Melatonin ameliorates cuprizone-induced reduction of hippocampal neurogenesis, brain-derived neurotrophic factor, and phosphorylation of cyclic AMP response element-binding protein in the mouse dentate gyrus

Therapeutic Options of Crystallin Mu and Protein Disulfide Isomerase A3 for Cuprizone-Induced Demyelination in Mouse Hippocampus

This study investigates the changes in hippocampal proteomic profiles during demyelination and remyelination using the cuprizone model. Employing two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry for protein profiling, we observed significant alterations in the expression of ketimine reductase mu-crystallin (CRYM) and protein disulfide isomerase A3 precursor (PDIA3) following exposure to and subsequent withdrawal from cuprizone. Immunohistochemical staining validated these protein expression patterns in the hippocampus, revealing that both PDIA3 and CRYM were downregulated in the hippocampal CA1 region during demyelination and upregulated during remyelination. Additionally, we explored the potential protective effects of CRYM and PDIA3 against cuprizone-induced demyelination by synthesizing cell-permeable Tat peptide-fusion proteins (Tat-CRYM and Tat-PDIA3) to facilitate their crossing through the blood-brain barrier. Our results indicated that administering Tat-CRYM and Tat-PDIA3 mitigated the reduction in proliferating cell and differentiated neuroblast counts compared to the group receiving cuprizone alone. Notably, Tat-PDIA3 demonstrated significant effects in enhancing myelin basic protein expression alongside phosphorylation of CREB in the hippocampus, suggesting its potential therapeutic role in the prevention or treatment of demyelination, and by extension, in conditions such as multiple sclerosis.

Comparative Neuroprotective Potential of Nanoformulated and Free Resveratrol Against Cuprizone-Induced Demyelination in Rats

Demyelination is a frequent yet crippling neurological disease associated with multiple sclerosis (MS). The cuprizone (CZ) model, which causes demyelination through oxidative stress and neuroinflammation, is a popular tool used by researchers to examine this process. The polyphenol resveratrol (RESV) has become a promising neuroprotective agent in seeking for efficient therapies. In a rat model given CZ, we created and examined iron oxide nanoparticles (IONPs) loaded with RESV (IONP-RESV) to see how effective they were as a therapeutic agent against free RESV. According to molecular mechanisms, exposure to CZ resulted in a marked downregulation of myelin proteolipid protein (PLP) expression and an overexpression of the inflammatory markers tumor necrosis factor-α (TNF-α) and S100β, which are indicators of demyelination and neuroinflammation. It is remarkable that these CZ-induced alterations could be reversed by therapy with either RESV or IONP-RESV. Interestingly, IONP-RESV showed even stronger anti-inflammatory activity, as shown by a more noticeable downregulation of TNF-α and S100β expression. These results were confirmed by histopathological examination of the cerebral cortices. Our findings support the better neuroprotective benefits of RESV-loaded IONPs over free RESV in reducing demyelination and neuroinflammation brought on by CZ. Owing to their pro-remyelinating, anti-inflammatory, and antioxidant properties, RESV-loaded IONPs show promise as a neurotherapeutic intervention in the future for neurological diseases such as multiple sclerosis.

Potential therapeutic value of melatonin in diabetic nephropathy: improvement beyond anti-oxidative stress

Diabetic nephropathy (DN) is a common complication of diabetes, and it is also the main cause of chronic renal failure. Physiological/pathological changes mediated by high glucose are the main factors causing injury of DN, including the enhancement of polyol pathway, the accumulation of advanced glycation products (AGEs), and the activation of protein kinase C (PKC) and transforming growth factor-β (TGF-β) signals. In addition, the abnormal activation of renin-angiotensin system (RAS) and oxidative stress are also involved. Melatonin is a physiological hormone mainly secreted by the pineal gland which has been proved to be related to diabetes. Studies have shown that exogenous melatonin intervention can reduce blood glucose and alleviate high glucose mediated pathological damage. At the same time, melatonin also has a strong antioxidant effect, and can inhibit the activation of RAS. Therefore, it is of great significance to explore the therapeutic effect and value of melatonin on DN.

