Actions of Brain-Derived Neurotrophic Factor and Glucocorticoid Stress in Neurogenesis

CGG repeats in the human FMR1 gene regulate mRNA localization and cellular stress in developing neurons

The human genome has many short tandem repeats, yet the normal functions of these repeats are unclear. The 5' untranslated region (UTR) of the fragile X messenger ribonucleoprotein 1 (FMR1) gene contains polymorphic CGG repeats, the length of which has differing effects on FMR1 expression and human health, including the neurodevelopmental disorder fragile X syndrome. We deleted the CGG repeats in the FMR1 gene (0CGG) in human stem cells and examined the effects on differentiated neurons. 0CGG neurons have altered subcellular localization of FMR1 mRNA and protein, and differential expression of cellular stress proteins compared with neurons with normal repeats (31CGG). In addition, 0CGG neurons have altered responses to glucocorticoid receptor (GR) activation, including FMR1 mRNA localization, GR chaperone HSP90α expression, GR localization, and cellular stress protein levels. Therefore, the CGG repeats in the FMR1 gene are important for the homeostatic responses of neurons to stress signals.

Depression and type 2 diabetes: A causal relationship and mechanistic pathway

Depression is a mood disorder that may increase risk for the development of insulin resistance (IR) and type 2 diabetes (T2D), and vice versa. However, the mechanistic pathway linking depression and T2D is not fully elucidated. The aim of this narrative review, therefore, was to discuss the possible link between depression and T2D. The coexistence of T2D and depression is twice as great compared to the occurrence of either condition independently. Hyperglycaemia and dyslipidaemia promote the incidence of depression by enhancing inflammation and reducing brain serotonin (5-hydroxytryptamine [5HT]). Dysregulation of insulin signalling in T2D impairs brain 5HT signalling, leading to the development of depression. Furthermore, depression is associated with the development of hyperglycaemia and poor glycaemic control. Psychological stress and depression promote the development of T2D. In conclusion, T2D could be a potential risk factor for the development of depression through the induction of inflammatory reactions and oxidative stress that affect brain neurotransmission. In addition, chronic stress in depression may induce the development of T2D through dysregulation of the hypothalamic-pituitary-adrenal axis and increase circulating cortisol levels, which triggers IR and T2D.

Recent advances in the crosstalk between the brain-derived neurotrophic factor and glucocorticoids

Brain-derived neurotrophic factor (BDNF), a key neurotrophin within the brain, by selectively activating the TrkB receptor, exerts multimodal effects on neurodevelopment, synaptic plasticity, cellular integrity and neural network dynamics. In parallel, glucocorticoids (GCs), vital steroid hormones, which are secreted by adrenal glands and rapidly diffused across the mammalian body (including the brain), activate two different groups of intracellular receptors, the mineralocorticoid and the glucocorticoid receptors, modulating a wide range of genomic, epigenomic and postgenomic events, also expressed in the neural tissue and implicated in neurodevelopment, synaptic plasticity, cellular homeostasis, cognitive and emotional processing. Recent research evidences indicate that these two major regulatory systems interact at various levels: they share common intracellular downstream pathways, GCs differentially regulate BDNF expression, under certain conditions BDNF antagonises the GC-induced effects on long-term potentiation, neuritic outgrowth and cellular death, while GCs regulate the intraneuronal transportation and the lysosomal degradation of BDNF. Currently, the BDNF-GC crosstalk features have been mainly studied in neurons, although initial findings show that this crosstalk could be equally important for other brain cell types, such as astrocytes. Elucidating the precise neurobiological significance of BDNF-GC interactions in a tempospatial manner, is crucial for understanding the subtleties of brain function and dysfunction, with implications for neurodegenerative and neuroinflammatory diseases, mood disorders and cognitive enhancement strategies.

Effect of 2-Week Naringin Supplementation on Neurogenesis and BDNF Levels in Ischemia-Reperfusion Model of Rats

BACKGROUND

Ischemic stroke is the leading cause of mortality and disability worldwide with more than half of survivors living with serious neurological sequelae; thus, it has recently attracted a lot of attention in the field of medical study.

PURPOSE

The aim of this study was to determine the effect of naringin supplementation on neurogenesis and brain-derived neurotrophic factor (BDNF) levels in the brain in experimental brain ischemia-reperfusion.

STUDY DESIGN

The research was carried out on 40 male Wistar-type rats (10-12 weeks old) obtained from the Experimental Animals Research and Application Center of Selçuk University. Experimental groups were as follows: (1) Control group, (2) Sham group, (3) Brain ischemia-reperfusion group, (4) Brain ischemia-reperfusion + vehicle group (administered for 14 days), and (5) Brain ischemia-reperfusion + Naringin group (100 mg/kg/day administered for 14 days).

METHODS

In the ischemia-reperfusion groups, global ischemia was performed in the brain by ligation of the right and left carotid arteries for 30 min. Naringin was administered to experimental animals by intragastric route for 14 days following reperfusion. The training phase of the rotarod test was started 4 days before ischemia-reperfusion, and the test phase together with neurological scoring was performed the day before and 1, 7, and 14 days after the operation. At the end of the experiment, animals were sacrificed, and then hippocampus and frontal cortex tissues were taken from the brain. Double cortin marker (DCX), neuronal nuclear antigen marker (NeuN), and BDNF were evaluated in hippocampus and frontal cortex tissues by Real-Time qPCR analysis and immunohistochemistry methods.

RESULTS

While ischemia-reperfusion increased the neurological score values, DCX, NeuN, and BDNF levels decreased significantly after ischemia in the hippocampus and frontal cortex tissues. However, naringin supplementation restored the deterioration to a certain extent.

CONCLUSION

The results of the study show that 2 weeks of naringin supplementation may have protective effects on impaired neurogenesis and BDNF levels after brain ischemia and reperfusion in rats.

TERT mediates the U-shape of glucocorticoids effects in modulation of hippocampal neural stem cells and associated brain function

BACKGROUND

Glucocorticoids (GCs) are steroidal hormones produced by the adrenal cortex. A physiological-level GCs have a crucial function in maintaining many cognitive processes, like cognition, memory, and mood, however, both insufficient and excessive GCs impair these functions. Although this phenomenon could be explained by the U-shape of GC effects, the underlying mechanisms are still not clear. Therefore, understanding the underlying mechanisms of GCs may provide insight into the treatments for cognitive and mood-related disorders.

METHODS

Consecutive administration of corticosterone (CORT, 10 mg/kg, i.g.) proceeded for 28 days to mimic excessive GCs condition. Adrenalectomy (ADX) surgery was performed to ablate endogenous GCs in mice. Microinjection of 1 μL of Ad-mTERT-GFP virus into mouse hippocampus dentate gyrus (DG) and behavioral alterations in mice were observed 4 weeks later.

RESULTS

Different concentrations of GCs were shown to affect the cell growth and development of neural stem cells (NSCs) in a U-shaped manner. The physiological level of GCs (0.01 μM) promoted NSC proliferation in vitro, while the stress level of GCs (10 μM) inhibited it. The glucocorticoid synthesis blocker metyrapone (100 mg/kg, i.p.) and ADX surgery both decreased the quantity and morphological development of doublecortin (DCX)-positive immature cells in the DG. The physiological level of GCs activated mineralocorticoid receptor and then promoted the production of telomerase reverse transcriptase (TERT); in contrast, the stress level of GCs activated glucocorticoid receptor and then reduced the expression of TERT. Overexpression of TERT by AD-mTERT-GFP reversed both chronic stresses- and ADX-induced deficiency of TERT and the proliferation and development of NSCs, chronic stresses-associated depressive symptoms, and ADX-associated learning and memory impairment.

CONCLUSION

The bidirectional regulation of TERT by different GCs concentrations is a key mechanism mediating the U-shape of GC effects in modulation of hippocampal NSCs and associated brain function. Replenishment of TERT could be a common treatment strategy for GC dysfunction-associated diseases.

The impact of flavonoids and BDNF on neurogenic process in various physiological/pathological conditions including ischemic insults: a narrative review

OBJECTIVE

Ischemic stroke is the leading cause of mortality and disability worldwide with more than half of survivors living with serious neurological sequelae thus, it has recently attracted considerable attention in the field of medical research. Neurogenesis is the process of formation of new neurons in the brain, including the human brain, from neural stem/progenitor cells [NS/PCs] which reside in neurogenic niches that contain the necessary substances for NS/PC proliferation, differentiation, migration, and maturation into functioning neurons which can integrate into a pre-existing neural network.Neurogenesis can be modulated by many exogenous and endogenous factors, pathological conditions. Both brain-derived neurotrophic factor, and flavonoids can modulate the neurogenic process in physiological conditions and after various pathological conditions including ischemic insults.

AIMS

This review aims to discuss neurogenesis after ischemic insults and to determine the role of flavonoids and BDNF on neurogenesis under physiological and pathological conditions with a concentration on ischemic insults to the brain in particular.

METHOD

Relevant articles assessing the impact of flavonoids and BDNF on neurogenic processes in various physiological/pathological conditions including ischemic insults within the timeline of 1965 until 2023 were searched using the PubMed database.

CONCLUSIONS

The selected studies have shown that ischemic insults to the brain induce NS/PC proliferation, differentiation, migration, and maturation into functioning neurons integrating into a pre-existing neural network. Flavonoids and BDNF can modulate neurogenesis in the brain in various physiological/pathological conditions including ischemic insults. In conclusion, flavonoids and BDNF may be involved in post-ischemic brain repair processes through enhancing endogenous neurogenesis.

