Cardiotrophin-1 (CTF1) ameliorates glucose-uptake defects and improves memory and learning deficits in a transgenic mouse model of Alzheimer's disease

Tirzepatide shows neuroprotective effects via regulating brain glucose metabolism in APP/PS1 mice

Tirzepatide (LY3298176), a GLP-1 and GIP receptor agonist, is fatty-acid-modified and 39-amino acid linear peptide, which ameliorates learning and memory impairment in diabetic rats. However, the specific molecular mechanism remains unknown. In the present study, we investigated the role of tirzepatide in the neuroprotective effects in Alzheimer's disease (AD) model mice. Tirzepatide was administrated intraperitoneal (i.p.) APP/PS1 mice for 8 weeks with at 10 nmol/kg once-weekly, it significantly decreased the levels of GLP-1R, and GFAP protein expression and amyloid plaques in the cortex, it also lowered neuronal apoptosis induced by amyloid-β (Aβ), but did not affect the anxiety and cognitive function in APP/PS1 mice. Moreover, tirzepatide reduced the blood glucose levels and increased the mRNA expression of GLP-1R, SACF1, ATF4, Glu2A, and Glu2B in the hypothalamus of APP/PS1 mice. Tirzepatide increased the mRNA expression of glucose transporter 1, hexokinase, glucose-6-phosphate dehydrogenase, and phosphofructokinase in the cortex. Lastly, tirzepatide improved the energetic metabolism by regulated reactive oxygen species production and mitochondrial membrane potential caused by Aβ, thereby decreasing mitochondrial function and ATP levels in astrocytes through GLP-1R. These results provide valuable insights into the mechanism of brain glucose metabolism and mitochondrial function of tirzepatide, presenting potential strategies for AD treatment.

Serum proteomics reveal APOE-ε4-dependent and APOE-ε4-independent protein signatures in Alzheimer's disease

A deeper understanding of the molecular processes underlying late-onset Alzheimer's disease (LOAD) could aid in biomarker and drug target discovery. Using high-throughput serum proteomics in the prospective population-based Age, Gene/Environment Susceptibility-Reykjavik Study (AGES) cohort of 5,127 older Icelandic adults (mean age, 76.6 ± 5.6 years), we identified 303 proteins associated with incident LOAD over a median follow-up of 12.8 years. Over 40% of these proteins were associated with LOAD independently of APOE-ε4 carrier status, were implicated in neuronal processes and overlapped with LOAD protein signatures in brain and cerebrospinal fluid. We identified 17 proteins whose associations with LOAD were strongly dependent on APOE-ε4 carrier status, with mostly consistent associations in cerebrospinal fluid. Remarkably, four of these proteins (TBCA, ARL2, S100A13 and IRF6) were downregulated by APOE-ε4 yet upregulated due to LOAD, a finding replicated in external cohorts and possibly reflecting a response to disease onset. These findings highlight dysregulated pathways at the preclinical stages of LOAD, including those both independent of and dependent on APOE-ε4 status.

Serum proteomics reveals APOE dependent and independent protein signatures in Alzheimer's disease

The current demand for early intervention, prevention, and treatment of late onset Alzheimer's disease (LOAD) warrants deeper understanding of the underlying molecular processes which could contribute to biomarker and drug target discovery. Utilizing high-throughput proteomic measurements in serum from a prospective population-based cohort of older adults (n = 5,294), we identified 303 unique proteins associated with incident LOAD (median follow-up 12.8 years). Over 40% of these proteins were associated with LOAD independently of APOE-ε4 carrier status. These proteins were implicated in neuronal processes and overlapped with protein signatures of LOAD in brain and cerebrospinal fluid. We found 17 proteins which LOAD-association was strongly dependent on APOE-ε4 carrier status. Most of them showed consistent associations with LOAD in cerebrospinal fluid and a third had brain-specific gene expression. Remarkably, four proteins in this group (TBCA, ARL2, S100A13 and IRF6) were downregulated by APOE-ε4 yet upregulated as a consequence of LOAD as determined in a bi-directional Mendelian randomization analysis, reflecting a potential response to the disease onset. Accordingly, the direct association of these proteins to LOAD was reversed upon APOE-ε4 genotype adjustment, a finding which we replicate in an external cohort (n = 719). Our findings provide an insight into the dysregulated pathways that may lead to the development and early detection of LOAD, including those both independent and dependent on APOE-ε4. Importantly, many of the LOAD-associated proteins we find in the circulation have been found to be expressed - and have a direct link with AD - in brain tissue. Thus, the proteins identified here, and their upstream modulating pathways, provide a new source of circulating biomarker and therapeutic target candidates for LOAD.

