A Galanin Receptor Subtype 1 Specific Agonist

The chimeric peptide M617, galanin(1–13)-Gln¹⁴-bradykinin(2–9)amide, is a novel galanin receptor ligand with increased subtype specificity for GalR1 and agonistic activity in cultured cells as well as in vivo. Displacement studies on cell membranes expressing hGalR1 or hGalR2 show the presence of a high affinity binding site for M617 on GalR1 (K_i=0.23±.12 nM) while lower affinity was seen towards GalR2 (K_i=5.71±1.28 nM) resulting in 25-fold specificity for GalR1. Activation of GalR1 upon stimulation with M617 is further confirmed by internalization of a GalR1-EGFP conjugate. Intracellular signaling studies show the ability of M617 to inhibit forskolin stimulated cAMP formation with 57% and to produce a 5-fold increase in inositol phosphate (IP) accumulation. Agonistic effects on signal transduction are shown on both receptors studied after treatment with M617 in the presence of galanin. In noradrenergic locus coeruleus neurons, M617 induces an outward current even in the presence of TTX plus Ca²⁺, high Mg²⁺, suggesting a postsynaptic effect. Intracerebroventricular (i.c.v.) administration of M617 dose-dependently stimulates food uptake in rats while, in contrast, M35 completely fails to affect the feeding behavior. Spinal cord flexor reflex is facilitated by intrathecal (i.t.) administration of M617 as well as galanin with no significant change upon pre-treatment with M617. M617 dose dependently antagonizes the spinal cord hyperexcitablility induced by C-fiber conditioning stimulus and does neither enhance nor antagonize the effect of galanin. These data demonstrate a novel galanin receptor ligand with subtype specificity for GalR1 and agonistic activity, both in vitro and in vivo.     

Rapid-Acting Insulin Analogues in Basal-Bolus Regimens in Type 1 Diabetes Mellitus

ObjectiveTo compare rapid-acting insulin analogues with regular human insulin in terms of hemoglobin A_1c, hypoglycemia, and insulin dose when used in a basal-bolus regimen in patients with type 1 diabetes mellitus.MethodsMEDLINE and congress proceedings were searched for randomized controlled trials comparing pran- dial insulins in a basal-bolus regimen in adults or children/ adolescents with type 1 diabetes. Studies in pregnancy, ob- servational studies, studies that compared premixed insulin or continuous subcutaneous insulin infusion/insulin pumps, and studies where the basal insulin was also changed were excluded. Only studies reporting baseline-endpoint change in insulin dose, or baseline and/or endpoint values, were included.ResultsTwenty-eight studies were identified (insulin glulisine, 4; insulin aspart, 7; insulin lispro, 17). Twenty- five studies compared a rapid-acting insulin analogue with regular human insulin, and 3 trials compared 2 rapid-acting insulin analogues. Overall, rapid-acting insulin analogues in a basal-bolus regimen provided similar or greater im- provements in glycemic control than regular human insulin at similar insulin doses, as well as a lower incidence of hypoglycemia.ConclusionsResults of the studies identified in this literature review indicate that a basal-bolus regimen with prandial rapid-acting insulin analogue provides advan- tages over basal-bolus regimens using prandial regular hu- man insulin, providing improvements in glycemic control comparable to those obtained with regular human insulin, as well as a lower incidence of hypoglycemia. (Endocr Pract. 2010;16:486-505)     

Hba1C Control And Cost-Effectiveness in Patients With Type 2 Diabetes Mellitus Initiated On Canagliflozin or A Glucagon-Like Peptide 1 Receptor Agonist in A Real-World Setting

