulation may reflect phenotypic differences, ultimately creating the widely observed diversity in social behavior.

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While current research highlights the role of Nav1. 8 sensory neurons from the peripheral nervous system, the anatomical and physiological characterization of encephalic Nav1.8 neurons remains unknown. Here, we use a Cre/fluorescent reporter mouse driven by the Nav1.8 gene promoter to reveal unexpected subpopulations of transiently-expressing Nav1.8 neurons within the limbic circuitry, a key mediator of the emotional component of pain. We observed that Nav1.8 neurons from the bed nuclei of the stria terminalis (BST), amygdala, and the periaqueductal gray (vPAG) are sensitive to noxious stimuli from an experimental model of chronic inflammatory pain. These findings identify a novel role for central Nav1.8 neurons in sensing nociception, which could be researched as a new approach to treating pain disorders.

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The c-fos gene was first described as a proto-oncogene responsible for the induction of bone tumors. A few decades ago, activation of the protein product c-fos was reported in the brain after seizures and other noxious stimuli. Since then, multiple studies have used c-fos as a brain activity marker. Although it has been attributed to neurons, growing evidence demonstrates that c-fos expression in the brain may also include glial cells. In this review, we collect data showing that glial cells also express this proto-oncogene. We present evidence demonstrating that at least astrocytes, oligodendrocytes, and microglia express this immediate early gene (IEG). Unlike neurons, whose expression changes used to be associated with depolarization, glial cells seem to express the c-fos proto-oncogene under the influence of proliferation, differentiation, growth, inflammation, repair, damage, plasticity, and other conditions. The collected evidence provides a complementary view of c-fos as an activity marker and urges the introduction of the glial cell perspective into brain activity studies. This glial cell view may provide additional information related to the brain microenvironment that is difficult to obtain from the isolated neuron paradigm. Thus, it is highly recommended that detection techniques are improved in order to better differentiate the phenotypes expressing c-fos in the brain and to elucidate the specific roles of c-fos expression in glial cells.

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Previous experiences can drive adaptive behavior based on different characteristics, including contextual ones. Indeed, contextual information can be used as a criterion to guide the recall of the most relevant memory trace and the inhibition of others. The medial Prefontal Cortex (mPFC) has been proposed as an area that plays a pivotal role in regulating the retrieval of memory traces in downstream regions. Also, we have shown that mPFC Serotonin 2a Receptors (5-HT2aR) modulates the retrieval of a contextually guided recognition memory task and modulates the retrieval and reconsolidation of memories in the Perirhinal Cortex (PRH). However, how the mPFC output mediated by the 5-HT2aR activity is modulating memory retrieval in the PRH is a question that remains unclear. To tackle this question, we analyzed neuronal activity in the PRH and mPFC, by measuring expression of the immediate early gene c-Fos. We combined behavioral, pharmacological and immunohistochemical techniques to examine how mPFC 5-HT2aR controls mPFC and the PRH activity. We found that blockade of mPFC 5-HT2aR increase the level of c-Fos expression in the PHR and that this increase correlates with animals' performance in the task. We also found an increase in c-Fos expression in the mPFC after mPFC 5-HT2aR blockade that does not correlate with the animals' behavioral response. However, these changes showed a significant correlation with those observed in the PRH. These results suggest that mPFC 5-HT2aR signaling may modulate the behavioral response during memory recall by controlling the neuronal activation in the PRH.