The neuroprotective effects of Chalcones from Ashitaba on cuprizone-induced demyelination via modulation of brain-derived neurotrophic factor and tumor necrosis factor α

INTRODUCTION

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. However, the limitations of available therapeutic strategies are frustrating, both in terms of their low efficacy and multiple side effects. Previous studies showed that natural compounds such as Chalcones possess neuroprotective effects on neurodegenerative disorders. However, few studies have so far been published on the potential effects of Chalcones on treating demyelinating disease. The present study was designed to investigate the effects of Chalcones from Ashitaba (ChA) on cuprizone-induced noxious changes in the C57BL6 mice model of MS.

METHODS

The mice received normal diets (Control group: CNT), or Cuprizone-supplemented diets either without ChA (Cuprizone group: CPZ) or with low or high (300, 600 mg/kg/day) doses of ChA (ChA-treated groups: CPZ+ChA300/600). Brain-derived neurotrophic factor (BDNF) and tumor necrosis factor alpha (TNFα) levels, demyelination scores in the corpus callosum (CC), and cognitive impairment were evaluated using the enzyme-linked immunosorbent assay, histological, and Y-maze tests, respectively.

RESULTS

The findings showed that ChA Co-treatment significantly reduced the extent of demyelination in the CC and the serum and brain levels of TNFα in the ChA-treated groups compared to the CPZ group. Besides, treatment with a higher dose of ChA significantly improved the behavioral responses and BDNF levels in the serum and brain of the CPZ+ChA600 group when compared with the CPZ group.

CONCLUSION

The present study provided evidence for the neuroprotective effects of ChA on cuprizone-induced demyelination and behavioral dysfunction in C57BL/6 mice, possibly by modulating TNFα secretion and BDNF expression.

Benefits of the Neurogenic Potential of Melatonin for Treating Neurological and Neuropsychiatric Disorders

There are several neurological diseases under which processes related to adult brain neurogenesis, such cell proliferation, neural differentiation and neuronal maturation, are affected. Melatonin can exert a relevant benefit for treating neurological disorders, given its well-known antioxidant and anti-inflammatory properties as well as its pro-survival effects. In addition, melatonin is able to modulate cell proliferation and neural differentiation processes in neural stem/progenitor cells while improving neuronal maturation of neural precursor cells and newly created postmitotic neurons. Thus, melatonin shows relevant pro-neurogenic properties that may have benefits for neurological conditions associated with impairments in adult brain neurogenesis. For instance, the anti-aging properties of melatonin seem to be linked to its neurogenic properties. Modulation of neurogenesis by melatonin is beneficial under conditions of stress, anxiety and depression as well as for the ischemic brain or after a brain stroke. Pro-neurogenic actions of melatonin may also be beneficial for treating dementias, after a traumatic brain injury, and under conditions of epilepsy, schizophrenia and amyotrophic lateral sclerosis. Melatonin may represent a pro-neurogenic treatment effective for retarding the progression of neuropathology associated with Down syndrome. Finally, more studies are necessary to elucidate the benefits of melatonin treatments under brain disorders related to impairments in glucose and insulin homeostasis.

Cu,Zn-Superoxide Dismutase has Minimal Effects Against Cuprizone-Induced Demyelination, Microglial Activation, and Neurogenesis Defects in the C57BL/6 Mouse Hippocampus

Cuprizone causes consistent demyelination and oligodendrocyte damage in the mouse brain. Cu,Zn-superoxide dismutase 1 (SOD1) has neuroprotective potential against various neurological disorders, such as transient cerebral ischemia and traumatic brain injury. In this study, we investigated whether SOD1 has neuroprotective effects against cuprizone-induced demyelination and adult hippocampal neurogenesis in C57BL/6 mice, using the PEP-1-SOD1 fusion protein to facilitate the delivery of SOD1 protein into hippocampal neurons. Eight weeks feeding of cuprizone-supplemented (0.2%) diets caused a significant decrease in myelin basic protein (MBP) expression in the stratum lacunosum-moleculare of the CA1 region, the polymorphic layer of the dentate gyrus, and the corpus callosum, while ionized calcium-binding adapter molecule 1 (Iba-1)-immunoreactive microglia showed activated and phagocytic phenotypes. In addition, cuprizone treatment reduced proliferating cells and neuroblasts as shown using Ki67 and doublecortin immunostaining. Treatment with PEP-1-SOD1 to normal mice did not show any significant changes in MBP expression and Iba-1-immunoreactive microglia. However, Ki67-positive proliferating cells and doublecortin-immunoreactive neuroblasts were significantly decreased. Simultaneous treatment with PEP-1-SOD1 and cuprizone-supplemented diets did not ameliorate the MBP reduction in these regions, but mitigated the increase of Iba-1 immunoreactivity in the corpus callosum and alleviated the reduction of MBP in corpus callosum and proliferating cells, not neuroblasts, in the dentate gyrus. In conclusion, PEP-1-SOD1 treatment only has partial effects to reduce cuprizone-induced demyelination and microglial activation in the hippocampus and corpus callosum and has minimal effects on proliferating cells in the dentate gyrus.