The early life growth of head circumference, weight, and height in infants with autism spectrum disorders: a systematic review

BACKGROUNDS

The Autism spectrum disorder (ASD) prevalence has increased significantly over the past two decades. This review summarizes the current knowledge of the association between the early life growth of head circumference (HC), weight, and height with ASD in infants.

METHODS

PubMed, Scopus, Science Direct, and Google Scholar databases were searched up to November 2021 using relevant keywords. All original articles are written in English evaluating the early life growth of HC, weight, and height in infants with ASD were eligible for the present review.

RESULTS

Totally, 23 articles involving 4959 infants were included in this review. Of 13 studies that evaluated HC of infants at birth, 10 studies (83.33%) showed that the HC at the birth of autistic children was similar to that of the average found in the control group. Among 21 studies that evaluated the HC and weight status in infants, 19 studies (90.47%) showed that autistic children had larger HC and weight than the control group or abnormal acceleration of head growth during infancy. Height growth of infants was investigated in 13 studies, of which 10 cases (76.92%) reported that infants with ASD were significantly longer than control groups. Most of he included studies had a good quality.

CONCLUSIONS

The findings suggest that in infants with ASD, without the contribution of birth growth factors and sex of the child, the growth of HC, weight, and height probably was faster than in infants with normal development, in early life. Therefore, these measurements might be useful as initial predictive biomarkers for the risk of developing ASD.

Association between NTRK2 Polymorphisms, Hippocampal Volumes and Treatment Resistance in Major Depressive Disorder

Despite the increasing availability of antidepressant drugs, a high rate of patients with major depression (MDD) does not respond to pharmacological treatments. Brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling is thought to influence antidepressant efficacy and hippocampal volumes, robust predictors of treatment resistance. We therefore hypothesized the possible role of BDNF and neurotrophic receptor tyrosine kinase 2 (NTRK2)-related polymorphisms in affecting both hippocampal volumes and treatment resistance in MDD. A total of 121 MDD inpatients underwent 3T structural MRI scanning and blood sampling to obtain genotype information. General linear models and binary logistic regressions were employed to test the effect of genetic variations related to BDNF and NTRK2 on bilateral hippocampal volumes and treatment resistance, respectively. Finally, the possible mediating role of hippocampal volumes on the relationship between genetic markers and treatment response was investigated. A significant association between one NTRK2 polymorphism with hippocampal volumes and antidepressant response was found, with significant indirect effects. Our results highlight a possible mechanistic explanation of antidepressant action, possibly contributing to the understanding of MDD pathophysiology.

Increased proliferation and neuronal fate in prairie vole brain progenitor cells cultured in vitro: effects by social exposure and sexual dimorphism

BACKGROUND

The prairie vole (Microtus ochrogaster) is a socially monogamous rodent that establishes an enduring pair bond after cohabitation, with (6 h) or without (24 h) mating. Previously, we reported that social interaction and mating increased cell proliferation and differentiation to neuronal fate in neurogenic niches in male voles. We hypothesized that neurogenesis may be a neural plasticity mechanism involved in mating-induced pair bond formation. Here, we evaluated the differentiation potential of neural progenitor cells (NPCs) isolated from the subventricular zone (SVZ) of both female and male adult voles as a function of sociosexual experience. Animals were assigned to one of the following groups: (1) control (Co), sexually naive female and male voles that had no contact with another vole of the opposite sex; (2) social exposure (SE), males and females exposed to olfactory, auditory, and visual stimuli from a vole of the opposite sex, but without physical contact; and (3) social cohabitation with mating (SCM), male and female voles copulating to induce pair bonding formation. Subsequently, the NPCs were isolated from the SVZ, maintained, and supplemented with growth factors to form neurospheres in vitro.

RESULTS

Notably, we detected in SE and SCM voles, a higher proliferation of neurosphere-derived Nestin + cells, as well as an increase in mature neurons (MAP2 +) and a decrease in glial (GFAP +) differentiated cells with some sex differences. These data suggest that when voles are exposed to sociosexual experiences that induce pair bonding, undifferentiated cells of the SVZ acquire a commitment to a neuronal lineage, and the determined potential of the neurosphere is conserved despite adaptations under in vitro conditions. Finally, we repeated the culture to obtain neurospheres under treatments with different hormones and factors (brain-derived neurotrophic factor, estradiol, prolactin, oxytocin, and progesterone); the ability of SVZ-isolated cells to generate neurospheres and differentiate in vitro into neurons or glial lineages in response to hormones or factors is also dependent on sex and sociosexual context.

CONCLUSION

Social interactions that promote pair bonding in voles change the properties of cells isolated from the SVZ. Thus, SE or SCM induces a bias in the differentiation potential in both sexes, while SE is sufficient to promote proliferation in SVZ-isolated cells from male brains. In females, proliferation increases when mating is performed. The next question is whether the rise in proliferation and neurogenesis of cells from the SVZ are plastic processes essential for establishing, enhancing, maintaining, or accelerating pair bond formation. Highlights 1. Sociosexual experiences that promote pair bonding (social exposure and social cohabitation with mating) induce changes in the properties of neural stem/progenitor cells isolated from the SVZ in adult prairie voles. 2. Social interactions lead to increased proliferation and induce a bias in the differentiation potential of SVZ-isolated cells in both male and female voles. 3. The differentiation potential of SVZ-isolated cells is conserved under in vitro conditions, suggesting a commitment to a neuronal lineage under a sociosexual context. 4. Hormonal and growth factors treatments (brain-derived neurotrophic factor, estradiol, prolactin, oxytocin, and progesterone) affect the generation and differentiation of neurospheres, with dependencies on sex and sociosexual context. 5. Proliferation and neurogenesis in the SVZ may play a crucial role in establishing, enhancing, maintaining, or accelerating pair bond formation.

Stress and DNA Methylation of Blood Leukocytes among Pregnant Latina Women

Latinas experience physical and psychological stressors in pregnancy leading to increased morbidity and higher risk for adverse birth outcomes. Epigenetic changes, including DNA methylation (DNAm), have been proposed as markers to create more refined risk stratification, yet few of these studies have examined these changes in Latinas. We conducted a secondary analysis of stored blood leukocytes of Latina women (n = 58) enrolled in a larger National Institutes of Health funded R01 project (2011-2016). We examined DNAm on eight candidate stress genes to compare physically and psychologically stressed participants to healthy (low stress) participants. We found unique CpGs that were differentially methylated in stressed women early- and mid-pregnancy compared to the healthy group, though none remained significant after FDR correction. Both physical and psychological stress were associated with hypomethylation at two consecutive CpG sites on NR3C1 in early pregnancy and one CpG site on NR3C1 in mid-pregnancy before adjustment. Stress was also associated with hypomethylation at two CpG sites on FKBP5 in early and mid-pregnancy but were no longer significant after FDR adjustment. Though we did not find statistically significant differences in DNAm during pregnancy between stressed and healthy women in this sample, signals were consistent with previous findings. Future work in larger samples should further examine the associations between stress and DNAm in pregnancy as this mechanism may explain underlying perinatal health inequities.

Mini review of molecules involved in altered postnatal neurogenesis in autism

The neurobiology of autism is complex, but emerging research points to potential abnormalities and alterations in neurogenesis. The aim of the present review is to describe the advances in the understanding of the role of selected neurotrophins, neuropeptides, and other compounds secreted by neuronal cells in the processes of postnatal neurogenesis in conjunction with autism. We characterize the fundamental mechanisms of neuronal cell proliferation, generation of major neuronal cell types with special emphasis on neurogenic niches - the subventricular zone and hippocampal areas. We also discuss changes in intracellular calcium levels and calcium-dependent transcription factors in the context of the regulation of neurogenesis and cell fate determination. To sum up, this review provides specific insight into the known association between alterations in the function of the entire spectrum of molecules involved in neurogenesis and the etiology of autism pathogenesis.

Anti-depression-like effect of Mogroside V is related to the inhibition of inflammatory and oxidative stress pathways

Siraitia grosvenorii (SG) is an edible medicinal plant found mainly in Guangxi, China, and Mogroside V (MGV) is the main component of SG extract. Previous research has shown that SG and MGV exert anti-inflammatory, antioxidative and neuroprotective effects. However, it is not clear whether MGV has anti-depression-like effect. In this study, we evaluated the neuroprotective effects and anti-depression-like effect of MGV both in vitro and in vivo. By performing in vitro tests, we evaluated the protective effects of MGV on PC12 cells with corticosterone-induced injury. In vivo tests, we used the chronic unpredictable mild stress (CUMS) depression model. Fluoxetine (10 mg/kg/day) and MGV (10 or 30 mg/kg/day) were administered by gavage for 21 days, and the open field test (OFT), novelty suppressed feeding test (NSFT), Tail suspension test (TST), and forced Swimming test (FST) were used to evaluate the depressive-like behaviors. In addition, we investigated the role of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and anti-inflammatory cytokine (IL-4) in the hippocampal and cortex tissues. The levels of Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-PX) in hippocampal and cortex tissues were also measured. Pathological changes in the hippocampal dentate gyrus and cortex regions were detected by immunofluorescence and Western blotting was used to measure the protein expression of BDNF, TrkB, TNF-α, and AKT. The results showed that MGV had a protective effect on PC12 cells with corticosterone-induced incurred injury. In addition, MGV treatment relieved the depressive symptoms and significantly reduced inflammatory levels (IL-1β, IL-6, and TNF-α). MGV also significantly reduced oxidative stress damage and reduced the levels of apoptosis in hippocampal nerve cells. These results suggested that the anti-depressive effect of MGV may occur through the inhibition of inflammatory and oxidative stress pathways and the BDNF/TrkB/AKT pathway. These findings provide a new concept for the identification of new anti-depressive strategies.

