Enhancing the GLP-1 receptor signaling pathway leads to proliferation and neuroprotection in human neuroblastoma cells

GLP- 1R status using validated monoclonal antibody in 689 cases of neuroendocrine neoplasm and its correlation with somatostatin receptor scintigraphy, insulin production, and histological grades

Radiolabeled glucagon-like peptide 1 (GLP- 1) analog scintigraphy is a new, high-sensitivity imaging method for detecting small insulinomas. Somatostatin receptor scintigraphy (SRS) is an established method for detecting gastroenteropancreatic neuroendocrine tumors. However, small benign insulinomas are difficult to detect using SRS. Furthermore, GLP- 1 receptor (GLP- 1R) expression and SRS results may be inversely correlated. We identified 689 neuroendocrine neoplasms, including pancreatic neuroendocrine tumors (PanNETs) and neuroendocrine neoplasms originating from non-pancreatic sites, and performed GLP- 1R immunostaining. Among the non-insulinoma PanNETs, immunohistochemical insulin or proinsulin positive cases were categorized as Inspos, and both negative cases as Insneg. High prevalence of GLP- 1R expression was detected in PanNETs and duodenal NETs (34% and 53%, respectively). Some pulmonary NETs were GLP- 1R positive (9%). In contrast, neither GI-NEC excluding one case nor pulmonary NEC exhibited GLP- 1R expression. The percentage of GLP- 1R positive cases for Inspos, Insneg, and insulinoma was 31%, 0%, and 84%, respectively. Among PanNETs, GLP- 1R positive cases showed higher expression of insulin and proinsulin than negative cases. SRS-positive patients showed lower expression levels of insulin, proinsulin, and GLP- 1R than SRS-negative patients. The expression in PanNETs and duodenal NETs may be derived from the expression in their normal counterparts. Insulinoma and Inspos cases showed GLP- 1R expression. Furthermore, as GLP- 1R-positive patients showed significantly higher expression of insulin and proinsulin than GLP- 1R negative patients, GLP- 1R may also be associated with neoplastic insulin production and GLP- 1 analog scintigraphy may detect subclinical insulinomas. In addition, SRS-negative cases showed significantly higher GLP- 1R expression than SRS-positive cases. These results suggest the application potential of GLP- 1 analog scintigraphy in combination with SRS as a detection tool.

Role of Glucagon-Like Peptide-1 on Amyloid, Tau, and α-Synuclein: Target Engagement and Rationale for the Development in Neurodegenerative Disorders

INTRODUCTION

Glucagon-like Peptide-1 (GLP-1) and Glucagon-Like Peptide-1 receptor agonist (GLP-1 RA) administration has been associated with neuroprotective effects in neurodegenerative disorders. We conducted a comprehensive synthesis of known effects of GLP-1 and GLP-1 RAs on the cognitive, cellular, and molecular changes in neurodegenerative diseases.

METHODS

We examined preclinical and clinical paradigms that investigated changes in neurodegenerative disease pathology following administration of GLP-1 and GLP-1 RAs. Relevant articles were retrieved through OVID (MedLine, Embase, AMED, PsychINFO, JBI EBP Database), PubMed, and Web of Science from database inception to September 27th, 2024. Primary studies investigating the aforementioned changes following GLP-1 and GLP-1 RA administration were retrieved for analysis (n = 62).

RESULTS

GLP-1 and GLP-1 RAs (i.e. dulaglutide, exenatide, liraglutide, lixisenatide, semaglutide, and tirzepatide) improved cognitive and motor function in neurodegenerative diseases in preclinical and clinical paradigms. Additionally, GLP-1 and GLP-1 RAs were associated with modulating changes in neuroinflammation, oxidative stress, and proliferative pathways.

DISCUSSION

We observed that GLP-1 and GLP-1 RAs modulate molecular and cellular changes known to govern the phenomenology of neurodegenerative diseases. Future research should examine the interaction between signaling molecules, neuronal subpopulations, and cognitive effects affected by GLP-1 and GLP-1 RA administration.

Novel Trajectories Towards Possible Effects of Semaglutide for Amelioration of Reserpine-induced Fibromyalgia in Rats: Contribution of cAMP/PKA/p-CREB and M1/M2 Microglia Polarization

Fibromyalgia (FM) is a pain disorder characterized by pervasive musculoskeletal pain associated with exhaustion, depression, and irregular sleep patterns. Semaglutide, an innovative glucagon-like peptide-1 (GLP-1) agonist, has shown analgesic effects by modulating pain hypersensitivity in animal models of inflammatory pain. The objective of this study is to ascertain semaglutide's therapeutic potential against FM-like symptoms caused by reserpine. Reserpine (1 mg/kg/day; SC) was administered into rats for 3 consecutive days, then they were treated daily with semaglutide intraperitoneally in low (5 nmol/kg), intermediate (10 nmol/kg), or high doses (20 nmol/kg), respectively, for 14 consecutive days. Semaglutide alleviated reserpine induced histopathological and immunohistopathological changes in spinal cord of rats evidenced by a remarkable rise in immuno-expression of cluster of differentiation 163 (CD163) contrary to a significant diminution in CD86 level as compared with reserpine group. Semaglutide also had an analgesic effect and improved motor incoordination, and depression brought on by reserpine. Furthermore, it had an anti-inflammatory impact via stimulating cyclic adenosine monophosphate (cAMP)/ protein kinase A (PKA)/ cAMP response element (CRE)-binding protein (CREB) signaling pathway and shifting M1/M2 macrophage polarization towards the M2. Semaglutide's anti-inflammatory actions were manifested through inhibition of inducible nitric oxide synthase and reduction in dorsal root ganglia concentrations of tumor necrosis factor-α together with elevation in the levels of arginase-1 and interleukin-4.

Targeting Ferroptosis in Parkinson's: Repurposing Diabetes Drugs as a Promising Treatment

This review explores the promising potential of repurposing type 2 diabetes (T2D) medications for the treatment of Parkinson's disease (PD), highlighting the shared pathophysiological mechanisms between these two age-related conditions, such as oxidative stress, mitochondrial dysfunction, and ferroptosis. The overlap suggests that existing diabetes drugs could target the common pathways involved in both conditions. Specifically, the review discusses how T2D medications, including metformin (Met), peroxisome-proliferator-activated receptor gamma (PPAR-γ) agonists, sodium-glucose cotransporter-2 (SGLT2) inhibitors, incretins, and dipeptidyl-peptidase 4 (DPP-4) inhibitors, can improve mitochondrial function, reduce neuroinflammation and oxidative stress, and potentially inhibit ferroptosis. The connection between ferroptosis and existing treatments, including diabetes medication, are only beginning to be explored. The limited data can be attributed also to the complexity of mechanisms involved in ferroptosis and Parkinson's disease and to the fact that the specific role of ferroptosis in Parkinson's disease pathogenesis has not been a primary focus until recent. Despite the promising preclinical evidence, clinical findings are mixed, underscoring the need for further research to elucidate these drugs' roles in neurodegeneration. Repurposing existing diabetes medications that have well-established safety profiles for Parkinson's disease treatment could significantly reduce the time and cost associated with drug development and could offer a more comprehensive approach to managing Parkinson's disease compared to treatments targeting a single mechanism.

Exploring Therapeutic Strategies: The Relationship between Metabolic Disorders and FOXO Signalling in Alzheimer's Disease

Alzheimer's disease is an ailment that is linked with the degeneration of the brain cells, and this illness is the main cause of dementia. Metabolic stress affects the activity of the brain in AD via FOXO signaling. The occurrence of AD will significantly surge as the world's population ages, along with lifestyle changes perceived in current decades, indicating a main contributor to such augmented prevalence. Similarly, metabolic disorders of current adulthood, such as obesity, stroke, and diabetes mellitus, have been observed as the risk-causing factors of AD. Environmental influences induce genetic mutations that result in the development of several diseases. Metabolic disorders develop when individuals are exposed to an environment where food is easily accessible and requires minimal energy expenditure. Obesity and diabetes are among the most significant worldwide health concerns. Obesity arises because of an imbalance between the amount of energy consumed and the amount of energy expended, which is caused by both behavioral and physiological factors. Obesity, insulin resistance syndrome, hypertension, and inflammation are factors that contribute to the worldwide risk of developing diabetes mellitus and neurodegenerative diseases. FOXO transcription factors are preserved molecules that play an important part in assorted biological progressions, precisely in aging as well as metabolism. Apoptosis, cell division and differentiation, oxidative stress, metabolism, and lifespan are among the physiological processes that the FOXO proteins are adept at controlling. In this review, we explored the correlation between signaling pathways and the cellular functions of FOXO proteins. We have also summarized the intricate role of FOXO in AD, with a focus on metabolic stress, and discussed the prospect of FOXO as a molecular link between AD and metabolic disorders.