Is S100B Involved in Attention-Deficit/Hyperactivity Disorder (ADHD)? Comparisons with Controls and Changes Following a Triple Therapy Containing Methylphenidate, Melatonin and ω-3 PUFAs

BACKGROUND

Increasing evidence supports a neuroinflammatory basis in ADHD damaging glial function and thereby altering dopaminergic (DA) neurotransmission. Previous studies focusing on the S100B protein as a marker of glial function have shown contradictory results. We conducted a clinical trial to investigate differences in S100B levels between ADHD patients and controls, as well as observe gradual changes in S100B concentrations after a triple therapy (TT) containing methylphenidate (MPH), melatonin (aMT) and omega-3 fatty acids (ω-3 PUFAs).

METHODS

62 medication-naïve children with ADHD (ADHD-G) and 65 healthy controls (C-G) were recruited. Serum S100B was measured at baseline (T0) in ADHD-G/C-G, and three (T3) and six months (T6) after starting TT in the ADHD-G, together with attention scores.

RESULTS

A significant increase in S100B was observed in the ADHD-G vs. C-G. In the ADHD-G, significantly higher S100B values were observed for comparisons between T0-T3 and between T0-T6, accompanied by a significant improvement in attention scores for the same timepoint comparisons. No significant differences were found for S100B between T3-T6.

CONCLUSION

Our results agree with the hypothesis of glial damage in ADHD. Further studies on the link between DA and S100B are required to explain the transient increase in S100B following TT.

Reaction of different cell types of the brain on neurotoxin cuprizone and hormone melatonin treatment in young and aging mice

Introduction

The brain myelin and neurons destruction in multiple sclerosis may be associated with the production of neuroinflammatory cells (macrophages, astrocytes, T-lymphocytes) of pro-inflammatory cytokines and free radicals. The age-associated changes of the above cells can influence on the response of nervous system cells to toxic damaging and regulatory factors of humoral/endocrine nature, in particular pineal hormone melatonin. The study aim was (1) to evaluate changes of the brain macrophages, astrocytes, T-cells, neural stem cells, neurons, and central nervous system (CNS) functioning in the neurotoxin cuprizone-treated mice of different age; and (2) to assess in such mice the effects of exogenous melatonin and possible courses of its action.

Methods

A toxic demyelination and neurodegeneration model was induced in 129/Sv mice aged 3-5 and 13-15 months by adding cuprizone neurotoxin to their food for 3 weeks. From the 8th day of the cuprizone treatment, melatonin was injected intraperitoneally at 6 p.m. daily, at a dose of 1 mg/kg. The brain GFPA + -cells were evaluated by immunohistochemical method, the proportion of CD11b+, CD3+CD11b+, CD3+, CD3+CD4+, CD3+CD8+, Nestin+-cells was determined via flow cytometry. Macrophage activity was evaluated by their ability to phagocytose latex beads Morphometric analysis of the brain neurons and the behavioral reactions ("open field" and rotarod tests) were performed. To assess the involvement of the bone marrow and thymus in the action of melatonin, the amount of granulocyte/macrophage colony-forming cells (GM-CFC), and blood monocytes and thymic hormone thymulin were evaluated.