Involvement of brain-derived neurotrophic factor signaling in the pathogenesis of stress-related brain diseases

Neurotrophins including brain-derived neurotrophic factor, BDNF, have critical roles in neuronal differentiation, cell survival, and synaptic function in the peripheral and central nervous system. It is well known that a variety of intracellular signaling stimulated by TrkB, a high-affinity receptor for BDNF, is involved in the physiological and pathological neuronal aspects via affecting cell viability, synaptic function, neurogenesis, and cognitive function. As expected, an alteration of the BDNF/TrkB system is suspected to be one of the molecular mechanisms underlying cognitive decline in cognitive diseases and mental disorders. Recent evidence has also highlighted a possible link between the alteration of TrkB signaling and chronic stress. Furthermore, it has been demonstrated that downregulation of the BDNF/TrkB system and chronic stress have a role in the pathogenesis of Alzheimer's disease (AD) and mental disorders. In this review, we introduce current evidence showing a close relationship between the BDNF/TrkB system and the development of cognition impairment in stress-related disorders, and the possible contribution of the upregulation of the BDNF/TrkB system in a therapeutic approach against these brain diseases.

Dynamic lipidome alterations associated with human health, disease and ageing

Lipids can be of endogenous or exogenous origin and affect diverse biological functions, including cell membrane maintenance, energy management and cellular signalling. Here, we report >800 lipid species, many of which are associated with health-to-disease transitions in diabetes, ageing and inflammation, as well as cytokine-lipidome networks. We performed comprehensive longitudinal lipidomic profiling and analysed >1,500 plasma samples from 112 participants followed for up to 9 years (average 3.2 years) to define the distinct physiological roles of complex lipid subclasses, including large and small triacylglycerols, ester- and ether-linked phosphatidylethanolamines, lysophosphatidylcholines, lysophosphatidylethanolamines, cholesterol esters and ceramides. Our findings reveal dynamic changes in the plasma lipidome during respiratory viral infection, insulin resistance and ageing, suggesting that lipids may have roles in immune homoeostasis and inflammation regulation. Individuals with insulin resistance exhibit disturbed immune homoeostasis, altered associations between lipids and clinical markers, and accelerated changes in specific lipid subclasses during ageing. Our dataset based on longitudinal deep lipidome profiling offers insights into personalized ageing, metabolic health and inflammation, potentially guiding future monitoring and intervention strategies.

Low-dose curcumin enhances hippocampal neurogenesis and memory retention in young mice

Adult neurogenesis generates new functional neurons from adult neural stem cells in various regions, including the subventricular zone (SVZ) of the lateral ventricles and subgranular zone (SGZ) of hippocampal dentate gyrus (DG). Available evidence shows hippocampal neurogenesis can be negatively or positively regulated by dietary components. In a previous study, we reported that curcumin (diferuloylmethane; a polyphenolic found in curry spice) stimulates the proliferation of embryonic neural stem cells (NSCs) by activating adaptive cellular stress responses. Here, we investigated whether subchronic administration of curcumin (once daily at 0.4, 2, or 10 mg/kg for 14 days) promotes hippocampal neurogenesis and neurocognitive function in young (5-week-old) mice. Oral administration of low-dose curcumin (0.4 mg/kg) increased the proliferation and survival of newly generated cells in hippocampus, but surprisingly, high-dose curcumin (10 mg/kg) did not effectively upregulate the proliferation or survival of newborn cells. Furthermore, hippocampal BDNF levels and phosphorylated CREB activity were elevated in only low-dose curcumin-treated mice. Passive avoidance testing revealed that low-dose curcumin increased cross-over latency times, indicating enhanced memory retention, and an in vitro study showed that low-concentration curcumin increased the proliferative activity of neural progenitor cells (NPCs) by upregulating NF1X levels. Collectively, our findings suggest that low-dose curcumin has neurogenic effects and that it may prevent age and neurodegenerative disease-related cognitive deficits.

Mechanisms of Maternal Diet-Induced Obesity Affecting the Offspring Brain and Development of Affective Disorders

Depression and metabolic disease are common disorders that share a bidirectional relationship and continue to increase in prevalence. Maternal diet and maternal behaviour both profoundly influence the developmental trajectory of offspring during the perinatal period. At an epidemiological level, both maternal depression and obesity during pregnancy have been shown to increase the risk of neuropsychiatric disease in the subsequent generation. Considerable progress has been made to understand the mechanisms by which maternal obesity disrupts the developing offspring gut-brain axis, priming offspring for the development of affective disorders. This review outlines such mechanisms in detail, including altered maternal care, the maternal microbiome, inflammation, breast milk composition, and maternal and placental metabolites. Subsequently, offspring may be prone to developing gut-brain interaction disorders with concomitant changes to brain energy metabolism, neurotransmission, and behaviour, alongside gut dysbiosis. The gut microbiome may act as a key modifiable, and therefore treatable, feature of the relationship between maternal obesity and the offspring brain function. Further studies examining the relationship between maternal nutrition, the maternal microbiome and metabolites, and offspring neurodevelopment are warranted to identify novel therapeutic targets.

5-Fluorouracil Induces an Acute Reduction in Neurogenesis and Persistent Neuroinflammation in a Mouse Model of the Neuropsychological Complications of Chemotherapy

The neuropsychological symptoms associated with chemotherapy treatment remain a major challenge with their prevention hampered by insufficient understanding of pathophysiology. While long-term neuroimmune changes have been identified as a hallmark feature shared by neurological symptoms, the exact timeline of mechanistic events preceding neuroinflammation, and the relationship between the glial cells driving this neuroinflammatory response, remain unclear. We therefore aimed to longitudinally characterize the neuroimmunological changes following systemic 5-fluorouracil (5-FU) treatment to gain insight into the timeline of events preceding the well-documented chronic neuroinflammation seen following chemotherapy. Eighteen female C57Bl/6 mice received a single intraperitoneal dose of 5-FU and groups were killed at days 1 and 2 (acute timepoint), days 4 and 8 (subacute timepoint), and days 16 and 32 (chronic timepoint). A further six mice were administered with vehicle control with tissues collected from three mice on day 1 and day 32 of the study. The expression of key genes of interest, BCL2, BDNF, TIMP1, MMP-9, MMP-2, TNFα, IL-1β, and IL-6R were assessed using real time polymerase chain reaction. Levels of neurogenesis were determined through immunofluorescent staining of doublecortin (DCX). The density of microglia and astrocytes were assessed using immunofluorescence staining of Iba1 and GFAP respectively. 5-FU treatment caused significant decreases to DCX staining at acute timepoints (p = 0.0030) which was positively correlated with BCL2 expression levels. An increase to microglial density was observed in the prefrontal cortex (p = 0.0256), CA3 region (p = 0.0283), and dentate gyrus (p = 0.0052) of the hippocampus at acute timepoints. 5-FU caused increases to astrocyte density, across multiple brains regions, at subacute and chronic timepoints which were positively correlated with TNFα, TIMP-1, MMP-2, and IL-6R expression. This study has identified acute objective neuroinflammatory changes suggesting that the role of early intervention should be explored to prevent the development of neuropsychological deficits in the longer-term following chemotherapy.

Dexmedetomidine Attenuates Methotrexate-Induced Neurotoxicity and Memory Deficits in Rats through Improving Hippocampal Neurogenesis: The Role of miR-15a/ROCK-1/ERK1/2/CREB/BDNF Pathway Modulation

Methotrexate (MTX) is a widely used neurotoxic drug with broad antineoplastic and immunosuppressant spectra. However, the exact molecular mechanisms by which MTX inhibits hippocampal neurogenesis are yet unclear. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has recently shown neuroprotective effects; however, its full mechanism is unexplored. This study investigated the potential of Dex to mitigate MTX-induced neurotoxicity and memory impairment in rats and the possible role of the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway. Notably, no former studies have linked this pathway to MTX-induced neurotoxicity. Male Sprague Dawley rats were placed into four groups. Group 1 received saline i.p. daily and i.v. on days 8 and 15. Group 2 received Dex at 10 μg/kg/day i.p. for 30 days. Group 3 received MTX at 75 mg/kg i.v. on days 8 and 15, followed by four i.p. doses of leucovorin at 6 mg/kg after 18 h and 3 mg/kg after 26, 42, and 50 h. Group 4 received MTX and leucovorin as in group 3 and Dex daily dosages as in group 2. Bioinformatic analysis identified the association of miR-15a with ROCK-1/ERK1/2/CREB/BDNF and neurogenesis. MTX lowered hippocampal doublecortin and Ki-67, two markers of neurogenesis. This was associated with the downregulation of miR-15a, upregulation of its target ROCK-1, and reduction in the downstream ERK1/2/CREB/BDNF pathway, along with disturbed hippocampal redox state. Novel object recognition and Morris water maze tests demonstrated the MTX-induced memory deficiencies. Dex co-treatment reversed the MTX-induced behavioral, biochemical, and histological alterations in the rats. These neuroprotective actions could be partly mediated through modulating the miR-15a/ROCK-1/ERK1/2/CREB/BDNF pathway, which enhances hippocampal neurogenesis.