Beyond insulin: The Intriguing role of GLP-1 in Parkinson's disease

GLP-1 (Glucagon-like peptide 1) serves as both a peptide hormone and a growth factor, is released upon nutrient intake and contributes to insulin secretion stimulated by glucose levels. Also, GLP-1 is synthesized within several brain areas and plays a vital function in providing neuroprotection and reducing inflammation through the activation of the GLP-1 receptor. Parkinson's Disease (PD) is a neurodegenerative illness that worsens with time and is defined by considerable morbidity. Presently, there are few pharmaceutical choices available, and none of the existing therapies are capable of modifying the course of the disease. There is a suggestion that type 2 diabetes mellitus (T2DM) could increase the risk of PD, and the presence of both conditions concurrently might exacerbate PD symptoms and hasten neurodegeneration. GLP-1 receptor (GLP-1R) agonists exhibit numerous implications like enhancement of glucose-dependent insulin release and biosynthesis, suppression of glucagon secretion and gastric emptying. Also, some GLP-1R agonists have received clinical approval for the management of T2DM. Moreover, the use of GLP-1R agonists has demonstrated counter-inflammatory, neurotrophic, and neuroprotective actions in various preclinical models of neurodegenerative disorders. Considering the significant amount of evidence backing the potential of GLP-1R agonists to protect the nervous system across different research settings, this article delves into examining the hopeful prospect of GLP-1R agonists as a treatment option for PD. This review sheds light on combined neuroprotective benefits of GLP-1R agonists and the possible mechanisms driving the protective effects on the PD brain, through the collection of data from various preclinical and clinical investigations.

Unlocking longevity with GLP-1: A key to turn back the clock?

Traditionally known for managing blood sugar, GLP-1, a gut hormone, is emerging as a potential key to both lengthening lifespan and combating age-related ailments. While widely recognized for its role in blood sugar control, GLP-1 is increasingly recognized for its diverse effects on various biological pathways beyond glucose metabolism. Research across organisms and humans suggests that activating GLP-1 receptors significantly impacts cellular processes linked to aging. Its ability to boost mitochondrial function, enhance cellular stress resistance, and quell inflammation hints at its wider influence on aging mechanisms. This intricate interplay between GLP-1 and longevity appears to act through multiple pathways. One key effect is its ability to modulate insulin sensitivity, potentially curbing age-related metabolic issues like type 2 diabetes. Its neuroprotective properties also make it a promising candidate for addressing age-related cognitive decline and neurodegenerative diseases. Furthermore, preclinical studies using GLP-1 analogs or agonists have shown promising results in extending lifespan and improving healthspan in various model organisms. These findings provide a compelling rationale for exploring GLP-1-based interventions in humans to extend healthy aging. However, despite the exciting therapeutic prospects of GLP-1 in promoting longevity, challenges remain. Determining optimal dosages, establishing long-term safety profiles, and investigating potential adverse effects require comprehensive clinical investigations before we can confidently translate these findings to humans. This article emphasises the wide applicability of GLP-1.

Incretin-Based Multi-Agonist Peptides Are Neuroprotective and Anti-Inflammatory in Cellular Models of Neurodegeneration

Glucagon-like peptide-1 (GLP-1)-based drugs have been approved by the United States Food and Drug Administration (FDA) and are widely used to treat type 2 diabetes mellitus (T2DM) and obesity. More recent developments of unimolecular peptides targeting multiple incretin-related receptors ("multi-agonists"), including the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) and the glucagon (Gcg) receptor (GcgR), have emerged with the aim of enhancing drug benefits. In this study, we utilized human and mouse microglial cell lines, HMC3 and IMG, respectively, together with the human neuroblastoma SH-SY5Y cell line as cellular models of neurodegeneration. Using these cell lines, we studied the neuroprotective and anti-inflammatory capacity of several multi-agonists in comparison with a single GLP-1 receptor (GLP-1R) agonist, exendin-4. Our data demonstrate that the two selected GLP-1R/GIPR dual agonists and a GLP-1R/GIPR/GcgR triple agonist not only have neurotrophic and neuroprotective effects but also have anti-neuroinflammatory properties, as indicated by the decreased microglial cyclooxygenase 2 (COX2) expression, nitrite production, and pro-inflammatory cytokine release. In addition, our results indicate that these multi-agonists have the potential to outperform commercially available single GLP-1R agonists in neurodegenerative disease treatment.

GLP-1 modulated the firing activity of nigral dopaminergic neurons in both normal and parkinsonian mice

The spontaneous firing activity of nigral dopaminergic neurons is associated with some important roles including modulation of dopamine release, expression of tyrosine hydroxylase (TH), as well as neuronal survival. The decreased neuroactivity of nigral dopaminergic neurons has been revealed in Parkinson's disease. Central glucagon-like peptide-1 (GLP-1) functions as a neurotransmitter or neuromodulator to exert multiple brain functions. Although morphological studies revealed the expression of GLP-1 receptors (GLP-1Rs) in the substantia nigra pars compacta, the possible modulation of GLP-1 on spontaneous firing activity of nigral dopaminergic neurons is unknown. The present extracellular in vivo single unit recordings revealed that GLP-1R agonist exendin-4 significantly increased the spontaneous firing rate and decreased the firing regularity of partial nigral dopaminergic neurons of adult male C57BL/6 mice. Blockade of GLP-1Rs by exendin (9-39) decreased the firing rate of nigral dopaminergic neurons suggesting the involvement of endogenous GLP-1 in the modulation of firing activity. Furthermore, the PKA and the transient receptor potential canonical (TRPC) 4/5 channels are involved in activation of GLP-1Rs-induced excitatory effects of nigral dopaminergic neurons. Under parkinsonian state, both the exogenous and endogenous GLP-1 could still induce excitatory effects on the surviving nigral dopaminergic neurons. As the mild excitatory stimuli exert neuroprotective effects on nigral dopaminergic neurons, the present GLP-1-induced excitatory effects may partially contribute to its antiparkinsonian effects.

Transcranial Irradiation Mitigates Paradoxical Sleep Deprivation Effect in an Age-Dependent Manner: Role of BDNF and GLP-1

The growing prevalence of aged sleep-deprived nations is turning into a pandemic state. Acute sleep deprivation (SD) accompanies aging, changing the hippocampal cellular pattern, neurogenesis pathway expression, and aggravating cognitive deterioration. The present study investigated the ability of Near Infra Red (NIR) light laser to ameliorate cognitive impairment induced by SD in young and senile rats. Wistar rats ≤ 2 months (young) and ≥ 14 months (senile) were sleep-deprived for 72 h with or without transcranial administration of NIR laser of 830 nm. Our results showed that NIR photobiomodulation (PBM) attenuated cognitive deterioration made by SD in young, but not senile rats, while both sleep-deprived young and senile rats exhibited decreased anxiety (mania)-like behavior in response to PBM. NIR PBM had an inhibitory effect on AChE, enhanced the production of ACh, attenuated ROS, and regulated cell apoptosis factors such as Bax and Bcl-2. NIR increased mRNA expression of BDNF and GLP-1 in senile rats, thus facilitating neuronal survival and differentiation. The present findings also revealed that age exerts an additive factor to the cellular assaults produced by SD where hippocampal damages made in 2-month rats were less severe than those of the aged one. In conclusion, NIR PBM seems to promote cellular longevity of senile hippocampal cells by combating ROS, elevating neurotrophic factors, thus improving cognitive performance. The present findings provide NIR as a possible candidate for hippocampal neuronal insults accompanying aging and SD.

GLP-1 Receptor Agonists: A New Treatment in Parkinson's Disease

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Recent data highlight similarities between neurodegenerative diseases, including PD and type 2 diabetes mellitus (T2DM), suggesting a crucial interplay between the gut-brain axis. Glucagon-like peptide-1 receptor (GLP-1R) agonists, known for their use in T2DM treatment, are currently extensively studied as novel PD modifying agents. For this narrative review article, we searched PubMed and Scopus databases for peer-reviewed research, review articles and clinical trials regarding GLP-1R agonists and PD published in the English language with no time restrictions. We also screened the references of the selected articles for possible additional articles in order to include most of the key recent evidence. Many data on animal models and preclinical studies show that GLP1-R agonists can restore dopamine levels, inhibit dopaminergic loss, attenuate neuronal degeneration and alleviate motor and non-motor features of PD. Evidence from clinical studies is also very promising, enhancing the possibility of adding GLP1-R agonists to the current armamentarium of drugs available for PD treatment.

Does gut brain axis has an impact on Parkinson's disease (PD)?

Parkinson's Disease (PD) is becoming a growing global concern by being the second most prevalent disease next to Alzheimer's Disease (AD). Henceforth new exploration is needed in search of new aspects towards the disease mechanism and origin. Evidence from recent studies has clearly stated the role of Gut Microbiota (GM) in the maintenance of the brain and as a root cause of various diseases and disorders including other neurological conditions. In the case of PD, with an unknown etiology, the GM is said to have a larger impact on the disease pathophysiology. Although GM and its metabolites are crucial for maintaining the normal physiology of the host, it is an undeniable fact that there is an influence of GM in the pathophysiology of PD. As such the Enteroendocrine Cells (EECs) in the epithelium of the intestine are one of the significant regulators of the gut-brain axis and act as a communication mediator between the gut and the brain. The communication is established via the molecules of neuroendocrine which are said to have a crucial part in neurological diseases such as AD, PD, and other psychiatry-related disorders. This review is focused on understanding the proper role of GM and EECs in PD. Here, we also focus on some of the metabolites and compounds that can interact with the PD genes causing various dysfunctions in the cell and facilitating the disease conditions using bioinformatical tools. Various mechanisms concerning EECs and PD, their identification, the latest studies, and available current therapies have also been discussed.

