Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders.

Dietary deficiency of docosahexaenoic acid (C22:6 n-3; DHA) is linked to the neuropathology of several cognitive disorders, including anxiety. DHA, which is essential for brain development and protection, is primarily obtained through the diet or synthesized from dietary precursors, however the conversion efficiency is low. Curcumin (diferuloylmethane), which is a principal component of the spice turmeric, complements the action of DHA in the brain, and this study was performed to determine molecular mechanisms involved. We report that curcumin enhances the synthesis of DHA from its precursor, α-linolenic acid (C18:3 n-3; ALA) and elevates levels of enzymes involved in the synthesis of DHA such as FADS2 and elongase 2 in both liver and brain tissues. Furthermore, in vivo treatment with curcumin and ALA reduced anxiety-like behavior in rodents. Taken together, these data suggest that curcumin enhances DHA synthesis, resulting in elevated brain DHA content. These findings have important implications for human health and the prevention of cognitive disease, particularly for populations eating a plant-based diet or who do not consume fish, a primary source of DHA, since DHA is essential for brain function and its deficiency is implicated in many types of neurological disorders.

Flavonoid derivative 7,8-DHF attenuates TBI pathology via TrkB activation.

Traumatic brain injury (TBI) is followed by a state of metabolic dysfunction, affecting the ability of neurons to use energy and support brain plasticity; there is no effective therapy to counteract the TBI pathology. Brain-derived neurotrophic factor (BDNF) has an exceptional capacity to support metabolism and plasticity, which highly contrasts with its poor pharmacological profile. We evaluated the action of a flavonoid derivative 7,8-dihydroxyflavone (7,8-DHF), a BDNF receptor (TrkB) agonist with the pharmacological profile congruent for potential human therapies. Treatment with 7,8-DHF (5mg/kg, ip, daily for 7 days) was effective to ameliorate the effects of TBI on plasticity markers (CREB phosphorylation, GAP-43 and syntaxin-3 levels) and memory function in Barnes maze test. Treatment with 7,8-DHF restored the decrease in protein and phenotypic expression of TrkB phosphorylation after TBI. In turn, intrahippocampal injections of K252a, a TrkB antagonist, counteracted the 7,8-DHF induced TrkB signaling activation and memory improvement in TBI, suggesting the pivotal role of TrkB signaling in cognitive performance after brain injury. A potential action of 7,8-DHF on cell energy homeostasis was corroborated by the normalization in levels of PGC-1α, TFAM, COII, AMPK and SIRT1 in animals subjected to TBI. Results suggest a potential mechanism by which 7,8-DHF counteracts TBI pathology via activation of the TrkB receptor and engaging the interplay between cell energy management and synaptic plasticity. Since metabolic dysfunction is an important risk factor for the development of neurological and psychiatric disorders, these results set a precedent for the therapeutic use of 7,8-DHF in a larger context.

Coupling energy homeostasis with a mechanism to support plasticity in brain trauma.

Metabolic dysfunction occurring after traumatic brain injury (TBI) is an important risk factor for the development of psychiatric illness. In the present study, we utilized an omega-3 diet during early life as a metabolic preconditioning to alter the course of TBI during adulthood. TBI animals under omega-3 deficiency were more prone to alterations in energy homeostasis (adenosine monophosphate-activated protein kinase; AMPK phosphorylation and cytochrome C oxidase II; COII levels) and mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator 1-alpha; PGC-1α and mitochondrial transcription factor A; TFAM). A similar response was found for brain-derived neurotrophic factor (BDNF) and its signaling through tropomyosin receptor kinase B (TrkB). The results from in vitro studies showed that 7,8-dihydroxyflavone (7,8-DHF), a TrkB receptor agonist, upregulates the levels of biogenesis activator PGC-1α, and CREB phosphorylation in neuroblastoma cells suggesting that BDNF-TrkB signaling is pivotal for engaging signals related to synaptic plasticity and energy metabolism. The treatment with 7,8-DHF elevated the mitochondrial respiratory capacity, which emphasizes the role of BDNF-TrkB signaling as mitochondrial bioenergetics stimulator. Omega-3 deficiency worsened the effects of TBI on anxiety-like behavior and potentiated a reduction of anxiolytic neuropeptide Y1 receptor (NPY1R). These results highlight the action of metabolic preconditioning for building long-term neuronal resilience against TBI incurred during adulthood. Overall, the results emphasize the interactive action of metabolic and plasticity signals for supporting neurological health.