Objective: To compare glycated hemoglobin (HbA1c) control and medication costs between patients with type 2 diabetes mellitus (T2DM) treated with canagliflozin 300 mg (CANA) or a glucagon-like peptide 1 receptor agonist (GLP-1 RA) in a real-world setting.Methods: Adults with T2DM newly initiated on CANA or a GLP-1 RA (index date) were identified from IQVIA™ Real-World Data Electronic Medical Records U.S. database (March 29, 2012–April 30, 2016). Inverse probability of treatment weighting accounted for differences in baseline characteristics. HbA1c levels at 3-month intervals were compared using generalized estimating equations. Medication costs used wholesale acquisition costs.Results: For both cohorts (CANA: n = 11,435; GLP-1 RA: n = 11,582), HbA1c levels decreased at 3 months postindex and remained lower through 30 months. Absolute changes in mean HbA1c from index to 3 months postindex for CANA and GLP-1 RA were -1.16% and -1.21% (patients with baseline HbA1c ≥7% [53 mmol/mol]); -1.54% and -1.51% (patients with baseline HbA1c ≥8% [64 mmol/mol]); and -2.13% and -1.99% (patients with baseline HbA1c ≥9% [75 mmol/mol]), respectively. Postindex, CANA patients with baseline HbA1c ≥7% had similar HbA1c levels at each interval versus GLP-1 RA patients, except 9 months (mean HbA1c, 7.75% [61 mmol/mol] vs. 7.86% [62 mmol/mol]; P = .0305). CANA patients with baseline HbA1c ≥8% and ≥9% had consistently lower HbA1c numerically versus GLP-1 RA patients and statistically lower HbA1c at 9 (baseline HbA1c ≥8% or ≥9%), 27, and 30 months (baseline HbA1c ≥9%). Continuous 12-month medication cost $3,326 less for CANA versus GLP-1 RA.Conclusion: This retrospective study demonstrated a similar evolution of HbA1c levels among CANA and GLP-1 RA patients in a real-world setting. Lower medication costs suggest CANA is economically dominant over GLP-1 RA (similar effectiveness, lower cost).Abbreviations:AHA = antihyperglycemic agentBMI = body mass indexCANA = canagliflozin 300 mgDCSI = diabetes complications severity indexeGFR = estimated glomerular filtration rateEMR = electronic medical recordGLP-1 RA = glucagon-like peptide 1 receptor agonistHbA1c = glycated hemoglobinICD-9-CM = International Classification of Diseases–Ninth Revision–Clinical ModificationICD-10-CM = International Classification of Diseases–Tenth Revision–Clinical ModificationIPTW = inverse probability of treatment weightingITT = intent-to-treatMPR = medication possession ratioPDC = proportion of days coveredPS = propensity scorePSM = propensity score matchingQuan-CCI = Quan-Charlson comorbidity indexSGLT2 = sodium-glucose cotransporter 2T2DM = type 2 diabetes mellitusWAC = wholesale acquisition cost     

Patient Factors Associated with Glucagonlike Peptide 1 Receptor Agonist use with and without Insulin

ObjectiveTo evaluate both the patient factors associated with the initiation of exenatide and the real-world treatment patterns of exenatide use with and without insulin.MethodsUsing retrospective electronic medical records from the General Electric Centricity database, we performed analyses of 2 cohorts to separately evaluate factors associated with initiation of exenatide among patients with type 2 diabetes mellitus and differences between those who initiated exenatide with and without concurrent insulin use. Cohort 1 was used to assess predictors of exenatide initiation and included adults with type 2 diabetes who were active in the database when exenatide became available (October 1, 2005). Cohort 2 was used to identify characteristics of patients who initiated exenatide with and without insulin.ResultsCohort 1 included 190444 adults, and cohort 2 included 9810 adults. In cohort 1, 7383 patients initiated exenatide therapy; factors associated with exenatide initiation were female sex, younger age, body weight of 102.3 kg or greater, body mass index of 35 kg/m² or greater, residence in the southern United States, a lower Charlson Comorbidity Index, previous or existing therapy with triple oral antidiabetic drugs, and insulin plus oral antidiabetic drugs. In cohort 2, 2470 exenatide-treated patients initiated exenatide with insulin (25%) (with or without oral antidiabetic drugs). They were more likely to weigh more than 113.6 kg, have a body mass index greater than 40 kg/m², have a Charlson Comorbidity Index of 2 or greater, and have a baseline hemoglobin A_1c level greater than 9%.ConclusionsExenatide concomitant with insulin use (with or without oral antidiabetic drugs) was common, and was more likely to be prescribed in patients with morbid obesity, comorbid conditions, and poor glycemic control. Randomized controlled trials are needed to confirm the safe and effective use of this combination. (Endocr Pract. 2011;17:707-716)     

