Identification, tissue distribution, and anorexigenic effect of amylin in Siberian sturgeon (Acipenser baeri).

Amylin is a 37-amino acid polypeptide that has been found to be involved in feeding regulation in some mammals, birds, and goldfish. We cloned amylin of Siberian sturgeon and detected its distribution pattern in 15 tissues. The expression levels in the periprandial period (pre-and post-feeding), the changes in the food intake, and the expression levels of related appetite factors after the intraperitoneal injection of amylin were detected. The expression of amylin was found to be the highest in the hypothalamus. Compared with 1 h pre-feeding, the expression levels of amylin in the hypothalamus and duodenum were increased significantly 1 h post-feeding. Compared with the control group (saline), intraperitoneal injection of 50 ng/g, 100 ng/g, and 200 ng/g of amylin significantly inhibited food intake at 1 h post injection, but not at 3 h and 6 h. The injection of 50 ng/g, 100 ng/g, and 200 ng/g amylin significantly inhibited the cumulative feed. After 1 h of 50 ng/g amylin injection, the levels of MC4R and somatostatin in the hypothalamus increased significantly, while the levels of amylin and NPY decreased significantly. The levels of CCK in the valvular intestine were increased significantly. Insulin in the duodenum was also increased significantly, but there was no significant change in ghrelin in the duodenum. These results show that amylin inhibits feeding in Siberian sturgeon by down-regulating the appetite-stimulating factor NPY and up-regulating the appetite-suppressing factors somatostatin, MC4R, CCK, and insulin. This study provides a theoretical basis for studying the feeding function and action mechanisms of amylin in Siberian sturgeon.

A fully artificial pancreas versus a hybrid artificial pancreas for type 1 diabetes: a single-centre, open-label, randomised controlled, crossover, non-inferiority trial.

BACKGROUND: For people with type 1 diabetes, there is currently no automated insulin delivery system that does not require meal input. We aimed to assess the efficacy of a novel faster-acting insulin aspart (Fiasp) plus pramlintide fully closed-loop system that does not require meal input. METHODS: In this open-label, randomised controlled, crossover, non-inferiority trial we compared the Fiasp (Novo Nordisk, Bagsværd, Denmark) plus pramlintide closed-loop system with no meal input (fully artificial pancreas) and the Fiasp-alone closed-loop system with precise carbohydrate counting (hybrid artificial pancreas). Adults (≥18 years) who had a clinical diagnosis of type 1 diabetes for at least 12 months, had glycated haemoglobin 12% or lower, and had been on insulin pump therapy for at least 6 months were enrolled at McGill University Health Centre, Montreal, QC, Canada. The Fiasp plus pramlintide fully closed-loop system delivered pramlintide in a basal-bolus manner with a fixed ratio of 10 µg:U relative to insulin. A research staff member counted the carbohydrate content of meals to input in the hybrid closed-loop system. Participants completed the two full-day crossover interventions in a random order allocated by a computer-generated code implementing a blocked randomisation (block size of four). The primary outcome was the percentage of time spent within the glucose target range (3·9-10·0 mmol/L), with a 6% non-inferiority margin, assessed in all participants who completed both interventions. This trial is registered with ClinicalTrials.gov, NCT03800875. FINDINGS: Between Feb 8, 2019, and Sept 19, 2020, we enrolled 28 adults, of whom 24 completed both interventions and were included in analyses. The percentage of time spent in the target range was 74·3% (IQR 61·5-82·8) with the fully closed-loop system versus 78·1% (66·3-87·5) with the hybrid Fiasp-alone closed-loop system (paired difference 2·6%, 95% CI -2·4 to 12·2; non-inferiority p=0·28). Eight (33%) participants had at least one hypoglycaemia event (<3·3 mmol/L) with the fully closed-loop system compared with 14 (58%) participants with the hybrid closed-loop system (2200-2200 h). Non-mild nausea was reported by three (13%) participants and non-mild bloating by one (4%) participant with the fully closed-loop system compared with zero participants with the hybrid closed-loop system. INTERPRETATION: The Fiasp plus pramlintide fully closed-loop system was not non-inferior to the Fiasp-alone hybrid closed-loop system for the overall percentage of time in the glucose target range. However, participants still spent a high percentage of time within the target range with the fully-closed loop system. Outpatient studies comparing the fully closed-loop hybrid systems with patient-estimated, rather than precise, carbohydrate counting are warranted. FUNDING: Diabetes Canada.

Establishment of an Adult Medaka Fatty Liver Model by Administration of a Gubra-Amylin-Nonalcoholic Steatohepatitis Diet Containing High Levels of Palmitic Acid and Fructose.

