leptin and Nervous-System-Diseases

Protein tyrosine phosphatase 1B (PTP1B) is a typical member of the PTP family, considered a direct negative regulator of several receptor and receptor-associated tyrosine kinases. This widely localized enzyme has been involved in the pathophysiology of several diseases. More recently, PTP1B has attracted attention in the field of neuroscience, since its activation in brain cells can lead to schizophrenia-like behaviour deficits, anxiety-like effects, neurodegeneration, neuroinflammation and depression. Conversely, PTP1B inhibition has been shown to prevent microglial activation, thus exerting a potent anti-inflammatory effect and has also shown potential to increase the cognitive process through the stimulation of hippocampal insulin, leptin and BDNF/TrkB receptors. Notwithstanding, most research on the clinical efficacy of targeting PTP1B has been developed in the field of obesity and type 2 diabetes mellitus (TD2M). However, despite the link existing between these metabolic alterations and neurodegeneration, no clinical trials assessing the neurological advantages of PTP1B inhibition have been performed yet. Preclinical studies, though, have provided strong evidence that targeting PTP1B could allow to reach different pathophysiological mechanisms at once. herefore, specific interventions or trials should be designed to modulate PTP1B activity in brain, since it is a promising strategy to decelerate or prevent neurodegeneration in aged individuals, among other neurological diseases. The present paper fails to include all neurological conditions in which PTP1B could have a role; instead, it focuses on those which have been related to metabolic alterations and neurodegenerative processes. Moreover, only preclinical data is discussed, since clinical studies on the potential of PTP1B inhibition for treating neurological diseases are still required.

Topics: Aged; Anti-Inflammatory Agents; Brain-Derived Neurotrophic Factor; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Humans; Insulin; Leptin; Nervous System Diseases; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Tyrosine

Cannabinoids exert a neuroprotective influence on some neurological diseases, including Alzheimer's, Parkinson's, Huntington's, multiple sclerosis and epilepsy. Synthetic cannabinoid receptor agonists/antagonists or compounds can provide symptom relief or control the progression of neurological diseases. However, the molecular mechanism and the effectiveness of these agents in controlling the progression of most of these diseases remain unclear. Cannabinoids may exert effects via a number of mechanisms and interactions with neurotransmitters, neurotropic factors and neuropeptides. Leptin is a peptide hormone involved in the regulation of food intake and energy balance via its actions on specific hypothalamic nuclei. Leptin receptors are widely expressed throughout the brain, especially in the hippocampus, basal ganglia, cortex and cerebellum. Leptin has also shown neuroprotective properties in a number of neurological disorders, such as Parkinson's and Alzheimer's. Therefore, cannabinoid and leptin hold therapeutic potential for neurological diseases. Further elucidation of the molecular mechanisms underlying the effects on these agents may lead to the development of new therapeutic strategies for the treatment of neurological disorders.

Topics: Animals; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Cannabinoids; Endocannabinoids; Humans; Leptin; Nervous System Diseases; Neuroprotective Agents

The metabolic syndrome is a cluster of common pathologies: abdominal obesity linked to an excess of visceral fat, insulin resistance, dyslipidemia and hypertension. At the molecular level, metabolic syndrome is accompanied not only by dysregulation in the expression of adipokines (cytokines and chemokines), but also by alterations in levels of leptin, a peptide hormone released by white adipose tissue. These changes modulate immune response and inflammation that lead to alterations in the hypothalamic 'bodyweight/appetite/satiety set point,' resulting in the initiation and development of metabolic syndrome. Metabolic syndrome is a risk factor for neurological disorders such as stroke, depression and Alzheimer's disease. The molecular mechanism underlying the mirror relationship between metabolic syndrome and neurological disorders is not fully understood. However, it is becoming increasingly evident that all cellular and biochemical alterations observed in metabolic syndrome like impairment of endothelial cell function, abnormality in essential fatty acid metabolism and alterations in lipid mediators along with abnormal insulin/leptin signaling may represent a pathological bridge between metabolic syndrome and neurological disorders such as stroke, Alzheimer's disease and depression. The purpose of this review is not only to describe the involvement of brain in the pathogenesis of metabolic syndrome, but also to link the pathogenesis of metabolic syndrome with neurochemical changes in stroke, Alzheimer's disease and depression to a wider audience of neuroscientists with the hope that this discussion will initiate more studies on the relationship between metabolic syndrome and neurological disorders.