Obesity and Depression: Common Link and Possible Targets

Depression is among the main causes of disability, and its protracted manifestations could make it even harder to treat metabolic diseases. Obesity is linked to episodes of depression, which is closely correlated to abdominal adiposity and impaired food quality. The present review is aimed at studying possible links between obesity and depression along with targets to disrupt it. Research output in Pubmed and Scopus were referred for writing this manuscript. Obesity and depression are related, with the greater propensity of depressed people to gain weight, resulting in poor dietary decisions and a sedentary lifestyle. Adipokines, which include adiponectin, resistin, and leptin are secretory products of the adipose tissue. These adipokines are now being studied to learn more about the connection underlying obesity and depression. Ghrelin, a gut hormone, controls both obesity and depression. Additionally, elevated ghrelin levels result in anxiolytic and antidepressant-like effects. The gut microbiota influences the metabolic functionalities of a person, like caloric processing from indigestible nutritional compounds and storage in fatty tissue, that exposes an individual to obesity, and gut microorganisms might connect to the CNS through interconnecting pathways, including neurological, endocrine, and immunological signalling systems. The alteration of brain activity caused by gut bacteria has been related to depressive episodes. Monoamines, including dopamine, serotonin, and norepinephrine, have been widely believed to have a function in emotions and appetite control. Emotional signals stimulate arcuate neurons in the hypothalamus that are directly implicated in mood regulation and eating. The peptide hormone GLP-1(glucagon-like peptide- 1) seems to have a beneficial role as a medical regulator of defective neuroinflammation, neurogenesis, synaptic dysfunction, and neurotransmitter secretion discrepancy in the depressive brain. The gut microbiota might have its action in mood and cognition regulation, in addition to its traditional involvement in GI function regulation. This review addressed the concept that obesity-related low-grade mild inflammation in the brain contributes to chronic depression and cognitive impairments.

Echinometra lucunter molecules reduce Aβ42-induced neurotoxicity in SH-SY5Y neuron-like cells: effects on disaggregation and oxidative stress

Background

Echinometra lucunter is a sea urchin commonly found on America's rocky shores. Its coelomic fluid contains molecules used for defense and biological processes, which may have therapeutic potential for the treatment of amyloid-based neurodegenerative diseases, such as Alzheimer's, that currently have few drug options available.

Methods

In this study, we incubated E. lucunter coelomic fluid (ELCF) and fractions obtained by solid phase extraction in SH-SY5Y neuron-like cells to evaluate their effect on cell viability caused by the oligomerized amyloid peptide 42 (Aβ42o). Moreover, the Aβ42o was quantified after the incubation with ELCF fractions in the presence or not of cells, to evaluate if samples could cause amyloid peptide disaggregation. Antioxidant activity was determined in ELCF fractions, and cells were evaluated to check the oxidative stress after incubation with samples. The most relevant fraction was analyzed by mass spectrometry for identification of molecules.

Results

ELCF and certain fractions could prevent and treat the reduction of cell viability caused by Aβ42o in SH-SY5Y neuron-like cells. We found that one fraction (El50) reduced the oligomerized Aβ42 and the oxidative stress caused by the amyloid peptide through its antioxidant molecules, which in turn reduced cell death. Mass spectrometry analysis revealed that El50 comprises small molecules containing flavonoid antioxidants, such as phenylpyridazine and dihydroquercetin, and two peptides.

Conclusion

Our results suggest that sea urchin molecules may interact with Aβ42o and oxidative stress, preventing or treating neurotoxicity, which may be useful in treating dementia.

Glucagon-like peptide 1 (GLP-1) receptor agonists in experimental Alzheimer's disease models: a systematic review and meta-analysis of preclinical studies

Alzheimer's disease (AD) is a degenerative disease of the nervous system. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), a drug used to treat type 2 diabetes, have been shown to have neuroprotective effects. This systematic review and meta-analysis evaluated the effects and potential mechanisms of GLP-1 RAs in AD animal models. 26 studies were included by searching relevant studies from seven databases according to a predefined search strategy and inclusion criteria. Methodological quality was assessed using SYRCLE's risk of bias tool, and statistical analysis was performed using ReviewManger 5.3. The results showed that, in terms of behavioral tests, GLP-1 RAs could improve the learning and memory abilities of AD rodents; in terms of pathology, GLP-1 RAs could reduce Aβ deposition and phosphorylated tau levels in the brains of AD rodents. The therapeutic potential of GLP-1 RAs in AD involves a range of mechanisms that work synergistically to enhance the alleviation of various pathological manifestations associated with the condition. A total of five clinical trials were retrieved from ClinicalTrials.gov. More large-scale and high-quality preclinical trials should be conducted to more accurately assess the therapeutic effects of GLP-1 RAs on AD.

The neuroprotective effects of glucagon-like peptide 1 in Alzheimer's and Parkinson's disease: An in-depth review

Currently, there is no disease-modifying treatment available for Alzheimer's and Parkinson's disease (AD and PD) and that includes the highly controversial approval of the Aβ-targeting antibody aducanumab for the treatment of AD. Hence, there is still an unmet need for a neuroprotective drug treatment in both AD and PD. Type 2 diabetes is a risk factor for both AD and PD. Glucagon-like peptide 1 (GLP-1) is a peptide hormone and growth factor that has shown neuroprotective effects in preclinical studies, and the success of GLP-1 mimetics in phase II clinical trials in AD and PD has raised new hope. GLP-1 mimetics are currently on the market as treatments for type 2 diabetes. GLP-1 analogs are safe, well tolerated, resistant to desensitization and well characterized in the clinic. Herein, we review the existing evidence and illustrate the neuroprotective pathways that are induced following GLP-1R activation in neurons, microglia and astrocytes. The latter include synaptic protection, improvements in cognition, learning and motor function, amyloid pathology-ameliorating properties (Aβ, Tau, and α-synuclein), the suppression of Ca2+ deregulation and ER stress, potent anti-inflammatory effects, the blockage of oxidative stress, mitochondrial dysfunction and apoptosis pathways, enhancements in the neuronal insulin sensitivity and energy metabolism, functional improvements in autophagy and mitophagy, elevated BDNF and glial cell line-derived neurotrophic factor (GDNF) synthesis as well as neurogenesis. The many beneficial features of GLP-1R and GLP-1/GIPR dual agonists encourage the development of novel drug treatments for AD and PD.

Beneficial Influence of Exendin-4 on Specific Organs and Mechanisms Favourable for the Elderly with Concomitant Obstructive Lung Diseases

Exendin-4 (Ex-4), better known in its synthetic form and used clinically as exenatide, currently applied in the treatment of diabetes, induces a beneficial impact on nerve cells, and shows promising effects in obstructive lung diseases. At an advanced age, the development of the neurodegenerative process of brain tissue is masked by numerous concomitant diseases. The initial latent phase of neurodegenerative disease results in occurrence of manifestations at an advanced stage. To protect the brain and to simultaneously ensure proper treatment of common coexisting conditions in late life, such as diabetes, chronic obstructive pulmonary disease, or asthma, a pleiotropic medication should be chosen. Molecular mechanisms of Ex-4 exert neuroprotective effects or lead to secondary neurogenesis. Additionally, Ex-4 plays an important role in anti-inflammatory actions which are necessary both in the case of asthma and Parkinson’s disease. Specific receptors in the lungs also reduce the secretion of surfactants, which decreases the risk of exacerbation in chronic obstructive lung disease. In a great number of patients suffering from diabetes, asthma, or chronic lung disease, there is a great potential for both treatment of the main condition and protection against brain neurodegeneration.

Activation of IGF-1/GLP-1 Signalling via 4-Hydroxyisoleucine Prevents Motor Neuron Impairments in Experimental ALS-Rats Exposed to Methylmercury-Induced Neurotoxicity

Amyotrophic lateral sclerosis (ALS) is a severe adult motor neuron disease that causes progressive neuromuscular atrophy, muscle wasting, weakness, and depressive-like symptoms. Our previous research suggests that mercury levels are directly associated with ALS progression. MeHg+-induced ALS is characterised by oligodendrocyte destruction, myelin basic protein (MBP) depletion, and white matter degeneration, leading to demyelination and motor neuron death. The selection of MeHg+ as a potential neurotoxicant is based on our evidence that it has been connected to the development of ALS-like characteristics. It causes glutamate-mediated excitotoxicity, calcium-dependent neurotoxicity, and an ALS-like phenotype. Dysregulation of IGF-1/GLP-1 signalling has been associated with ALS progression. The bioactive amino acid 4-hydroxyisoleucine (HI) from Trigonella foenum graecum acts as an insulin mimic in rodents and increases insulin sensitivity. This study examined the neuroprotective effects of 4-HI on MeHg+-treated adult Wistar rats with ALS-like symptoms, emphasising brain IGF1/GLP-1 activation. Furthermore, we investigated the effect of 4-HI on MBP levels in rat brain homogenate, cerebrospinal fluid (CSF), blood plasma, and cell death indicators such as caspase-3, Bax, and Bcl-2. Rats were assessed for muscular strength, locomotor deficits, depressed behaviour, and spatial learning in the Morris water maze (MWM) to measure neurobehavioral abnormalities. Doses of 4-HI were given orally for 42 days in the MeHg+ rat model at 50 mg/kg or 100 mg/kg to ameliorate ALS-like neurological dysfunctions. Additionally, neurotransmitters and oxidative stress markers were examined in rat brain homogenates. Our findings suggest that 4-HI has neuroprotective benefits in reducing MeHg+-induced behavioural, neurochemical, and histopathological abnormalities in ALS-like rats exposed to methylmercury.