Among lifestyle-related diseases, fatty liver is the most common liver disease. To date, mammalian models have been used to develop methods for inhibiting fatty liver progression; however, new, more efficient models are expected. This study investigated the creation of a new model to produce fatty liver more efficiently than the high-fat diet medaka model that has been used to date. We compared the GAN (Gubra-Amylin nonalcoholic steatohepatitis) diet, which has been used in recent years to induce fatty liver in mice, and the high-fat diet (HFD). Following administration of the diets for three months, enlarged livers and pronounced fat accumulation was noted. The GAN group had large fat vacuoles and lesions, including ballooning, compared to the HFD group. The GAN group had a higher incidence of lesions. When fenofibrate was administered to the fatty liver model created via GAN administration and liver steatosis was assessed, a reduction in liver fat deposition was observed, and this model was shown to be useful in drug evaluations involving fatty liver. The medaka fatty liver model administered with GAN will be useful in future fatty liver research.

Dual-hormone artificial pancreas for management of type 1 diabetes: Recent progress and future directions.

Over the last few years, technological advances have led to tremendous improvement in the management of type 1 diabetes (T1D). Artificial pancreas systems have been shown to improve glucose control compared with conventional insulin pump therapy. However, clinically significant hypoglycemic and hyperglycemic episodes still occur with the artificial pancreas. Postprandial glucose excursions and exercise-induced hypoglycemia represent major hurdles in improving glucose control and glucose variability in many patients with T1D. In this regard, dual-hormone artificial pancreas systems delivering other hormones in addition to insulin (glucagon or amylin) may better reproduce the physiology of the endocrine pancreas and have been suggested as an alternative tool to overcome these limitations in clinical practice. In addition, novel ultra-rapid-acting insulin analogs with a more physiological time-action profile are currently under investigation for use in artificial pancreas devices, aiming to address the unmet need for further improvements in postprandial glucose control. This review article aims to discuss the current progress and future outlook in the development of novel ultra-rapid insulin analogs and dual-hormone closed-loop systems, which offer the next steps to fully closing the loop in the artificial pancreas.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of concomitant administration of multiple doses of cagrilintide with semaglutide 2·4 mg for weight management: a randomised, controlled, phase 1b trial.

BACKGROUND: Cagrilintide, a long-acting amylin analogue, and semaglutide 2·4 mg, a glucagon-like peptide-1 analogue, are both being investigated as options for weight management. We aimed to determine the safety, tolerability, pharmacokinetics, and pharmacodynamics of this drug combination. METHODS: In this randomised, placebo-controlled, multiple-ascending dose, phase 1b trial, individuals aged 18-55 years with a body-mass index 27·0-39·9 kg/m2 and who were otherwise healthy were recruited from a single centre in the USA. The trial included six sequential overlapping cohorts, and in each cohort eligible participants were randomly assigned (3:1) to once-weekly subcutaneous cagrilintide (0·16, 0·30, 0·60, 1·2, 2·4, or 4·5 mg) or matched placebo, in combination with once-weekly subcutaneous semaglutide 2·4 mg, without lifestyle interventions. In each cohort, the doses of cagrilintide and semaglutide were co-escalated in 4-week intervals to the desired dose over 16 weeks, participants were treated at the target dose for 4 weeks, and then followed up for 5 weeks. Participants, investigators, and the sponsor were masked to treatment assignment. The primary endpoint was number of treatment-emergent adverse events from baseline to end of follow-up. Secondary pharmacokinetic endpoints assessed from day of last dose (week 19) to end of treatment (week 20) were area under the plasma concentration-time curve from 0 to 168 h (AUC0-168 h) and maximum concentration [Cmax] of cagrilintide and semaglutide; exploratory pharmacokinetic endpoints were half-life, time to Cmax [tmax], plasma clearance, and volume of distribution of cagrilintide and semaglutide; and exploratory pharmacodynamic endpoints were changes in bodyweight, glycaemic parameters, and hormones. Safety, pharmacokinetic, and pharmacodynamic endpoints were assessed in all participants who were exposed to at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT03600480, and is now complete. FINDINGS: Between July 25, 2018, and Dec 17, 2019, 285 individuals were screened and 96 were randomly assigned to cagrilintide (0·16-2·4 mg group n=12; 4·5 mg group n=11) or placebo (n=24), in combination with semaglutide 2·4 mg, of whom 95 were exposed to treatment (one patient in 0·60 mg cagrilintide group was not exposed) and included in the safety and full analysis datasets. The mean age was 40·6 years (SD 9·2), 56 (59%) of 95 participants were men and 51 (54%) were Black or African American. Of 566 adverse events reported in 92 participants (69 [97%] of 71 participants assigned to 0·16-4·5 mg cagrilintide and 23 [96%] of 24 assigned to placebo), 207 (37%) were gastrointestinal disorders. Most adverse events were mild to moderate in severity and the proportion of participants with one or more adverse event was similar across treatment groups. Exposure was proportional to cagrilintide dose and did not affect semaglutide exposure or elimination. AUC0-168 h ranged from 926 nmol × h/L to 24 271 nmol × h/L, and Cmax ranged from 6·14 nmol/L to 170 nmol/L with cagrilintide 0·16-4·5 mg. AUC0-168 h ranged from 12 757 nmol × h/L to 15 305 nmol × h/L, and Cmax ranged from 96·4 nmol/L to 120 nmol/L with semaglutide 2·4 mg. Cagrilintide 0·16-4·5 mg had a half-life of 159-195 h, with a median tmax of 24-72 h. Semaglutide 2·4 mg had a half-life of 145-165 h, with a median tmax of 12-24 h. Plasma clearance and volume of distribution for both cagrilintide and semaglutide were similar across treatment groups. At week 20, mean percentage bodyweight reductions were greater with cagrilintide 1·2 and 2·4 mg than with placebo (15·7% [SE 1·6] for cagrilintide 1·2 mg and 17·1% [1·5] for cagrilintide 2·4 mg vs 9·8% [1·2] for pooled placebo cohorts 1-5; estimated treatment difference of -6·0% [95% CI -9·9 to -2·0] for cagrilintide 1·2 mg and -7·4% [-11·2 to -3·5] for cagrilintide 2·4 mg vs pooled placebo), and with cagrilintide 4·5 mg than with matched placebo (15·4% [1·3] vs 8·0% [2·2]; estimated treatment difference -7·4% [-12·8 to -2·1]), all in combination with semaglutide 2·4 mg. Glycaemic parameters improved in all treatment groups, independently of cagrilintide dose. Changes in hormones were similar across treatment groups. INTERPRETATION: Concomitant treatment with cagrilintide and semaglutide 2·4 mg was well tolerated with an acceptable safety profile. Future larger and longer trials are needed to fully assess the efficacy and safety of this treatment combination. FUNDING: Novo Nordisk A/S.