Results and discussion

The numbers of the GFAP+-, CD3+-, CD3+CD4+, CD3+CD8+, CD11b+, CD3+CD11b+, Nestin+-cells and macrophages phagocytic latex beads and malondialdehyde (MDA) content were increased in the brain of young and aging mice under cuprizone influence. The proportion of undamaged neurons within the brain, motor, affective, and exploratory activities, and muscle tone decreased in mice of both ages. Introducing melatonin to mice of any age reduced the number of GFAP+-, CD3+- cells and their subpopulations, macrophage activation, and MDA content. At the same time, the percentage of brain neurons that were unchanged increased as the number of Nestin+ cells decreased. The behavioral responses were also improved. Besides, the number of bone marrow GM-CFC and the blood level of monocytes and thymulin increased. The effects of both neurotoxin and melatonin on the brain astrocytes, macrophages T-cells, and immune system organs as well as the structure and functioning of neurons were more pronounced in the young mice.

Conclusion

We have observed the involvement of the astrocytes, macrophages, T-cells, neural stem cells, and neurons in the brain reaction of mice different age after administration of neurotoxin cuprizone and melatonin. The brain cell composition reaction has the age features. The neuroprotective effects of melatonin in cuprizone-treated mice have been realized through an improvement of the brain cell composition and oxidative stress factors and functioning of bone marrow and thymus.

Melatonin: A Neurotrophic Factor?

Melatonin, N-acetyl-5-hydroxytryptamine, is a hormone that synchronizes the internal environment with the photoperiod. It is synthesized in the pineal gland and greatly depends on the endogenous circadian clock located in the suprachiasmatic nucleus and the retina's exposure to different light intensities. Among its most studied functions are the regulation of the waking-sleep rhythm and body temperature. Furthermore, melatonin has pleiotropic actions, which affect, for instance, the modulation of the immune and the cardiovascular systems, as well as the neuroprotection achieved by scavenging free radicals. Recent research has supported that melatonin contributes to neuronal survival, proliferation, and differentiation, such as dendritogenesis and axogenesis, and its processes are similar to those caused by Nerve Growth Factor, Brain-Derived Neurotrophic Factor, Neurotrophin-3, and Neurotrophin-4/5. Furthermore, this indolamine has apoptotic and anti-inflammatory actions in specific brain regions akin to those exerted by neurotrophic factors. This review presents evidence suggesting melatonin's role as a neurotrophic factor, describes the signaling pathways involved in these processes, and, lastly, highlights the therapeutic implications involved.

Melatonin and the Programming of Stem Cells

Melatonin interacts with various types of stem cells, in multiple ways that comprise stimulation of proliferation, maintenance of stemness and self-renewal, protection of survival, and programming toward functionally different cell lineages. These various properties are frequently intertwined but may not be always jointly present. Melatonin typically stimulates proliferation and transition to the mature cell type. For all sufficiently studied stem or progenitor cells, melatonin’s signaling pathways leading to expression of respective morphogenetic factors are discussed. The focus of this article will be laid on the aspect of programming, particularly in pluripotent cells. This is especially but not exclusively the case in neural stem cells (NSCs) and mesenchymal stem cells (MSCs). Concerning developmental bifurcations, decisions are not exclusively made by melatonin alone. In MSCs, melatonin promotes adipogenesis in a Wnt (Wingless-Integration-1)-independent mode, but chondrogenesis and osteogenesis Wnt-dependently. Melatonin upregulates Wnt, but not in the adipogenic lineage. This decision seems to depend on microenvironment and epigenetic memory. The decision for chondrogenesis instead of osteogenesis, both being Wnt-dependent, seems to involve fibroblast growth factor receptor 3. Stem cell-specific differences in melatonin and Wnt receptors, and contributions of transcription factors and noncoding RNAs are outlined, as well as possibilities and the medical importance of re-programming for transdifferentiation.

