RESUMO
Amylin, a member of the calcitonin family, acts via amylin receptors in the hindbrain and hypothalamus to suppress appetite. Native ligands of these receptors are peptides with short half-lives. Conjugating fatty acids to these peptides can increase their half-lives. The long-acting human amylin analog, NN1213, was generated from structure-activity efforts optimizing solubility, stability, receptor affinity, and selectivity, as well as in vivo potency and clearance. In both rats and dogs, a single dose of NN1213 reduced appetite in a dose-dependent manner and with a long duration of action. Consistent with the effect on appetite, studies in obese rats demonstrated that daily NN1213 dosing resulted in a dose-dependent reduction in body weight over a 21-day period. Magnetic resonance imaging indicated that this was primarily driven by loss of fat mass. Based on these data, NN1213 could be considered an attractive option for weight management in the clinical setting.
Assuntos
Polipeptídeo Amiloide das Ilhotas Pancreáticas , Animais , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Humanos , Cães , Ratos , Relação Estrutura-Atividade , Masculino , Obesidade/tratamento farmacológico , Peso Corporal/efeitos dos fármacos , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismoRESUMO
Amylin, a pancreatic hormone that is cosecreted with insulin, has been highlighted as a potential treatment target for obesity. Amylin receptors are distributed widely throughout the brain and are coexpressed on mesolimbic dopamine neurons. Activation of amylin receptors is known to reduce food intake, but the neurochemical mechanisms behind this remain to be elucidated. Amylin receptor activation in the ventral tegmental area (VTA), a key dopaminergic nucleus in the mesolimbic reward system, has a potent ability to suppress intake of palatable fat and sugar solutions. Although previous work has demonstrated that VTA amylin receptor activation can dampen mesolimbic dopamine signaling elicited by random delivery of sucrose, whether this is also the case for fat remains unknown. Herein we tested the hypothesis that amylin receptor activation in the VTA of male rats would attenuate dopamine signaling in the nucleus accumbens core in response to random intraoral delivery of either fat or sugar solutions. Results show that fat solution produces a greater potentiation of accumbens dopamine than an isocaloric sucrose solution. Moreover, activation of VTA amylin receptors elicits a more robust suppression of accumbens dopamine signaling in response to fat solution than to sucrose. Taken together these results shed new light on the amylin system as a therapeutic target for obesity and emphasize the reinforcing nature of high-fat/high-sugar diets.
Assuntos
Dopamina , Núcleo Accumbens , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas , Área Tegmentar Ventral , Animais , Área Tegmentar Ventral/efeitos dos fármacos , Área Tegmentar Ventral/metabolismo , Masculino , Dopamina/metabolismo , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Ratos Sprague-Dawley , Gorduras na Dieta/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Agonistas dos Receptores da Amilina/farmacologia , Ratos , Sacarose/administração & dosagem , Sacarose/farmacologiaRESUMO
Inhibition of calcitonin gene-related peptide (CGRP) or its cognate CGRP receptor (CGRPR) has arisen as a major breakthrough in the treatment of migraine. However, a second CGRP-responsive receptor exists, the amylin (Amy) 1 receptor (AMY1R), yet its involvement in the pathology of migraine is poorly understood. AMY1R and CGRPR are heterodimers consisting of receptor activity-modifying protein 1 (RAMP1) with the calcitonin receptor (CTR) and the calcitonin receptor-like receptor (CLR), respectively. Here, we present the structure of AMY1R in complex with CGRP and Gs protein and compare it with the reported structures of the AMY1R complex with rat amylin (rAmy) and the CGRPR in complex with CGRP. Despite similar protein backbones observed within the receptors and the N- and C-termini of the two peptides bound to the AMY1R complexes, they have distinct organization in the peptide midregions (the bypass motif) that is correlated with differences in the dynamics of the respective receptor extracellular domains. Moreover, divergent conformations of extracellular loop (ECL) 3, intracellular loop (ICL) 2, and ICL3 within the CTR and CLR protomers are evident when comparing the CGRP bound to the CGRPR and AMY1R, which influences the binding mode of CGRP. However, the conserved interactions made by the C-terminus of CGRP to the CGRPR and AMY1R are likely to account for cross-reactivity of nonpeptide CGRPR antagonists observed at AMY1R, which also extends to other clinically used CGRPR blockers, including antibodies.