Serum proteomics reveals APOE dependent and independent protein signatures in Alzheimer's disease

The current demand for early intervention, prevention, and treatment of late onset Alzheimer's disease (LOAD) warrants deeper understanding of the underlying molecular processes which could contribute to biomarker and drug target discovery. Utilizing high-throughput proteomic measurements in serum from a prospective population-based cohort of older adults (n=5,294), we identified 303 unique proteins associated with incident LOAD (median follow-up 12.8 years). Over 40% of these proteins were associated with LOAD independently of APOE-ε4 carrier status. These proteins were implicated in neuronal processes and overlapped with protein signatures of LOAD in brain and cerebrospinal fluid. We found 17 proteins which LOAD-association was strongly dependent on APOE-ε4 carrier status. Most of them showed consistent associations with LOAD in cerebrospinal fluid and a third had brain-specific gene expression. Remarkably, four proteins in this group (TBCA, ARL2, S100A13 and IRF6) were downregulated by APOE-ε4 yet upregulated as a consequence of LOAD as determined in a bi-directional Mendelian randomization analysis, reflecting a potential response to the disease onset. Accordingly, the direct association of these proteins to LOAD was reversed upon APOE-ε4 genotype adjustment, a finding which we replicate in an external cohort (n=719). Our findings provide an insight into the dysregulated pathways that may lead to the development and early detection of LOAD, including those both independent and dependent on APOE-ε4. Importantly, many of the LOAD-associated proteins we find in the circulation have been found to be expressed - and have a direct link with AD - in brain tissue. Thus, the proteins identified here, and their upstream modulating pathways, provide a new source of circulating biomarker and therapeutic target candidates for LOAD.

Genome-wide association study identifies four pan-ancestry loci for suicidal ideation in the Million Veteran Program

Suicidal ideation (SI) often precedes and predicts suicide attempt and death, is the most common suicidal phenotype and is over-represented in veterans. The genetic architecture of SI in the absence of suicide attempt (SA) is unknown, yet believed to have distinct and overlapping risk with other suicidal behaviors. We performed the first GWAS of SI without SA in the Million Veteran Program (MVP), identifying 99,814 SI cases from electronic health records without a history of SA or suicide death (SD) and 512,567 controls without SI, SA or SD. GWAS was performed separately in the four largest ancestry groups, controlling for sex, age and genetic substructure. Ancestry-specific results were combined via meta-analysis to identify pan-ancestry loci. Four genome-wide significant (GWS) loci were identified in the pan-ancestry meta-analysis with loci on chromosomes 6 and 9 associated with suicide attempt in an independent sample. Pan-ancestry gene-based analysis identified GWS associations with DRD2, DCC, FBXL19, BCL7C, CTF1, ANNK1, and EXD3. Gene-set analysis implicated synaptic and startle response pathways (q's<0.05). European ancestry (EA) analysis identified GWS loci on chromosomes 6 and 9, as well as GWS gene associations in EXD3, DRD2, and DCC. No other ancestry-specific GWS results were identified, underscoring the need to increase representation of diverse individuals. The genetic correlation of SI and SA within MVP was high (rG = 0.87; p = 1.09e-50), as well as with post-traumatic stress disorder (PTSD; rG = 0.78; p = 1.98e-95) and major depressive disorder (MDD; rG = 0.78; p = 8.33e-83). Conditional analysis on PTSD and MDD attenuated most pan-ancestry and EA GWS signals for SI without SA to nominal significance, with the exception of EXD3 which remained GWS. Our novel findings support a polygenic and complex architecture for SI without SA which is largely shared with SA and overlaps with psychiatric conditions frequently comorbid with suicidal behaviors.