Metformin Therapy Attenuates Pro-inflammatory Microglia by Inhibiting NF-κB in Cuprizone Demyelinating Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic disorder characterized by reactive gliosis, inflammation, and demyelination. Microglia plays a crucial role in the pathogenesis of MS and has the dynamic plasticity to polarize between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes. Metformin, a glucose-lowering drug, attenuates inflammatory responses by activating adenosine monophosphate protein kinase (AMPK) which suppresses nuclear factor kappa B (NF-κB). In this study, we indirectly investigated whether metformin therapy would regulate microglia activity in the cuprizone (CPZ)-induced demyelination mouse model of MS via measuring the markers associated with pro- and anti-inflammatory microglia. Evaluation of myelin by luxol fast blue staining revealed that metformin treatment (CPZ + Met) diminished demyelination, in comparison to CPZ mice. In addition, metformin therapy significantly alleviated reactive microgliosis and astrogliosis in the corpus callosum, as measured by Iba-1 and GFAP staining. Moreover, metformin treatment significantly downregulated the expression of pro-inflammatory associated genes (iNOS, H2-Aa, and TNF-α) in the corpus callosum, whereas expression of anti-inflammatory markers (Arg1, Mrc1, and IL10) was not promoted, compared to CPZ mice. Furthermore, protein levels of iNOS (pro-inflammatory marker) were significantly decreased in the metformin group, while those of Trem2 (anti-inflammatory marker) were increased. In addition, metformin significantly increased AMPK activation in CPZ mice. Finally, metformin administration significantly reduced the activation level of NF-κB in CPZ mice. In summary, our data revealed that metformin attenuated pro-inflammatory microglia markers through suppressing NF-κB activity. The positive effects of metformin on microglia and remyelination suggest that it could be used as a promising candidate to lessen the incidence of inflammatory neurodegenerative diseases such as MS.

Extracts from the Leaves of Cissus verticillata Ameliorate High-Fat Diet-Induced Memory Deficits in Mice

We investigated the effects of Cissus verticillata leaf extract (CVE) on a high-fat diet (HFD)-induced obesity and memory deficits. Male mice (5 weeks of age) were fed vehicle (distilled water), or 30, 100, or 300 mg/kg of CVE once a day for 8 weeks with an HFD. Treatment with CVE resulted in lower body weight and glucose levels in a concentration- and feeding time-dependent manner. LDL cholesterol and triglyceride levels were significantly lower in the CVE-treated HFD group than in the vehicle-treated HFD group. In contrast, high-density lipoprotein cholesterol levels did not show any significant changes. Lipid droplets and ballooning were reduced depending on the concentration of CVE treatment compared to the HFD group. Treatment with CVE ameliorated the increase in glucagon and immunoreactivities in the pancreas, and novel object recognition memory was improved by 300 mg/kg CVE treatment compared to the HFD group. More proliferating cells and differentiated neuroblasts were higher in mice treated with CVE than in vehicle-treated HFD-fed mice. Brain-derived neurotrophic factor (BDNF) levels were significantly decreased in the HFD group, which was facilitated by treatment with 300 mg/kg CVE in hippocampal homogenates. These results suggest that CVE ameliorates HFD-induced obesity and memory deficits in mice, associated with increased BDNF levels in the hippocampus.

The Role of Supplementation with Natural Compounds in Post-Stroke Patients

Malnutrition is a serious problem in post-stroke patients. Importantly, it intensifies with hospitalization, and is related to both somatic and psychological reasons, as well as is associated with the insufficient knowledge of people who accompany the patient. Malnutrition is a negative prognostic factor, leading to a reduction in the quality of life. Moreover, this condition significantly extends hospitalization time, increases the frequency of treatment in intensive care units, and negatively affects the effectiveness of rehabilitation. Obtaining growing data on the therapeutic effectiveness of new compounds of natural origin is possible through the use of pharmacodynamic and analytical methods to assess their therapeutic properties. The proper supply of nutrients, as well as compounds of natural origin, is an important element of post-stroke therapy, due to their strong antioxidant, anti-inflammatory, neuroprotective and neuroplasticity enhancing properties. Taking the above into account, in this review we present the current state of knowledge on the benefits of using selected substances of natural origin in patients after cerebral stroke.