Topics: Adipokines; Cannabinoid Receptor Modulators; Ceramides; Humans; Insulin; Insulin Resistance; Leptin; Lipid Metabolism; Metabolic Syndrome; Nervous System Diseases; Risk Factors

Helicobacter pylori (H. pylori) infection is reported to be associated with many extragastrointestinal manifestations, such as hematological diseases [idiopathic thrombocytopenic purpura (ITP) and unexplained iron deficiency anemia (IDA)], cardiovascular diseases (ischemic heart diseases), neurological disorders (stroke, Parkinson's disease, Alzheimer's disease), obesity and skin disorders. Among these, the best evidence so far is in ITP and unexplained IDA, with high-quality studies showing the improvement of IDA and ITP after H. pylori eradication. The evidence of its association with coronary artery disease is weak and many of the results may be erroneous. The role of H. pylori infection in affecting serum leptin and ghrelin levels has attracted a lot of attention recently and available data to date have been conflicting. There have also been many uncontrolled, small sample studies suggesting an association between H. pylori infection and neurological disorders or chronic urticaria. However, more studies are required to clarify such proposed causal links.

Topics: Anemia, Iron-Deficiency; Cardiovascular Diseases; Ghrelin; Helicobacter Infections; Helicobacter pylori; Humans; Leptin; Nervous System Diseases; Obesity; Purpura, Thrombocytopenic, Idiopathic

This review critically reappraises recent scientific evidence concerning central leptin insufficiency versus leptin resistance formulations to explain metabolic and neural disorders resulting from subnormal or defective leptin signaling in various sites in the brain. Research at various fronts to unravel the complexities of the neurobiology of leptin is surveyed to provide a comprehensive account of the neural and metabolic effects of environmentally imposed fluctuations in leptin availability at brain sites and the outcome of newer technology to restore leptin signaling in a site-specific manner. The cumulative new knowledge favors a unified central leptin insufficiency syndrome over the, in vogue, central resistance hypothesis to explain the global adverse impact of deficient leptin signaling in the brain. Furthermore, the leptin insufficiency syndrome delineates a novel role of leptin in the hypothalamus in restraining rhythmic pancreatic insulin secretion while concomitantly enhancing glucose metabolism and non-shivering thermogenic energy expenditure, sequelae that would otherwise promote fat accrual to store excess energy resulting from consumption of energy-enriched diets. A concerted effort should now focus on development of newer technologies for delivery of leptin or leptin mimetics to specifically target neural pathways for remediation of diverse ailments encompassing the central leptin insufficiency syndrome.

Topics: Animals; Humans; Leptin; Metabolic Diseases; Nervous System Diseases; Obesity; Syndrome

Recent studies demonstrate major effects of adrenal medullary and catecholaminergic pathways on a wide variety of normal physiologic and regulatory events. Alterations in these pathways, involving changes in catecholamines or in proteins and peptides costored and coreleased with catecholamines, may lead to profound changes in autonomic, cardiovascular, neuroendocrine, metabolic, nociceptive, and immune function. These findings have important implications for a variety of human disease states. In addition, molecules associated with catecholaminergic function may provide novel diagnostic and therapeutic strategies for human disease and suggest specific genetic loci as important and fruitful targets for further genetic and pharmacogenetic studies.