Facilitatory and inhibitory role of central amylin administration in the regulation of the gonadotropin-releasing hormone pulse generator activity in goats.

Pulsatile gonadotropin-releasing hormone (GnRH) secretion is essential for regulating reproductive functions in mammals. GnRH pulses are governed by a neural mechanism that is termed the GnRH pulse generator. In the present study, we investigated the role of central calcitonin receptor (CTR) signaling in the regulation of the GnRH pulse generator activity in ovariectomized goats by administering amylin, an endogenous ligand for CTR, into the lateral ventricle. GnRH pulse generator activity was measured using multiple unit activity (MUA) recordings in the mediobasal hypothalamus. We analyzed changes in the interval of characteristic increases in MUA (MUA volleys). The MUA volley interval shortened immediately after amylin administration, followed by prolonged intervals. Double in situ hybridization for KISS1 (kisspeptin gene) and CALCR (CTR gene) revealed that low expression levels of CALCR were found in the arcuate kisspeptin neurons, which is suggested as the main population of neurons, involved in GnRH pulse generator activity. These results suggest that central amylin-CTR signaling has a biphasic role in the regulation of GnRH pulse generator activity by acting on cells other than the arcuate kisspeptin neurons in goats.

A co-formulation of supramolecularly stabilized insulin and pramlintide enhances mealtime glucagon suppression in diabetic pigs.

Treatment of patients with diabetes with insulin and pramlintide (an amylin analogue) is more effective than treatment with insulin only. However, because mixtures of insulin and pramlintide are unstable and have to be injected separately, amylin analogues are only used by 1.5% of people with diabetes needing rapid-acting insulin. Here, we show that the supramolecular modification of insulin and pramlintide with cucurbit[7]uril-conjugated polyethylene glycol improves the pharmacokinetics of the dual-hormone therapy and enhances postprandial glucagon suppression in diabetic pigs. The co-formulation is stable for over 100 h at 37 °C under continuous agitation, whereas commercial formulations of insulin analogues aggregate after 10 h under similar conditions. In diabetic rats, the administration of the stabilized co-formulation increased the area-of-overlap ratio of the pharmacokinetic curves of pramlintide and insulin from 0.4 ± 0.2 to 0.7 ± 0.1 (mean ± s.d.) for the separate administration of the hormones. The co-administration of supramolecularly stabilized insulin and pramlintide better mimics the endogenous kinetics of co-secreted insulin and amylin, and holds promise as a dual-hormone replacement therapy.