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina , Microscopia Crioeletrônica , Proteína 1 Modificadora da Atividade de Receptores , Humanos , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Peptídeo Relacionado com Gene de Calcitonina/química , Proteína 1 Modificadora da Atividade de Receptores/metabolismo , Proteína 1 Modificadora da Atividade de Receptores/química , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/química , Animais , Ratos , Modelos Moleculares , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/metabolismo , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/química , Conformação ProteicaRESUMO
Amylin is released by pancreatic beta-cells in response to a meal and its major soluble mature form (37 amino acid-peptide) produces its biological effects by activating amylin receptors. Amylin is derived from larger propeptides that are processed within the synthesizing beta-cell. There are suggestions that a partially processed form, pro-amylin(1-48) is also secreted. We tested the hypothesis that pro-amylin(1-48) has biological activity and that human pro-amylin(1-48) may also form toxic pre-amyloid species. Amyloid formation, the ability to cross-seed and in vitro toxicity were similar between human pro-amylin(1-48) and amylin. Human pro-amylin(1-48) was active at amylin-responsive receptors, though its potency was reduced at rat, but not human amylin receptors. Pro-amylin(1-48) was able to promote anorexia by activating neurons of the area postrema, amylin's primary site of action, indicating that amylin can tolerate significant additions at the N-terminus without losing bioactivity. Our studies help to shed light on the possible roles of pro-amylin(1-48) which may be relevant for the development of future amylin-based drugs.
Assuntos
Amiloide , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Humanos , Ratos , Animais , Receptores de Polipeptídeo Amiloide de Ilhotas PancreáticasRESUMO
Dual amylin and calcitonin receptor agonists (DACRAs) show promise as efficacious therapeutics for treatment of metabolic disease, including obesity. However, differences in efficacy in vivo have been observed for individual DACRAs, indicating that detailed understanding of the pharmacology of these agents across target receptors is required for rational drug development. To date, such understanding has been hampered by lack of direct, subtype-selective, functional assays for the amylin receptors (AMYRs). Here, we describe the generation of receptor-specific assays for recruitment of Venus-tagged Gs protein through fusion of luciferase to either the human calcitonin receptor (CTR), human receptor activity-modifying protein (RAMP)-1, RAMP1 (AMY1R), human RAMP2 (AMY2R), or human RAMP3 (AMY3R). These assays revealed a complex pattern of receptor activation by calcitonin, amylin, or DACRA peptides that was distinct at each receptor subtype. Of particular note, although both of the CT-based DACRAs, sCT and AM1784, displayed relatively similar behaviors at CTR and AMY1R, they generated distinct responses at AMY2R and AMY3R. These data aid the rationalization of in vivo differences in response to DACRA peptides in rodent models of obesity. Direct assessment of the pharmacology of novel DACRAs at AMYR subtypes is likely to be important for development of optimized therapeutics for treatment of metabolic diseases. SIGNIFICANCE STATEMENT: Amylin receptors (AMYRs) are important obesity targets. Here we describe a novel assay that allows selective functional assessment of individual amylin receptor subtypes that provides unique insight into the pharmacology of potential therapeutic ligands. Direct assessment of the pharmacology of novel agonists at AMYR subtypes is likely to be important for development of optimized therapeutics for treatment of metabolic diseases.