Therapeutic application of GLP-1 and GIP receptor agonists in Parkinson's disease

INTRODUCTION

Diabetes is a risk factor for Parkinson's disease (PD) and shares similar dysregulated insulin pathways. Glucagon-like peptide-1 (GLP-1) analogs originally designed to treat diabetes have shown potent neuroprotective activity in preclinical studies of PD. They are neuroprotective by inhibiting inflammation, improving neuronal survival, maintenance of synapses, and dopaminergic transmission in the brain. Building on this, three clinical studies have reported impressive effects in patients with PD, testing exendin-4 (Exenatide, Bydureon) or liraglutide (Victoza, Saxenda). Glucose-dependent insulinotropic peptide (GIP) is another peptide hormone that has shown good effects in animal models of PD. Novel dual GLP-1/GIP agonists have been developed that can penetrate the blood-brain barrier (BBB) and show superior effects in animal models compared to GLP-1 drugs.

AREAS COVERED

The review summarizes preclinical and clinical studies testing GLP-1R agonists and dual GLP-1/GIPR agonists in PD and discusses possible mechanisms of action.

EXPERT OPINION

Current strategies to treat PD by lowering the levels of alpha-synuclein have not shown effects in clinical trials. It is time to move on from the 'misfolding protein' hypothesis. Growth factors such as GLP-1 that can cross the BBB have already shown impressive effects in patients and are the future of drug discovery in PD.

The Role of Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RA) in Diabetes-Related Neurodegenerative Diseases

Recent clinical guidelines have emphasized the importance of screening for cognitive impairment in older adults with diabetes, however, there is still a lack of understanding about the drug therapy. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are widely used in the treatment of type 2 diabetes and potential applications may include the treatment of obesity as well as the adjunctive treatment of type 1 diabetes mellitus in combination with insulin. Growing evidence suggests that GLP-1 RA has the potential to treat neurodegenerative diseases, particularly in diabetes-related Alzheimer’s disease (AD) and Parkinson’s disease (PD). Here, we review the molecular mechanisms of the neuroprotective effects of GLP-1 RA in diabetes-related degenerative diseases, including AD and PD, and their potential effects.

Novel Insights into the Roles and Mechanisms of GLP-1 Receptor Agonists against Aging-Related Diseases

Aging and aging-related diseases have emerged as increasingly severe health and social problems. Therefore, it is imperative to discover novel and effective therapeutics to delay the aging process and to manage aging-related diseases. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), one of the classes of antihyperglycemic drugs, have been recommended to manage type 2 diabetes mellitus (T2DM). Moreover, GLP-1 RAs have been shown to protect against oxidative stress, cellular senescence and chronic inflammation, which are widely accepted as the major risk factors of aging. However, their significance in aging or aging-related diseases has not been elucidated. Herein, we explain the underlying mechanisms and protective roles of GLP-1 RAs in aging from a molecular, cellular and phenotypic perspective. We provide novel insights into the broad prospect of GLP-1 RAs in preventing and treating aging-related diseases. Additionally, we highlight the gaps for further studies in clinical applications of GLP-1 RAs in aging-related diseases. This review forms a basis for further studies on the relationship between aging-related diseases and GLP-1 RAs.

Emerging Therapeutic Strategies for Parkinson’s Disease and Future Prospects: A 2021 Update

Parkinson’s disease (PD) is a neurodegenerative disorder pathologically distinguished by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Muscle rigidity, tremor, and bradykinesia are all clinical motor hallmarks of PD. Several pathways have been implicated in PD etiology, including mitochondrial dysfunction, impaired protein clearance, and neuroinflammation, but how these factors interact remains incompletely understood. Although many breakthroughs in PD therapy have been accomplished, there is currently no cure for PD, only trials to alleviate the related motor symptoms. To reduce or stop the clinical progression and mobility impairment, a disease-modifying approach that can directly target the etiology rather than offering symptomatic alleviation remains a major unmet clinical need in the management of PD. In this review, we briefly introduce current treatments and pathophysiology of PD. In addition, we address the novel innovative therapeutic targets for PD therapy, including α-synuclein, autophagy, neurodegeneration, neuroinflammation, and others. Several immunomodulatory approaches and stem cell research currently in clinical trials with PD patients are also discussed. Moreover, preclinical studies and clinical trials evaluating the efficacy of novel and repurposed therapeutic agents and their pragmatic applications with encouraging outcomes are summarized. Finally, molecular biomarkers under active investigation are presented as potentially valuable tools for early PD diagnosis.

L-dopa-Dependent Effects of GLP-1R Agonists on the Survival of Dopaminergic Cells Transplanted into a Rat Model of Parkinson Disease

Cell therapy is a promising treatment for Parkinson's disease (PD), however clinical trials to date have shown relatively low survival and significant patient-to-patient variability. Glucagon Like Peptide-1 receptor (GLP-1R) agonists have potential neuroprotective effects on endogenous dopaminergic neurons. This study explores whether these agents could similarly support the growth and survival of newly transplanted neurons. 6-OHDA lesioned Sprague Dawley rats received intra-striatal grafts of dopaminergic ventral mesencephalic cells from embryonic day 14 Wistar rat embryos. Transplanted rats then received either saline or L-dopa (12 mg/kg) administered every 48 h prior to, and following cell transplantation. Peripheral GLP-1R agonist administration (exendin-4, 0.5 μg/kg twice daily or liraglutide, 100 μg/kg once daily) commenced immediately after cell transplantation and was maintained throughout the study. Graft survival increased under administration of exendin-4, with motor function improving significantly following treatment with both exendin-4 and liraglutide. However, this effect was not observed in rats administered with L-dopa. In contrast, L-dopa treatment with liraglutide increased graft volume, with parallel increases in motor function. However, this improvement was accompanied by an increase in leukocyte infiltration around the graft. The co-administration of L-dopa and exendin-4 also led to indicators of insulin resistance not seen with liraglutide, which may underpin the differential effects observed between the two GLP1-R agonists. Overall, there may be some benefit to the supplementation of grafted patients with GLP-1R agonists but the potential interaction with other pharmacological treatments needs to be considered in more depth.

The metabolite GLP-1 (9-36) is neuroprotective and anti-inflammatory in cellular models of neurodegeneration

Glucagon-like peptide-1 (GLP-1) is best known for its insulinotropic action following food intake. Its metabolite, GLP-1 (9-36), was assumed biologically inactive because of low GLP-1 receptor (GLP-1R) affinity and non-insulinotropic properties; however, recent studies contradict this assumption. Increased use of FDA approved GLP-1 analogues for treating metabolic disorders and neurodegenerative diseases raises interest in GLP-1 (9-36)'s biological role. We use human SH-SY5Y neuroblastoma cells and a GLP-1R over-expressing variety (#9), in both undifferentiated and differentiated states, to evaluate the neurotrophic/neuroprotective effects of GLP-1 (9-36) against toxic glutamate exposure and other oxidative stress models (via the MTS, LDH or ROS assays). In addition, we examine GLP-1 (9-36)'s signaling pathways, including cyclic-adenosine monophosphate (cAMP), protein kinase-A (PKA), and 5' adenosine monophosphate-activated protein kinase (AMPK) via the use of ELISA, pharmacological inhibitors, or GLP-1R antagonist. Human HMC3 and mouse IMG microglial cell lines were used to study the anti-inflammatory effects of GLP-1 (9-36) against lipopolysaccharide (LPS) (via ELISA). Finally, we applied GLP-1 (9-36) to primary dissociation cultures challenged with α-synuclein or amyloid-β and assessed survival and morphology via immunochemistry. We demonstrate evidence of GLP-1R, cAMP, PKA, and AMPK-mediated neurotrophic and neuroprotective effects of GLP-1 (9-36). The metabolite significantly reduced IL-6 and TNF-α levels in HMC3 and IMG microglial cells, respectively. Lastly, we show mild but significant effects of GLP-1 (9-36) in primary neuron cultures challenged with α-synuclein or amyloid-β. These studies enhance understanding of GLP-1 (9-36)'s effects on the nervous system and its potential as a primary or complementary treatment in pathological contexts.

Exendin-4 Pretreatment Attenuates Kainic Acid-Induced Hippocampal Neuronal Death

Exendin-4 (Ex-4) is a glucagon-like peptide-1 receptor (GLP-1R) agonist that protects against brain injury. However, little is known about the effect of Ex-4 on kainic acid (KA)-induced seizures and hippocampal cell death. Therefore, this study evaluated the neuroprotective effects of Ex-4 pretreatment in a mouse model of KA-induced seizures. Three days before KA treatment, mice were intraperitoneally injected with Ex-4. We found that Ex-4 pretreatment reversed KA-induced reduction of GLP-1R expression in the hippocampus and attenuated KA-induced seizure score, hippocampal neuronal death, and neuroinflammation. Ex-4 pretreatment also dramatically reduced hippocampal lipocalin-2 protein in KA-treated mice. Furthermore, immunohistochemical studies showed that Ex-4 pretreatment significantly alleviated blood–brain barrier leakage. Finally, Ex-4 pretreatment stimulated hippocampal expression of phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB), a known target of GLP-1/GLP-1R signaling. These findings indicate that Ex-4 pretreatment may protect against KA-induced neuronal damage by regulating GLP-1R/CREB-mediated signaling pathways.