Interactive actions of Bdnf methylation and cell metabolism for building neural resilience under the influence of diet.

Quality nutrition during the period of brain formation is a predictor of brain functional capacity and plasticity during adulthood; however it is not clear how this conferred plasticity imparts long-term neural resilience. Here we report that early exposure to dietary omega-3 fatty acids orchestrates key interactions between metabolic signals and Bdnf methylation creating a reservoir of neuroplasticity that can protect the brain against the deleterious effects of switching to a Western diet (WD). We observed that the switch to a WD increased Bdnf methylation specific to exon IV, in proportion to anxiety-like behavior, in Sprague Dawley rats reared in low omega-3 fatty acid diet, and these effects were abolished by the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine. Blocking methylation also counteracted the reducing action of WD on the transcription regulator CTCF binding to Bdnf promoter IV. In vitro studies confirmed that CTCF binding to Bdnf promoter IV is essential for the action of DHA on BDNF regulation. Diet is also intrinsically associated to cell metabolism, and here we show that the switch to WD downregulated cell metabolism (NAD/NADH ratio and SIRT1). The fact that DNA methyltransferase inhibitor did not alter these parameters suggests they occur upstream to methylation. In turn, the methylation inhibitor counteracted the action of WD on PGC-1α, a mitochondrial transcription co-activator and BDNF regulator, suggesting that PGC-1α is an effector of Bdnf methylation. Results support a model in which diet can build an "epigenetic memory" during brain formation that confers resilience to metabolic perturbations occurring in adulthood.

Diet and cognition: interplay between cell metabolism and neuronal plasticity.

PURPOSE OF STUDY: To discuss studies in humans and animals revealing the ability of foods to benefit the brain: new information with regards to mechanisms of action and the treatment of neurological and psychiatric disorders. RECENT FINDINGS: Dietary factors exert their effects on the brain by affecting molecular events related to the management of energy metabolism and synaptic plasticity. Energy metabolism influences neuronal function, neuronal signaling, and synaptic plasticity, ultimately affecting mental health. Epigenetic regulation of neuronal plasticity appears as an important mechanism by which foods can prolong their effects on long-term neuronal plasticity. SUMMARY: The prime focus of the discussion is to emphasize the role of cell metabolism as a mediator for the action of foods on the brain. Oxidative stress promotes damage to phospholipids present in the plasma membrane such as the omega-3 fatty acid docosahexenoic acid, disrupting neuronal signaling. Thus, dietary docosahexenoic acid seems crucial for supporting plasma membrane function, interneuronal signaling, and cognition. The dual action of brain-derived neurotrophic factor in neuronal metabolism and synaptic plasticity is crucial for activating signaling cascades under the action of diet and other environmental factors, using mechanisms of epigenetic regulation.

Discovery of a Conditionally Activated IL-2 that Promotes Antitumor Immunity and Induces Tumor Regression.

IL-2 is a cytokine clinically approved for the treatment of melanoma and renal cell carcinoma. Unfortunately, its clinical utility is hindered by serious side effects driven by the systemic activity of the cytokine. Here, we describe the design and characterization of a conditionally activated IL-2 prodrug, WTX-124, that takes advantage of the dysregulated protease milieu of tumors. WTX-124 was engineered as a single molecule containing an inactivation domain and a half-life extension domain that are tethered to a fully active IL-2 by protease-cleavable linkers. We show that the inactivation domain prevented IL-2 from binding to its receptors in nontumor tissues, thereby minimizing the toxicity associated with systemic exposure to IL-2. The half-life extension element improves the pharmacokinetic profile of WTX-124 over free IL-2, allowing for greater exposure. WTX-124 was preferentially activated in tumor tissue by tumor-associated proteases, releasing active IL-2 in the tumor microenvironment. In vitro assays confirmed that the activity of WTX-124 was dependent on proteolytic activation, and in vivo WTX-124 treatment resulted in complete rejection of established tumors in a cleavage-dependent manner. Mechanistically, WTX-124 treatment triggered the activation of T cells and natural killer (NK) cells, and markedly shifted the immune activation profile of the tumor microenvironment, resulting in significant inhibition of tumor growth in syngeneic tumor models. Collectively, these data demonstrate that WTX-124 minimizes the toxicity of IL-2 treatment in the periphery while retaining the full pharmacology of IL-2 in the tumor microenvironment, supporting its further development as a cancer immunotherapy treatment. See related Spotlight by Silva, p. 544.