A Novel Peptide with Similar Pharmacology to Exenatide in Rodents as GLP-1 Receptor Agonist

The prevalence of type-2 diabetes is rapidly increasing. Currently, exenatide is the first medicine which mimics incretin. However, it requires subcutaneous injection twice a day, an inconvenient way for patients. In this study, we identified a novel peptide with similar pharmacology to exenatide in rodents as GLP-1 receptor agonist which consists of 17 amino acids (17P). It promotes Ins-1 cell proliferation and insulin secretion and lowers blood glucose of diabetic rats. 17P was synthetized by solid-phase peptide synthesis. Interactions between GLP-1 receptor and 17P were studied by Bio-layer interferometry. Ins-1 cell proliferation was studied by MTT assay. ELISA was used to study Ins-1 cell insulin secretion. In vivo tests were performed with male Wistar rats. We used high fat diet and STZ injection to induce a type-2 diabetic rats model. Then, those rats were randomized to different test groups, and administered exenatide, 17P and saline water injection, to evaluate different responses. Based on HPLC (high performance liquid chromatography) and MS (mass spectrometry), 17P synthesis was successful. Bio-layer interferometry data showed a close interaction between GLP-1 receptor and 17P. 17P treatment of Ins-1 cells for 24 h could promote cell proliferation and insulin secretion in a dose-dependent manner. Administration of 17P in HF-STZ male Wistar rats demonstrated that 17P could lower the level of blood glucose and stabilize the body weight of the diabetic rats. All 17P treatments were similar to treatment with exenatide. In vitro and in vivo studies demonstrated that 17P could relieve symptoms of type-2 diabetes. Therefore, 17P could be developed as a promising type-2 diabetes therapeutic drug.     

Metabolic Implications when Employing Heavy Pre- and Post-Exercise Rapid-Acting Insulin Reductions to Prevent Hypoglycaemia in Type 1 Diabetes Patients: A Randomised Clinical Trial

Aim

To examine the metabolic, gluco-regulatory-hormonal and inflammatory cytokine responses to large reductions in rapid-acting insulin dose administered prandially before and after intensive running exercise in male type 1 diabetes patients.

Methods

This was a single centre, randomised, controlled open label study. Following preliminary testing, 8 male patients (24±2 years, HbA1c 7.7±0.4%/61±4 mmol.l⁻¹) treated with insulin''s glargine and aspart, or lispro attended the laboratory on two mornings at ∼08:00 h and consumed a standardised breakfast carbohydrate bolus (1 g carbohydrate.kg⁻¹BM; 380±10 kcal) and self-administered a 75% reduced rapid-acting insulin dose 60 minutes before 45 minutes of intensive treadmill running at 73.1±0.9% VO_2peak. At 60 minutes post-exercise, patients ingested a meal (1 g carbohydrate.kg⁻¹BM; 660±21 kcal) and administered either a Full or 50% reduced rapid-acting insulin dose. Blood glucose and lactate, serum insulin, cortisol, non-esterified-fatty-acids, β-Hydroxybutyrate, and plasma glucagon, adrenaline, noradrenaline, IL-6, and TNF-α concentrations were measured for 180 minutes post-meal.