Amyloidogenesis and Neurotrophic Dysfunction in Alzheimer’s Disease: Do They have a Common Regulating Pathway?

The amyloid cascade hypothesis has predominately been used to describe the pathogenesis of Alzheimer’s disease (AD) for decades, as Aβ oligomers are thought to be the prime cause of AD. Meanwhile, the neurotrophic factor hypothesis has also been proposed for decades. Accumulating evidence states that the amyloidogenic process and neurotrophic dysfunction are mutually influenced and may coincidently cause the onset and progress of AD. Meanwhile, there are intracellular regulators participating both in the amyloidogenic process and neurotrophic pathways, which might be the common original causes of amyloidogenesis and neurotrophic dysfunction. In this review, the current understanding regarding the role of neurotrophic dysfunction and the amyloidogenic process in AD pathology is briefly summarized. The mutual influence of these two pathogenesis pathways and their potential common causal pathway are further discussed. Therapeutic strategies targeting the common pathways to simultaneously prevent amyloidogenesis and neurotrophic dysfunction might be anticipated for the disease-modifying treatment of AD.

Mechanisms associated with the dysregulation of mitochondrial function due to lead exposure and possible implications on the development of Alzheimer's disease

Lead (Pb) is a multimedia contaminant with various pathophysiological consequences, including cognitive decline and neural abnormalities. Recent findings have reported an association of Pb toxicity with Alzheimer's disease (AD). Studies have revealed that mitochondrial dysfunction is a pathological characteristic of AD. According to toxicology reports, Pb promotes mitochondrial oxidative stress by lowering complex III activity in the electron transport chain, boosting reactive oxygen species formation, and reducing the cell's antioxidant defence system. Here, we review recent advances in the role of mitochondria in Pb-induced AD pathology, as well as the mechanisms associated with the mitochondrial dysfunction, such as the depolarisation of the mitochondrial membrane potential, mitochondrial permeability transition pore opening; mitochondrial biogenesis, bioenergetics and mitochondrial dynamics alterations; and mitophagy and apoptosis. We also discuss possible therapeutic options for mitochondrial-targeted neurodegenerative disease (AD).

Therapeutic potential of neurotrophic factors in Alzheimer's Disease

INTRODUCTION

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia among the elderly population. AD is accompanied with the dysregulation of specific neurotrophic factors (NTFs) and their receptors, which plays a critical role in neuronal degeneration. NTFs are small proteins with therapeutic potential for human neurodegenerative diseases. These growth factors are categorized into four families: neurotrophins, neurokines, the glial cell line-derived NTF family of ligands, and the newly discovered cerebral dopamine NTF/mesencephalic astrocyte-derived NTF family. NTFs are capable of preventing cell death in degenerative conditions and can increase the neuronal growth and function in these disorders. Nevertheless, the adverse side effects of NTFs delivery and poor diffusion of these factors in the brain restrict the efficacy of NTFs therapy in clinical situations.

MATERIALS AND METHODS

In this review, we focus on the current advances in the use of NTFs to treat AD and summarize previous experimental and clinical studies for supporting the protective and therapeutic effects of these factors.

CONCLUSION

Based on reports, NTFs are considered as new and promising candidates for treating AD and AD-associated cognitive impairment.