Neuroprotective Effect of Wharton's Jelly-Derived Mesenchymal Stem Cell-Conditioned Medium (WJMSC-CM) on Diabetes-Associated Cognitive Impairment by Improving Oxidative Stress, Neuroinflammation, and Apoptosis

According to strong evidence, diabetes mellitus increases the risk of cognitive impairment. Mesenchymal stem cells have been shown to be potential therapeutic agents for neurological disorders. In the current study, we aimed to examine the effects of Wharton's jelly-derived mesenchymal stem cell-conditioned medium (WJMSC-CM) on learning and memory, oxidative stress, apoptosis, and histological changes in the hippocampus of diabetic rats. Randomly, 35 male Sprague Dawley rats weighing 260-300 g were allocated into five groups: control, diabetes, and three diabetic groups treated with insulin, WJMSC-CM, and DMEM. The injections of insulin (3 U/day, S.C.) and WJMSC-CM (10 mg/week, I.P.) were done for 60 days. The Morris water maze and open field were used to measure cognition and anxiety-like behaviors. Colorimetric assays were used to determine hippocampus glutathione (GSH), malondialdehyde (MDA) levels, and antioxidant enzyme activity. The histopathological evaluation of the hippocampus was performed by Nissl staining. The expression levels of Bax, Bcl-2, BDNF, and TNF-α were detected by real-time polymerase chain reaction (RT-PCR). According to our findings, WJMSC-CM significantly reduced and increased blood glucose and insulin levels, respectively. Enhanced cognition and improved anxiety-like behavior were also found in WJMSC-CM-treated diabetic rats. In addition, WJMSC-CM treatment reduced oxidative stress by lowering MDA and elevating GSH and antioxidant enzyme activity. Reduced TNF-α and enhanced Bcl-2 gene expression levels and elevated neuronal and nonneuronal (astrocytes and oligodendrocytes) cells were detected in the hippocampus of WJMSC-CM-treated diabetic rats. In conclusion, WJMSC-CM alleviated diabetes-related cognitive impairment by reducing oxidative stress, neuroinflammation, and apoptosis in diabetic rats.

Major depression and the biological hallmarks of aging

Major depressive disorder (MDD) is characterized by psychological and physiological manifestations contributing to the disease severity and outcome. In recent years, several lines of evidence have suggested that individuals with MDD have an elevated risk of age-related adverse outcomes across the lifespan. This review provided evidence of a significant overlap between the biological abnormalities in MDD and biological changes commonly observed during the aging process (i.e., hallmarks of biological aging). Based on such evidence, we formulate a mechanistic model showing how abnormalities in the hallmarks of biological aging can be a common denominator and mediate the elevated risk of age-related health outcomes commonly observed in MDD. Finally, we proposed a roadmap for novel studies to investigate the intersection between the biology of aging and MDD, including the use of geroscience-guided interventions, such as senolytics, to delay or improve major depression by targeting biological aging.

Contribution of hippocampal BDNF/CREB signaling pathway and gut microbiota to emotional behavior impairment induced by chronic unpredictable mild stress during pregnancy in rats offspring

Background

Numerous studies have shown that exposure to prenatal maternal stress (PMS) is associated with various psychopathological outcomes of offspring. The accumulating evidence linking bacteria in the gut and neurons in the brain (the microbiota-gut-brain axis) has been aconsensus; however, there is a lack of research on the involvement mechanism of gut microbiota in the regulation of the BDNF/CREB signaling pathway in the hippocampus of prenatally stressed offspring.

Methods

Pregnant rats were subjected to chronic unpredictable mild stress (CUMS) to establish the prenatal maternal stress model. The body weight was measured and the behavioral changes were recorded. Offspring were tested to determine emotional state using sucrose preference test (SPT), open-field test (OFT) and suspended tail test (STT). Gut microbiota was evaluated by sequencing the microbial 16S rRNA V3-V4 region, and the interactive analysis of bacterial community structure and diversity was carried out. The expression of hippocampal BDNF, TrkB and CREB mRNA and proteins were respectively measured using RT-PCR and Western blotting.

Results

Prenatal maternal stress increased maternal plasma corticosterone levels, slowed maternal weight gain and caused depression-like behaviors (all P < 0.05). In offspring, prenatal maternal stress increased plasma corticosterone levels (P < 0.05) and emotional behavior changes (depression-like state) were observed (P < 0.05). The species abundance, diversity and composition of the offspring's gut microbiota changed after the maternal stress during pregnancy (P < 0.05). Compared with the control group's offspring, the species abundance of Lactobacillaceae was dropped, while the abundance of the Muribaculaceae species abundance was risen. Concurrent, changes in the hippocampal structure of the offspring and decreases in expression of BDNF/CREB signaling were noted (P < 0.05).

Conclusions

Prenatal maternal stress leads to high corticosterone status and abnormal emotion behavior of offspring, which may be associated with the abnormal BDNF/CREB signaling in hippocampus of offspring caused by the change of gut microbiota composition.

Pedicularis resupinata Extract Prevents Depressive-like Behavior in Repeated Corticosterone-Induced Depression in Mice: A Preliminary Study

Excessive corticosterone (CORT), resulting from a dysregulated hypothalamic–pituitary–adrenal (HPA) axis, is associated with cognitive impairment and behavioral changes, including depression. In Korean oriental medicine, Pedicularis resupinata is used for the treatment of inflammatory diseases such as rheumatoid arthritis. However, the antidepressant properties of P. resupinata have not been well characterized. Here, the antidepressant-like effects of P. resupinata extract (PRE) were evaluated in terms of CORT-induced depression using in vivo models. HPLC confirmed that acteoside, a phenylethanoid glycoside, was the main compound from PRE. Male ICR mice (8 weeks old) were injected with CORT (40 mg/kg, i.p.) and orally administered PRE daily (30, 100, and 300 mg/kg) for 21 consecutive days. Depressive-like behaviors were evaluated using the open-field test, sucrose preference test, passive avoidance test, tail suspension test, and forced swim test. Treatment with a high dose of PRE significantly alleviated CORT-induced, depressive-like behaviors in mice. Additionally, repeated CORT injection markedly reduced brain-derived neurotrophic factor levels, whereas total glucocorticoid receptor (GR) and GR phosphorylation at serine 211 were significantly increased in the mice hippocampus but improved by PRE treatment. Thus, our findings suggest that PRE has potential antidepressant-like effects in CORT-induced, depressive-like behavior in mice.

Restoration of BDNF, DARPP32, and D2R Expression Following Intravenous Infusion of Human Immature Dental Pulp Stem Cells in Huntington's Disease 3-NP Rat Model

Huntington's disease (HD) is a neurodegenerative inherited genetic disorder, which leads to the onset of motor, neuropsychiatric and cognitive disturbances. HD is characterized by the loss of gamma-aminobutyric acid (GABA)ergic medium spiny neurons (MSNs). To date, there is no treatment for HD. Mesenchymal stem cells (MSCs) provide a substantial therapeutic opportunity for the HD treatment. Herein, we investigated the therapeutic potential of human immature dental pulp stem cells (hIDPSC), a special type of MSC originated from the neural crest, for HD treatment. Two different doses of hIDPSC were intravenously administrated in a subacute 3-nitropropionic acid (3NP)-induced rat model. We demonstrated hIDPSC homing in the striatum, cortex and subventricular zone using specific markers for human cells. Thirty days after hIDPSC administration, the cells found in the brain are still express hallmarks of undifferentiated MSC. Immunohistochemistry quantities analysis revealed a significant increase in the number of BDNF, DARPP32 and D2R positive stained cells in the striatum and cortex in the groups that received hIDPSC. The differences were more expressive in animals that received only one administration of hIDPSC. Altogether, these data suggest that the intravenous administration of hIDPSCs can restore the BDNF, DARPP32 and D2R expression, promoting neuroprotection and neurogenesis.

Flavonoids and intestinal microbes interact to alleviate depression

Flavonoids have a variety of biological activities that are beneficial to human health. However, owing to low bioavailability, most flavonoids exert beneficial effects in the intestine through metabolism by the flora into a variety of structurally different derivatives. Also, flavonoids can modulate the type and structure of intestinal microorganisms to improve human health. It has been reported that the development of depression is accompanied by changes in the type and number of intestinal microorganisms, and gut microbes can significantly improve depressive symptoms through the gut-brain axis. Therefore, the interaction between flavonoids and intestinal microbes to alleviate depression is discussed. © 2021 Society of Chemical Industry.

Relating neurosteroid modulation of inhibitory neurotransmission to behaviour

Studies in the 1980s revealed endogenous metabolites of progesterone and deoxycorticosterone to be potent, efficacious, positive allosteric modulators (PAMs) of the GABA_A receptor (GABA_A R). The discovery that such steroids are locally synthesised in the central nervous system (CNS) promoted the thesis that neural inhibition in the CNS may be "fine-tuned" by these neurosteroids to influence behaviour. In preclinical studies, these neurosteroids exhibited anxiolytic, anticonvulsant, analgesic and sedative properties and, at relatively high doses, induced a state of general anaesthesia, a profile consistent with their interaction with GABA_A Rs. However, realising the therapeutic potential of either endogenous neurosteroids or synthetic "neuroactive" steroids has proven challenging. Recent approval by the Food and Drug Administration of the use of allopregnanolone (brexanolone) to treat postpartum depression has rekindled enthusiasm for exploring their potential as new medicines. Although neurosteroids are selective for GABA_A Rs, they exhibit little or no selectivity across the many GABA_A R subtypes. Nevertheless, a relatively minor population of receptors incorporating the δ-subunit (δ-GABA_A Rs) appears to be an important contributor to their behavioural effects. Here, we consider how neurosteroids acting upon GABA_A Rs influence neuronal signalling, as well as how such effects may acutely and persistently influence behaviour, and explore the case for developing selective PAMs of δ-GABA_A R subtypes for the treatment of psychiatric disorders.