A Novel Dual-Hormone Insulin-and-Pramlintide Artificial Pancreas for Type 1 Diabetes: A Randomized Controlled Crossover Trial.

OBJECTIVE: The rapid insulin-alone artificial pancreas improves glycemia in type 1 diabetes but daytime control remains suboptimal. We propose two novel dual-hormone artificial pancreas systems. RESEARCH DESIGN AND METHODS: We conducted a randomized crossover trial comparing a rapid insulin-alone artificial pancreas with rapid insulin-and-pramlintide and with regular insulin-and-pramlintide artificial pancreas systems in adults with type 1 diabetes. Participants were assigned to the interventions in random order during three 24-h inpatient visits. Each visit was preceded by an outpatient hormonal open-loop run-in period of 10-14 days. The dual-hormone artificial pancreas delivered pramlintide in a basal-bolus manner, using a novel dosing algorithm, with a fixed ratio relative to insulin. The primary outcome was time in the range 3.9-10.0 mmol/L. RESULTS: Compared with the rapid insulin-alone artificial pancreas system, the rapid insulin-and-pramlintide system increased the time in range from 74% (SD 18%) to 84% (13%) (P = 0.0014), whereas the regular insulin-and-pramlintide system did not change the time in range (69% [19%]; P = 0.22). The increased time in range with the rapid insulin-and-pramlintide system was due to improved daytime control (daytime time in range increased from 63% [23%] to 78% [16%], P = 0.0004). There were 11 (1 per 2.5 days) hypoglycemic events (<3.3 mmol/L with symptoms or <3.0 mmol/L irrespective of symptoms) with the rapid insulin-alone system, compared with 12 (1 per 2.3 days) and 18 (1 per 1.4 days) with the rapid and regular insulin-and-pramlintide systems, respectively. Gastrointestinal symptoms were reported after 0% (0 of 112) of meals with the rapid insulin-alone system, compared with 6% (6 of 108) and 11% (11 of 104) with the rapid and regular insulin-and-pramlintide systems, respectively; none of the symptoms were severe. CONCLUSIONS: A novel rapid insulin-and-pramlintide artificial pancreas improves glucose control compared with a rapid insulin-alone artificial pancreas (ClinicalTrials.gov number NCT02814123).

Validity of biopsy-based drug effects in a diet-induced obese mouse model of biopsy-confirmed NASH.

BACKGROUND: Compounds in clinical development for nonalcoholic steatohepatitis (NASH) improve liver histopathology in diet-induced obese mouse models of biopsy-confirmed NASH. Since the biopsy section used for histopathological evaluation represents only < 1% of the whole mouse liver, we evaluated how well biopsy-based quantitative image analyses correlate to stereology-based whole-liver quantitative changes upon drug treatment. METHODS: Male leptin-deficient Lepob/Lepob mice were fed the Amylin liver NASH (AMLN) diet for 16 weeks before stratification into treatment groups using a biopsy-based evaluation of type I collagen αI (col1a1) levels. Mice were treated for 8 weeks with either vehicle (PO, QD), liraglutide (0.4 mg/kg, SC, QD), elafibranor (30 mg/kg, PO, QD) or INT-767 (10 mg/kg, PO, QD). Terminal quantitative histological assessment of liver lipid (hematoxylin-eosin staining), inflammation (galectin-3 immunohistochemistry (IHC); gal-3), and fibrosis (col1a1 IHC) was performed on terminal liver biopsies and compared with stereologically sampled serial sections spanning the medial, left and right lateral lobe of the liver. RESULTS: The distribution of liver lipid and fibrosis was markedly consistent across lobes, whereas inflammation showed some variability. While INT-767 and liraglutide significantly reduced total liver weight by 20 and 48%, respectively, elafibranor tended to exacerbate hepatomegaly in Lepob/Lepob-NASH mice. All three compounds markedly reduced biopsy-based relative liver lipid content. Elafibranor and INT-767 significantly reduced biopsy-based relative gal-3 levels (P < 0.001), whereas INT-767 and liraglutide tended to reduce relative col1a1 levels. When changes in liver weight was accounted for, both INT-767 and liraglutide significantly reduced biopsy-based total col1a1 content. Although minor differences in absolute and relative liver lipid, inflammation and fibrosis levels were observed across lobes, the interpretation of drug-induced effects were consistent with biopsy-based conclusions. Notably, the incorporation of changes in total liver mass revealed that liraglutide's efficacy reached statistical significances for all analyzed parameters. CONCLUSIONS: In conclusion, in-depth analyses of liver homogeneity demonstrated that drug-induced improvement in liver biopsy-assessed histopathology is representative for overall liver effects assessed using stereology. Importantly, these findings reveal how changes in whole-liver mass should be considered to provide a deeper understanding of apparent drug treatment efficacy in preclinical NASH studies.