Gauging the role and impact of drug interactions and repurposing in neurodegenerative disorders

Neurodegenerative diseases (ND) are of vast origin which are characterized by gradual progressive loss of neurons in the brain region. ND can be classified according to the clinical symptoms present (e.g. Cognitive decline, hyperkinetic, and hypokinetic movements disorder) or by the pathological protein deposited (e.g., Amyloid, tau, Alpha-synuclein, TDP-43). Alzheimer's disease preceded by Parkinson's is the most prevalent form of ND world-wide. Multiple factors like aging, genetic mutations, environmental factors, gut microbiota, blood-brain barrier microvascular complication, etc. may increase the predisposition towards ND. Genetic mutation is a major contributor in increasing the susceptibility towards ND, the concept of one disease-one gene is obsolete and now multiple genes are considered to be involved in causing one particular disease. Also, the involvement of multiple pathological mechanisms like oxidative stress, neuroinflammation, mitochondrial dysfunction, etc. contributes to the complexity and makes them difficult to be treated by traditional mono-targeted ligands. In this aspect, the Poly-pharmacological drug approach which targets multiple pathological pathways at the same time provides the best way to treat such complex networked CNS diseases. In this review, we have provided an overview of ND and their pathological origin, along with a brief description of various genes associated with multiple diseases like Alzheimer's, Parkinson's, Multiple sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), Huntington's and a comprehensive detail about the Poly-pharmacology approach (MTDLs and Fixed-dose combinations) along with their merits over the traditional single-targeted drug is provided. This review also provides insights into current repurposing strategies along with its regulatory considerations.

ACTH(6-9)PGP Peptide Protects SH-SY5Y Cells from H2O2, tert-Butyl Hydroperoxide, and Cyanide Cytotoxicity via Stimulation of Proliferation and Induction of Prosurvival-Related Genes

Stabilized melanocortin analog peptide ACTH(6-9)PGP (HFRWPGP) possesses a wide range of neuroprotective activities. However, its mechanism of action remains poorly understood. In this paper, we present a study of the proproliferative and cytoprotective activity of the adrenocorticotropic hormone fragment 6-9 (HFRW) linked with the peptide prolyine-glycyl-proline on the SH-SY5Y cells in the model of oxidative stress-related toxicity. The peptide dose-dependently protected cells from H2O2, tert-butyl hydroperoxide, and KCN and demonstrated proproliferative activity. The mechanism of its action was the modulation of proliferation-related NF-κB genes and stimulation of prosurvival NRF2-gene-related pathway, as well as a decrease in apoptosis.

Sustained Release GLP-1 Agonist PT320 Delays Disease Progression in a Mouse Model of Parkinson's Disease

GLP-1 agonists have become increasingly interesting as a new Parkinson's disease (PD) clinical treatment strategy. Additional preclinical studies are important to validate this approach and define the disease stage when they are most effective. We hence characterized the efficacy of PT320, a sustained release formulation of the long acting GLP-1 agonist, exenatide, in a progressive PD (MitoPark) mouse model. A clinically translatable biweekly PT320 dose was administered starting at 5 weeks of age and longitudinally evaluated to 24 weeks, and multiple behavioral/cellular parameters were measured. PT320 significantly improved spontaneous locomotor activity and rearing in MitoPark PD mice. "Motivated" behavior also improved, evaluated by accelerating rotarod performance. Behavioral improvement was correlated with enhanced cellular and molecular indices of dopamine (DA) midbrain function. Fast scan cyclic voltammetry demonstrated protection of striatal and nucleus accumbens DA release and reuptake in PT320 treated MitoPark mice. Positron emission tomography showed protection of striatal DA fibers and tyrosine hydroxylase protein expression was augmented by PT320 administration. Early PT320 treatment may hence provide an important neuroprotective therapeutic strategy in PD.

Characterization of CB2 Receptor Expression in Peripheral Blood Monocytes of Acute Ischemic Stroke Patients

Both preclinical and clinical evidence supports the involvement of the endocannabinoid system in the pathobiology of cerebral ischemia. Selective cannabinoid-2 (CB2) receptor agonists exert significant neuroprotection in animal models of focal brain ischemia through a robust anti-inflammatory effect, involving both resident and peripheral immune cells. Nevertheless, no definitive studies demonstrating the relevance of CB2 receptors in human stroke exist.Using rtPCR and flow cytometry assays, we investigated CB2 receptor expression in circulating monocytes from 26 acute ischemic stroke patients and 16 age-matched healthy controls (CT). We also evaluated miR-665 expression, as potential CB2 receptor regulator. The median mRNA levels of CB2 were significantly (p < 0.0001) increased in total monocytes 24 h and 48 h after stroke as compared with CT. This was paralleled by elevation of miR-665 levels in monocytes collected from patients 24 h (p < 0.05 vs CT) and 48 h (p < 0.05 vs CT and p < 0.0001 vs 24 h) after ischemic stroke. Furthermore, an increased percentage of CB2+/CD16+ events, but not CB2+/CD14+ events, was found 24 h [20.17% (IQR, 17.22-23.58)] and 48 h [18.61% (IQR, 15.44-22.06)] after ischemic stroke when compared with CT [10.96% (IQR, 9.185-13.32)]. The percentage of CB2+/CD16+ events in monocytes was positively correlated with NIHSS score at entrance (r = 0.4327, p = 0.027). The potential beneficial functions of CD16+ intermediate and nonclassical monocytes in stroke and the elevated expression of CB2 receptor in these subsets strongly suggest that CB2 receptor agonists can be exploited for the treatment of ischemic stroke patients.

Alleviation of Depression by Glucagon-Like Peptide 1 Through the Regulation of Neuroinflammation, Neurotransmitters, Neurogenesis, and Synaptic Function

Depression has emerged as a major cause of mortality globally. Many studies have reported risk factors and mechanisms associated with depression, but it is as yet unclear how these findings can be applied to the treatment and prevention of this disorder. The onset and recurrence of depression have been linked to diverse metabolic factors, including hyperglycemia, dyslipidemia, and insulin resistance. Recent studies have suggested that depression is accompanied by memory loss as well as depressive mood. Thus, many researchers have highlighted the relationship between depressive behavior and metabolic alterations from various perspectives. Glucagon-like peptide-1 (GLP-1), which is secreted from gut cells and hindbrain areas, has been studied in metabolic diseases such as obesity and diabetes, and was shown to control glucose metabolism and insulin resistance. Recently, GLP-1 was highlighted as a regulator of diverse pathways, but its potential as the therapeutic target of depressive disorder was not described comprehensively. Therefore, in this review, we focused on the potential of GLP-1 modulation in depression.

Preventive Effects of Dulaglutide on Disuse Muscle Atrophy Through Inhibition of Inflammation and Apoptosis by Induction of Hsp72 Expression

Pathological conditions such as joint immobilization, long-time bed rest, or inactivity may result in disuse-induced muscle wasting and dysfunction. To investigate the effect of dulaglutide, a long-acting glucagon-like peptide-1 receptor agonist, on disuse muscle atrophy, disuse condition was induced by spiral wire immobilization in C57BL/6 mice and the mice were treated with dulaglutide. Dulaglutide treatment effectively improved muscle function and increased muscle mass compared with vehicle treatment. Dulaglutide inhibited the decrease of muscle fiber size and the expression of atrophic factors such as myostatin, atrogin-1/MAFbx, and muscle RING-finger protein-1 in immobilized mice. In addition, dulaglutide inhibited nuclear factor kappa B activation, leading to a decrease in the mRNA levels of proinflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in muscle of immobilized mice. Dulaglutide suppressed the expression of apoptotic markers such as caspase-3, cleaved poly-ADP ribose polymerase, and Bax under immobilization condition and increased the expression of heat shock protein 72 (Hsp72), which is related to the amelioration of inflammation and apoptosis during disuse time. Further study showed that dulaglutide could induce Hsp72 expression via the regulation of 5′-AMP-activated protein kinase signaling. Our data suggest that dulaglutide could exert beneficial effects against disuse-induced muscle atrophy.

Utility of Neuronal-Derived Exosomes to Examine Molecular Mechanisms That Affect Motor Function in Patients With Parkinson Disease: A Secondary Analysis of the Exenatide-PD Trial

Importance

Exenatide, a glucagon-like peptide 1 agonist used in type 2 diabetes, was recently found to have beneficial effects on motor function in a randomized, placebo-controlled trial in Parkinson disease (PD). Accumulating evidence suggests that impaired brain insulin and protein kinase B (Akt) signaling play a role in PD pathogenesis; however, exploring the extent to which drugs engage with putative mechnisms in vivo remains a challenge.

Objective

To assess whether participants in the Exenatide-PD trial have augmented activity in brain insulin and Akt signaling pathways.

Design, Setting, and Participants

Serum samples were collected from 60 participants in the single-center Exenatide-PD trial (June 18, 2014, to June 16, 2016), which compared patients with moderate PD randomized to 2 mg of exenatide once weekly or placebo for 48 weeks followed by a 12-week washout period. Serum extracellular vesicles, including exosomes, were extracted, precipitated, and enriched for neuronal source by anti-L1 cell adhesion molecule antibody absorption, and proteins of interest were evaluated using electrochemiluminescence assays. Statistical analysis was performed from May 1, 2017, to August 31, 2017.

Main Outcomes and Measures

The main outcome was augmented brain insulin signaling that manifested as a change in tyrosine phosphorylated insulin receptor substrate 1 within neuronal extracellular vesicles at the end of 48 weeks of exenatide treatment. Additional outcome measures were changes in other insulin receptor substrate proteins and effects on protein expression in the Akt and mitogen-activated protein kinase pathways.