Results

All participants were analysed. All glycaemic, metabolic, hormonal, and cytokine responses were similar between conditions up to 60 minutes following exercise. Following the post-exercise meal, serum insulin concentrations were lower under 50% (p<0.05) resulting in 75% of patients experiencing hyperglycaemia (blood glucose ≥8.0 mmol.l⁻¹; 50% n = 6, Full n = 3). β-Hydroxybutyrate concentrations decreased similarly, such that at 180 minutes post-meal concentrations were lower than rest under Full and 50%. IL-6 and TNF-α concentrations remained similar to fasting levels under 50% but declined under Full. Under 50% IL-6 concentrations were inversely related with serum insulin concentrations (r = −0.484, p = 0.017).

Conclusions

Heavily reducing rapid-acting insulin dose with a carbohydrate bolus before, and a meal after intensive running exercise may cause hyperglycaemia, but does not augment ketonaemia, raise inflammatory cytokines TNF-α and IL-6 above fasting levels, or cause other adverse metabolic or hormonal disturbances.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01531855","term_id":"NCT01531855"}}NCT01531855     

Optimized Basal-Bolus Insulin Regimens in Type 1 Diabetes: Insulin Glulisine Versus Regular Human Insulin in Combination with Basal Insulin Glargine

ObjectiveTo compare the efficacy and safety of insulin glulisine (GLU), a new rapid-acting insulin analogue, injected 0 to 15 minutes before or immediately after meals, with regular human insulin (RHI), injected 30 to 45 minutes before meals.MethodsPatients with type 1 diabetes (N = 860) received once-daily insulin glargine and subcutaneous injections of either GLU (premeal or postmeal) or premeal RHI in this open-label, randomized, controlled, multicenter, parallel-group, 12-week study.ResultsBaseline to endpoint changes in mean glycated hemoglobin (as A1c equivalents) (A1c) occurred in the premeal GLU, postmeal GLU, and premeal RHI groups (-0.26%, -0.11%, and -0.13%, respectively). The reduction in A1c was greater for the premeal GLU group in comparison with the RHI group (P = 0.02) and the post-meal GLU group (P = 0.006); no significant between-treatment difference was found for postmeal GLU versus RHI. Overall, blood glucose profiles were similar in all 3 treatment groups but were significantly lower for premeal GLU 2-hour postbreakfast measurements (premeal versus postmeal GLU, P = 0.0017; premeal GLU versus RHI, P = 0.0001) and 2-hour postdinner measurements (premeal GLU versus RHI, P = 0.0001; premeal versus postmeal GLU, P = 0.0137). Severe hypoglycemic episodes were comparable for premeal GLU, postmeal GLU, and pre-meal RHI groups (8.4%, 8.4%, and 10.1%, respectively). Body weight increased (+ 0.3 kg) in the RHI and premeal GLU groups; however, weight decreased in the postmeal GLU group (-0.3 kg; between-treatment difference, P = 0.03).ConclusionBetter A1c reductions were obtained with premeal GLU, but postmeal administration of GLU was as safe and effective as premeal GLU or RHI in combination with insulin glargine and was not associated with weight gain. (Endocr Pract. 2005;11:11-17)     

The Human Insulin Receptor Cdna: A New Tool to study the Function of this Receptor

Abstract

The human insulin receptor (hIR) is an integral transmembrane glycoprotein comprised of two α and two β subunits. An immediate consequence of insulin binding to the extracellular α subunit is the autophosphorylation of tyrosine residues on the intracellular domain of the β subunit. The placental hIR cDNA has been cloned and sequenced, providing the primary structural features of the protein.

In order to investigate the functions of the β subunit and particularly the role of autophosphorylation and tyrosine phosphokinase (TPK) activity (a feature shared by other receptors and oncogene proteins) in transmembrane signalling, we designed an expression system of the hIR cDNA in eucaryotic cells. Superexpressing CHO cell lines that contain about 10⁶ functional hIR/cell have been developed. In these cells half maximum stimulation of glucose uptake occurs at 5x 10^-10M insulin, whereas normal CHO cells require 5x 10^-12M insulin. In this expression system we have carried out site-directed mutagenesis experiments in which domains of the molecule have been deleted or particular amino acids have been replaced by others. The replacement of either or both the tyrosine residues 1162 and 1163 compromise an autophosphorylated site that is important for kinase function and the insulin response. Expression of an isolated membrane-bound form of the β-subunit produces a 6 fold increase in glucose uptake. This insulin-independent effect disappears if the twin tyrosines are mutated or if the β subunit is expressed in the cytoplasm. These studies also show that the C terminal 112 amino acid portion of the β subunit is important for the stability of this protein.     