Maternal separation: Does it hold the potential to model consequences of postpartum depression?

The postpartum period is a sensitive time where women are especially vulnerable to develop postpartum depression (PPD), with 10%-15% of women affected. This review investigates whether the maternal separation (MS) paradigm in rodents holds the potential to help to understand mothers suffering from PPD. MS is a well-established stress model to investigate effects on infants, whereas effects on the dam are often overlooked. The database PubMed was searched for studies investigating effects of daily MS within the first weeks after parturition on dams in rats and mice and compared to findings in PPD mothers. MS was categorized as brief MS (5-45 min) with or without handling of pups and long MS (3-4 h and longer). MS alters maternal care, depressive-like behavior, anxiety, and aggression; leads to alterations in neuronal gene expression; and affects hormone and neurotransmitter levels similar to observations in PPD patients. Even though there are disparities between human and rodent mothers, with some results differing in directionality, as well as the reason for separation (self-induced in PPD, externally induced in MS), the overall effects found on neurobiological, hormonal, and behavioral levels mostly coincide. Thus, the MS paradigm can add relevant knowledge to existing PPD animal models, further advancing the study of PPD.

Neurogenesis in the rat neonate's hippocampus with maternal short-term REM sleep deprivation restores by royal jelly treatment

BACKGROUND

Numerous studies have shown the effects of rapid eye movement sleep deprivation (REM-SD) on behavior and brain structures. The impact of REM-SD on learning and memory, thus neurogenesis, has been reported in previous studies. Royal jelly (RJ) is known as the wealthiest biological nutrient with various physiological properties. This study aimed to study the possible effect of RJ on neurogenesis of the rat hippocampus neonates following exposure of mother to REM-SD during pregnancy.

METHODS

Thirty neonate rats from 15 pregnant Wistar rats were used. To induce REM-SD, the flowerpot method was used. The pregnant rats were divided into five groups (n = 3): group 1, no treatment; group 2, REM-SD; groups 3, 4, and 5, REM-SD +RJ. The former group received 72 h REM-SD during pregnancy (days 7, 14, 21), and the latter group received REM-SD + RJ (three trial groups). At week 4, the rat neonates of all groups were sacrificed (n = 6 each group). Their brains were fixed, removed, and prepared for Nissl and Hoechst 33342 staining. By using real time polymerase chain reaction methode the brain-derived neurotrophic factor BDNF gene expression was studied (RT-PCR), brain-derived neurotrophic factor (BDNF) gene expression was studied. The results were analyzed statistically, and the Pv  < .05 was considered significant.

RESULTS

The results showed a significant decrease in the number of neurons in the hippocampus of neonatal rats of REM-SD mothers compared to the neonates of the mother with REM-SD + RJ. REM-SD also led to an increase in apoptosis reaching the neonates from the REM-SD + RJ animals. High expression of BDNF was observed in the hippocampus of the neonates from REM-SD + RJ treated mothers.

CONCLUSION

RJ acts as a neuroprotective agent that could compensate for the effects of REM-SD on learning and memory via restoring neurogenesis.

Comparison of the effects of open vs. closed skill exercise on the acute and chronic BDNF, IGF-1 and IL-6 response in older healthy adults

BACKGROUND

Accumulating evidence shows that physical exercise has a positive effect on the release of neurotrophic factors and myokines. However, evidence regarding the optimal type of physical exercise for these release is still lacking. The aim of this study was to assess the acute and chronic effects of open-skill exercise (OSE) compared to closed-skill exercise (CSE) on serum and plasma levels of brain derived neurotrophic factor (BDNFS, BDNFP), and serum levels of insulin like growth factor 1 (IGF-1), and interleukin 6 (IL-6) in healthy older adults.

METHODS

To investigate acute effects, thirty-eight participants were randomly assigned to either an intervention (badminton (aOSE) and bicycling (aCSE), n  = 24, 65.83 ± 5.98 years) or control group (reading (CG), n  = 14, 67.07 ± 2.37 years). Blood samples were taken immediately before and 5 min after each condition. During each condition, heart rate was monitored. The mean heart rate of aOSE and aCSE were equivalent (65 ± 5% of heart rate reserve). In a subsequent 12-week training-intervention, twenty-two participants were randomly assigned to either a sport-games (cOSE, n  = 6, 64.50 ± 6.32) or a strength-endurance training (cCSE, n  = 9, 64.89 ± 3.51) group to assess for chronic effects. Training intensity for both groups was adjusted to a subjective perceived exertion using the CR-10 scale (value 7). Blood samples were taken within one day after the training-intervention.

RESULTS

BDNFS, BDNFP, IGF-1, and IL-6 levels increased after a single exercise session of 30 min. After 12 weeks of training BDNFS and IL-6 levels were elevated, whereas IGF-1 levels were reduced in both groups. However, only in the cOSE group these changes were significant. We could not find any significant differences between the exercise types.

CONCLUSION

Our results indicate that both exercise types are efficient to acutely increase BDNFS, BDNFP, IGF-1 and IL-6 serum levels in healthy older adults. Additionally, our results tend to support that OSE is more effective for improving basal BDNFS levels after 12 weeks of training.

Short high fat diet triggers reversible and region specific effects in DCX+ hippocampal immature neurons of adolescent male mice

Adolescence represents a crucial period for maturation of brain structures involved in cognition. Early in life unhealthy dietary patterns are associated with inferior cognitive outcomes at later ages; conversely, healthy diet is associated with better cognitive results. In this study we analyzed the effects of a short period of hypercaloric diet on newborn hippocampal doublecortin⁺ (DCX) immature neurons in adolescent mice. Male mice received high fat diet (HFD) or control low fat diet (LFD) from the 5th week of age for 1 or 2 weeks, or 1 week HFD followed by 1 week LFD. After diet supply, mice were either perfused for immunohistochemical (IHC) analysis or their hippocampi were dissected for biochemical assays. Detailed morphometric analysis was performed in DCX⁺ cells that displayed features of immature neurons. We report that 1 week-HFD was sufficient to dramatically reduce dendritic tree complexity of DCX⁺ cells. This effect occurred specifically in dorsal and not ventral hippocampus and correlated with reduced BDNF expression levels in dorsal hippocampus. Both structural and biochemical changes were reversed by a return to LFD. Altogether these studies increase our current knowledge on potential consequences of hypercaloric diet on brain and in particular on dorsal hippocampal neuroplasticity.

The Potential Role of Cytokines and Growth Factors in the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most prominent neurodegenerative diseases, which impairs cognitive function in afflicted individuals. AD results in gradual decay of neuronal function as a consequence of diverse degenerating events. Several neuroimmune players (such as cytokines and growth factors that are key players in maintaining CNS homeostasis) turn aberrant during crosstalk between the innate and adaptive immunities. This aberrance underlies neuroinflammation and drives neuronal cells toward apoptotic decline. Neuroinflammation involves microglial activation and has been shown to exacerbate AD. This review attempted to elucidate the role of cytokines, growth factors, and associated mechanisms implicated in the course of AD, especially with neuroinflammation. We also evaluated the propensities and specific mechanism(s) of cytokines and growth factors impacting neuron upon apoptotic decline and further shed light on the availability and accessibility of cytokines across the blood-brain barrier and choroid plexus in AD pathophysiology. The pathogenic and the protective roles of macrophage migration and inhibitory factors, neurotrophic factors, hematopoietic-related growth factors, TAU phosphorylation, advanced glycation end products, complement system, and glial cells in AD and neuropsychiatric pathology were also discussed. Taken together, the emerging roles of these factors in AD pathology emphasize the importance of building novel strategies for an effective therapeutic/neuropsychiatric management of AD in clinics.

Potential Role of Adult Hippocampal Neurogenesis in Traumatic Brain Injury

Traumatic brain injury (TBI) is a serious cause of disability and death among young and adult individuals, displaying complex pathophysiology including cellular and molecular mechanisms that are not fully elucidated. Many experimental and clinical studies investigated the potential relationship between TBI and the process by which neurons are formed in the brain, known as neurogenesis. Currently, there are no available treatments for TBI's long-term consequences being the search for novel therapeutic targets, a goal of highest scientific and clinical priority. Some studies evaluated the benefits of treatments aimed at improving neurogenesis in TBI. In this scenario, herein, we reviewed current pre-clinical studies that evaluated different approaches to improving neurogenesis after TBI while achieving better cognitive outcomes, which may consist in interesting approaches for future treatments.