Results

Sixty patients (mean [SD] age, 59.9 [8.4] years; 43 [72%] male) participated in the study: 31 in the exenatide group and 29 in the placebo group (data from 1 patient in the exenatide group were excluded). Patients treated with exenatide had augmented tyrosine phosphorylation of insulin receptor substrate 1 at 48 weeks (0.27 absorbance units [AU]; 95% CI, 0.09-0.44 AU; P = .003) and 60 weeks (0.23 AU; 95% CI, 0.05-0.41 AU; P = .01) compared with patients receiving placebo. Exenatide-treated patients had elevated expression of downstream substrates, including total Akt (0.35 U/mL; 95% CI, 0.16-0.53 U/mL; P < .001) and phosphorylated mechanistic target of rapamycin (mTOR) (0.22 AU; 95% CI, 0.04-0.40 AU; P = .02). Improvements in Movement Disorders Society Unified Parkinson's Disease Rating Scale part 3 off-medication scores were associated with levels of total mTOR (F4,50 = 5.343, P = .001) and phosphorylated mTOR (F4,50 = 4.384, P = .04).

Conclusions and Relevance

The results of this study are consistent with target engagement of brain insulin, Akt, and mTOR signaling pathways by exenatide and provide a mechanistic context for the clinical findings of the Exenatide-PD trial. This study suggests the potential of using exosome-based biomarkers as objective measures of target engagement in clinical trials using drugs that target neuronal pathways.

Neuroprotective Effects and Treatment Potential of Incretin Mimetics in a Murine Model of Mild Traumatic Brain Injury

Traumatic brain injury (TBI) is a commonly occurring injury in sports, victims of motor vehicle accidents, and falls. TBI has become a pressing public health concern with no specific therapeutic treatment. Mild TBI (mTBI), which accounts for approximately 90% of all TBI cases, may frequently lead to long-lasting cognitive, behavioral, and emotional impairments. The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are gastrointestinal hormones that induce glucose-dependent insulin secretion, promote β-cell proliferation, and enhance resistance to apoptosis. GLP-1 mimetics are marketed as treatments for type 2 diabetes mellitus (T2DM) and are well tolerated. Both GLP-1 and GIP mimetics have shown neuroprotective properties in animal models of Parkinson's and Alzheimer's disease. The aim of this study is to evaluate the potential neuroprotective effects of liraglutide, a GLP-1 analog, and twincretin, a dual GLP-1R/GIPR agonist, in a murine mTBI model. First, we subjected mice to mTBI using a weight-drop device and, thereafter, administered liraglutide or twincretin as a 7-day regimen of subcutaneous (s.c.) injections. We then investigated the effects of these drugs on mTBI-induced cognitive impairments, neurodegeneration, and neuroinflammation. Finally, we assessed their effects on neuroprotective proteins expression that are downstream to GLP-1R/GIPR activation; specifically, PI3K and PKA phosphorylation. Both drugs ameliorated mTBI-induced cognitive impairments evaluated by the novel object recognition (NOR) and the Y-maze paradigms in which neither anxiety nor locomotor activity were confounds, as the latter were unaffected by either mTBI or drugs. Additionally, both drugs significantly mitigated mTBI-induced neurodegeneration and neuroinflammation, as quantified by immunohistochemical staining with Fluoro-Jade/anti-NeuN and anti-Iba-1 antibodies, respectively. mTBI challenge significantly decreased PKA phosphorylation levels in ipsilateral cortex, which was mitigated by both drugs. However, PI3K phosphorylation was not affected by mTBI. These findings offer a new potential therapeutic approach to treat mTBI, and support further investigation of the neuroprotective effects and mechanism of action of incretin-based therapies for neurological disorders.

Vildagliptin Attenuates Huntington's Disease through Activation of GLP-1 Receptor/PI3K/Akt/BDNF Pathway in 3-Nitropropionic Acid Rat Model

Vildagliptin (Vilda), a dipeptidyl peptidase-4 (DPP-4) inhibitor, has been highlighted as a promising therapeutic agent for neurodegenerative diseases as Alzheimer's and Parkinson's diseases. Vilda's effect is mostly linked to PI3K/Akt signaling in CNS. Moreover, PI3K/Akt activation reportedly enhanced survival and dampened progression of Huntington's disease (HD). However, Vilda's role in HD is yet to be elucidated. Thus, the aim of the study is to uncover the potentiality of Vilda in HD and unfold its link with PI3K/Akt pathway in 3-nitropropionic acid (3NP) rat model. Rats were randomly assigned into 4 groups; group 1 received saline, whereas, groups 2, 3 and 4 received 3NP (10 mg/kg/day; i.p.) for 14 days, concomitantly with Vilda (5 mg/kg/day; p.o.) in groups 3 and 4, and wortmannin (WM), a PI3K inhibitor, (15 μg/kg/day; i.v.) in group 4. Vilda improved cognitive and motor perturbations induced by 3NP, as confirmed by striatal histopathological specimens and immunohistochemical examination of GFAP. The molecular signaling of Vilda was estimated by elevation of GLP-1 level and protein expressions of survival proteins; p85/p55 (pY458/199)-PI3K, pS473-Akt. Together, it boosted striatal neurotrophic factors and receptor; pS133-CREB, BDNF, pY515-TrKB, which subsequently maintained mitochondrial integrity, as indicated by enhancing both SDH and COX activities, and the redox modulators; Sirt1, Nrf2. Such neuroprotection restored imbalance of neurotransmitters through increasing GABA and suppressing glutamate as well PDE10A. These effects were reversed by WM pre-administration. In conclusion, Vilda purveyed significant anti-Huntington effect which may be mediated, at least in part, via activation of GLP-1/PI3K/Akt pathway in 3NP rat model.

DPP-4 Inhibitor Linagliptin is Neuroprotective in Hyperglycemic Mice with Stroke via the AKT/mTOR Pathway and Anti-apoptotic Effects

Dipeptidyl peptidase 4 (DPP-4) inhibitors have been shown to have neuroprotective effects in diabetic patients suffering from stroke, but less research has focused on patients with mild hyperglycemia below the threshold for a diagnosis of diabetes. In this investigation, a hyperglycemic mouse model was generated by intraperitoneal injection of streptozotocin and then subjected to focal cerebral ischemia. We demonstrated that the DPP-4 inhibitor linagliptin significantly decreased the infarct volume, reduced neuronal cell death, decreased inflammation, and improved neurological deficit compared with control mice. Linagliptin up-regulated the expression of p-Akt and p-mTOR and regulated the apoptosis factors Bcl-2, Bax, and caspase 9. Taken together, these results suggest that linagliptin exerts a neuroprotective action likely through activation of the Akt/mTOR pathway along with anti-apoptotic and anti-inflammatory mechanisms. Therefore, linagliptin may be considered as a therapeutic treatment for stroke patients with mild hyperglycemia.

Animal Venom Peptides as a Treasure Trove for New Therapeutics Against Neurodegenerative Disorders

BACKGROUND

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and cerebral ischemic stroke, impose enormous socio-economic burdens on both patients and health-care systems. However, drugs targeting these diseases remain unsatisfactory, and hence there is an urgent need for the development of novel and potent drug candidates.

METHODS

Animal toxins exhibit rich diversity in both proteins and peptides, which play vital roles in biomedical drug development. As a molecular tool, animal toxin peptides have not only helped clarify many critical physiological processes but also led to the discovery of novel drugs and clinical therapeutics.

RESULTS

Recently, toxin peptides identified from venomous animals, e.g. exenatide, ziconotide, Hi1a, and PcTx1 from spider venom, have been shown to block specific ion channels, alleviate inflammation, decrease protein aggregates, regulate glutamate and neurotransmitter levels, and increase neuroprotective factors.

CONCLUSION

Thus, components of venom hold considerable capacity as drug candidates for the alleviation or reduction of neurodegeneration. This review highlights studies evaluating different animal toxins, especially peptides, as promising therapeutic tools for the treatment of different neurodegenerative diseases and disorders.

Neuroprotective Effects of Brain-Gut Peptides: A Potential Therapy for Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease and is typically associated with progressive motor and non-motor dysfunctions. Currently, dopamine replacement therapy is mainly used to relieve the motor symptoms, while its long-term application can lead to various complications and does not cure the disease. Numerous studies have demonstrated that many brain-gut peptides have neuroprotective effects in vivo and in vitro, and may be a promising treatment for PD. In recent years, some progress has been made in studies on the neuroprotective effects of some newly-discovered brain-gut peptides, such as glucagon-like peptide 1, pituitary adenylate cyclase activating polypeptide, nesfatin-1, and ghrelin. However, there is still no systematic review on the neuroprotective effects common to these peptides. Thus, here we review the neuroprotective effects and the associated mechanisms of these four peptides, as well as other brain-gut peptides related to PD, in the hope of providing new ideas for the treatment of PD and related clinical research.

Incretin Mimetics as Rational Candidates for the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is becoming an increasing public health issue. With an annually estimated 1.7 million TBIs in the United States (U.S) and nearly 70 million worldwide, the injury, isolated or compounded with others, is a major cause of short- and long-term disability and mortality. This, along with no specific treatment, has made exploration of TBI therapies a priority of the health system. Age and sex differences create a spectrum of vulnerability to TBI, with highest prevalence among younger and older populations. Increased public interest in the long-term effects and prevention of TBI have recently reached peaks, with media attention bringing heightened awareness to sport and war related head injuries. Along with short-term issues, TBI can increase the likelihood for development of long-term neurodegenerative disorders. A growing body of literature supports the use of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon (Gcg) receptor (R) agonists, along with unimolecular combinations of these therapies, for their potent neurotrophic/neuroprotective activities across a variety of cellular and animal models of chronic neurodegenerative diseases (Alzheimer's and Parkinson's diseases) and acute cerebrovascular disorders (stroke). Mild or moderate TBI shares many of the hallmarks of these conditions; recent work provides evidence that use of these compounds is an effective strategy for its treatment. Safety and efficacy of many incretin-based therapies (GLP-1 and GIP) have been demonstrated in humans for the treatment of type 2 diabetes mellitus (T2DM), making these compounds ideal for rapid evaluation in clinical trials of mild and moderate TBI.