Insulin Receptor Isoforms A and B as well as Insulin Receptor Substrates-1 and -2 Are Differentially Expressed in Prostate Cancer

Aims/Hypothesis

In different cancers types, insulin receptor isoform composition or insulin receptor substrate (IRS) isoforms are different to healthy tissue. This may be a molecular link to increased cancer risk in diabetes and obesity. Since this is yet unclear for prostate cancer, we investigated IR isoform composition and IRS balance in prostate cancer compared to benign and tumor adjacent benign prostate tissue and brought this into relation to cell proliferation.

Methods

We studied 23 benign prostate samples from radical cystectomy or benign prostatic hyperplasia surgery, 30 samples from benign tissue directly adjacent to prostate cancer foci and 35 cancer samples from different patients. RNA expression levels for insulin receptor isoforms A and B, IRS-1, IRS-2, and IGF-1 receptor were assessed by quantitative real-time RT-PCR. In addition, RNA- and protein expression of the cell cycle regulator p27^Kip1 was quantified by real-time RT-PCR and immunohistochemistry.

Results

Insulin receptor isoform A to B ratio was significantly higher in cancer as well as in tumor adjacent benign prostate tissue compared to purely benign prostates (p<0.05). IRS-1 to IRS-2 ratios were lower in malignant than in benign prostatic tissue (p<0.05). These altered ratios both in cancer and adjacent tissue were significantly associated with reduced p27^Kip1 content (p<0.02). Interestingly, IGF-1 receptor levels were significantly lower in patients with type 2 diabetes (p = 0.0019).

Conclusions/Interpretation

We found significant differences in the insulin signaling cascade between benign prostate tissue and prostate cancer. Histological benign tissue adjacent to cancer showed expression patterns similar to the malignancies. Our findings suggest a role of the insulin signaling pathway in prostate cancer and surrounding tissue and can hence be relevant for both novel diagnostic and therapeutic approaches in this malignancy.     

Breastfeeding and the Basal Insulin Requirement in Type 1 Diabetic Women

ObjectiveTo evaluate whether breastfeeding in women with type 1 diabetes mellitus is associated with a decreased insulin requirement.MethodsIn this prospective study conducted between September 2006 and August 2008, type 1 diabetic pregnant women were recruited before the third trimester of pregnancy. Eligible women had no evidence of diabetes-related complications and were treated with continuous subcutaneous insulin infusion pump therapy. During pregnancy and in the first 8 weeks of the postpartum period, participants performed daily fingerstick blood glucose monitoring with at least 12 measurements per day; insulin dosages were adjusted to maintain normoglycemia. Participant characteristics, diabetic parameters, and neonatal growth were compared between women who breastfed exclusively and women who did not breastfeed.ResultsOf 18 women, 12 breastfed and 6 did not. Compared with nonbreastfeeding mothers, breastfeeding mothers showed a decreased need for total daily basal insulin (0.21 ± 0.05 units/kg per day vs 0.33 ± 0.02 units/kg per day). The mean value of total daily basal insulin was significantly lower in the breastfeeding group than in the nonbreastfeeding group. The mean number of hyperglycemic episodes in the first 2 weeks post partum and during the third to eighth weeks was not different between the groups.However, the mean number of hypoglycemic episodes in the first 2 weeks post partum in the breastfeeding group was significantly higher than in the nonbreastfeeding group (11.9 ± 2.6 episodes vs 5.5 ± 1.6 episodes, P < .001). No differences were observed between the groups in neonatal birth weight or infant weight after 8 weeks of age.ConclusionsDecreased need in total daily basal insulin is caused by increased glucose use during lactation. We recommend that the starting total daily basal insulin dosage for type 1 diabetic women who breastfeed be calculated as 0.21 units times the weight in kg per day. This regimen results in normoglycemia and minimizes the risk of severe hypoglycemia associated with lactation. (Endocr Pract. 2009;15:187-193)     