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Background and Objectives: The commissural nucleus of the tractus solitarius (cNTS) not only responds to glucose levels directly, but also receives afferent signals from the liver, and from the carotid chemoreceptors (CChR). In addition, leptin, through its receptors in the cNTS, regulates food intake, body weight, blood glucose levels, and brain glucose retention (BGR). These leptin effects on cNTS are thought to be mediated through the sympathetic-adrenal system. How these different sources of information converging in the NTS regulate blood glucose levels and brain glucose retention remains largely unknown. The goal of the present study was to determine whether the local administration of leptin in cNTS alone, or after local anoxic stimulation using sodium cyanide (NaCN) in the carotid sinus, modifies the expression of leptin Ob-Rb and of c-Fos mRNA. We also investigated how leptin, alone, or in combination with carotid sinus stimulation, affected brain glucose retention. Materials and Methods: The experiments were carried out in anesthetized male Wistar rats artificially ventilated to maintain homeostatic values for pO2, pCO2, and pH. We had four groups: (a) experimental 1, leptin infusion in cNTS and NaCN in the isolated carotid sinus (ICS; n = 10); (b) experimental 2, leptin infusion in cNTS and saline in the ICS (n = 10); (c) control 1, artificial cerebrospinal fluid (aCSF) in cNTS and NaCN in the ICS (n = 10); (d) control 2, aCSF in cNTS and saline in the ICS (n = 10). Results: Leptin in cNTS, preceded by NaCN in the ICS increased BGR and leptin Ob-Rb mRNA receptor expression, with no significant increases in c-Fos mRNA in the NTSc. Conclusions: Leptin in the cNTS enhances brain glucose retention induced by an anoxic stimulus in the carotid chemoreceptors, through an increase in Ob-Rb receptors, without persistent changes in neuronal activation.

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The expression of c-Fos protein has been extensively used as a marker of neuronal activation in response to stressful stimuli. Early maternal separation (MS) is a model of early life adversity that affects the responsiveness of the brain areas to stressors. Thus, this study examined the impact of early MS on activating stress-responsive areas in the brain of adult rats in response to physical (ether) or psychological (restraint) stressors. Male pups were divided for the MS or non-handled (NH) groups. The MS was carried out daily between the 2nd and 14th day of postnatal life and consisted in removing the dams from the cage for 180 min. The rats were then subjected to experimental protocols of restraint or ether exposure at 10-12 weeks old. The rats were anesthetized 90 min after exposure to the stressors, and their brains were prepared for immunohistochemical analysis of c-Fos immunoreactive (c-Fos-ir) neurons in the hypothalamic paraventricular nucleus (PVN), supraoptic nucleus (SON), medial preoptic area (MPA), medial amygdaloid nucleus (MeA), locus coeruleus (LC), and nucleus of the solitary tract (NST). The MS-group presented 86%, 125%, 73%, 56%, and 137% higher c-Fos-ir neurons in the LC, PVN, SON, MPA, and MeA, respectively, compared to NH-group in response to the restraint stressor. In addition, the MS-group presented 180%, 137%, 170%, and 138% higher c-Fos-ir neurons for the ether exposure in the LC, PVN, MPA, and MeA, respectively. Our results show a greater increase in neuronal activation in the MS group, indicating that early life adversity can induce reprogramming in the brain response to stress in adulthood.

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RESUMO

Abstract This study aimed to investigate possible changes in the spatial memory of rats and the expression or activity of EGR-1, c-Fos, PKA, and PKC after propofol anesthesia. Thirty-six Sprague-Dawley rats aged 20 months and 36 Sprague-Dawley rats aged three months were each randomly divided into three groups: the control group, the Morris Water Maze (MWM) group, and the propofol group. In the propofol groups of both young and aged rats, the rats were anesthetized by propofol for two or four hours and then performed the MWM test two days or two weeks after anesthesia to assess cognitive function. EGR-1, c-Fos, PKA, and PKC expressions in the rat hippocampus were determined via immunohistochemistry. For the older rats, the escape latency in the P4h/2d group was significantly prolonged (P < 0.05), and the learning curve was right-shifted in the P4h/2w group (P < 0.05). The expression levels of EGR-1, c-Fos, PKA, and PKC in the MWM groups were significantly higher than those in the control groups (P < 0.05). In the P4h/2d group of aged rats, the expression levels of both PKA and PKC were decreased compared with those of the MWM groups. The decreased expression of both protein kinases may be responsible for the observed impairment after propofol anesthesia

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