Effect of curcumin on brain insulin receptors and memory functions in STZ (ICV) induced dementia model of rat.

Curcumin, the principal curcuminoid of turmeric, exhibits beneficial role in several neurodegenerative disorders such as dementia of Alzheimer type. Recent evidences suggest the involvement of brain insulin receptors (IRs) in the pathophysiology of dementia disorders. Therefore, the present study was undertaken to investigate the effect of curcumin on memory functions, brain IRs, acetylcholinesterase (AChE) activity and oxidative stress in intracerebroventricular (ICV) administered streptozotocin (STZ) induced dementia in rats. Rats were injected with STZ (3 mg/kg, ICV) bilaterally twice, on day 1 and 3 and curcumin (200 mg/kg, po) was administered in pre- and post-treatment schedules. STZ (ICV) treated group had shown memory deficit as indicated by no significant decrease in latency time in Morris water maze test and significant decrease in IR protein level in both hippocampus and cerebral cortex. Pre- and post-treatment of curcumin in STZ (ICV) treated rats significantly restored the memory deficit and IR protein level in both the regions. Furthermore, STZ (ICV) resulted into enhanced AChE activity in hippocampus and cerebral cortex which was normalized by curcumin pre- and post-treatment. An increase in MDA level and decrease in GSH level were obtained in both hippocampus and cerebral cortex in STZ treated group, indicating state of oxidative stress, which was also attenuated by pre- and post-treatment of curcumin. The results suggest that besides the anticholinesterase and antioxidant activity, effect on brain IR may also be an important factor for protective effect of curcumin against STZ induced dementia model.

A comparative study on oxidative stress induced by LPS and rotenone in homogenates of rat brain regions.

Lipopolysaccharide (LPS) and rotenone induced oxidative stress was investigated in homogenates of rat brain regions - striatum, mid brain, frontal cortex and hippocampus. LPS at concentration 1, 25 and 50µg and rotenone 1, 2 and 4mM was incubated with the brain homogenates and caused decrease in reduced glutathione (GSH) and rise in malondialdehyde (MDA) in different brain regions but in a varied manner. Anti-oxidants melatonin and nimesulide (0.75, 1.5 and 3mM) were incubated concurrently with LPS (50µg) and rotenone (4mM) in the homogenates. Melatonin as well as nimesulide (3mM) suppressed the LPS and rotenone induced increase in MDA but their effect on GSH differed. Lack of uniform response by different brain areas to LPS, rotenone and antioxidants indicate that sensitivity to oxidative stress may differ among the brain areas; this variability in sensitivity may be of significance in relation to free radicals induced selective neuronal degeneration.

Influence of LPS-induced neuroinflammation on acetylcholinesterase activity in rat brain.

In the present study, neuroinflammation was induced by bilateral intracerebroventricular (ICV) administration of Lipopolysaccharide (LPS). Proinflammatory cytokines (TNF-alpha and IL-1beta), acetylcholinesterase (AChE) activity, malondialdehyde (MDA) and reduced glutathione (GSH) were studied as markers for neuroinflammation, cholinergic activity and oxidative stress respectively in different brain regions at different time points after LPS injection. LPS produced increase in proinflammatory cytokines, MDA and the decrease in level of GSH at 24 h indicating a state of inflammation in brain regions, which was significantly blocked by Ibuprofen, a non steroidal anti-inflammatory drug. Enhanced AChE activity with these inflammatory markers after LPS administration indicates a possible relationship between neuroinflammation and cholinergic system during the development of neurodegenerative diseases.

Effect of insulin and melatonin on acetylcholinesterase activity in the brain of amnesic mice.