Pancreatic Safety in Studies of The Glucagon-Like Peptide-1 Receptor Agonist Albiglutide

Objective: Albiglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), reduces glycated hemoglobin with a low risk of hypoglycemia in patients with type 2 diabetes. The relationship between GLP-1RAs and risk of pancreatitis is unresolved. This independent, rigorous, expert review of the albiglutide HARMONY Phase III clinical program examined suspected cases of acute pancreatitis.Methods: An independent pancreatitis adjudication committee (PAC), composed of physicians with expertise in gastroenterology and pancreatic disease, was prospectively established to review cases of suspected acute pancreatitis in the HARMONY studies.Results: Patients treated in Phase III trials with albiglutide (n = 2,365), or active or placebo comparators (n = 2,530), averaged 56 years of age with a mean 8.3-year diabetes duration. Across the 8 studies, the PAC reviewed potential cases of treatment-emergent acute pancreatitis in 43 patients. Definite or probable acute pancreatitis was adjudicated for 11 patients (8 albiglutide; 3 active comparators). Most of these were considered by the PAC to be at least possibly related to study treatment (6 of 8 albiglutide cases and 2 of 3 active comparator cases). Both cases in the active comparator group adjudicated as definite or probable pancreatitis with at least a possible relationship to study treatment were in patients treated with a GLP-1RA. The frequency of pancreatitis was higher among patients treated with albiglutide (6/2,365, 0.3%) than with placebo (0/486, 0%) or active comparators (2/2,062, 0.08%).Conclusion: In the HARMONY Phase III program, adjudicated cases of acute pancreatitis were uncommon. However, within the limitations of available data, the incidence of acute pancreatitis with albiglutide appears to be within the range described for other studies of GLP-1RAs.Abbreviations: AE = adverse event; CI = confidence interval; DPP-4 = dipeptidyl peptidase-4; GLP-1 = glucagon-like peptide-1; GLP-1RA = glucagon-like peptide-1 receptor agonist; MH-OR = Mantel-Haenszel odds ratio; OR = odds ratio; PAC = pancreatitis adjudication committee; SAE = serious adverse event; ULN = upper limit of normal     

A Proposed EPR Approach to Evaluating Agonist Binding Site of a Peptide Receptor

Angiotensin II (Ang II) and its transmembrane AT₁ receptor were selected in order to test an innovative strategy that might allow the assessment of the agonist binding site in the receptor molecule. With the use of the 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) paramagnetic probe, a biologically active agonist (TOAC¹-Ang II), as well as an inactive control (TOAC⁴-Ang II) analogs were mixed in solution with various synthesized AT₁ fragments. Comparative intermolecular interactions, as estimated by analyzing the EPR spectra of solutions, suggested the existence of an agonist binding site containing a sequence composed of portions of the N-terminal (13-17) and the third extracellular loop (266-278) fragments of the AT₁ molecule. Therefore, this combined EPR-TOAC approach shows promise as an alternative for use also in other applications related to specific intermolecular association processes. In memoriam of Professor Paiva.     