GLP-1's role in neuroprotection: a systematic review

Glucagon-like peptide 1 (GLP-1) is a target for treatment of diabetes; however, its function in the brain is not well studied. In this systematic review, we aimed to analyze the neuroprotective role of GLP-1 and its defined mechanisms. Methods: We searched 'Web of Science' and 'Pubmed' to identify relevant studies using GLP-1 as the keyword. Two hundred and eighty-nine clinical and preclinical studies have been included. Data have been presented by grouping neurodegenerative, neurovascular and specific cell culture models. Results: Recent literature shows that GLP-1 and its agonists, DPP-4 inhibitors and combined GLP-1/GIP molecules are effective in partially or fully reversing the effects of neurotoxic compounds, neurovascular complications of diabetes, neuropathological changes related with Alzheimer's disease, Parkinson's disease or vascular occlusion. Possible mechanisms that provide neuroprotection are enhancing the viability of the neurons and restoring neurite outgrowth by increased neurotrophic factors, increasing subventricular zone progenitor cells, decreasing apoptosis, decreasing the level of pro-inflammatory factors, and strengthening blood-brain barrier. Conclusion: Based on the preclinical studies, GLP-1 modifying agents are promising targets for neuroprotection. On the other hand, the number of clinical studies that investigate GLP-1 as a treatment is low and further clinical trials are needed for a benchside to bedside translation of recent findings.

Pharmacokinetics and efficacy of PT302, a sustained-release Exenatide formulation, in a murine model of mild traumatic brain injury

Traumatic brain injury (TBI) is a neurodegenerative disorder for which no effective pharmacological treatment is available. Glucagon-like peptide 1 (GLP-1) analogues such as Exenatide have previously demonstrated neurotrophic and neuroprotective effects in cellular and animal models of TBI. However, chronic or repeated administration was needed for efficacy. In this study, the pharmacokinetics and efficacy of PT302, a clinically available sustained-release Exenatide formulation (SR-Exenatide) were evaluated in a concussive mild (m)TBI mouse model. A single subcutaneous (s.c.) injection of PT302 (0.6, 0.12, and 0.024 mg/kg) was administered and plasma Exenatide concentrations were time-dependently measured over 3 weeks. An initial rapid regulated release of Exenatide in plasma was followed by a secondary phase of sustained-release in a dose-dependent manner. Short- and longer-term (7 and 30 day) cognitive impairments (visual and spatial deficits) induced by weight drop mTBI were mitigated by a single post-injury treatment with Exenatide delivered by s.c. injection of PT302 in clinically translatable doses. Immunohistochemical evaluation of neuronal cell death and inflammatory markers, likewise, cross-validated the neurotrophic and neuroprotective effects of SR-Exenatide in this mouse mTBI model. Exenatide central nervous system concentrations were 1.5% to 2.0% of concomitant plasma levels under steady-state conditions. These data demonstrate a positive beneficial action of PT302 in mTBI. This convenient single, sustained-release dosing regimen also has application for other neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple system atrophy and multiple sclerosis where prior preclinical studies, likewise, have demonstrated positive Exenatide actions.

microRNA-665 silencing improves cardiac function in rats with heart failure through activation of the cAMP signaling pathway

Heart failure (HF) is a disease with high mortality and morbidity rate. Previous studies have shown that microRNAs (miRNAs) may be implicated in the pathogenesis of HF, potentially being able to improve the cardiac function in an HF rat model. The present study was designed to define the role of miR-665 in the cardiac function of the HF rats. Following the establishm;ent of the rat models of HF, the functional role miR-665 in HF was determined using an ectopic expression and knockdown experiments. The cardiac function was evaluated with the determination of ventricular mass index and hemodynamic parameters. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was performed, with the apoptosis of cardiac cells detected in the process. The expression of miR-665, glucagon-like peptide 1 receptor (GLP1R), cyclic adenosine monophosphate (cAMP) signaling pathway-related, and apoptosis-related genes was examined. Enzyme-linked immunosorbent assay was conducted to determine the levels of inflammation-related genes. Initially, the upregulation of miR-665, downregulation of GLP1R, and inactivation of cAMP signaling pathway were observed in HF rats. GLP1R was a target of miR-665. Forced expression of miR-665 promoted cell apoptosis and inhibited GLP1R and the cAMP signaling pathway. In addition, miR-665 overexpression has been known to impair cardiac function, promote inflammatory response while elevating malondialdehyde and superoxide dismutase levels, and decreasing mitochondrial respiratory chain enzyme activities. Furthermore, we also observed that the effects of miR-665 inhibition had been reversed when the cAMP signaling pathway was also inhibited. This study demonstrates that miR-665 inhibition can stabilize the cardiac function of HF rats via the cAMP signaling pathway via upregulation of the GLP1R.

Post-treatment with PT302, a long-acting Exendin-4 sustained release formulation, reduces dopaminergic neurodegeneration in a 6-Hydroxydopamine rat model of Parkinson's disease

We previously demonstrated that pretreatment with Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist, reduces 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -mediated dopaminergic neurodegeneration. The use of GLP-1 or Exendin-4 for Parkinson's disease (PD) patients is limited by their short half-lives. The purpose of this study was to evaluate a new extended release Exendin-4 formulation, PT302, in a rat model of PD. Subcutaneous administration of PT302 resulted in sustained elevations of Exendin-4 in plasma for >20 days in adult rats. To define an efficacious dose within this range, rats were administered PT302 once every 2 weeks either before or following the unilaterally 6-hydroxydopamine lesioning. Pre- and post-treatment with PT302 significantly reduced methamphetamine-induced rotation after lesioning. For animals given PT302 post lesion, blood and brain samples were collected on day 47 for measurements of plasma Exendin-4 levels and brain tyrosine hydroxylase immunoreactivity (TH-IR). PT302 significantly increased TH-IR in the lesioned substantia nigra and striatum. There was a significant correlation between plasma Exendin-4 levels and TH-IR in the substantia nigra and striatum on the lesioned side. Our data suggest that post-treatment with PT302 provides long-lasting Exendin-4 release and reduces neurodegeneration of nigrostriatal dopaminergic neurons in a 6-hydroxydopamine rat model of PD at a clinically relevant dose.

Tackling dipeptidyl peptidase IV in neurological disorders

Dipeptidyl peptidase IV (DPP-IV) is a serine protease best known for its role in inactivating glucagon-like peptide-1 (GLP-1), pituitary adenylate cyclase-activating polypeptide (PACAP) and glucose-dependent insulinotropic peptide (GIP), three stimulators of pancreatic insulin secretion with beneficial effects on glucose disposal. Owing to the relationship between DPP-IV and these peptides, inhibition of DPP-IV enzyme activity is considered as an attractive treatment option for diabetic patients. Nonetheless, increasing studies support the idea that DPP-IV might also be involved in the development of neurological disorders with a neuroinflammatory component, potentially through its non-incretin activities on immune cells. In this review article, we aim at highlighting recent literature describing the therapeutic value of DPP-IV inhibitors for the treatment of such neurological conditions. Finally, we will illustrate some of the promising results obtained using berberine, a plant extract with potent inhibitory activity on DPP-IV.

A New Treatment Strategy for Parkinson's Disease through the Gut-Brain Axis: The Glucagon-Like Peptide-1 Receptor Pathway

Molecular communications in the gut-brain axis, between the central nervous system and the gastrointestinal tract, are critical for maintaining healthy brain function, particularly in aging. Epidemiological analyses indicate type 2 diabetes mellitus (T2DM) is a risk factor for neurodegenerative disorders including Alzheimer's disease (AD) and Parkinson's diseases (PD) for which aging shows a major correlative association. Common pathophysiological features exist between T2DM, AD, and PD, including oxidative stress, inflammation, insulin resistance, abnormal protein processing, and cognitive decline, and suggest that effective drugs for T2DM that positively impact the gut-brain axis could provide an effective treatment option for neurodegenerative diseases. Glucagon-like peptide-1 (GLP-1)-based antidiabetic drugs have drawn particular attention as an effectual new strategy to not only regulate blood glucose but also decrease body weight by reducing appetite, which implies that GLP-1 could affect the gut-brain axis in normal and pathological conditions. The neurotrophic and neuroprotective effects of GLP-1 receptor (R) stimulation have been characterized in numerous in vitro and in vivo preclinical studies using GLP-1R agonists and dipeptidyl peptidase-4 inhibitors. Recently, the first open label clinical study of exenatide, a long-acting GLP-1 agonist, in the treatment of PD showed long-lasting improvements in motor and cognitive function. Several double-blind clinical trials of GLP-1R agonists including exenatide in PD and other neurodegenerative diseases are already underway or are about to be initiated. Herein, we review the physiological role of the GLP-1R pathway in the gut-brain axis and the therapeutic strategy of GLP-1R stimulation for the treatment of neurodegenerative diseases focused on PD, for which age is the major risk factor.