The BDNF Protein and its Cognate mRNAs in the Rat Spinal Cord during Amylin-induced Reversal of Morphine Tolerance.

The pancreatic peptide, Amylin (AMY), reportedly affects nociception in rodents. Here, we investigated the potential effect of AMY on the tolerance to morphine and on the expression of BDNF at both levels of protein and RNA in the lumbar spinal cord of morphine tolerant rats. Animals in both groups of control and test received a single daily dose of intrathecal (i.t.) morphine for 10 days. Rats in the test group received AMY (1, 10 and 60 pmoles) in addition to morphine from days 6 to10. Morphine tolerance was established at day 5. AMY alone showed enduring antinociceptive effects for 10 days. Real-Time PCR, western blotting and ELISA were used respectively to assess levels of BDNF transcripts and their encoded proteins. Rats tolerant to i.t. morphine showed increased expression of exons I, IV, and IX of the BDNF gene, and had elevated levels of pro-BDNF and BDNF protein in their lumbar spinal cord. AMY, when co-administered with morphine from days 6 to 10, reversed morphine tolerance and adversely affected the morphine-induced expression of the BDNF gene at both levels of protein and mRNAs containing exons I, IV and IX. AMY alone increased levels of exons I and IV transcripts. Levels of pro-BDNF and BDNF proteins remained unchanged in the lumbar spinal cord of rats treated by AMY alone. These results suggest that i.t. AMY not only abolished morphine tolerance, but also reduced the morphine induced increase in the expression of both BDNF transcripts and protein in the lumbar spinal cord.

Control of Postprandial Hyperglycemia in Type 1 Diabetes by 24-Hour Fixed-Dose Coadministration of Pramlintide and Regular Human Insulin: A Randomized, Two-Way Crossover Study.

OBJECTIVE: Healthy pancreatic ß-cells secrete the hormones insulin and amylin in a fixed ratio. Both hormones are lacking in type 1 diabetes, and postprandial glucose control using insulin therapy alone is difficult. This study tested the pharmacodynamic effects of the amylin analog pramlintide and insulin delivered in a fixed ratio over a 24-h period. RESEARCH DESIGN AND METHODS: Patients with type 1 diabetes were stabilized on insulin pump therapy with insulin lispro before a randomized, single-masked, two-way crossover, 24-h inpatient study in which regular human insulin was administered with pramlintide or placebo using separate infusion pumps in a fixed ratio (9 µg/unit). Meal content and timing and patient-specific insulin doses were the same with each treatment. The primary outcome measure was change in mean glucose by continuous glucose monitoring (CGM). Profiles of laboratory-measured glucose, insulin, glucagon, and triglycerides were also compared. RESULTS: Mean 24-h glucose measured by CGM was lower with pramlintide versus placebo (8.5 vs. 9.7 mmol/L, respectively; P = 0.012) due to a marked reduction of postprandial increments. Glycemic variability was reduced, and postprandial glucagon and triglycerides were also lower with pramlintide versus placebo. Gastrointestinal side effects were more frequent during use of pramlintide; no major hypoglycemic events occurred with pramlintide or placebo. CONCLUSIONS: Coadministration of fixed-ratio pramlintide and regular human insulin for 24 h improved postprandial hyperglycemia and glycemic variability in patients with type 1 diabetes. Longer studies including dose titration under daily conditions are needed to determine whether this regimen could provide long-term improvement of glycemic control.

Pramlintide: The Effects of a Single Drug Injection on Blood Phosphatidylcholine Profile for Alzheimer's Disease.

Studies suggest that a single injection of pramlintide, an amylin analog, induces changes in Alzheimer's disease (AD) biomarkers in the blood of AD mouse models and AD patients. The aim of this study was to examine whether a pramlintide challenge combined with a phosphatidylcholine (PC) profile diagnoses of AD and mild cognitive impairment (MCI) better than PC alone. Non-diabetic subjects with cognitive status were administered a single subcutaneous injection of 60 mcg of pramlintide under fasting condition. A total of 71 PCs, amyloid-ß peptide (Aß), and total tau (t-tau) in plasma at different time points were measured and treated as individual variables. A single injection of pramlintide altered the levels of 7 PCs in the blood, while a pramlintide injection plus food modulated the levels of 10 PCs in the blood (p < 0.05). The levels of 2 PCs in MCI and 12 PCs in AD in the pramlintide challenge were significantly lower than the ones in controls. We found that while some PCs were associated with only Aß levels, other PCs were associated with both Aß and t-tau levels. A receiver operating characteristic analysis of the PCs was combined with the Aß and t-tau data to produce an area under the curve predictive value of 0.9799 between MCI subjects and controls, 0.9794 between AD subjects and controls, and 0.9490 between AD and MCI subjects. A combination of AD biomarkers and a group of PCs post a pramlintide challenge may provide a valuable diagnostic and prognostic test for AD and MCI.