Assuntos
Doenças Metabólicas , Neuropeptídeos , Humanos , Receptores da Calcitonina/metabolismo , Proteínas Modificadoras da Atividade de Receptores , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Receptores de Peptídeos/metabolismo , Proteínas de Membrana/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , ObesidadeRESUMO
BACKGROUND: Amylin, a pancreatic amyloid peptide involved in energy homeostasis, is increasingly studied in the context of Alzheimer's disease (AD) etiology. To date, conflicting pathogenic and neuroprotective roles for this peptide and its analogs for AD pathogenesis have been described. OBJECTIVE: Whether the benefits of amylin are associated with peripheral improvement of metabolic tone/function or directly through the activation of central amylin receptors is also unknown and downstream signaling mechanisms of amylin receptors are major objectives of this study. METHODS: To address these questions more directly we delivered the amylin analog pramlintide systemically (IP), at previously identified therapeutic doses, while centrally (ICV) inhibiting the receptor using an amylin receptor antagonist (AC187), at doses known to impact CNS function. RESULTS: Here we show that pramlintide improved cognitive function independently of CNS receptor activation and provide transcriptomic data that highlights potential mechanisms. Furthermore, we show than inhibition of the amylin receptor increased amyloid-beta pathology in female APP/PS1 mice, an effect than was mitigated by peripheral delivery of pramlintide. Through transcriptomic analysis of pramlintide therapy in AD-modeled mice we found sexual dimorphic modulation of neuroprotective mechanisms: oxidative stress protection in females and membrane stability and reduced neuronal excitability markers in males. CONCLUSION: These data suggest an uncoupling of functional and pathology-related events and highlighting a more complex receptor system and pharmacological relationship that must be carefully studied to clarify the role of amylin in CNS function and AD.
Assuntos
Doença de Alzheimer , Agonistas dos Receptores da Amilina , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas , Animais , Feminino , Masculino , Camundongos , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Modelos Animais de Doenças , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Camundongos Transgênicos , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/antagonistas & inibidores , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Agonistas dos Receptores da Amilina/farmacologiaRESUMO
BACKGROUND: The clinical use of calcitonin gene-related peptide receptor (CGRP-R) antagonists and monoclonal antibodies against CGRP and CGRP-R has offered new treatment possibilities for migraine patients. CGRP activates both the CGRP-R and structurally related amylin 1 receptor (AMY1-R). The relative effect of erenumab and the small-molecule CGRP-R antagonist, rimegepant, towards the CGRP-R and AMY-R needs to be further characterized. METHODS: The effect of CGRP and two CGRP-R antagonists were examined in Xenopus laevis oocytes expressing human CGRP-R, human AMY1-R and their subunits. RESULTS: CGRP administered to receptor expressing oocytes induced a concentration-dependent increase in current with the order of potency CGRP-R> > AMY1-R > calcitonin receptor (CTR). There was no effect on single components of the CGRP-R; calcitonin receptor-like receptor and receptor activity-modifying protein 1. Amylin was only effective on AMY1-R and CTR. Inhibition potencies (pIC50 values) for erenumab on CGRP induced currents were 10.86 and 9.35 for CGRP-R and AMY1-R, respectively. Rimegepant inhibited CGRP induced currents with pIC50 values of 11.30 and 9.91 for CGRP-R and AMY1-R, respectively. CONCLUSION: Our results demonstrate that erenumab and rimegepant are potent antagonists of CGRP-R and AMY1-R with 32- and 25-times preference for the CGRP-R over the AMY1-R, respectively. It is discussed if this difference in affinity between the two receptors is the likely reason why constipation is a common and serious adverse effect during CGRP-R antagonism but less so with CGRP binding antibodies.