A Stepwise Approach to Insulin Therapy in Patients with Type 2 Diabetes Mellitus and Basal Insulin Treatment Failure

ObjectiveTo determine whether 1 or 2 preprandial injections before the meals of greatest glycemic impact can be as effective as 3 preprandial injections in patients with type 2 diabetes mellitus and basal insulin treatment failure.MethodsThis was an open-label, parallel-group, 1:1:1 randomized study of adults with type 2 diabetes mellitus on oral antidiabetic drugs with glycated hemoglobin (A1C) levels of 8.0% or greater. After a 14week run-in with insulin glargine, patients with an A1C level greater than 7.0% were randomly assigned to 1, 2, or 3 time(s) daily insulin glulisine for 24 weeks. Changes in A1C from randomization to study end; percentage of patients achieving an A1C level less than 7.0%; changes in A1C, fasting glucose concentrations, and weight at individual study points; and safety (adverse events and hypoglycemia) were assessed throughout the study.ResultsThree hundred forty-three of 631 patients (54%) completing the run-in phase with insulin glargine were randomly assigned to treatment arms. During the randomization phase, A1C reductions with insulin glulisine once or twice daily were noninferior to insulin glulisine 3 times daily (confidence intervals: -0.39 to 0.36 and -0.30 to 0.43; P > .5 for both). However, more patients met the target A1C with 3 preprandial injections (46 [46%]) than with 2 injections (34 [33%]) or 1 injection (30 [30%]). Severe hypoglycemia occurred in twice as many patients receiving 3 preprandial injections (16%) compared with those receiving 2 injections (8%) and 1 injection (7%), but these differences did not reach significance.ConclusionThis study provides evidence that initiation of prandial insulin in a simplified stepwise approach is an effective alternative to the current routine 3 preprandial injection basal-bolus approach. (Endocr Pract. 2011;17:395-403)     

The GIP Receptor Displays Higher Basal Activity than the GLP-1 Receptor but Does Not Recruit GRK2 or Arrestin3 Effectively

Background and Objectives

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are important regulators of insulin secretion, and their functional loss is an early characteristic of type 2 diabetes mellitus (T2DM). Pharmacological levels of GLP-1, but not GIP, can overcome this loss. GLP-1 and GIP exert their insulinotropic effects through their respective receptors expressed on pancreatic β-cells. Both the GLP-1 receptor (GLP-1R) and the GIP receptor (GIPR) are members of the secretin family of G protein-coupled receptors (GPCRs) and couple positively to adenylate cyclase. We compared the signalling properties of these two receptors to gain further insight into why GLP-1, but not GIP, remains insulinotropic in T2DM patients.

Methods

GLP-1R and GIPR were transiently expressed in HEK-293 cells, and basal and ligand-induced cAMP production were investigated using a cAMP-responsive luciferase reporter gene assay. Arrestin3 (Arr3) recruitment to the two receptors was investigated using enzyme fragment complementation, confocal microscopy and fluorescence resonance energy transfer (FRET).

Results

GIPR displayed significantly higher (P<0.05) ligand-independent activity than GLP-1R. Arr3 displayed a robust translocation to agonist-stimulated GLP-1R but not to GIPR. These observations were confirmed in FRET experiments, in which GLP-1 stimulated the recruitment of both GPCR kinase 2 (GRK2) and Arr3 to GLP-1R. These interactions were not reversed upon agonist washout. In contrast, GIP did not stimulate recruitment of either GRK2 or Arr3 to its receptor. Interestingly, arrestin remained at the plasma membrane even after prolonged (30 min) stimulation with GLP-1. Although the GLP-1R/arrestin interaction could not be reversed by agonist washout, GLP-1R and arrestin did not co-internalise, suggesting that GLP-1R is a class A receptor with regard to arrestin binding.

Conclusions

GIPR displays higher basal activity than GLP-1R but does not effectively recruit GRK2 or Arr3.     