Topics: Catecholamines; Chromaffin Cells; Chromogranin A; Chromogranins; Dopamine beta-Hydroxylase; Humans; Hypertension; Leptin; Mutation; Nervous System Diseases; Parkinson Disease; Pheochromocytoma

The potential of neural stem cells (NSCs) for neurological disorders the treatment has relied in large part upon identifying the NSCs fate decision. The hormone leptin has been reported to be a crucial regulator of brain development, able to influence the glial and neural development, yet, the underlying mechanism of leptin acting on NSCs' biological characteristics is still poorly understood. This study aims to investigate the role of leptin in the biological properties of NSCs. In this study, we investigate the possibility that leptin may regulate the NSCs' fate decision, which may promote the proliferation and neuronal differentiation of NSCs and thus act positively in neurological disorders. NSCs from the embryonic cerebral cortex were used in this study. We used CCK-8 assay, ki67 immunostaining, and FACS analysis to confirm that 25-100 ng/mL leptin promotes the proliferation of NSCs in a concentration-dependent pattern. This change was accompanied by the upregulation of p-AKT and p-ERK1/2, which are the classical downstream signaling pathways of leptin receptors b (LepRb). Inhibition of PI3K/AKT or MAPK/ERK signaling pathways both abolished the effect of leptin-induced proliferation. Moreover, leptin also enhanced the directed neuronal differentiation of NSCs. A blockade of the PI3K/AKT pathway reversed leptin-stimulated neurogenesis, while a blockade of JAK2/STAT3 had no effect on it. Taken together, our results support a role for leptin in regulating the fate of NSCs differentiation and promoting NSCs proliferation, which could be a promising approach for brain repair via regulating the biological characteristics of NSCs.

Topics: Cell Differentiation; Cell Proliferation; Humans; Janus Kinase 2; Leptin; MAP Kinase Signaling System; Nervous System Diseases; Neural Stem Cells; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; STAT3 Transcription Factor

The rates for traumatic brain injury (TBI) have risen in the last decade. Studies in animal models and clinical trials have not yet resulted in an effective treatment for TBI. Leptin, a 16kDa peptidic hormone is mainly known as a regulator of energy balance and has been shown to exert neuroprotective effects in different models of brain pathology. In this study, we have assessed whether leptin exerts protective actions in a TBI mouse model. In addition, the possible implication of CB2 cannabinoid receptor in leptin actions has been explored, since it is known that the endocannabinoid system interacts with leptin and actively participates in brain recovery after lesions.. Swiss (CD1) male mice were subjected to weigh-drop model for TBI. Prior to the lesion, mice were injected with an antagonist of CB2 receptor (AM630) or the vehicle and immediately after TBI, they received leptin or vehicle treatment. Data were analyzed using a two-way ANOVA or the non-parametric test Kruskal-Wallis when appropriate. For correlation analyses, Spearman's rho test, followed by linear regression test, was used.. TBI induced a neurological deficit, which was improved by leptin treatment. Leptin recovered several parameters affected by TBI, including the expression of cannabinoid receptors, axonal injury marker and neuroinflammatory components. The effects of leptin were prevented or reduced when it was administered in combination with the CB2 receptor antagonist, AM630.. Since some of the beneficial effects of leptin were not evident in the presence of AM630, our results suggest that CB2 receptor might be involved in the full expression of the neuroprotective effects of the hormone. These findings open new avenues for the study of leptin as a therapeutic treatment for TBI and enhance the importance of CB2 receptor in TBI pathophysiology and recovery.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Axons; Behavior, Animal; Body Weight; Brain Injuries; Cannabinoid Receptor Antagonists; Cytokines; Indoles; Leptin; Male; Mice; Nervous System Diseases; Neuritis; Neuroprotective Agents; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2

Ischemic stroke is a medical emergency triggered by a rapid reduction in blood supply to localized portions of the brain, usually because of thrombosis or embolism, which leads to neuronal dysfunction and death in the affected brain areas. Leptin is generally considered to be a strong and quick stress mediator after injuries. However, whether and how peripherally administered leptin performs neuroprotective potency in cerebral stroke has not been fully investigated. It has been reported that CGRP(8-37), an antagonist of the CGRP receptor, could reverse the protective effect of leptin on rats with CIP (caerulein-induced pancreatitis). However, the question remains: are leptin and CGRP associated in cerebral ischemia/reperfusion injury? The present study attempted to evaluate the relationship between CGRP expression and leptin neuroprotective effects (1mg/kg in 200 μL normal saline, i.p.) on focal cerebral ischemia/reperfusion injury in mice and the protective effect of leptin (500 μg/L) on neurons during hypoxia/reoxygenation injury. Peripheral administration of leptin alleviated injury-evoked brain damage by promoting CGRP expression, improving regional cerebral blood flow, and reducing local infarct volume and neurological deficits. Furthermore, leptin also promoted bcl-2 expression and suppressed caspase-3 in vivo and vitro after injury. Administration of CGRP(8-37) (4 × 10(-8)mol/L) partly abolished the beneficial effects of leptin, and restored the normal expression levels of bcl-2 and caspase-3 in neurons, which indicated that leptin-induced protection of neurons was correlated with release of CGRP. These results indicate that the neuroprotective effect of leptin against cerebral ischemia/reperfusion injury may be strongly relevant to the increase of CGRP expression.

