Background: Parkinson's disease (PD) is a progressive neurodegenerative disease for which there is no cure. In a clinical trial, the glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 has shown good protective effects in PD patients. The hormone glucose-dependent insulinotropic polypeptide (GIP) has also shown protective effects in animal models of PD. Objective: We tested DA-CH5, a novel dual GLP-1/GIP receptor agonist. Methods: DA-CH5 activity was tested on cells expressing GLP-1, GLP-2, GIP or glucagon receptors. The ability to cross the blood-brain barrier (BBB) of DA-CH5, exendin-4, liraglutide or other dual receptor agonists was tested with fluoresceinlabelled peptides. DA-CH5, exendin-4 and liraglutide were tested in the MPTP mouse model of PD. Results: Analysing the receptor activating properties showed a balanced activation of GLP-1 and GIP receptors while not activating GLP-2 or glucagon receptors. DA-CH5 crossed the BBB better than other single or other dual receptor agonists. In a dose-response comparison, DA-CH5 was more effective than the GLP-1 receptor agonist exendin-4. When comparing the neuroprotective effect of DA-CH5 with Liraglutide, a GLP-1 analogue, both DA-CH5 and Liraglutide improved MPTPinduced motor impairments. In addition, the drugs reversed the decrease of the number of neurons expressing tyrosine hydroxylase (TH) in the SN, alleviated chronic inflammation, reduced lipid peroxidation, inhibited the apoptosis pathway (TUNEL assay) and increased autophagy -related proteins expression in the substantia nigra (SN) and striatum. Importantly, we found DA-CH5 was superior to Liraglutide in reducing microglia and astrocyte activation, improving mitochondrial activity by reducing the Bax/Bcl-2 ratio and normalising autophagy as found in abnormal expression of LC3 and p62. Conclusion:The results demonstrate that the DA-CH5 is superior to liraglutide and could be a therapeutic treatment for PD.

Alzheimer’s disease (AD) is a neurodegenerative disorder for which there is no cure. Here, we test a dual GLP-1/GIP receptor agonist (DA4-JC) that has a cell penetrating sequence added to enhance blood-brain barrier penetration. We show in a receptor activity study that DA4-JC has balanced activity on both GLP-1 and GIP receptors but not on GLP-2 or Glucagon receptors. A dose-response study in the APP/PS1 mouse model of AD showed both a dose-dependent drug effect on the inflammation response and the reduction of amyloid plaques in the brain. When comparing DA4-JC with the GLP-1 analogue liraglutide at equal doses of 10nmol/kg bw ip. once-daily for 8 weeks, DA4-JC was more effective in reversing memory loss, enhancing synaptic plasticity (LTP) in the hippocampus, reducing amyloid plaques and lowering pro-inflammatory cytokine levels in the brain. The results suggest that DA4-JC may be a novel treatment for AD.

Context Impact of lost GLP-1 receptor function in human physiology. Objective Identify coding nonsynonymous GLP1R variants in Danish individuals to link their in vitro phenotypes and clinical phenotypic associations. Methods We sequenced GLP1R in 8,642 Danish individuals with type 2 diabetes or normal glucose tolerance and examined the ability of nonsynonymous variants to bind GLP-1 and to signal in transfected cells via cAMP formation and beta-arrestin recruitment. We performed a cross-sectional study between the burden of loss-of-signalling (LoS) variants and cardiometabolic phenotypes in 2,930 patients with type 2 diabetes and 5,712 participants in a population-based cohort. Furthermore, we studied the association between cardiometabolic phenotypes and the burden of the LoS variants and 60 partly overlapping predicted loss-of-function (pLoF) GLP1R variants found in 330,566 unrelated Caucasian exome-sequenced participants in the UK Biobank cohort. Results We identified 36 nonsynonymous variants in GLP1R of which 10 had a statistically significant loss in GLP-1-induced cAMP signalling compared to wildtype. However, no association was observed between the LoS variants and type 2 diabetes, although LoS variant carriers had a minor increased fasting plasma glucose level. Moreover, pLoF variants from the UK Biobank also did not reveal substantial cardiometabolic associations, despite a small effect on HbA1c. Conclusion Since no homozygous LoS nor pLoF variants were identified and heterozygous carriers had similar cardiometabolic phenotype as non-carriers, we conclude that GLP-1R may be of particular importance in human physiology, due to a potential evolutionary intolerance of harmful homozygous GLP1R variants.

Background Alzheimer’s disease (AD) is a progressive neurodegenerative disorder for which there is no cure. Type II diabetes is a risk factor for developing AD, and drugs that initially have been developed to treat diabetes have shown good neuroprotective effects in animal models of AD. We have tested the agonist of glucagon‐like peptide 1 (GLP‐1) liraglutide in patients with Alzheimer’s disease and present the results at this meeting. In addition, GLP‐1 analogues and Glucose‐dependent insulinotropic polypeptide (GIP) analogues have shown good effects in animal models of AD. Method Here, we test a dual GLP‐1/GIP receptor agonist (DA4‐JC) that has a cell penetrating sequence added to enhance blood‐brain barrier penetration. We test the receptor activation properties in cell culture measuring cAMP levels and test liraglutide and DA4‐JC head‐to‐head in the APP/PS1 transgenic mouse model of AD. Memory formation in the water maze, synaptic plasticity (LTP) in the hippocampus, amyloid plaque load, and chronic inflammation was evaluated. Result We show in a receptor activation study that when measuring cAMP levels, DA4‐JC has balanced activity on both GLP‐1 and GIP receptors but not on GLP‐2 or Glucagon receptors. A dose‐response study in the APP/PS1 mouse model of AD showed a dose‐dependent drug effect on both the chronic inflammation response and the reduction of amyloid plaques in the brain. When comparing DA4‐JC with the GLP‐1 analogue liraglutide at equal doses of 10nmol/kg bw ip. once‐daily for 8 weeks, DA4‐JC was more effective in reversing memory loss, enhancing synaptic plasticity (LTP) in the hippocampus, reducing amyloid plaque load in the cortex, and reducing the number of activated microglia and astroglia and lowering pro‐inflammatory cytokine levels in the brain. Conclusion The results show good neuroprotective effects of liraglutide and DA4‐JC, and suggest that the dual GLP‐1/GIP receptor agonist DA4‐JC may be more effective in treating AD than a single GLP‐1 receptor agonist. Funded in part by the Alzheimer Society UK.