Evidence That Methylphenidate Treatment Evokes Anxiety-Like Behavior Through Glucose Hypometabolism and Disruption of the Orbitofrontal Cortex Metabolic Networks

Methylphenidate (MPH) has been widely misused by children and adolescents who do not meet all diagnostic criteria for attention-deficit/hyperactivity disorder without a consensus about the consequences. Here, we evaluate the effect of MPH treatment on glucose metabolism and metabolic network in the rat brain, as well as on performance in behavioral tests. Wistar male rats received intraperitoneal injections of MPH (2.0 mg/kg) or an equivalent volume of 0.9% saline solution (controls), once a day, from the 15th to the 44th postnatal day. Fluorodeoxyglucose-18 was used to investigate cerebral metabolism, and a cross-correlation matrix was used to examine the brain metabolic network in MPH-treated rats using micro-positron emission tomography imaging. Performance in the light-dark transition box, eating-related depression, and sucrose preference tests was also evaluated. While MPH provoked glucose hypermetabolism in the auditory, parietal, retrosplenial, somatosensory, and visual cortices, hypometabolism was identified in the left orbitofrontal cortex. MPH-treated rats show a brain metabolic network more efficient and connected, but careful analyses reveal that the MPH interrupts the communication of the orbitofrontal cortex with other brain areas. Anxiety-like behavior was also observed in MPH-treated rats. This study shows that glucose metabolism evaluated by micro-positron emission tomography in the brain can be affected by MPH in different ways according to the region of the brain studied. It may be related, at least in part, to a rewiring in the brain the metabolic network and behavioral changes observed, representing an important step in exploring the mechanisms and consequences of MPH treatment.

The seed of Litchi chinensis fraction ameliorates hippocampal neuronal injury in an Aβ25-35-induced Alzheimer's disease rat model via the AKT/GSK-3β pathway

Context: The seed of Litchi chinensis Sonn., a famous traditional Chinese medicine, was recently reported to enhance cognitive function by inhibiting neuronal apoptosis in rats.Objective: We determined whether the seed of Litchi chinensis fraction (SLF) can ameliorate hippocampal neuronal injury via the AKT/GSK-3β pathway.Materials and methods: We established Alzheimer's disease (AD) model by infusing Aβ_25-35 into the lateral ventricle of Sprague-Dawley (SD) rats and randomly divided into five groups (n = 10): sham, donepezil and SLF (120, 240 and 480 mg/kg/d). Rats were treated by intragastric administration for 28 consecutive days. Spatial learning and memory were evaluated with Morris water maze, while protein expression of AKT, GSK-3β and tau in the hippocampal neurons was measured by Western blotting and immunohistochemistry.Results: On the fifth day, escape latency of the AD model group was 45.78 ± 2.52 s and that of the sham operative group was 15.98 ± 2.32 s. SLF could improve cognitive functions by increasing the number of rats that crossed the platform (p < 0.01), and their platform quadrant dwell time (p < 0.05). The protein expression level of AKT was upregulated (p < 0.001), while that of GSK-3β and tau (p < 0.01) was remarkably downregulated in the hippocampal CA1 area.Discussion and conclusions: To our knowledge, the present study is the first to show that SLF may exert neuroprotective effect in AD rats via the AKT/GSK-3β signalling pathway, thereby serving as evidence for the potential utility of SLF as an effective drug against AD.

Neuronostatin Promotion Soluble Aβ1-42 Oligomers: Induced Dysfunctional Brain Glucose Metabolism in Mice