Cannabidiol Displays Proteomic Similarities to Antipsychotics in Cuprizone-Exposed Human Oligodendrocytic Cell Line MO3.13

Cannabidiol, a compound of Cannabis sativa, has been proposed as an alternative treatment of schizophrenia. Preclinical and clinical data have suggested that cannabidiol shares more similarity with atypical antipsychotics than typical, both of which are customarily used to manage schizophrenia symptoms. While oligodendrocytes are known to be relevant targets of antipsychotics, the biochemical knowledge in this regard is still limited. Here we evaluated the molecular pathways modulated by cannabidiol compared to the antipsychotics clozapine (atypical) and haloperidol (typical), additionally evaluating the effects of benztropine, a muscarinic receptor antagonist that displays a protective effect in oligodendrocytes and myelination. For this purpose, we employed nano-chromatography coupled with mass spectrometry to investigate the proteomic response to these drugs both in healthy oligodendrocytic cells and in a cuprizone-based toxicity model, using the human oligodendrocyte precursor cell line MO3.13. Cannabidiol shares similarities of biochemical pathways with clozapine and benztropine, in agreement with other studies that indicated an atypical antipsychotic profile. All drugs tested affected metabolic and gene expression pathways and cannabidiol, benztropine, and clozapine modulated cell proliferation and apoptosis when administered after cuprizone-induced toxicity. These general pathways are associated with cuprizone-induced cytotoxicity in MO3.13 cells, indicating a possible proteomic approach when acting against the toxic effects of cuprizone. In conclusion, although modeling oligodendrocytic cytotoxicity with cuprizone does not represent the entirety of the pathophysiology of oligodendrocyte impairments, these results provide insight into the mechanisms associated with the effects of cannabidiol and antipsychotics against cuprizone toxicity, offering new directions of study for myelin-related processes and deficits.

Maternal pineal melatonin in gestation and lactation physiology, and in fetal development and programming

Pregnancy and lactation are reproductive processes that rely on physiological adaptations that should be timely and adequately triggered to guarantee both maternal and fetal health. Pineal melatonin is a hormone that presents daily and seasonal variations that synchronizes the organism's physiology to the different demands across time through its specific mechanisms and ways of action. The reproductive system is a notable target for melatonin as it actively participates on reproductive physiology and regulates the hypothalamus-pituitary-gonads axis, influencing gonadotropins and sexual hormones synthesis and release. For its antioxidant properties, melatonin is also vital for the oocytes and spermatozoa quality and viability, and for blastocyst development. Maternal pineal melatonin blood levels increase during pregnancy and triggers the maternal physiological alterations in energy metabolism both during pregnancy and lactation to cope with the energy demands of both periods and to promote adequate mammary gland development. Moreover, maternal melatonin freely crosses the placenta and is the only source of this hormone to the fetus. It importantly times the conceptus physiology and influences its development and programing of several functions that depend on neural and brain development, ultimately priming adult behavior and energy and glucose metabolism. The present review aims to explain the above listed melatonin functions, including the potential alterations observed in the progeny gestated under maternal chronodisruption and/or hypomelatoninemia.

In Vivo Measurement of Neurochemical Abnormalities in the Hippocampus in a Rat Model of Cuprizone-Induced Demyelination

This study quantitatively measured the changes in metabolites in the hippocampal lesions of a rat model of cuprizone-induced demyelination as detected using in vivo 7 T proton magnetic resonance spectroscopy. Nineteen Sprague Dawley rats were randomly divided into two groups and fed a normal chow diet or cuprizone (0.2%, w/w) for 7 weeks. Demyelinated hippocampal lesions were quantitatively measured using a 7 T magnetic resonance imaging scanner. All proton spectra were quantified for metabolite concentrations and relative ratios. Compared to those in the controls, the cuprizone-induced rats had significantly higher concentrations of glutamate (p = 0.001), gamma-aminobutyric acid (p = 0.019), and glutamate + glutamine (p = 0.001); however, creatine + phosphocreatine (p = 0.006) and myo-inositol (p = 0.001) concentrations were lower. In addition, we found that the glutamine and glutamate complex/total creatine (p < 0.001), glutamate/total creatine (p < 0.001), and GABA/total creatine (p = 0.002) ratios were significantly higher in cuprizone-treated rats than in control rats. Our results showed that cuprizone-induced neuronal demyelination may influence the severe abnormal metabolism in hippocampal lesions, and these responses could be caused by microglial activation, mitochondrial dysfunction, and astrocytic necrosis.