Assuntos
Anticorpos Monoclonais Humanizados , Peptídeo Relacionado com Gene de Calcitonina , Piperidinas , Piridinas , Receptores de Peptídeo Relacionado com o Gene de Calcitonina , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas , Animais , Anticorpos Monoclonais Humanizados/farmacologia , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Peptídeo Relacionado com Gene de Calcitonina/farmacologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Oócitos/metabolismo , Piperidinas/farmacologia , Piridinas/farmacologia , Receptores da Calcitonina/química , Receptores da Calcitonina/metabolismo , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Xenopus laevis/metabolismoRESUMO
BACKGROUND AND AIM: Therapeutics that reduce calcitonin gene-related peptide activity are effective migraine treatments. However, gaps remain in our understanding of the molecular mechanisms that link calcitonin gene-related peptide to migraine. The amylin 1 receptor responds potently to calcitonin gene-related peptide, and to the related peptide amylin, but its role in relation to either peptide or to migraine is unclear. We sought to better understand the expression of the amylin 1 receptor protein subunit, the calcitonin receptor, in the rodent brain. METHODS: We profiled three antibodies for immunodetection of calcitonin receptor, using immunocytochemistry, western blotting, and calcitonin receptor conditional knockout mouse tissue. Selected migraine-relevant rat brain regions were then examined for calcitonin receptor-like immunoreactivity. RESULTS: All three antibodies detected calcitonin receptor protein but only one (188/10) produced robust immunostaining in rodent brain, under the conditions used. Calcitonin receptor-like immunoreactivity was apparent in the rat brainstem and midbrain including the locus coeruleus, periaqueductal grey and spinal trigeminal nucleus. CONCLUSIONS: Anti-calcitonin receptor antibodies require comprehensive profiling to ensure confidence in the detection of calcitonin receptor. Using a validated antibody, calcitonin receptor-like immunoreactivity was detected in several brain regions relevant to migraine. Further research is needed to understand the functional consequences of calcitonin receptor expression for calcitonin gene-related peptide or amylin physiology and pathophysiology.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina , Transtornos de Enxaqueca , Animais , Encéfalo , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Camundongos , Ratos , Receptores da Calcitonina/metabolismo , Receptores de Peptídeo Relacionado com o Gene de Calcitonina/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas PancreáticasRESUMO
Extracellular vesicles (EVs) are double membrane structures released by all cell types with identified roles in the generation, transportation, and degradation of amyloid-ß protein (Aß) oligomers in Alzheimer's disease (AD). EVs are thus increasingly recognized to play a neuroprotective role in AD, through their ability to counteract the neurotoxic effects of Aß, possibly through interactions with specific receptors on cell membranes. Our previous studies have identified the amylin receptor (AMY), particularly AMY3 subtype, as a mediator of the deleterious actions of Aß in vitro and in vivo experimental paradigms. In the present study, we demonstrate that AMY3 enriched EVs can bind soluble oligomers of Aß and protect N2a cells against toxic effects of this peptide. The effect was specific to amylin receptor as it was blocked in the presence of amylin receptor antagonist AC253. This notion was supported by reduced Aß binding to EVs from AMY depleted mice compared to those from wild type (Wt) mice. Finally, application of AMY3, but not Wt derived, EVs to hippocampal brain slices improved Aß-induced reduction of long-term potentiation, a cellular surrogate of memory. Collectively, our observations support the role of AMY receptors, particularly AMY3, in EVs as a potential therapeutic target for AD.
Assuntos
Doença de Alzheimer , Vesículas Extracelulares , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Vesículas Extracelulares/metabolismo , Potenciação de Longa Duração , Camundongos , Fragmentos de Peptídeos/toxicidade , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismoRESUMO
Type 2 diabetes is a common manifestation of metabolic dysfunction due to obesity and constitutes a major burden for modern health care systems, in concert with the alarming rise in obesity worldwide. In recent years, several successful pharmacotherapies improving glucose metabolism have emerged and some of these also promote weight loss, thus, ameliorating insulin resistance. However, the progressive nature of type 2 diabetes is not halted by these new anti-diabetic pharmacotherapies. Therefore, novel therapies promoting weight loss further and delaying diabetes progression are needed. Amylin, a beta cell hormone, has satiating properties and also delays gastric emptying and inhibits postprandial glucagon secretion with the net result of reducing postprandial glucose excursions. Amylin acts through the six amylin receptors, which share the core component with the calcitonin receptor. Calcitonin, derived from thyroid C cells, is best known for its role in humane calcium metabolism, where it inhibits osteoclasts and reduces circulating calcium. However, calcitonin, particularly of salmon origin, has also been shown to affect insulin sensitivity, reduce the gastric emptying rate and promote satiation. Preclinical trials with agents targeting the calcitonin receptor and the amylin receptors, show improvements in several parameters of glucose metabolism including insulin sensitivity and some of these agents are currently undergoing clinical trials. Here, we review the physiological and pharmacological effects of amylin and calcitonin and discuss the future potential of amylin and calcitonin-based treatments for patients with type 2 diabetes and obesity.
Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Calcitonina/uso terapêutico , Cálcio/uso terapêutico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glucose , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/uso terapêutico , Obesidade/tratamento farmacológico , Receptores da Calcitonina/uso terapêutico , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas , Redução de PesoRESUMO
Amylin receptors (AMYRs) are heterodimers of the calcitonin (CT) receptor (CTR) and one of three receptor activity-modifying proteins (RAMPs), AMY1R, AMY2R, and AMY3R. Selective AMYR agonists and dual AMYR/CTR agonists are being developed as obesity treatments; however, the molecular basis for peptide binding and selectivity is unknown. We determined the structure and dynamics of active AMYRs with amylin, AMY1R with salmon CT (sCT), AMY2R with sCT or human CT (hCT), and CTR with amylin, sCT, or hCT. The conformation of amylin-bound complexes was similar for all AMYRs, constrained by the RAMP, and an ordered midpeptide motif that we call the bypass motif. The CT-bound AMYR complexes were distinct, overlapping the CT-bound CTR complexes. Our findings indicate that activation of AMYRs by CT-based peptides is distinct from their activation by amylin-based peptides. This has important implications for the development of AMYR therapeutics.
Assuntos
Agonistas dos Receptores da Amilina/química , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/química , Animais , Microscopia Crioeletrônica , Humanos , Fenótipo , Conformação Proteica , Multimerização Proteica , SalmãoRESUMO
Social animals actively engage in contact with conspecifics and experience stress upon isolation. However, the neural mechanisms coordinating the sensing and seeking of social contacts are unclear. Here we report that amylin-calcitonin receptor (Calcr) signaling in the medial preoptic area (MPOA) mediates affiliative social contacts among adult female mice. Isolation of females from free social interactions first induces active contact-seeking, then depressive-like behavior, concurrent with a loss of Amylin mRNA expression in the MPOA. Reunion with peers induces physical contacts, activates both amylin- and Calcr-expressing neurons, and leads to a recovery of Amylin mRNA expression. Chemogenetic activation of amylin neurons increases and molecular knockdown of either amylin or Calcr attenuates contact-seeking behavior, respectively. Our data provide evidence in support of a previously postulated origin of social affiliation in mammals.
Assuntos
Comportamento Animal/fisiologia , Área Pré-Óptica/fisiologia , Receptores da Calcitonina/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Comportamento Social , Animais , Feminino , Técnicas de Inativação de Genes , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Camundongos , RNA Mensageiro/metabolismo , Transdução de Sinais/fisiologiaRESUMO
The metabolic peptide hormone amylin, in concert with other metabolic peptides like insulin and leptin, has an important role in metabolic homeostasis and has been intimately linked to Alzheimer's disease (AD). Interestingly, this pancreatic amyloid peptide is known to self-aggregate much like amyloid-beta and has been reported to be a source of pathogenesis in both Type II diabetes mellitus (T2DM) and Alzheimer's disease. The traditional "gain of toxic function" properties assigned to amyloid proteins are, however, contrasted by several reports highlighting neuroprotective effects of amylin and a recombinant analog, pramlintide, in the context of these two diseases. This suggests that pharmacological therapies aimed at modulating the amylin receptor may be therapeutically beneficial for AD development, as they already are for T2DMM. However, the nature of amylin receptor signaling is highly complex and not well studied in the context of CNS function. Therefore, to begin to address this pharmacological paradox in amylin research, the goal of this review is to summarize the current research on amylin signaling and CNS functions and critically address the paradoxical nature of this hormone's signaling in the context of AD pathogenesis.
Assuntos
Doença de Alzheimer , Diabetes Mellitus Tipo 2 , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Amiloide , Peptídeos beta-Amiloides/metabolismo , Diabetes Mellitus Tipo 2/tratamento farmacológico , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/farmacologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/uso terapêutico , Receptores de Polipeptídeo Amiloide de Ilhotas PancreáticasRESUMO
The peptide hormone amylin reduces food intake and body weight and is an attractive candidate target for novel pharmacotherapies to treat obesity. However, the short half-life of native amylin and amylin analogs like pramlintide limits these compounds' potential utility in promoting sustained negative energy balance. Here, we evaluate the ability of the novel long-acting amylin/calcitonin receptor agonist ZP5461 to reduce feeding and body weight in rats, and also test the role of calcitonin receptors (CTRs) in the dorsal vagal complex (DVC) of the hindbrain in the energy balance effects of chronic ZP5461 administration. Acute dose-response studies indicate that systemic ZP5461 (0.5-3 nmol/kg) robustly suppresses energy intake and body weight gain in chow- and high-fat diet (HFD)-fed rats. When HFD-fed rats received chronic systemic administration of ZP5461 (1-2 nmol/kg), the compound initially produced reductions in energy intake and weight gain but failed to produce sustained suppression of intake and body weight. Using virally mediated knockdown of DVC CTRs, the ability of chronic systemic ZP5461 to promote early reductions in intake and body weight gain was determined to be mediated in part by activation of DVC CTRs, implicating the DVC as a central site of action for ZP5461. Future studies should address other dosing regimens of ZP5461 to determine whether an alternative dose/frequency of administration would produce more sustained body weight suppression.