Basal forebrain cholinergic neurons and oxidative stress in brain have been suggested to play an important role in the regulation of memory functions. Therefore, the present study was planned to study the effect of donepezil, an anticholinesterase antidementia drug, insulin and melatonin, an antioxidant, on memory deficit and acetylcholinesterase (AChE) activity in brain areas of scopolamine-induced amnesic mice. Memory was tested by passive avoidance (PA) test in Swiss adult male mice. A significant increase in transfer latency time (TLT) in 2nd trial as compared to 1st trial is considered as successful learning. Scopolamine (3 mg/kg i.p.) was administered 5 min prior to 1st trial to induce amnesia. AChE activity in detergent soluble (DS) and salt soluble (SS) fractions was estimated in brain areas after completion of 2nd trial. Scopolamine was effective in producing memory impairment (amnesia) which was reverted by donepezil (5 mg/kg p.o.), insulin (1 IU/kg i.p.) and melatonin (20 mg/kg p.o.). AChE activity in DS fraction of scopolamine amnesic mice was inhibited by donepezil, insulin and melatonin with varying extent in different brain regions, whereas AChE activity in SS fraction was not much affected. The results demonstrate that anti-amnesic effect of donepezil, insulin and melatonin may be mediated through enhancement of cholinergic activity.

Involvement of monoamines and proinflammatory cytokines in mediating the anti-stress effects of Panax quinquefolium.

Panax quinquefolium (PQ) is well acclaimed in literature for its effects on central and peripheral nervous system. The present study explores the effects of PQ on stress induced changes of corticosterone level in plasma, monoamines (NA, DA and 5-HT) and interleukin (IL-2 and IL-6) levels in cortex and hippocampus regions of brain and also indicate their possible roles in modulating stress. Mice subjected to chronic unpredictable stress (CUS, for 7 days) showed significant increase in plasma corticosterone level and depletion of noradrenaline (NA), dopamine (DA) and 5-hydroxytryptamine (5-HT) levels in cortex and hippocampal regions along with an increased level of IL-2 and IL-6 in the same areas. Aqueous suspension of PQ was administered daily at a dose of 100 and 200mg/kg p.o. prior to the stress regimen and its effects on selected stress markers in plasma and brain was evaluated. PQ at a dose of 200mg/kg p.o. was found to be effective in normalizing the CUS induced elevation of plasma corticosterone and IL-2, IL-6 levels in brain. Moreover, it was significantly effective in reinstating the CUS induced depletion of NA, DA and 5-HT in hippocampus, while NA and 5-HT in cortex of brain. However, PQ at a dose of 100mg/kg p.o. was found ineffective in regulating any of these CUS induced changes. Present study provides an insight into the possible role of PQ on hyperactive HPA axis in the regulation of immediate stress effectors like corticosterone, cytokines and brain monoamines. In this study, PQ has emerged as a potential therapeutic in the cure of stress related disorders and needs to be evaluated in clinical studies to ascertain its efficacy.

Aspirin Suppresses PGE2 and Activates AMP Kinase to Inhibit Melanoma Cell Motility, Pigmentation, and Selective Tumor Growth In Vivo.

There are conflicting epidemiologic data on whether chronic aspirin (ASA) use may reduce melanoma risk in humans. Potential anticancer effects of ASA may be mediated by its ability to suppress prostaglandin E2 (PGE2) production and activate 5'-adenosine monophosphate-activated protein kinase (AMPK). We investigated the inhibitory effects of ASA in a panel of melanoma and transformed melanocyte cell lines, and on tumor growth in a preclinical model. ASA and the COX-2 inhibitor celecoxib did not affect melanoma cell viability, but significantly reduced colony formation, cell motility, and pigmentation (melanin production) in vitro at concentrations of 1 mmol/L and 20 µmol/L, respectively. ASA-mediated inhibition of cell migration and pigmentation was rescued by exogenous PGE2 or Compound C, which inhibits AMPK activation. Levels of tyrosinase, MITF, and p-ERK were unaffected by ASA exposure. Following a single oral dose of 0.4 mg ASA to NOD/SCID mice, salicylate was detected in plasma and skin at 4 hours and PGE2 levels were reduced up to 24 hours. Some human melanoma tumors xenografted into NOD/SCID mice were sensitive to chronic daily ASA administration, exhibiting reduced growth and proliferation. ASA-treated mice bearing sensitive and resistant tumors exhibited both decreased PGE2 in plasma and tumors and increased phosphorylated AMPK in tumors. We conclude that ASA inhibits colony formation, cell motility, and pigmentation through suppression of PGE2 and activation of AMPK and reduces growth of some melanoma tumors in vivo This preclinical model could be used for further tumor and biomarker studies to support future melanoma chemoprevention trials in humans. Cancer Prev Res; 11(10); 629-42. ©2018 AACR.