Protective effects of a G. lucidum proteoglycan on INS-1 cells against IAPP-induced apoptosis via attenuating endoplasmic reticulum stress and modulating CHOP/JNK pathways.

Fudan-Yueyang-G. lucidum (FYGL) is a water-soluble macromolecular proteoglycan extracted from Ganoderma lucidum which has been used for health promotion for a long time in China. The aim of this study was to investigate the protective effects of FYGL on INS-1 rat insulinoma beta cells against IAPP-induced cell apoptosis, as well as the underlying mechanisms. The results showed that apoptotic cells were significantly increased when incubated with islet amyloid polypeptide (IAPP). However, cytotoxicity of IAPP was significantly attenuated by co-incubation of the cells with FYGL. The results of RT-PCR showed that mRNA expression of caspase-3, caspase-12 and C/EBP homologous protein (CHOP) in IAPP-treated cells were inhibited by FYGL. Moreover, FYGL significantly prevented the IAPP-induced abnormal expression of inositol-requiring protein-1α (IRE1α), protein kinase RNA (PKR)-like ER kinase (PERK), activating transcription factor 6 (ATF6), as well as suppressed the activation of CHOP and c-Jun N-terminal kinase (JNK). Taken together, our results suggest that FYGL protects INS-1 pancreatic beta cells against IAPP-induced apoptosis through attenuating endoplasmic reticulum stress (ERS) and modulating CHOP/JNK pathways.

Pramlintide but Not Liraglutide Suppresses Meal-Stimulated Glucagon Responses in Type 1 Diabetes.

Context: Postprandial hyperglycemia remains a challenge in type 1 diabetes (T1D) due, in part, to dysregulated increases in plasma glucagon levels after meals. Objective: This study was undertaken to examine whether 3 to 4 weeks of therapy with pramlintide or liraglutide might help to blunt postprandial hyperglycemia in T1D by suppressing plasma glucagon responses to mixed-meal feedings. Design: Two parallel studies were conducted in which participants underwent mixed-meal tolerance tests (MMTTs) without premeal bolus insulin administration before and after 3 to 4 weeks of treatment with either pramlintide (8 participants aged 20 ± 3 years, hemoglobin A1c 6.9 ± 0.5%) or liraglutide (10 participants aged 22 ± 3 years, hemoglobin A1c 7.6 ± 0.9%). Results: Compared with pretreatment responses to the MMTT, treatment with pramlintide reduced the peak increment in glucagon from 32 ± 16 to 23 ± 12 pg/mL (P < 0.02). In addition, the incremental area under the plasma glucagon curve from 0 to 120 minutes dropped from 1988 ± 590 to 737 ± 577 pg/mL/min (P < 0.001), which was accompanied by a similar reduction in the meal-stimulated increase in the plasma glucose curve from 11,963 ± 1424 mg/dL/min pretreatment vs 2493 ± 1854 mg/dL/min after treatment (P < 0.01). In contrast, treatment with liraglutide had no effect on plasma glucagon and glucose responses during the MMTT. Conclusions: Adjunctive treatment with pramlintide may provide an effective means to blunt postmeal hyperglycemia in T1D by suppressing dysregulated plasma glucagon responses. In contrast, plasma glucose and glucagon responses were unchanged after 3 to 4 weeks of treatment with liraglutide.

Amylin and diabetic cardiomyopathy - amylin-induced sarcolemmal Ca2+ leak is independent of diabetic remodeling of myocardium.