DCX+ neuronal progenitors contribute to new oligodendrocytes during remyelination in the hippocampus

A pool of different types of neural progenitor cells resides in the adult hippocampus. Apart from doublecortin-expressing (DCX⁺) neuronal progenitor cells (NPCs), the hippocampal parenchyma also contains oligodendrocyte precursor cells (OPCs), which can differentiate into myelinating oligodendrocytes. It is not clear yet to what extent the functions of these different progenitor cell types overlap and how plastic these cells are in response to pathological processes. The aim of this study was to investigate whether hippocampal DCX⁺ NPCs can generate new oligodendrocytes under conditions in which myelin repair is required. For this, the cell fate of DCX-expressing NPCs was analyzed during cuprizone-induced demyelination and subsequent remyelination in two regions of the hippocampal dentate gyrus of DCX-CreER^T2/Flox-EGFP transgenic mice. In this DCX reporter model, the number of GFP⁺ NPCs co-expressing Olig2 and CC1, a combination of markers typically found in mature oligodendrocytes, was significantly increased in the hippocampal DG during remyelination. In contrast, the numbers of GFP⁺PDGFRα⁺ cells, as well as their proliferation, were unaffected by de- or remyelination. During remyelination, a higher portion of newly generated BrdU-labeled cells were GFP⁺ NPCs and there was an increase in new oligodendrocytes derived from these proliferating cells (GFP⁺Olig2⁺BrdU⁺). These results suggest that DCX-expressing NPCs were able to contribute to the generation of mature oligodendrocytes during remyelination in the adult hippocampus.

Protective Effects of Melatonin on Neurogenesis Impairment in Neurological Disorders and Its Relevant Molecular Mechanisms

Neurogenesis is the process by which functional new neurons are generated from the neural stem cells (NSCs) or neural progenitor cells (NPCs). Increasing lines of evidence show that neurogenesis impairment is involved in different neurological illnesses, including mood disorders, neurogenerative diseases, and central nervous system (CNS) injuries. Since reversing neurogenesis impairment was found to improve neurological outcomes in the pathological conditions, it is speculated that modulating neurogenesis is a potential therapeutic strategy for neurological diseases. Among different modulators of neurogenesis, melatonin is a particularly interesting one. In traditional understanding, melatonin controls the circadian rhythm and sleep-wake cycle, although it is not directly involved in the proliferation and survival of neurons. In the last decade, it was reported that melatonin plays an important role in the regulation of neurogenesis, and thus it may be a potential treatment for neurogenesis-related disorders. The present review aims to summarize and discuss the recent findings regarding the protective effects of melatonin on the neurogenesis impairment in different neurological conditions. We also address the molecular mechanisms involved in the actions of melatonin in neurogenesis modulation.

Melatonin-A Potent Therapeutic for Stroke and Stroke-Related Dementia

Secreted by the pineal gland to regulate the circadian rhythm, melatonin is a powerful antioxidant that has been used to combat oxidative stress in the central nervous system. Melatonin-based therapies have been shown to provide neuroprotective effects in the setting of ischemic stroke by mitigating neuroinflammation and accelerating brain tissue restoration. Melatonin treatment includes injection of exogenous melatonin, pineal gland grafting and melatonin-mediated stem cell therapy. This review will discuss the current preclinical and clinical studies investigating melatonin-based therapeutics to treat stroke.

Changes of fat-mass and obesity-associated protein expression in the hippocampus in animal models of high-fat diet-induced obesity and D-galactose-induced aging

Fat-mass and obesity-associated protein (Fto) is highly expressed in the brain including, the hippocampus, and its expression is significantly decreased in the brain of Alzheimer’s disease patients. In the present study, we measured Fto immunoreactivity and protein levels in the hippocampus of obese and aged mice, which were induced by high-fat diet for 12 weeks and D-galactose treatment for 10 weeks, respectively. The obesity and aging phenotypes were assessed by physiological parameters and Morris water maze test, respectively. High fat diet fed mice showed significant increases in body weight and blood glucose levels compared to that in the control or D-galactose-induced aged mice. In addition, treatment with D-galactose significantly decreased the spatial memory. Fto immunoreactivity in the control group was mainly detected in the pyramidal cells of the CA1 and CA3 regions and in the granule cells of the dentate gyrus. In the hippocampus of high-fat diet-fed mice, Fto immunoreactive structures were similarly found in the hippocampus compared to that in the control group, but Fto immunoreactivity in high-fat diet-fed mice was also found in the stratum oriens and radiatum of the CA1 and CA3 regions and the polymorphic layer of the dentate gyrus. In the hippocampus of D-galactose-induced aged mice, fewer Fto immunoreactive structures were detected in the granule cell layer of the dentate gyrus compared to the control group. Fto mRNA and protein levels based on quantitative real-time polymerase chain reaction and western blot assays were slightly increased in the hippocampus of high-fat diet-fed mice compared to that in control mice. In addition, Fto mRNA and protein levels were significantly decreased in the aged hippocampus compared to that in the control group. Fto protein levels are susceptible to the aging process, but not in the hippocampus of high-fat diet-induced obesity. The reduction of Fto in aged mice may be associated with reduced memory impairment in mice.