Effect of anti-dementia drugs on LPS induced neuroinflammation in mice.

Inflammation has been recently implicated in pathogenesis of dementia disorders. Effect of anti-dementia (Acetylcholinesterase inhibitor) drugs tacrine, rivastigmine and donepezil were studied on neuroinflammation induced by intraperitoneal administration of lipopolysaccharide (LPS) in mice. Interleukin-2 (IL-2) and isoforms of acetylcholinesterase (AChE) were estimated in different brain areas as marker for neuroinflammation and cholinergic activity respectively. LPS significantly increased the level of IL-2 in all the brain areas while enhancement of AChE activity varied in brain areas. It was found that administration of tacrine, rivastigmine and donepezil in mice significantly attenuated the LPS induced increased levels of IL-2 along with the significant reduction of AChE activity predominantly in salt soluble (SS) fraction as compared to the detergent soluble (DS) fraction in a dose dependent manner. In vitro effect of LPS was also studied in different brain areas. LPS significantly increased the AChE activity in SS fractions but the significant increase was not found in DS fractions. The present study indicate that cholinesterase inhibitor anti-dementia drugs are effective against LPS induced neuroinflammation that may be linked to enhanced cholinergic activity.

Loss of p16INK4A stimulates aberrant mitochondrial biogenesis through a CDK4/Rb-independent pathway.

The tumor suppressor p16INK4A (p16) inhibits cell cycle progression through the CDK4/Rb pathway. We have previously shown that p16 regulates cellular oxidative stress, independent of its role in cell cycle control. We investigated whether loss of p16 had a direct impact on the mitochondria. We found that p16-null primary mouse fibroblasts (PMFs) displayed increased mitochondrial mass and expression of mitochondrial respiratory subunit proteins compared to wild-type (WT) PMFs. These findings in p16-null PMFs were associated with increased expression of the mitochondrial biogenesis transcription factors PRC and TFAM. On the other hand, p16-deficient PMFs demonstrated reduced mitochondrial respiration capacity consistent with electron microscopy findings showing that mitochondria in p16-deficient PMFs have abnormal morphology. Consistent with increased mitochondrial mass and reduced respiratory capacity, p16-deficient PMFs generated increased mitochondrial superoxide. One biological consequence of elevated ROS in p16-deficient PMFs was enhanced migration, which was reduced by the ROS scavenger N-acetylcysteine. Finally, p16-deficient PMFs displayed increased mitochondrial membrane potential, which was also required for their enhanced migration. The mitochondrial and migration phenotype was restored in p16-deficient PMFs by forced expression of p16. Similarly, over-expression of p16 in human melanocytes and A375 melanoma cells led to decreased expression of some mitochondrial respiratory proteins, enhanced respiration, and decreased migration. Inhibition of Rb phosphorylation in melanocytes and melanoma cells, either by addition of chemical CDK4 inhibitors or RNAi-mediated knockdown of CDK4, did not mimic the effects of p16 loss. These results suggest that p16 regulates mitochondrial biogenesis and function, which is independent of the canonical CDK4/Rb pathway.

Systems Nutrigenomics Reveals Brain Gene Networks Linking Metabolic and Brain Disorders.