Assuntos
Agonistas dos Receptores da Amilina/farmacologia , Depressores do Apetite/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Receptores da Calcitonina/agonistas , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/efeitos dos fármacos , Rombencéfalo/efeitos dos fármacos , Nervo Vago/efeitos dos fármacos , Aumento de Peso/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Ingestão de Energia/efeitos dos fármacos , Masculino , Ratos Sprague-Dawley , Receptores da Calcitonina/genética , Receptores da Calcitonina/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/genética , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Rombencéfalo/metabolismo , Transdução de Sinais , Fatores de Tempo , Nervo Vago/metabolismoRESUMO
Based upon its interactions with amyloid ß peptide (Aß), the amylin receptor, a class B G protein-coupled receptor (GPCR), is a potential modulator of Alzheimer's disease (AD) pathogenesis. However, past pharmacological approaches have failed to resolve whether activation or blockade of this receptor would have greater therapeutic benefit. To address this issue, we generated compound mice expressing a human amyloid precursor protein gene with familial AD mutations in combination with deficiency of amylin receptors produced by hemizygosity for the critical calcitonin receptor subunit of this heterodimeric GPCR. These compound transgenic AD mice demonstrated attenuated responses to human amylin- and Aß-induced depression of hippocampal long-term potentiation (LTP) in keeping with the genetic depletion of amylin receptors. Both the LTP responses and spatial memory (as measured with Morris water maze) in these mice were improved compared to AD mouse controls and, importantly, a reduction in both the amyloid plaque burden and markers of neuroinflammation was observed. Our data support the notion of further development of antagonists of the amylin receptor as AD-modifying therapies.
Assuntos
Doença de Alzheimer/genética , Aprendizagem em Labirinto/fisiologia , Receptores da Calcitonina/genética , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/genética , Memória Espacial/fisiologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/psicologia , Precursor de Proteína beta-Amiloide/genética , Animais , Células Cultivadas , Endotélio Vascular/metabolismo , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Técnicas de Cultura de Órgãos , Receptores da Calcitonina/deficiência , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/deficiênciaRESUMO
OBJECTIVE: Dual amylin and calcitonin receptor agonists (DACRAs) are novel therapeutic agents that not only improve insulin sensitivity but also work as an adjunct to established T2DM therapies. DACRAs are currently administered once daily, though it is unknown whether DACRAs with increased plasma half-life can be developed as a once-weekly therapy. METHODS: The in vitro potencies of the KBP-066A and KBP-066 (non-acylated) were assessed using reporter assays. Acylation functionality was investigated by a combination of pharmacokinetics and acute food intake in rats. in vivo efficacies were investigated head-to-head in obese (HFD) and T2D (ZDF) models. RESULTS: In in vitro, KBP-066A activated the CTR and AMY-R potently, with no off-target activity. Acylation functionality was confirmed by acute tests, as KBP-066A demonstrated a prolonged PK and PD response compared to KBP-066. Both compounds induced potent and dose-dependent weight loss in the HFD rat model. In ZDF rats, fasting blood glucose/fasting insulin levels (tAUC) were reduced by 39%/50% and 36%/47% for KBP-066 and KBP-066A, respectively. This effect resulted in a 31% and 46% vehicle-corrected reduction in HbA1c at the end of the study for KBP-066 and KBP-066A, respectively. CONCLUSIONS: Here, we present pre-clinical data on an acylated DACRA, KBP-066A. The in vivo efficacy of KBP-066A is significantly improved compared to its non-acylated variant regarding weight loss and glycemic control in obese (HFD) and obese diabetic rats (ZDF). This compendium of pre-clinical studies highlights KBP-066A as a promising, once-weekly therapeutic agent for treating T2DM and obesity.