Amylin is a pancreatic ß-cell hormone co-secreted with insulin, plays a role in normal glucose homeostasis, and forms amyloid in the pancreatic islets of individuals with type-2 diabetes. Aggregated amylin is also found in blood and extra-pancreatic tissues, including myocardium. Myocardial amylin accumulation is associated with myocyte Ca2+ dysregulation in diabetic rats expressing human amylin. Whether deposition of amylin in the heart is a consequence of or a contributor to diabetic cardiomyopathy remains unknown. We used amylin knockout (AKO) mice intravenously infused with either human amylin (i.e, the aggregated form) or non-amyloidogenic (i.e., monomeric) rodent amylin to test the hypothesis that aggregated amylin accumulates in the heart in the absence of diabetes. AKO mice infused with human amylin, but not rodent amylin, showed amylin deposits in the myocardium. Cardiac amylin level was larger in males compared to females. Sarcolemmal Ca2+ leak and Ca2+ transients were increased in myocytes isolated from males infused with human amylin while no significant changes occurred in either females injected with human amylin or in rat amylin-infused mice. In isolated cardiac myocytes, the amylin receptor antagonist AC-187 did not effectively block the interaction of amylin with the sarcolemma. In conclusion, circulating aggregated amylin accumulates preferentially in male vs. female hearts and its effects on myocyte Ca2+ cycling do not require diabetic remodeling of the myocardium. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.

Early postnatal amylin treatment enhances hypothalamic leptin signaling and neural development in the selectively bred diet-induced obese rat.

Selectively bred diet-induced obese (DIO) rats become obese on a high-fat diet and are leptin resistant before becoming obese. Compared with diet-resistant (DR) neonates, DIO neonates have impaired leptin-dependent arcuate (ARC) neuropeptide Y/agouti-related peptide (NPY/AgRP) and α-melanocyte-stimulating hormone (α-MSH; from proopiomelanocortin (POMC) neurons) axon outgrowth to the paraventricular nucleus (PVN). Using phosphorylation of STAT3 (pSTAT3) as a surrogate, we show that reduced DIO ARC leptin signaling develops by postnatal day 7 (P7) and is reduced within POMC but not NPY/AgRP neurons. Since amylin increases leptin signaling in adult rats, we treated DIO neonates with amylin during postnatal hypothalamic development and assessed leptin signaling, leptin-dependent ARC-PVN pathway development, and metabolic changes. DIO neonates treated with amylin from P0-6 and from P0-16 increased ARC leptin signaling and both AgRP and α-MSH ARC-PVN pathway development, but increased only POMC neuron number. Despite ARC-PVN pathway correction, P0-16 amylin-induced reductions in body weight did not persist beyond treatment cessation. Since amylin enhances adult DIO ARC signaling via an IL-6-dependent mechanism, we assessed ARC-PVN pathway competency in IL-6 knockout mice and found that the AgRP, but not the α-MSH, ARC-PVN pathway was reduced. These results suggest that both leptin and amylin are important neurotrophic factors for the postnatal development of the ARC-PVN pathway. Amylin might act as a direct neurotrophic factor in DIO rats to enhance both the number of POMC neurons and their α-MSH ARC-PVN pathway development. This suggests important and selective roles for amylin during ARC hypothalamic development.

Mitigating Meal-Related Glycemic Excursions in an Insulin-Sparing Manner During Closed-Loop Insulin Delivery: The Beneficial Effects of Adjunctive Pramlintide and Liraglutide.

OBJECTIVE: Closed-loop (CL) insulin delivery effectively maintains glucose overnight but struggles when challenged with meals. Use of single-day, 30-µg/meal pramlintide lowers meal excursions during CL. We sought to further elucidate the potential benefits of adjunctive agents after 3-4 weeks of outpatient dose titration. RESEARCH DESIGN AND METHODS: Two CL studies were conducted: one evaluating adjunctive pramlintide and the other liraglutide. Ten subjects (age 16-23 years; A1C 7.2 ± 0.6% [55 ± 6.6 mmol/mol]) completed two 24-h sessions: one on CL alone and one on CL plus 60-µg pramlintide (CL + P), after a 3-4-week outpatient dose escalation. Eleven subjects (age 18-27 years; A1C 7.5 ± 0.9% [58 ± 9.8 mmol/mol]) were studied before and after treatment with 1.8 mg liraglutide (CL + L) after a similar 3-4-week dose escalation period. Timing and content of meals during CL were identical within experiments; meals were not announced. RESULTS: Pramlintide delayed the time to peak plasma glucose (PG) excursion (CL 1.6 ± 0.5 h vs. CL + P 2.6 ± 0.9 h, P < 0.001) with concomitant blunting of peak postprandial increments in PG (P < 0.0001) and reductions in postmeal incremental PG area under the curve (AUC) (P = 0.0002). CL + L also led to reductions in PG excursions (P = 0.05) and incremental PG AUC (P = 0.004), with a 28% reduction in prandial insulin delivery. Outpatient liraglutide therapy led to a weight loss of 3.2 ± 1.8 kg, with a 26% reduction in total daily insulin dose. CONCLUSIONS: Adjunctive pramlintide and liraglutide treatment mitigated postprandial hyperglycemia during CL control; liraglutide demonstrated the additional benefit of weight loss in an insulin-sparing manner. Further investigations of these and other adjunctive agents in long-term outpatient CL studies are needed.