Psychological Stresses in Children Trigger Cytokine- and Kynurenine Metabolite-Mediated Abdominal Pain and Proinflammatory Changes

Recurrent abdominal pain (RAP) is a common medically unexplained symptom among children worldwide. However, the biological mechanisms behind the development of functional and behavioral symptoms and changes in blood markers have not been well explored. This study aimed to assess changes in the concentrations of inflammatory markers, including cytokines and tryptophan catabolites, in the serum of children with RAP compared to those with subclinical infections. Children with RAP but without organic diseases were included, and those with asymptomatic intestinal parasitic infections were used as a subclinical infection cohort. Blood samples were collected and used to measure the cytokine profile using Multiplex Immunoassay and tryptophan catabolites using high performance liquid chromatography. Children with RAP showed significantly higher concentrations of serum tumor necrotic factor-α, p<0.05, but lower concentrations of IL-10, p<0.001, IL-6, p<0.001 and brain-derived neurotrophic factors (BDNF) p<0.01. In addition, a significant increase in the metabolite of the kynurenine pathway, 3-hydroxyanthranilic acid (3-HAA) p<0.01, a significant decrease in the concentrations of anthranilic acid (AA) p<0.001, together with an increased ratio of serum 3-HAA to AA (3-HAA/AA) p<0.001, was found in this cohort. These findings indicate the significant activation of the immune system and presence of inflammation in children with RAP than those with subclinical parasitic infections. Moreover, children with RAP tested with the Strengths and Difficulties Questionnaire (SDQ), displayed high psychological problems though these SDQ scores were not statistically associated with measured cytokines and kynurenine metabolites. We however could hypothesize that the pro-inflammatory state together with concomitant low concentrations of BDNF in those children with RAP could play a role in psychological stress and experiencing medically unexplained symptoms.

Neural stem cells derived from primitive mesenchymal stem cells reversed disease symptoms and promoted neurogenesis in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis

Background

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system (CNS). MS affects millions of people and causes a great economic and societal burden. There is no cure for MS. We used a novel approach to investigate the therapeutic potential of neural stem cells (NSCs) derived from human primitive mesenchymal stem cells (MSCs) in an experimental autoimmune encephalomyelitis (EAE) mouse model of MS.

Methods

MSCs were differentiated into NSCs, labeled with PKH26, and injected into the tail vein of EAE mice. Neurobehavioral changes in the mice assessed the effect of transplanted cells on the disease process. The animals were sacrificed two weeks following cell transplantation to collect blood, lymphatic, and CNS tissues for analysis. Transplanted cells were tracked in various tissues by flow cytometry. Immune infiltrates were determined and characterized by H&E and immunohistochemical staining, respectively. Levels of immune regulatory cells, Treg and Th17, were analyzed by flow cytometry. Myelination was determined by Luxol fast blue staining and immunostaining. In vivo fate of transplanted cells and expression of inflammation, astrogliosis, myelination, neural, neuroprotection, and neurogenesis markers were investigated by using immunohistochemical and qRT-PCR analysis.

Results

MSC-derived NSCs expressed specific neural markers, NESTIN, TUJ1, VIMENTIN, and PAX6. NSCs improved EAE symptoms more than MSCs when transplanted in EAE mice. Post-transplantation analyses also showed homing of MSCs and NSCs into the CNS with concomitant induction of an anti-inflammatory response, resulting in reducing immune infiltrates. NSCs also modulated Treg and Th17 cell levels in EAE mice comparable to healthy controls. Luxol fast blue staining showed significant improvement in myelination in treated mice. Further analysis showed that NSCs upregulated genes involved in myelination and neuroprotection but downregulated inflammatory and astrogliosis genes more significantly than MSCs. Importantly, NSCs differentiated into neural derivatives and promoted neurogenesis, possibly by modulating BDNF and FGF signaling pathways.

Conclusions

NSC transplantation reversed the disease process by inducing an anti-inflammatory response and promoting myelination, neuroprotection, and neurogenesis in EAE disease animals. These promising results provide a basis for clinical studies to treat MS using NSCs derived from primitive MSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02563-8.

New Molecular Targets for Antidepressant Drugs

Major depressive disorder (MDD) is a common and severe mental disorder that is usually recurrent and has a high risk of suicide. This disorder manifests not only with psychological symptoms but also multiple changes throughout the body, including increased risks of obesity, diabetes, and cardiovascular disease. Peripheral markers of oxidative stress and inflammation are elevated. MDD is therefore best described as a multisystem whole-body disease. Pharmacological treatment with antidepressants usually requires several weeks before the desired effects manifest. Previous theories of depression, such as the monoamine or neurogenesis hypotheses, do not explain these characteristics well. In recent years, new mechanisms of action have been discovered for long-standing antidepressants that also shed new light on depression, including the sphingolipid system and the receptor for brain-derived neurotrophic factor (BDNF).

The Prostate Cancer Therapy Enzalutamide Compared with Abiraterone Acetate/Prednisone Impacts Motivation for Exploration, Spatial Learning and Alters Dopaminergic Transmission in Aged Castrated Mice

Simple Summary

Cognitive side effects and fatigue after cancer treatment now constitute a major challenge in oncology. Abiraterone acetate plus prednisone (AAP) and enzalutamide (ENZ) are next-generation therapies improving metastatic castration-resistant prostate cancer (mCRPC) patient survival, but also associated with neurological disturbances. We developed a behavioral 17 months-aged and castrated mouse model receiving AAP or ENZ for 5 days per week for six weeks. We establish that ENZ impacts locomotor and explorative behaviors, and strength capacity likely by preventing binding of central synthetized androgens to androgen receptors expressed by dopamine neurons of the Substantia Nigra and the Ventral Tegmentum. ENZ also reduces the cognitive score, associated with less neuronal activity in dorsal hippocampal areas. This demonstrates ENZ-specific consequences on motivation to exploration and cognition, being of particular importance for future management of elderly prostate cancer patients and their quality of life.

Abstract

Cognitive side effects after cancer treatment threatening quality of life (QoL) constitute a major challenge in oncology. Abiraterone acetate plus prednisone (AAP) and enzalutamide (ENZ) are examples of next-generation therapy (NGT) administered to metastatic castration-resistant prostate cancer (mCRPC) patients. NGT significantly improved mCRPC overall survival but neurological side effects such as fatigue and cognitive impairment were reported. We developed a behavioral 17 months-aged and castrated mouse model receiving per os AAP or ENZ for 5 days per week for six consecutive weeks. ENZ exposure reduced spontaneous activity and exploratory behavior associated with a decreased tyrosine hydroxylase (TH)-dopaminergic activity in the substantia nigra pars compacta and the ventral tegmental area. A decrease in TH⁺-DA afferent fibers and Phospho-DARPP32-related dopaminergic neuronal activities in the striatum and the ventral hippocampus highlighted ENZ-induced dopaminergic regulation within the nigrostriatal and mesolimbocortical pathways. ENZ and AAP treatments did not substantially modify spatial learning and memory performances, but ENZ led to a thygmotaxis behavior impacting the cognitive score, and reduced c-fos-related activity of NeuN⁺-neurons in the dorsal hippocampus. The consequences of the mCRPC treatment ENZ on aged castrated mouse motivation to exploration and cognition should make reconsider management strategy of elderly prostate cancer patients.

Effect of acute psychosocial stress on the brain-derived neurotrophic factor in humans - a randomized cross within trial

The brain-derived neurotrophic factor (BDNF) is involved in the plasticity and development of the central nervous system. Thereby the protein synthesis is highly related to neuronal activity, and its signaling pathways are associated with several substances like, e.g. glucocorticoids, which seem to be able to activate BDNF-Tropomyosin receptor kinase B (TrkB). While there is evidence that acute physical stress can result in advantageous physiological outcomes like an enhanced BDNF level, outcome parameters in response to psychosocial stress are primarily focused on psychological parameters. The existing literature pointing on the impact of acute psychosocial stress on physiological parameters is controversial and differs depending on the species, the stressor used, and the study methodology. It was hypothesized that an acute standardized psychosocial stressor would increase the BDNF level and therefore show beneficial physiological outcome parameters through psychosocial stress. The serum BDNF levels of 32 healthy young males (M = 24.31 years of age, SD = 3.35), who performed the Trier Social Stress Test (TSST), were assessed and compared to a control condition. To prove the stress-generating effect of the TSST, additional cortisol levels were measured. Acute psychosocial stress significantly increased the serum BDNF- and the cortisol-level, whereby no alteration was found during the control. This study expands the rare literature focusing on the effect of an acute standardized psychosocial stressor on the BDNF level in healthy humans, including a control condition. Implications for future studies are being discussed.

Effects of stress associated with academic examination on the kynurenine pathway profile in healthy students

The effects of stress on the neuroendocrine, central nervous and immune systems are extremely complex. The kynurenine pathway (KP) of the tryptophan metabolism is recognised as a cross-link between the neuroendocrine- and immune systems. However, the effects of acute stress from everyday life on KP activation have not yet been studied. This study aims to investigate changes in the levels of the KP neuroactive metabolites and cytokines in response to stress triggered by academic examinations. Ninety-two healthy first year medical students benevolently participated in the study. Parameters were measured pre- examination, which is considered to be a high-stress period, and post-examination, as a low-stress period. Stress induced by academic examinations significantly increases the perceived stress scores (p<0.001), serum cortisol levels (p<0.001) and brain-derived neurotrophic factor (BDNF) levels (p<0.01). It decreased IL-10 levels (p<0.05) but had no effect on IL-6 and TNF-alpha levels. Only the KP neuroactive metabolite, 3-hydroxykynurenine (3-HK) significantly increased (p<0.01) in the post-examination period. In addition, the stress scores positively correlated with the levels of cortisol (r² = 0.297, p<0.01) at post examination. Acute stress triggered by academic examinations increases cortisol and BDNF production and suppresses the anti-inflammatory cytokine, IL-10, but did not increase significantly the levels of other pro-inflammatory cytokines, tryptophan, kynurenine and downstream KP metabolites. The concomitant increased levels of BDNF under the duress of acute examination stress appear to limit the levels pro-inflammatory markers, which may attenuate the action of cortisol and the neuroinflammatory branch of the KP.