Assuntos
Agonistas dos Receptores da Amilina/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Obesidade/tratamento farmacológico , Receptores da Calcitonina/agonistas , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Agonistas dos Receptores da Amilina/química , Animais , Linhagem Celular , Dieta Hiperlipídica/efeitos adversos , Controle Glicêmico , Humanos , Masculino , Ratos , Ratos Sprague-Dawley , Redução de Peso/efeitos dos fármacosRESUMO
Intraperitoneal injection of amylin or its analog reduces Alzheimer's disease (AD) pathology in the brains. However, self-injecting amylin analogs is difficult for patients due to cognitive deficits. This work aims to study the effects of amylin on the brain could be achieved by oral delivery as some study reported that amylin receptor may be present in the gastrointestinal tract. A 6-week course of oral amylin treatment reduced components of AD pathology, including the levels of amyloid-ß, phosphorylated tau, and ionized calcium binding adaptor molecule 1. The treatment reduced active forms of cyclin-dependent kinase 5. Oral amylin treatment led to improvements in social deficit in AD mouse. Using immunofluorescence, we observed the amylin receptor complexed with the calcitonin receptor and receptor activity-modifying proteins in the enteric neurons. The study suggests the potential of the oral delivery of amylin analogs for the treatment of AD and other neurodegenerative diseases through enteric neurons.
Assuntos
Doença de Alzheimer , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Transgênicos , Receptores de Polipeptídeo Amiloide de Ilhotas PancreáticasRESUMO
BACKGROUND: Weight loss therapy is becoming more and more important, and two classes of molecules, namely amylin receptor and GLP-1 receptor agonists, have shown promise in this regard. Interestingly, these molecules have several overlapping pharmacological effects, such as suppression of gastric emptying, reduction of glucagon secretion and weight loss in common; however, they also have distinct effects on prandial insulin secretion. Hence, a combination of these two mechanisms is of significant interest. METHODS: In this study, we investigated the add-on potential of the dual amylin and calcitonin receptor agonist (DACRA) KBP-089 in combination with the GLP-1 receptor agonist liraglutide as obesity treatment in high-fat diet (HFD) fed rats. RESULTS: Increasing doses of KBP-089 and liraglutide alone and in combination were studied with respect to their effects on body weight, food intake and glucose metabolism during a 9-week intervention study conducted in HFD rats. Further, the gastric emptying rate during an oral glucose tolerance was assessed. Treatment with KBP-089 and liraglutide dose-dependently lowered body weight 15% (at 2.5 µg/kg/day) and 7% (at 400 µg/kg/day) in HFD rats, respectively, while the combination resulted in a 21% body weight reduction, which was mirrored by reduction in fat depot sizes. Gastric emptying and glucose metabolism were improved, primarily by KBP-089, although liraglutide led to a reduction in fasting plasma glucagon. CONCLUSION: DACRAs complement GLP-1 on food intake, body weight, and glucose tolerance indicating the potential for an add-on therapy.