Nutrition plays a significant role in the increasing prevalence of metabolic and brain disorders. Here we employ systems nutrigenomics to scrutinize the genomic bases of nutrient-host interaction underlying disease predisposition or therapeutic potential. We conducted transcriptome and epigenome sequencing of hypothalamus (metabolic control) and hippocampus (cognitive processing) from a rodent model of fructose consumption, and identified significant reprogramming of DNA methylation, transcript abundance, alternative splicing, and gene networks governing cell metabolism, cell communication, inflammation, and neuronal signaling. These signals converged with genetic causal risks of metabolic, neurological, and psychiatric disorders revealed in humans. Gene network modeling uncovered the extracellular matrix genes Bgn and Fmod as main orchestrators of the effects of fructose, as validated using two knockout mouse models. We further demonstrate that an omega-3 fatty acid, DHA, reverses the genomic and network perturbations elicited by fructose, providing molecular support for nutritional interventions to counteract diet-induced metabolic and brain disorders. Our integrative approach complementing rodent and human studies supports the applicability of nutrigenomics principles to predict disease susceptibility and to guide personalized medicine.

TBI and sex: crucial role of progesterone protecting the brain in an omega-3 deficient condition.

We assessed whether the protective action of progesterone on traumatic brain injury (TBI) could be influenced by the consumption of omega-3 fatty acids during early life. Pregnant Sprague-Dawley rats were fed on omega-3 adequate or deficient diet from 3rd day of pregnancy and their female offspring were kept on the same diets up to the age of 15 weeks. Ovariectomy was performed at the age of 12 weeks to deprive animals from endogenous steroids until the time of a fluid percussion injury (FPI). Dietary n-3 fatty acid deficiency increased anxiety in sham animals and TBI aggravated the effects of the deficiency. Progesterone replacement counteracted the effects of TBI on the animals reared under n-3 deficiency. A similar pattern was observed for markers of membrane homeostasis such as 4-Hydroxynonenal (HNE) and secreted phospholipases A2 (sPLA2), synaptic plasticity such as brain derived neurotrophic factor (BDNF), syntaxin (STX)-3 and growth associated protein (GAP)-43, and for growth inhibitory molecules such as myelin-associated glycoprotein (MAG) and Nogo-A. Results that progesterone had no effects on sham n-3 deficient animals suggest that the availability of progesterone is essential under injury conditions. Progesterone treatment counteracted several parameters related to synaptic plasticity and membrane stability reduced by FPI and n-3 deficiency suggest potential targets for therapeutic applications. These results reveal the importance of n-3 preconditioning during early life and the efficacy of progesterone therapy during adulthood to counteract weaknesses in neuronal and behavioral plasticity.

Alpha 1-Antichymotrypsin, an Inflammatory Protein Overexpressed in the Brains of Patients with Alzheimer's Disease, Induces Tau Hyperphosphorylation through c-Jun N-Terminal Kinase Activation.

The association of inflammatory proteins with neuritic plaques in the brains of Alzheimer's disease (AD) patients has led to the hypothesis that inflammation plays a pivotal role in the development of pathology in AD. Earlier studies have shown that alpha 1-antichymotrypsin (ACT) enhances amyloid beta fibrillization and accelerated plaque formation in APP transgenic mice. Later studies from our laboratory have shown that purified ACT induces tau hyperphosphorylation and degeneration in neurons. In order to understand the mechanisms by which inflammatory proteins enhance tau hyperphosphorylation, we injected interleukin-1 ß (IL-1 ß ) intracerebroventricularly into mice expressing human ACT, human tau, or both transgenes. It was found that the hyperphosphorylation of tau in ACT and ACT/htau mice after IL-1 ß injection correlated with increased phosphorylation of c-Jun N-terminal kinase (JNK). We verified the involvement of JNK in ACT-induced tau phosphorylation by utilizing JNK inhibitors in cultured primary neurons treated with ACT, and we found that the inhibitor showed complete prevention of ACT-induced tau phosphorylation. These results indicate that JNK is one of the major kinases involved in the ACT-mediated tau hyperphosphorylation and suggest that inhibitors of this kinase may protect against inflammation-induced tau hyperphosphorylation and neurodegeneration associated with AD.

Vulnerability imposed by diet and brain trauma for anxiety-like phenotype: implications for post-traumatic stress disorders.