Activation of Glucagon-Like Peptide-1 Receptor Promotes Neuroprotection in Experimental Autoimmune Encephalomyelitis by Reducing Neuroinflammatory Responses

The signaling axis of glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) has been an important component in overcoming diabetes, and recent reports have uncovered novel beneficial roles of this signaling axis in central nervous system (CNS) disorders, such as Alzheimer's disease, Parkinson's disease, and cerebral ischemia, accelerating processes for exendin-4 repositioning. Here, we studied whether multiple sclerosis (MS) could be a complement to the CNS disorders that are associated with the GLP-1/GLP-1R signaling axis. Both components of the signaling axis, GLP-1 and GLP-1R proteins, are expressed in neurons, astrocytes, and microglia in the spinal cord of normal mice. In particular, they are abundant in Iba1-positive microglia. Upon challenge by experimental autoimmune encephalomyelitis (EAE), an animal model of MS, the mRNA expression of both GLP-1 and GLP-1R was markedly downregulated in EAE-symptomatic spinal cords, indicating attenuated activity of GLP-1/GLP-1R signaling in EAE. Such a downregulation obviously occurred in LPS-stimulated rat primary microglia, a main cell type to express both GLP-1 and GLP-1R, further indicating attenuated activity of GLP-1/GLP-1R signaling in activated microglia. To investigate whether increased activity of GLP-1R has a therapeutic benefit, exendin-4 (5 μg/kg, i.p.), a GLP-1R agonist, was administered daily to EAE-symptomatic mice. Exendin-4 administration to symptomatic EAE mice significantly improved the clinical signs of the disease, along with the reversal of histopathological sequelae such as cell accumulation, demyelination, astrogliosis, microglial activation, and morphological transformation of activated microglia in the injured spinal cord. Such an improvement by exendin-4 was comparable to that by FTY720 (3 mg/kg, i.p.), a drug for MS. The neuroprotective effects of exendin-4 against EAE were also associated with decreased mRNA expression of proinflammatory cytokines, such as interleukin (IL)-17, IL-1β, IL-6, and tumor necrosis factor (TNF)-α, all of which are usually upregulated in injured sites of the EAE spinal cord. Interestingly, exendin-4 exposure similarly reduced mRNA levels of IL-1β and TNF-α in LPS-stimulated microglia. Furthermore, exendin-4 administration significantly attenuated activation of NF-κB signaling in EAE spinal cord and LPS-stimulated microglia. Collectively, the current study demonstrates the therapeutic potential of exendin-4 for MS by reducing immune responses in the CNS, highlighting the importance of the GLP-1/GLP-1R signaling axis in the development of a novel therapeutic strategy for MS.

Novel GLP-1R/GIPR co-agonist "twincretin" is neuroprotective in cell and rodent models of mild traumatic brain injury

Several single incretin receptor agonists that are approved for the treatment of type 2 diabetes mellitus (T2DM) have been shown to be neuroprotective in cell and animal models of neurodegeneration. Recently, a synthetic dual incretin receptor agonist, nicknamed "twincretin," was shown to improve upon the metabolic benefits of single receptor agonists in mouse and monkey models of T2DM. In the current study, the neuroprotective effects of twincretin are probed in cell and mouse models of mild traumatic brain injury (mTBI), a prevalent cause of neurodegeneration in toddlers, teenagers and the elderly. Twincretin is herein shown to have activity at two different receptors, dose-dependently increase levels of intermediates in the neurotrophic CREB pathway and enhance viability of human neuroblastoma cells exposed to toxic concentrations of glutamate and hydrogen peroxide, insults mimicking the inflammatory conditions in the brain post-mTBI. Additionally, twincretin is shown to improve upon the neurotrophic effects of single incretin receptor agonists in these same cells. Finally, a clinically translatable dose of twincretin, when administered post-mTBI, is shown to fully restore the visual and spatial memory deficits induced by mTBI, as evaluated in a mouse model of weight drop close head injury. These results establish twincretin as a novel neuroprotective agent and suggest that it may improve upon the effects of the single incretin receptor agonists via dual agonism.

Neurotrophic and neuroprotective effects of oxyntomodulin in neuronal cells and a rat model of stroke

Proglucagon-derived peptides, especially glucagon-like peptide-1 (GLP-1) and its long-acting mimetics, have exhibited neuroprotective effects in animal models of stroke. Several of these peptides are in clinical trials for stroke. Oxyntomodulin (OXM) is a proglucagon-derived peptide that co-activates the GLP-1 receptor (GLP-1R) and the glucagon receptor (GCGR). The neuroprotective action of OXM, however, has not been thoroughly investigated. In this study, the neuroprotective effect of OXM was first examined in human neuroblastoma (SH-SY5Y) cells and rat primary cortical neurons. GLP-1R and GCGR antagonists, and inhibitors of various signaling pathways were used in cell culture to characterize the mechanisms of action of OXM. To evaluate translation in vivo, OXM-mediated neuroprotection was assessed in a 60-min, transient middle cerebral artery occlusion (MCAo) rat model of stroke. We found that OXM dose- and time-dependently increased cell viability and protected cells from glutamate toxicity and oxidative stress. These neuroprotective actions of OXM were mainly mediated through the GLP-1R. OXM induced intracellular cAMP production and activated cAMP-response element-binding protein (CREB). Furthermore, inhibition of the PKA and MAPK pathways, but not inhibition of the PI3K pathway, significantly attenuated the OXM neuroprotective actions. Intracerebroventricular administration of OXM significantly reduced cerebral infarct size and improved locomotor activities in MCAo stroke rats. Therefore, we conclude that OXM is neuroprotective against ischemic brain injury. The mechanisms of action involve induction of intracellular cAMP, activation of PKA and MAPK pathways and phosphorylation of CREB.

The GLP-1 Receptor Agonist Liraglutide Improves Memory Function and Increases Hippocampal CA1 Neuronal Numbers in a Senescence-Accelerated Mouse Model of Alzheimer's Disease

Recent studies indicate that glucagon-like peptide 1 (GLP-1) receptor agonists, currently used in the management of type 2 diabetes, exhibit neurotrophic and neuroprotective effects in amyloid-β (Aβ) toxicity models of Alzheimer’s disease (AD). We investigated the potential pro-cognitive and neuroprotective effects of the once-daily GLP-1 receptor agonist liraglutide in senescence-accelerated mouse prone 8 (SAMP8) mice, a model of age-related sporadic AD not dominated by amyloid plaques. Six-month-old SAMP8 mice received liraglutide (100 or 500 μg/kg/day, s.c.) or vehicle once daily for 4 months. Vehicle-dosed age-matched 50% back-crossed as well as untreated young (4-month-old) SAMP8 mice were used as control groups for normal memory function. Vehicle-dosed 10-month-old SAMP8 mice showed significant learning and memory retention deficits in an active-avoidance T-maze, as compared to both control groups. Also, 10-month-old SAMP8 mice displayed no immunohistological signatures of amyloid-β plaques or hyperphosphorylated tau, indicating the onset of cognitive deficits prior to deposition of amyloid plaques and neurofibrillary tangles in this AD model. Liraglutide significantly increased memory retention and total hippocampal CA1 pyramidal neuron numbers in SAMP8 mice, as compared to age-matched vehicle-dosed SAMP8 mice. In conclusion, liraglutide delayed or partially halted the progressive decline in memory function associated with hippocampal neuronal loss in a mouse model of pathological aging with characteristics of neurobehavioral and neuropathological impairments observed in early-stage sporadic AD.

Glucose-Dependent Insulinotropic Polypeptide Ameliorates Mild Traumatic Brain Injury-Induced Cognitive and Sensorimotor Deficits and Neuroinflammation in Rats

Mild traumatic brain injury (mTBI) is a major public health issue, representing 75-90% of all cases of TBI. In clinical settings, mTBI, which is defined as a Glascow Coma Scale (GCS) score of 13-15, can lead to various physical, cognitive, emotional, and psychological-related symptoms. To date, there are no pharmaceutical-based therapies to manage the development of the pathological deficits associated with mTBI. In this study, the neurotrophic and neuroprotective properties of glucose-dependent insulinotropic polypeptide (GIP), an incretin similar to glucagon-like peptide-1 (GLP-1), was investigated after its steady-state subcutaneous administration, focusing on behavior after mTBI in an in vivo animal model. The mTBI rat model was generated by a mild controlled cortical impact (mCCI) and used to evaluate the therapeutic potential of GIP. We used the Morris water maze and novel object recognition tests, which are tasks for spatial and recognition memory, respectively, to identify the putative therapeutic effects of GIP on cognitive function. Further, beam walking and the adhesive removal tests were used to evaluate locomotor activity and somatosensory functions in rats with and without GIP administration after mCCI lesion. Lastly, we used immunohistochemical (IHC) staining and Western blot analyses to evaluate the inflammatory markers, glial fibrillary acidic protein (GFAP), amyloid-β precursor protein (APP), and bone marrow tyrosine kinase gene in chromosome X (BMX) in animals with mTBI. GIP was well tolerated and ameliorated mTBI-induced memory impairments, poor balance, and sensorimotor deficits after initiation in the post-injury period. In addition, GIP mitigated mTBI-induced neuroinflammatory changes on GFAP, APP, and BMX protein levels. These findings suggest GIP has significant benefits in managing mTBI-related symptoms and represents a novel strategy for mTBI treatment.