Assuntos
Agonistas dos Receptores da Amilina/farmacologia , Receptor do Peptídeo Semelhante ao Glucagon 1/agonistas , Peptídeos Semelhantes ao Glucagon/farmacologia , Liraglutida/farmacologia , Obesidade/tratamento farmacológico , Receptores da Calcitonina/agonistas , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/química , Redução de Peso/efeitos dos fármacos , Animais , Glicemia/análise , Dieta Hiperlipídica/efeitos adversos , Quimioterapia Combinada , Teste de Tolerância a Glucose , Hipoglicemiantes/farmacologia , Masculino , Metaboloma , Obesidade/etiologia , Obesidade/metabolismo , Obesidade/patologia , Ratos , Ratos Sprague-DawleyRESUMO
OBJECTIVE: Amylin was found to regulate glucose and lipid metabolism by acting on the arcuate nucleus of the hypothalamus (ARC). Maternal high-fat diet (HFD) induces sex-specific metabolic diseases mediated by the ARC in offspring. This study was performed to explore 1) the effect of maternal HFD-induced alterations in amylin on the differentiation of hypothalamic neurons and metabolic disorders in male offspring and 2) the specific molecular mechanism underlying the regulation of amylin and its receptor in response to maternal HFD. METHODS: Maternal HFD and gestational hyper-amylin mice models were established to explore the role of hypothalamic amylin and receptor activity-modifying protein 3 (Ramp3) in regulating offspring metabolism. RNA pull-down, mass spectrometry, RNA immunoprecipitation, and RNA decay assays were performed to investigate the mechanism underlying the influence of maternal HFD on Ramp3 deficiency in the fetal hypothalamus. RESULTS: Male offspring with maternal HFD grew heavier and developed metabolic disorders, whereas female offspring with maternal HFD showed a slight increase in body weight and did not develop metabolic disorders compared to those exposed to maternal normal chow diet (NCD). Male offspring exposed to a maternal HFD had hyperamylinemia from birth until adulthood, which was inconsistent with offspring exposed to maternal NCD. Hyperamylinemia in the maternal HFD-exposed male offspring might be attributed to amylin accumulation following Ramp3 deficiency in the fetal hypothalamus. After Ramp3 knockdown in hypothalamic neural stem cells (htNSCs), amylin was found to fail to promote the differentiation of anorexigenic alpha-melanocyte-stimulating hormone-proopiomelanocortin (α-MSH-POMC) neurons but not orexigenic agouti-related protein-neuropeptide Y (AgRP-Npy) neurons. An investigation of the mechanism involved showed that IGF2BP1 could specifically bind to Ramp3 in htNSCs and maintain its mRNA stability. Downregulation of IGF2BP1 in htNSCs in the HFD group could decrease Ramp3 expression and lead to an impairment of α-MSH-POMC neuron differentiation. CONCLUSIONS: These findings suggest that gestational exposure to HFD decreases the expression of IGF2BP1 in the hypothalami of male offspring and destabilizes Ramp3 mRNA, which leads to amylin resistance. The subsequent impairment of POMC neuron differentiation induces sex-specific metabolic disorders in adulthood.
Assuntos
Diferenciação Celular , Dieta Hiperlipídica/efeitos adversos , Hipotálamo/metabolismo , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Receptores de Polipeptídeo Amiloide de Ilhotas Pancreáticas/metabolismo , Proteína Relacionada com Agouti/metabolismo , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Peso Corporal , Feminino , Células HEK293 , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurogênese , Neuropeptídeo Y/metabolismo , Gravidez , Proteínas de Ligação a RNA/metabolismo , Proteína 3 Modificadora da Atividade de Receptores/genética , Proteína 3 Modificadora da Atividade de Receptores/metabolismo , Células-Tronco , alfa-MSH/metabolismoRESUMO
This article in the Neural and Endocrine Section of Comprehensive Physiology discusses the physiology and pathophysiology of the pancreatic hormone amylin. Shortly after its discovery in 1986, amylin has been shown to reduce food intake as a satiation signal to limit meal size. Amylin also affects food reward, sensitizes the brain to the catabolic actions of leptin, and may also play a prominent role in the development of certain brain areas that are involved in metabolic control. Amylin may act at different sites in the brain in addition to the area postrema (AP) in the caudal hindbrain. In particular, the sensitizing effect of amylin on leptin action may depend on a direct interaction in the hypothalamus. The concept of central pathways mediating amylin action became more complex after the discovery that amylin is also synthesized in certain hypothalamic areas but the interaction between central and peripheral amylin signaling remains currently unexplored. Amylin may also play a dominant pathophysiological role that is associated with the aggregation of monomeric amylin into larger, cytotoxic molecular entities. This aggregation in certain species may contribute to the development of type 2 diabetes mellitus but also cardiovascular disease. Amylin receptor pharmacology is complex because several distinct amylin receptor subtypes have been described, because other neuropeptides [e.g., calcitonin gene-related peptide (CGRP)] can also bind to amylin receptors, and because some components of the functional amylin receptor are also used for other G-protein coupled receptor (GPCR) systems. © 2020 American Physiological Society. Compr Physiol 10:811-837, 2020.