Cuprizone Affects Hypothermia-Induced Neuroprotection and Enhanced Neuroblast Differentiation in the Gerbil Hippocampus after Ischemia

In the present study, we investigated the effects of cuprizone on cell death, glial activation, and neuronal plasticity induced by hypothermia after ischemia in gerbils. Food was supplemented with cuprizone at 0.2% ad libitum for eight weeks. At six weeks after diet feeing, gerbils received transient forebrain ischemia with or without hypothermic preconditioning. Cuprizone treatment for 8 weeks increased the number of astrocytes, microglia, and pro-inflammatory cytokine levels in the hippocampus. In addition, cuprizone treatment significantly decreased the number of proliferating cells and neuroblasts in the dentate gyrus. Brain ischemia caused cell death, disruption of myelin basic proteins, and reactive gliosis in CA1. In addition, ischemia significantly increased pro-inflammatory cytokines and the number of proliferating cells and differentiating neuroblasts in the dentate gyrus. In contrast, hypothermic conditioning attenuated these changes in CA1 and the dentate gyrus. However, cuprizone treatment decreased cell survival induced by hypothermic preconditioning after ischemia and increased the number of reactive microglia and astrocytes in CA1 as well as that of macrophages in the subcallosal zone. These changes occurred because the protective effect of hypothermia in ischemic damage was disrupted by cuprizone administration. Furthermore, cuprizone decreased ischemia-induced proliferating cells and neuroblasts in the dentate gyrus.

Melatonin ameliorates cuprizone-induced reduction of hippocampal neurogenesis, brain-derived neurotrophic factor, and phosphorylation of cyclic AMP response element-binding protein in the mouse dentate gyrus

INTRODUCTION

The aim of this study was to investigate the effects of cuprizone on adult hippocampal neurogenesis in naïve mice. Additionally, we also studied how melatonin affects the neuronal degeneration induced by cuprizone.

METHODS

Eight-week-old male C57BL/6J mice were randomly divided into three groups: (a) the control group, (b) the group treated with cuprizone only, and (c) the group treated with both cuprizone and melatonin. Cuprizone was administered with food at 0.2% ad libitum for 6 weeks. Melatonin was also administered with tap water at 6 g/L ad libitum for 6 weeks; the animals were then euthanized for immunohistochemistry with Ki67, doublecortin (DCX), glucose transporter 3 (GLUT3), and phosphorylation of cyclic adenosine monophosphate (AMP) response element binding (pCREB); double immunofluorescence of neuronal nuclei (NeuN) and myelin basic protein (MBP); and Western blot analysis of brain-derived neurotrophic factor (BDNF) expression to reveal the effects of cuprizone and melatonin on cell damage and hippocampal neurogenesis.

RESULTS

Administration of cuprizone significantly decreased the number of differentiating (DCX-positive) neuroblasts and proliferating (Ki67-positive) cells in the dentate gyrus. Moreover, cuprizone administration decreased glucose utilization (GLUT3-positive cells) and cell transcription (pCREB-positive cells and BDNF protein expression) in the dentate gyrus. Administration of melatonin ameliorated the cuprizone-induced reduction of differentiating neuroblasts and proliferating cells, glucose utilization, and cell transcription.

CONCLUSION

The results of the study suggest that cuprizone treatment disrupts hippocampal neurogenesis in the dentate gyrus by reducing BDNF levels and decreasing the phosphorylation of CREB. These effects were ameliorated by melatonin treatment.