Adverse Maternal Environment Alters MicroRNA-10b-5p Expression and Its Epigenetic Profile Concurrently with Impaired Hippocampal Neurogenesis in Male Mouse Hippocampus

An adverse maternal environment (AME) predisposes adult offspring toward cognitive impairment in humans and mice. However, the underlying mechanisms remain poorly understood. Epigenetic changes in response to environmental exposure may be critical drivers of this change. Epigenetic regulators, including microRNAs, have been shown to affect cognitive function by altering hippocampal neurogenesis which is regulated in part by brain-derived neurotropic factor (BDNF). We sought to investigate the effects of AME on miR profile and their epigenetic characteristics, as well as neurogenesis and BDNF expression in mouse hippocampus. Using our mouse model of AME which is composed of maternal Western diet and prenatal environmental stress, we found that AME significantly increased hippocampal miR-10b-5p levels. We also found that AME significantly decreased DNA methylation and increased accumulations of active histone marks H3 lysine (K) 4me3, H3K14ac, and -H3K36me3 at miR-10b promoter. Furthermore, AME significantly decreased hippocampal neurogenesis by decreasing cell numbers of Ki67+ (proliferation marker), NeuroD1+ (neuronal differentiation marker), and NeuN+ (mature neuronal marker) in the dentate gyrus (DG) region concurrently with decreased hippocampal BDNF protein levels. We speculate that the changes in epigenetic profile at miR-10b promoter may contribute to upregulation of miR-10b-5p and subsequently lead to decreased BDNF levels in a model of impaired offspring hippocampal neurogenesis and cognition in mice.

Effect of neural therapy on NGF and BDNF serum levels in patients with chronic pain. A pilot study

Introduction: Neurotrophins (NT) are a family of proteins consisting of the nerve growth factor (NGF), the brain-derived neurotrophic factor (BDNF) and NT-3 and NT-4/5. These proteins play an essential role in neuronal survival, differentiation, and proliferation. Objectives: To analyze the variations of NGF and BDNF serum levels in patients with chronic pain after undergoing neural therapy and to establish the effects of this type of intervention on their quality of life. Materials and methods: Prospective pilot study conducted in 10 patients with chronic pain treated with neural therapy between July 2017 and April 2018 in Bogotá D.C., Colombia. Three consultations were performed (one in which the intervention was initiated, and two follow-up visits every three weeks). During each consultation, the patients’ quality of life was assessed using the SF-12 scale and their NGF and BDNF serum levels were measured. Data were analyzed by means of descriptive statistics, using medians and interquartile ranges for quantitative variables, and absolute frequencies and percentages for qualitative variables. Results: The median score on the SF-12 scale tended to improve in the first and second follow-up visits compared with the baseline score (pre-intervention), particularly during the first follow-up visit (consultation No. 1: 34.5; follow-up No. 1: 39.5, and follow-up No. 2: 38). Median NGF serum levels had a downward trend after the intervention, particularly in the first follow-up visit (157.6, 42.95, and 237.8, respectively), and in the case of BNDF, an overall downward trend was also found (29.96, 19.24 and 20.43, respectively). An improvement in quality of life related to the decrease in the serum levels of both neurotrophins was observed. Conclusion: Neural therapy intervention reduced NGF and BDNF serum levels and improved the quality of life of the participants. Therefore, the behavior of these neurotrophins could become a biomarker for the diagnosis, treatment, and follow-up of patients with chronic pain.

Effects of high-intensity interval training and flaxseed oil supplement on learning, memory and immobility: relationship with BDNF and TrkB genes

This study examined the independent and combined effects of high-intensity interval training (HIIT) and flaxseed oil supplementation on cognitive/executive functions in middle-aged rats. Hippocampal neurotropic brain factor (BDNF) and tyrosine kinase receptor B (TrkB) gene expression were also measured. Animals were randomly divided into groups including no exercise control and saline (CS), no exercise control and flaxseed oil supplement (CF), exercise training-and saline (TS) and exercise training and flaxseed oil supplement (TF). The training groups undertook a program of HIIT (10 weeks, five sessions per week) and the supplement groups received flaxseed oil supplement (300 mg/kg). The results showed that HIIT and flaxseed oil supplementation independently had positive effects on memory and learning (P<0.05). HIIT and flaxseed oil independently decreased immobility behaviour and increased hippocampal BDNF and TrkB genes expression (P<0.05). HIIT and flaxseed oil combination had a greater effect on some variables (hippocampal TrkB gene expression, memory and immobility) compared to each intervention alone (P<0.05). In conclusion, HIIT and flaxseed oil can independently improve cognitive/executive functions. In addition, HIIT had a greater positive effect than flaxseed oil supplementation on memory and immobility. The combination of HIIT and flaxseed oil supplement had a more positive effect compared to each intervention alone on memory, and immobility. Hippocampal BDNF gene expression did not significantly differ in the combination or independent groups. Thus, future work is needed on several other genes in different segments of the brain to find the additive-mechanisms involved in memory and immobility regulation and younger and older species of rat should be examined.

Transplantation of 3D MSC/HUVEC spheroids with neuroprotective and proangiogenic potentials ameliorates ischemic stroke brain injury

Ischemic stroke, and the consequent brain cell death, is a common cause of death and disability worldwide. Current treatments that primarily aim to relieve symptoms are relatively inefficient in achieving brain tissue regeneration and functional recovery, and thus novel therapeutic options are urgently needed. Although cell-based therapies have shown promise for treating the infarcted brain, a recurring challenge is the inadequate retention and engraftment of transplanted cells at the target tissue, thereby limiting the ultimate therapeutic efficacy. Here, we show that transplantation of preassembled three-dimensional (3D) spheroids of mesenchymal stem cells (MSCs) and vascular endothelial cells (ECs) results in significantly improved cell retention and survival compared with conventional mixed-cell suspensions. The transplanted 3D spheroids exhibit notable neuroprotective, proneurogenic, proangiogenic and anti-scarring potential as evidenced by clear extracellular matrix structure formation and paracrine factor expression and secretion; this ultimately results in increased structural and motor function recovery in the brain of an ischemic stroke mouse model. Therefore, transplantation of MSCs and ECs using the 3D cell spheroid configuration not only reduces cell loss during cell harvesting/administration but also enhances the resultant therapeutic benefit, thus providing important proof-of-concept for future clinical translation.

Quercetin alleviates chronic unpredictable mild stress-induced depressive-like behaviors by promoting adult hippocampal neurogenesis via FoxG1/CREB/ BDNF signaling pathway

Quercetin, a naturally occurring flavonoid, has been reported to exert antidepressant effects, however, the underlying mechanisms are still uncertain. Recent studies have demonstrated that Forkhead box transcription factor G1 (FoxG1) regulates the process of adult hippocampal neurogenesis (AHN) and exerts neuroprotective effects. In this study, we explored whether quercetin plays an anti-depressant role via regulation of FoxG1 signaling in mice and revealed the potential mechanisms. To explore the antidepressant effects of quercetin, mice were subjected to behavioral tests after a chronic unpredictable mild stress (CUMS) exposure. We found that chronic quercetin treatment (15 mg/kg, 30 mg/kg) obviously restored the weight loss of mice caused by CUMS and alleviated CUMS-induced depression-like behaviors, such as increased sucrose consumption, improved locomotor activity and shorten immobility time. In addition, to clarify the relationship between quercetin and AHN, we detected neurogenesis markers in the dentate gyrus (DG) of the hippocampus. Furthermore, FoxG1-siRNA was employed and then stimulated with quercetin to further investigate the mechanism by which FoxG1 participates in the antidepressant effects of quercetin. Our results indicate that chronic quercetin treatment dramatically increased the number of doublecortin (DCX)-positive and BrdU/NeuN-double positive cells. Besides, the expression levels of FoxG1, p-CREB and Brain-derived neurotrophic factor (BDNF) were also enhanced by quercetin in the DG. Strikingly, quercetin failed to reverse the levels of p-CREB and BDNF after FoxG1-siRNA was performed in SH-SY5Y cells and Neural Progenitor Cells (NPCs). Our results thus far suggest that quercetin might exert antidepressant effects via promotion of AHN by FoxG1/CREB/ BDNF signaling pathway.

Family-effects in the epigenomic response of red blood cells to a challenge test in the European sea bass (Dicentrarchus labrax, L.)

Abstract

Background

In fish, minimally invasive blood sampling is widely used to monitor physiological stress with blood plasma biomarkers. As fish blood cells are nucleated, they might be a source a potential new markers derived from ‘omics technologies. We modified the epiGBS (epiGenotyping By Sequencing) technique to explore changes in genome-wide cytosine methylation in the red blood cells (RBCs) of challenged European sea bass (Dicentrarchus labrax), a species widely studied in both natural and farmed environments.

Results

We retrieved 501,108,033 sequencing reads after trimming, with a mean mapping efficiency of 73.0% (unique best hits). Minor changes in RBC methylome appeared to manifest after the challenge test and a family-effect was detected. Only fifty-seven differentially methylated cytosines (DMCs) close to 51 distinct genes distributed on 17 of 24 linkage groups (LGs) were detected between RBCs of pre- and post-challenge individuals. Thirty-seven of these genes were previously reported as differentially expressed in the brain of zebrafish, most of them involved in stress coping differences. While further investigation remains necessary, few DMC-related genes associated to the Brain Derived Neurotrophic Factor, a protein that favors stress adaptation and fear memory, appear relevant to integrate a centrally produced stress response in RBCs.

Conclusion

Our modified epiGBS protocol was powerful to analyze patterns of cytosine methylation in RBCs of D. labrax and to evaluate the impact of a challenge using minimally invasive blood samples. This study is the first approximation to identify epigenetic biomarkers of exposure to stress in fish.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07420-9.