Neuronostatin (NST) is an endogenous peptide hormone, it has the ability to improve oligomeric Aβ (oAβ)-induced cognitive impairments and increase blood glucose levels in mice. However, the relationship between NST and oAβ regarding brain glucose metabolism has not yet been established. The present study defined the contributions of NST and oAβ in the brain glucose metabolism in mice. It was found that i.c.v. co-administration of NST (3 nmol/mouse) and oAβ (1 nmol/mouse) decreased the mRNA expressions of glucose-6-phosphate dehydrogenase and phosphofructokinase. The treatments were observed to reduce ATP production and the enzyme activities of glucose-6-phosphate dehydrogenase and hexokinase in both the cortex and hippocampus. Simultaneously, co-injection of NST and oAβ inhibited the mRNA and protein expression of glucose transporters GLUT3 and GLUT1 in the cortex and hippocampus. NST promoted the oAβ-induced decreased the cortical NeuN staining, while oAβ increased the levels of NST in both the cortex and hippocampus. I.c.v. co-administration of NST and oAβ led to increase the levels of GPR107 expression and the phosphorylation of PKA, Akt, PERK and eIF-2α in the cortex. These findings suggest that NST promoted oAβ-induced dysfunctional glucose metabolism through the GPR107/PKA/Akt signaling pathway and PERK/eIF2α axis in the brain, which thus contributes to metabolic dysfunction and Alzheimer's disease (AD) pathophysiology.

A serum protein signature of APOE genotypes in centenarians

The discovery of treatments to prevent or delay dementia and Alzheimer's disease is a priority. The gene APOE is associated with cognitive change and late-onset Alzheimer's disease, and epidemiological studies have provided strong evidence that the e2 allele of APOE has a neuroprotective effect, it is associated with increased longevity and an extended healthy lifespan in centenarians. In this study, we correlated APOE genotype data of 222 participants of the New England Centenarian Study, including 75 centenarians, 82 centenarian offspring, and 65 controls, comprising 55 carriers of APOE e2 , with aptamer-based serum proteomics (SomaLogic technology) of 4,785 human proteins corresponding to 4,137 genes. We discovered a signature of 16 proteins that associated with different APOE genotypes and replicated the signature in three independent studies. We also show that the protein signature tracks with gene expression profiles in brains of late-onset Alzheimer's disease versus healthy controls. Finally, we show that seven of these proteins correlate with cognitive function patterns in longitudinally collected data. This analysis in particular suggests that Baculoviral IAP repeat containing two (BIRC2) is a novel biomarker of neuroprotection that associates with the neuroprotective allele of APOE. Therefore, targeting APOE e2 molecularly may preserve cognitive function.

The ERK signaling pathway is involved in cardiotrophin-1-induced neural differentiation of human umbilical cord blood mesenchymal stem cells in vitro

Central nervous system diseases remain the most challenging pathologies, with limited or even no therapeutic possibilities and a poor prognosis. This study aimed to investigate the differentiation properties of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) transfected with recombinant adenovirus expressing enhanced green fluorescence protein cardiotrophin-1 (Adv-EGFP-CT-1) and the possible mechanisms involved. Cells were isolated, and MSC immunophenotypes were confirmed. The resulting differentiated cells treated with Adv-EGFP-CT-1 and cultured in neural induction medium (NIM) expressed higher levels of Nestin, neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) markers than cells in other treatments. Expression of glycoprotein 130/leukemia inhibitory factor receptor β (gp130/LiFRβ), Raf-1, phosphorylated Raf-1 (p-Raf-1), extracellular signal-regulated kinase 1/2 (ERK1/2) and phospho-ERK1/2 (p-ERK1/2) increased gradually within 72 h after transfection with Adv-EGFP-CT-1 and NIM culture. Additionally, inhibition of extracellular signal-regulated kinase kinase (MEK) abrogated expression of p-ERK1/2, Nestin, GFAP and NeuN. Thus, the ERK1/2 pathway may contribute to CT1-stimulated neural differentiation of hUCB-MSCs.