Topics: Animals; Apoptosis; Brain; Brain Ischemia; Calcitonin Gene-Related Peptide; Caspase 3; Cell Hypoxia; Cerebrovascular Circulation; Gene Expression Regulation; Leptin; Male; Mice; Nervous System Diseases; Neurons; Neuroprotective Agents; Oxygen; Proto-Oncogene Proteins c-bcl-2; Rats; Regional Blood Flow; Reperfusion Injury; RNA, Messenger; Up-Regulation

Unbalanced diets and stressful situations disrupt energy homeostasis and are implicated in the development of severe pathologies. The present study investigated the effects of a 7-day diet, enriched in corn oil (20%) and proportionally lower in protein and carbohydrate, on the major regulators of energy expenditure and stress response of adult male Wistar rats exposed to acute swimming stress at the end of the dietary treatment. Food intake and body weight gain were lower in diet-fed as compared with normal-chow-fed controls. The circulating leptin levels were elevated in both nonstressed and stressed diet-fed rats, while the glucose levels were significantly increased only in the diet-fed group subjected to stress. The plasma insulin levels were not affected by the diet, but were significantly reduced in acutely stressed rats. Acute swimming increased corticosterone levels both in chow-fed and diet-fed rats. No significant effect of diet was observed on corticosterone levels. Northern blot analysis showed increased glucocorticoid receptor mRNA levels in the hypothalamus of normally fed rats subjected to stress. This increase was not observed in the diet-fed stressed group, which on the contrary showed reduced glucocorticoid receptor mRNA levels following stress. The data presented indicate that even a moderately unbalanced, fat-enriched diet can within a short time disrupt the metabolic neuroendocrine balance and the stress response, rendering the organism more vulnerable to potential stressful insults.

Topics: Animals; Blood Glucose; Blotting, Northern; Corticosterone; Dietary Fats; Hippocampus; Hypothalamus; Insulin; Leptin; Male; Nervous System Diseases; Neurosecretory Systems; Rats; Rats, Wistar; Receptors, Glucocorticoid; RNA; Stress, Physiological

Recently, hypocretins have been implicated in the pathophysiology of narcolepsy, a sleep disorder characterized particularly by the occurrence of excessive daytime sleepiness and cataplexy. Hypocretins, which stimulate food intake, have been reported to be absent in the cerebrospinal fluid (CSF) of the majority of patients suffering from narcolepsy. Because these patients also display an increased body mass index (BMI), it has been suggested that disturbances in metabolism and food intake regulation may be present. To further investigate these presumed alterations, we studied the production of leptin, a fat-cell-derived hormone signaling to the brain the size of the adipose tissue. We measured the levels of leptin in serum and CSF from 15 narcoleptic patients and compared the results to those from age-, sex- and BMI-matched control groups of depressive patients and patients suffering from a noninflammatory neurological disorder. Compared to both control groups, leptin levels in serum, but not in the CSF, were significantly reduced in narcoleptic patients by more than 50%. These results support the hypothesis that human narcolepsy is accompanied by complex alterations of the regulation of food intake and metabolism. The significance of these alterations for the core symptomatology of narcolepsy should be a target of future research.

Topics: Depressive Disorder, Major; Humans; Leptin; Narcolepsy; Nervous System Diseases; Osmolar Concentration; Reference Values