Antidepressant-Like Activity of YL-0919: A Novel Combined Selective Serotonin Reuptake Inhibitor and 5-HT1A Receptor Agonist

It has been suggested that drugs combining activities of selective serotonin reuptake inhibitor and 5-HT_1A receptor agonist may form a novel strategy for higher therapeutic efficacy of antidepressant. The present study aimed to examine the pharmacology of YL-0919, a novel synthetic compound with combined high affinity and selectivity for serotonin transporter and 5-HT_1A receptors. We performed in vitro binding and function assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of YL-0919. YL-0919 displayed high affinity in vitro to both 5-HT_1A receptor and 5-HT transporter prepared from rat cortical tissue. It exerted an inhibitory effect on forskolin-stimulated cAMP formation and potently inhibited 5-HT uptake in both rat cortical synaptosomes and recombinant cells. After acute p.o. administration, very low doses of YL-0919 reduced the immobility time in tail suspension test and forced swimming test in mice and rats, with no significant effect on locomotor activity in open field test. Furthermore, WAY-100635 (a selective 5-HT_1A receptor antagonist, 0.3 mg/kg) significantly blocked the effect of YL-0919 in tail suspension test and forced swimming test. In addition, chronic YL-0919 treatment significantly reversed the depressive-like behaviors in chronically stressed rats. These findings suggest that YL-0919, a novel structure compound, exerts dual effect on the serotonergic system, as both 5-HT_1A receptor agonist and 5-HT uptake blocker, showing remarkable antidepressant effects in animal models. Therefore, YL-0919 may be used as a new option for the treatment of major depressive disorder.     

胰岛素受体底物1的PH结构域与PKC的结合

从大鼠的肝脏克隆胰岛素受体底物１（ＩＲＳ－１）的ＰＨ结构域基因并进行谷胱甘肽Ｓ－转移酶（ＧＳＴ）融合表达,研究该结构域与蛋白激酶Ｃ（ＰＫＣ）的结合情况,并为进一步寻找其新配基打下基础,研究采用一步法从大鼠新鲜肝组织中提取总ＲＮＡ,以ＲＴ－ＰＣＲ的方法扩增目的基因片段,测序证明序列正确,再将正确的目的基因片段定向克隆到表达载体ｐＧＥＸ－４Ｔ－１中,以ＩＰＴＧ在２６℃下诱导,获得与ＧＳＴ的融合表达,表     

Basal Insulin Degludec and Glycemic Control Compared to Aspart Via Insulin Pump in Type 1 Diabetes (BIGLEAP): A Single-Center,Open-Label,Randomized, Crossover Trial

ObjectiveWe compared the efficacy of the second-generation basal insulin degludec (IDeg) to that of insulin aspart via pump using continuous glucose monitoring in patients with well-controlled type 1 diabetes.MethodsIn this 40-week, single-center, randomized, crossover-controlled trial, adults with well-controlled type 1 diabetes (hemoglobin A1C of <7.5% [<58 mmol/mol]) (N = 52) who were using an insulin pump and continuous glucose monitoring were randomized to 1 of 2 treatments for a 20-week period: a single daily injection of IDeg with bolus aspart via pump or a continuous subcutaneous insulin infusion (CSII) with aspart, followed by crossover to the other treatment. The primary endpoint was time in range (70-180 mg/dL) during the final 2 weeks of each treatment period.ResultsFifty-two patients were randomized and completed both treatment periods. The time in range for IDeg and CSII was 71.5% and 70.9%, respectively (P = .553). The time in level 1 hypoglycemia for the 24-hour period with IDeg and CSII was 2.19% and 1.75%, respectively (P = .065). The time in level 2 hypoglycemia for the 24-hour period with IDeg and CSII was 0.355% and 0.271%, respectively (P = .212), and the nocturnal period was 0.330% and 0.381%, respectively (P = .639). The mean standard deviation of blood glucose levels for the 24-hour period for IDeg and CSII was 52.4 mg/dL and 51.0 mg/dL, respectively (P = .294). The final hemoglobin A1C level for each treatment was 7.04% (53 mmol/mol) with IDeg, and 6.95% (52 mmol/mol) with CSII (P = .288). Adverse events were similar between treatments.ConclusionWe observed similar glycemic control between IDeg and insulin aspart via CSII for basal insulin coverage in patients with well-controlled type 1 diabetes.     

A Hallucinogenic Serotonin-2A Receptor Agonist Reduces Visual Response Gain and Alters Temporal Dynamics in Mouse V1

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