Mild traumatic brain injury (mTBI, cerebral concussion) is a risk factor for the development of psychiatric illness such as posttraumatic stress disorder (PTSD). We sought to evaluate how omega-3 fatty acids during brain maturation can influence challenges incurred during adulthood (transitioning to unhealthy diet and mTBI) and predispose the brain to a PTSD-like pathobiology. Rats exposed to diets enriched or deficient in omega-3 fatty acids (n-3) during their brain maturation period, were transitioned to a western diet (WD) when becoming adult and then subjected to mTBI. TBI resulted in an increase in anxiety-like behavior and its molecular counterpart NPY1R, a hallmark of PTSD, but these effects were more pronounced in the animals exposed to n-3 deficient diet and switched to WD. The n-3 deficiency followed by WD disrupted BDNF signaling and the activation of elements of BDNF signaling pathway (TrkB, CaMKII, Akt and CREB) in frontal cortex. TBI worsened these effects and more prominently in combination with the n-3 deficiency condition. Moreover, the n-3 deficiency primed the immune system to the challenges imposed by the WD and brain trauma as evidenced by results showing that the WD or mTBI affected brain IL1ß levels and peripheral Th17 and Treg subsets only in animals previously conditioned to the n-3 deficient diet. These results provide novel evidence for the capacity of maladaptive dietary habits to lower the threshold for neurological disorders in response to challenges.

Insulin receptor signaling in rat hippocampus: a study in STZ (ICV) induced memory deficit model.

Brain insulin receptors (IRs) have been suggested as an important regulatory factor for cognitive functions but the involvement of IR signaling in memory deficit associated with neurodegenerative conditions is not yet explored. In the present study, IR gene expression was studied by RT-PCR and signaling pathways by immunoblotting in CA1, DG and CA3 subregions of hippocampus in intracerebroventricular (ICV) administered streptozotocin (STZ, 3mg/kg twice) induced memory deficit model in rat. The effect of pre- and post-treatment of donepezil (5mg/kg po) and melatonin (20mg/kg po) on signaling pathways were studied. Effect of LY294002 (ICV), a PI3 Kinase inhibitor, was also investigated on memory functions and Akt phosphorylation. An increased IR expression (both gene and protein), phosphorylation of Shc, Erk1/2, IRS-1 and Akt in CA1 and CA3 region of P2M fraction was observed after training as compared to control. STZ treated rats showed memory deficit and significant decrease in IR expression, phosphorylation of IRS-1 and Akt only in CA3 region as compared to trained group which were reversed by pre and post-treatment of melatonin but donepezil was effective only against memory deficit. LY294002 (3mM) treatment showed delayed learning and decrease in Akt phosphorylation. This study suggests that IR expression and its signaling pathways in hippocampal CA1 and CA3 regions are involved in memory functions and STZ (ICV) induced memory deficit. Hippocampal IR system might be playing an important role in regulation of memory functions, however only IR/IRS-1/Akt pathway in CA3 region is associated with STZ induced memory deficit.

Cholinergic protection via alpha7 nicotinic acetylcholine receptors and PI3K-Akt pathway in LPS-induced neuroinflammation.

The present study was planned to investigate the effect of anti-cholinesterase drugs donepezil and neostigmine on neuroinflammation induced by intracerebroventricular administration of lipopolysaccharide (LPS, 50 microg) in rat. Proinflammatory cytokines (TNF-alpha and IL-1beta), expressions of iNOS and COX-2, acetylcholinesterase activity, malondialdehyde and reduced glutathione were studied in different brain regions at 24h of LPS injection. Donepezil was found to decrease the LPS-induced AChE activity and oxidative stress in all the brain regions. It also inhibited the LPS-induced proinflammatory cytokines and iNOS expression but did not affect the increased COX-2 expression whereas neostigmine treatment had no effect on LPS-induced proinflammatory cytokines. Methyllycaconitine (MLA), a alpha7 nicotinic acetylcholine receptor antagonist, significantly antagonized the donepezil mediated inhibition of LPS-induced proinflammatory cytokines, indicating that alpha7 nicotinic acetylcholine receptor subunit was playing a role in regulation of neuroinflammation. The phosphorylation of Akt, an effector of PI3K, increased with donepezil treatment. These results suggest that increased cholinergic activity in brain by donepezil prevents LPS-induced neuroinflammation via alpha7-nAChRs, followed by the PI3K-Akt pathway and this system may form the basis for the development of novel agents for reversing neuroinflammation or provide new indications for existing drugs.