Locomotor activity, emotionality, sensori-motor gating, learning and memory in the APPswe/PS1dE9 mouse model of Alzheimer's disease

The APPswe/PS1dE9 mouse (line 85) is a double transgenic model of Alzheimer's disease (AD) with familial amyloid precursor protein and presenilin-1 mutations. These mice develop age-related behavioral changes reflective of the neuropsychiatric symptoms (altered anxiety-like behaviour, hyperactivity) and cognitive dysfunction (impaired learning and memory) observed in AD. The APPswe/PS1dE9 mouse has been used to examine the efficacy of therapeutic interventions on behaviour, despite previous difficulties in replicating behavioural phenotypes. Therefore, the purpose of this study was to establish the reliability of these phenotypes by further characterizing the behaviour of male APPswe/PS1dE9 and wild-type mice between 7 and 14 months of age. Mice were tested on the open-field over 5-days to examine emotionality, locomotor activity and inter-session habituation. Mice were also tested on the repeated-reversal water maze task and spontaneous alternation on the Y-maze to assess working memory. Sensori-motor gating was examined with acoustic startle and pre-pulse inhibition. Lastly contextual and cued (trace) memory was assessed with fear conditioning. The results show that among non-cognitive behaviours, APPswe/PS1dE9 mice have normal locomotor activity, anxiety-like behavior, habituation and sensori-motor gating. However, APPswe/PS1dE9 mice show impaired working memory on the repeated-reversal water-maze and impaired memory in contextual but not trace-cued fear conditioning. These results indicate that the APPswe/PS1dE9 (line 85) mice have deficits in some types of hippocampal-dependent learning and memory and, at the ages tested, APPswe/PS1dE9 mice model cognitive dysfunction but not neuropsychiatric symptoms.

Activation of brain glucose metabolism ameliorating cognitive impairment in APP/PS1 transgenic mice by electroacupuncture

An essential feature of Alzheimer's disease (AD) is implicated in brain energy metabolic impairment that is considered underlying pathogenesis of cognitive impairment. Therefore, therapeutic interventions to allay cognitive deficits that target energy metabolism may be an efficacy strategy in AD. In this study, we found that electroacupuncture (EA) at the DU20 acupoint obviously increased glucose metabolism in specific brain regions such as cortex, hippocampus, cingulate gyrus, basal forebrain septum, brain stem, and cerebellum in APP/PS1 transgenic mice by animal ¹⁸F-Fluoro-2-deoxy-D-Glucose (¹⁸F-FDG)/positron emission tomography (PET) imaging, accompanied by cognitive improvements in the spatial reference learning and memory and memory flexibility and novel object recognition performances. Further evidence shown energy metabolism occurred in neurons or non-neuronal cells of the cortex and hippocampus in terms of the co-location of GLUT3/NeuN and GLUT1/GFAP. Simultaneously, metabolic homeostatic factors were critical for glucose metabolism, including phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and AKT serine/threonine kinase. Furthermore, EA-induced phosphorylated AMPK and AKT inhibited the phosphorylation level of the mammalian target of rapamycin (mTOR) to decrease the accumulation of amyloid-beta (Aβ) in the cortex and hippocampus. These findings are concluded that EA is a potential therapeutic target for delaying memory decline and Aβ deposition of AD. The AMPK and AKT are implicated in the EA-induced cortical and hippocampal energy metabolism, which served as a contributor to improving cognitive function and Aβ deposition in a transgenic mouse model of AD.

Cardiotrophin-1 stimulates the neural differentiation of human umbilical cord blood-derived mesenchymal stem cells and survival of differentiated cells through PI3K/Akt-dependent signaling pathways

Cardiotrophin-1 (CT1) plays an important role in the differentiation, development, and survival of neural stem cells. In this study, we analyzed its effects on the stimulation of human umbilical cord blood-derived mesenchymal stem cells in terms of their potential to differentiate into neuron-like cells, their survival characteristics, and the molecular mechanisms involved. The treatment of cells with neural induction medium (NIM) and CT1 generated more cells that were neuron-like and produced stronger expression of neural-lineage markers than cells treated with NIM and without CT1. Bcl-2 and Akt phosphorylation (p-Akt) expression levels increased significantly in cells treated with both NIM and CT1. This treatment also effectively blocked cell death following neural induction and decreased Bax, Bak and cleaved-caspase 3 expression compared with cells treated with NIM without CT1. In addition, the inhibition of phosphatidylinositol 3-kinase (PI3K) abrogated p-Akt and Bcl-2 expression. Thus, PI3K/Akt contribute to CT1-stimulated neural differentiation and to the survival of differentiated cells.