Peripheral blood neurotrophic factor levels in children with autism spectrum disorder: a meta-analysis

Increasing evidence suggests that abnormal regulation of neurotrophic factors is involved in the etiology and pathogenesis of Autism Spectrum Disorder (ASD). However, clinical data on neurotrophic factor levels in children with ASD were inconsistent. Therefore, we performed a systematic review of peripheral blood neurotrophic factors levels in children with ASD, and quantitatively summarized the clinical data of peripheral blood neurotrophic factors in ASD children and healthy controls. A systematic search of PubMed and Web of Science identified 31 studies with 2627 ASD children and 4418 healthy controls to be included in the meta-analysis. The results of random effect meta-analysis showed that the peripheral blood levels of brain-derived neurotrophic factor (Hedges’ g = 0.302; 95% CI = 0.014 to 0.591; P = 0.040) , nerve growth factor (Hedges’ g = 0.395; 95% CI = 0.104 to 0.686; P = 0.008) and vascular endothelial growth factor (VEGF) (Hedges’ g = 0.097; 95% CI = 0.018 to 0.175; P = 0.016) in children with ASD were significantly higher than that of healthy controls, whereas blood neurotrophin-3 (Hedges’ g =  − 0.795; 95% CI =  − 1.723 to 0.134; P = 0.093) and neurotrophin-4 (Hedges’ g = 0.182; 95% CI =  − 0.285 to 0.650; P = 0.445) levels did not show significant differences between cases and controls. Taken together, these results clarified circulating neurotrophic factor profile in children with ASD, strengthening clinical evidence of neurotrophic factor aberrations in children with ASD.

Sulfoquinovosyl oleoyl palmitoyl glycerol (SQDG) and hexane extract of Sargassum plagyophylum prevent depression induced by dexamethasone or stress in mice

Introduction: M Glucocorticoids and stress are a leading cause of depression by dysregulation of hypothalamic hypophyseal adrenal axis. Sargassum plagyophylum hexane extract (HxE) has proven antidepressant-like effects in mice. We aimed at evaluating HxE and sulfoquinovosyl oleoyl palmitoyl glycerol (SQDG) isolated compound antidepressant effects following dexamethasone (Dex) or water avoidance stress (WAS) induced depression in mice. Methods: The HxE was prepared and fractionated by different chromatography methods to isolate active compounds. Depression was induced in male mice by Dex single dose or by four days of WAS. After the locomotor test, depression was assessed by measuring the immobility time during the forced swimming test (FST) and sucrose preference test. Results: 6-Deoxy-6-sulpho-α-D-glucopyranosyl-1,2-O-diacyl-glycerol was isolated and elucidated from the seaweed. The manipulations did not cause important changes in animals’ locomotor activity. During FST, immobility time increased dramatically by Dex (193 ± 13 s vs control 109 ± 7 s) or WAS (189 ± 13 s vs sham 86 ± 14 s), that indicated depression. HxE 40 mg/kg reduced the immobility time when it was administered with Dex (110 ± 28 s, P < 0.01 vs Dex alone) or together with WAS (86 ± 11 s, P < 0.001 vs WAS). SQDG 40 mg/kg reduced the immobility time when co-administered with Dex (22 ± 9 s, P < 0.001 vs Dex alone) and when it was administered along with WAS (68 ± 16 s, P < 0.001 vs WAS). The results of the sucrose preference test were in line with FST results as sucrose preference below 65% was considered for anhedonia. Conclusion: SQDG and probably the steroid content in S. plagyophylum HxE prevented depression in mice; thus, they should be considered for further clinical evaluations.

Neurobiology of zinc and its role in neurogenesis

BACKGROUND

Zinc (Zn) has a diverse role in many biological processes, such as growth, immunity, anti-oxidation system, homeostatic, and repairing. It acts as a regulatory and structural catalyst ion for activities of various proteins, enzymes, and signal transcription factors, as well as cell proliferation, differentiation, and survival. The Zn ion is essential for neuronal signaling and is mainly distributed within presynaptic vesicles. Zn modulates neuronal plasticity and synaptic activity in both neonatal and adult stages. Alterations in brain Zn status results in a dozen neurological diseases including impaired brain development. Numerous researchers are working on neurogenesis, however, there is a paucity of knowledge about neurogenesis, especially in neurogenesis in adults. Neurogenesis is a multifactorial process and is regulated by many metal ions (e.g. Fe, Cu, Zn, etc.). Among them, Zn has an essential role in neurogenesis. At the molecular level, Zn controls cell cycle, apoptosis, and binding of DNA and several proteins including transcriptional and translational factors. Zn is needed for protein folding and function and Zn acts as an anti-apoptotic agent; organelle stabilizer; and an anti-inflammatory agent. Zn deficiency results in aging, neurodegenerative disease, immune deficiency, abnormal growth, cancer, and other symptoms. Prenatal deficiency of Zn results in developmental disorders in humans and animals.

CONCLUSION

Both in vitro and in vivo studies have shown an association between Zn deficiency and increased risk of neurological disorders. This article reviews the existing knowledge on the role of Zn and its importance in neurogenesis.

Neutral Sphingomyelinase is an Affective Valence-Dependent Regulator of Learning and Memory

Sphingolipids and enzymes of the sphingolipid rheostat determine synaptic appearance and signaling in the brain, but sphingolipid contribution to normal behavioral plasticity is little understood. Here we asked how the sphingolipid rheostat contributes to learning and memory of various dimensions. We investigated the role of these lipids in the mechanisms of two different types of memory, such as appetitively and aversively motivated memory, which are considered to be mediated by different neural mechanisms. We found an association between superior performance in short- and long-term appetitively motivated learning and regionally enhanced neutral sphingomyelinase (NSM) activity. An opposite interaction was observed in an aversively motivated task. A valence-dissociating role of NSM in learning was confirmed in mice with genetically reduced NSM activity. This role may be mediated by the NSM control of N-methyl-d-aspartate receptor subunit expression. In a translational approach, we confirmed a positive association of serum NSM activity with long-term appetitively motivated memory in nonhuman primates and in healthy humans. Altogether, these data suggest a new sphingolipid mechanism of de-novo learning and memory, which is based on NSM activity.

Cryptotanshinone ameliorates CUS-induced depressive-like behaviors in mice

Objectives

Cryptotanshinone (CPT), a natural quinoid diterpene, isolated from Salvia miltiorrhiza, has shown various pharmacological properties. However, its effect on chronic unpredictable stress (CUS)-induced depression phenotypes and the underlying mechanism remain unclear. Therefore, the aim of this study was to investigate whether CPT could exert an antidepressant effect.

Methods

We investigated the effects of CPT in a CUS-induced depression model and explored whether these effects were related to the anti-inflammatory and neurogenesis promoting properties by investigating the expression levels of various signaling molecules at the mRNA and protein levels.

Results

Administration of CPT improved depression-like behaviors in CUS-induced mice. CPT administration increased the levels of doublecortin-positive cells and reversed the decrease in the expression levels of brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) signaling transduction, as well as the downstream functional proteins, phosphorylated extracellular regulated protein kinases (p-ERK), and cyclic adenosine monophosphate (cAMP)-response element-binding protein levels (p-CREB) in hippocampus. CPT treatment also inhibited the activation of microglia and suppressed M1 microglial polarization, while promoting M2 microglial polarization by monitoring the expression levels of arginase 1 (Arg-1) and inducible nitric oxide synthase (iNOS), and further inhibited the expression of proinflammatory cytokines, including interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α), and increased the expression of the anti-inflammatory cytokine IL-10 by regulating nuclear factor-κB (NF-κB) activation.

Conclusions

CPT relieves the depressive-like state in CUS-induced mice by enhancing neurogenesis and inhibiting inflammation through the BDNF/TrkB and NF-κB pathways and could therefore serve as a promising candidate for the treatment of depression.

Glucocorticoid-mediated mechanisms of hippocampal damage: Contribution of subgranular neurogenesis

A comprehensive overview of the interplay between glucocorticoids (GCs) and adult hippocampal neurogenesis (AHN) is presented, particularly, in the context of a diseased brain. The effectors of GCs in the dentate gyrus neurogenic niche of the hippocampal are reviewed, and the consequences of the GC signaling on the generation and integration of new neurons are discussed. Recent findings demonstrating how GC signaling mediates impairments of the AHN in various brain pathologies are overviewed. GC-mediated effects on the generation and integration of adult-born neurons in the hippocampal dentate gyrus depend on the nature, severity, and duration of the acting stress factor. GCs realize their effects on the AHN primarily via specific glucocorticoid and mineralocorticoid receptors. Disruption of the reciprocal regulation between the hypothalamic-pituitary-adrenal (HPA) axis and the generation of the adult-born granular neurons is currently considered to be a key mechanism implicating the AHN into the pathogenesis of numerous brain diseases, including those without a direct hippocampal damage. These alterations vary from reduced proliferation of stem and progenitor cells to increased cell death and abnormalities in morphology, connectivity, and localization of young neurons. Although the involvement of the mutual regulation between the HPA axis and the AHN in the pathogenesis of cognitive deficits and mood impairments is evident, several unresolved critical issues are stated. Understanding the details of GC-mediated mechanisms involved in the alterations in AHN could enable the identification of molecular targets for ameliorating pathology-induced imbalance in the HPA axis/AHN mutual regulation to conquer cognitive and psychiatric disturbances.