Impact of Disease Duration on the Effects of Pramlintide in Type 1 Diabetes: A Post Hoc Analysis of Three Clinical Trials.

INTRODUCTION: Adjunctive mealtime use of the amylin analog pramlintide improves postprandial hyperglycemia in patients with type 1 diabetes. This post hoc analysis of three randomized trials evaluated whether disease duration affected responses to pramlintide. METHODS: Patients received mealtime pramlintide 30 or 60 µg (n = 714) or placebo (n = 537) as an adjunct to insulin and were stratified into tertiles by diabetes duration at baseline. Efficacy and safety end points were assessed at week 26 using analysis of covariance and logistic regression models. RESULTS: Disease durations for tertiles 1, 2, and 3 were 6.7, 16.5, and 29.9 years, respectively. In all tertiles, pramlintide resulted in greater reductions in glycated hemoglobin (HbA1c) and weight than placebo, with greater weight reductions and insulin sparing in tertiles 2 and 3. Insulin dose and weight increased in the placebo group in all tertiles. Baseline HbA1c was a predictor of HbA1c lowering in both treatment groups (P < 0.0001); higher daily insulin predicted a smaller percent increase in insulin dose for placebo (P = 0.01); and higher body weight predicted greater weight loss in both pramlintide- and placebo-treated patients (P < 0.05). Event rates for severe hypoglycemia were similar for pramlintide and placebo and increased with longer duration of diabetes for both groups. Nausea with pramlintide increased with longer disease duration. CONCLUSION: Mealtime pramlintide resulted in greater reductions in HbA1c than placebo, regardless of diabetes duration at baseline. Longer disease duration appeared to augment insulin sparing and weight loss with pramlintide, with a potential for increased incidence of hypoglycemia and nausea. FUNDING: The design and conduct of the study were supported by Amylin Pharmaceuticals, San Diego, CA, USA.

Effects of intrathecal amylin on formalin-induced nociception and on cAMP accumulation in the rat embryonic spinal cells.

Amylin (AMY) is a member of calcitonin family of peptides. In this study, the effects of intrathecal (i.t) injection of AMY on the inflammatory pain and on the cAMP accumulation in the rat spinal cells were investigated. By using AMY receptor antagonists, we also studied the pharmacology of AMY receptors in the spinal cells. Formalin model of inflammatory pain was induced by intraplantar injection of formalin. AMY (0.06250-2500pmol/rat) was administrated i.t 15min before the injection of formalin. Antagonists were injected i.t 10min before the injection of AMY and/or morphine. AMY reduced formalin-induced pain in a dose dependent mode. This effect was inhibited by the potent AMY antagonist, AC187 but not CGRP8-37. rAMY8-37, most commonly reported as a weak AMY antagonist, showed to be equally or more potent than AC187 in antagonizing the above effects. The opioid antagonist, naloxone, had no significant effects on AMY antinociceptive effects. Primary dissociated cell culture was used to investigate the effect of AMY on cAMP production and to characterize AMY receptors in the spinal cells. AMY moderately increases cAMP accumulation in the spinal cells with an EC50 value of 74.62nM. This effect was not affected by CGRP8-37 but was inhibited by AC187 and rAMY8-37 with pA2 values of 7.94 and 7.87 respectively. In conclusion, effects of AMY in reducing formalin induced pain and on the cAMP accumulation by spinal cells are mediated through undefined receptors.

Fixed ratio dosing of pramlintide with regular insulin before a standard meal in patients with type 1 diabetes.

Amylin is co-secreted with insulin and is therefore lacking in patients with type 1 diabetes. Replacement with fixed ratio co-administration of insulin and the amylin analogue pramlintide may be superior to separate dosing. This concept was evaluated in a ratio-finding study. Patients with type 1 diabetes were enrolled in a randomized, single-masked, standard breakfast crossover study using regular human insulin injected simultaneously with pramlintide 6, 9 or 12 mcg/unit insulin or placebo. Insulin dosage was reduced by 30% from patients' usual estimates. Plasma glucose, glucagon and pramlintide and adverse events were assessed. All ratios reduced 0-3-h glucose and glucagon increments by >50%. No hypoglycaemia occurred. Adverse events were infrequent and generally mild. All pramlintide/insulin ratios markedly and safely reduced glycaemic excursions and suppressed glucagon secretion in the immediate postprandial state. Further study using one of these ratios to explore the efficacy and safety of longer-term meal-time and basal hormone replacement is warranted.