Chronic Monoarthritis Pain Accelerates the Processes of Cognitive Impairment and Increases the NMDAR Subunits NR2B in CA3 of Hippocampus from 5-month-old Transgenic APP/PS1 Mice

Many factors impact cognitive impairment; however, the effects of chronic pain and the mechanisms underlying these effects on cognitive impairment are currently unknown. Here we tested the hypothesis that chronic pain accelerates the transition from normal cognition to mild cognitive impairment (MCI) in 5-month-old transgenic APP/PS1 mice, an animal model of Alzheimer’s disease (AD), and that neurotoxicity induced by N-methyl-D-aspartic acid receptor (NMDAR) subunits may be involved in this process. Chronic monoarthritis pain was induced in transgenic APP/PS1 mice and 5-month-old wild-type (WT) mice by intra- and pre-articular injections of Freund’s complete adjuvant (FCA) into one knee joint. Pain behavior, learning and memory function, and the distribution and quantity of NMDAR subunits (NR1, NR2A and NR2B) in hippocampal CA1 and CA3 regions were assessed. Our results showed that although persistent and robust monoarthritis pain was induced by the FCA injections, only the transgenic APP/PS1 mice with chronic monoarthritis pain exhibited marked learning and memory impairments. This result suggested that chronic monoarthritis pain accelerated the cognitive impairment process. Furthermore, only transgenic APP/PS1 mice with chronic monoarthritis pain exhibited an overexpression of NR2B and an increased NR2B/NR2A ratio in the hippocampus CA3. These findings suggest that chronic pain is a risk factor for cognitive impairment and that increased neurotoxicity associated with NMDAR subunit activation may underpin the impairment. Thus, NMDARs may be a therapeutic target for the prevention of chronic pain-induced cognitive impairment.

Cardiotrophin-1: A multifaceted cytokine

Cardiotrophin-1 (CT-1) is a member of the gp130 family of cytokines that have pleiotropic functions on different tissues and cell types. Although many effects of CT-1 have been described on the heart, there is an extensive research showing important protective effects in other organs such as liver, kidney or nervous system. Recently, several studies have pointed out that CT-1 might also play a key role in the regulation of body weight and intermediate metabolism. This paper will review many aspects of CT-1 physiological role in several organs and discuss data for consideration in therapeutic approaches.

Methylphenidate increases glucose uptake in the brain of young and adult rats

BACKGROUND

Methylphenidate (MPH) is the drug of choice for pharmacological treatment of attention deficit hyperactivity disorder. Studies have pointed to the role of glucose and lactate as well as in the action mechanisms of drugs used to treat these neuropsychiatric diseases. Thus, this study aims to evaluate the effects of MPH administration on lactate release and glucose uptake in the brains of young and adult rats.

METHODS

MPH (1.0, 2.0 and 10.0mg/kg) or saline was injected in young and adult Wistar male rats either acutely (once) or chronically (once daily for 28 days). Then, the levels of lactate release and glucose uptake were assessed in the prefrontal cortex, hippocampus, striatum, cerebellum and cerebral cortex.

RESULTS

Chronic MPH treatment increased glucose uptake at the dose of 10.0mg/kg in the prefrontal cortex and striatum, and at the dose of 2.0mg/kg in the cerebral cortex of young rats. In adult rats, an increase in glucose uptake was observed after acute administration of MPH at the dose of 10.0mg/kg in the prefrontal cortex. After chronic treatment, there was an increase in glucose uptake with MPH doses of 2.0 and 10.0mg/kg in the prefrontal cortex, and at an MPH dose of 2.0mg/kg in the striatum of adult rats. The lactate release did not change with either acute or chronic treatments in young or adult rats.

CONCLUSIONS

These findings indicate that MPH increases glucose consumption in the brain, and that these changes are dependent on age and posology.