The Effect of Glucagon on Rates of Hepatic Mitochondrial Oxidation in Man Assessed by PINTA

• ClinicalTrials.gov Identifier: NCT03965130
• Recruitment Status: Active, not recruiting
• First Posted: May 28, 2019
• Last Update Posted: July 20, 2020
• Sponsor: Yale University
• Collaborators: Merck Sharp & Dohme Corp.; National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Information provided by (Responsible Party): Yale University

Study Description

Brief Summary:

It is well established that alterations in the portal vein insulin:glucagon ratio play a major role in the dysregulated hepatic glucose metabolism in type 2 diabetes but the molecular mechanism by which glucagon promotes alterations in hepatic glucose production and mitochondrial oxidation remain poorly understood. This is borne out of the fact that both glucagon agonists and antagonists are being developed to treat type 2 diabetes with unclear mechanisms of action.

This study will directly assess the effects of glucagon on rates of mitochondrial oxidation and pyruvate carboxylase flux for the first time in humans using PINTA analysis. The results will have important implications for the possibility of intervening in the pathogenesis of non alcoholic fatty liver and type 2 diabetes via chronic dual GLP-1/glucagon receptor antagonism and provide an important rationale for why a dual agonist may be more efficacious for treatment of non alcoholic fatty liver and T2D than GLP-1 alone.

Condition or disease	Intervention/treatment	Phase
Healthy Participants	Drug: Glucagon	Early Phase 1

Detailed Description:

Objectives:

To examine the effects of glucagon on hepatic glucose and fat metabolism in vivo, this study will apply a novel Positional Isotopomer NMR Tracer Analysis (PINTA) method to quantify rates of hepatic mitochondrial oxidation and pyruvate carboxylase flux, which has been cross-validated in awake rodents and humans (Perry et al. Nature Communications 2017). Preliminary rodent studies have found that glucagon stimulates intrahepatic lipolysis through an InsP3R-I-dependent process, leading to increases in hepatic acetyl-CoA content, which allosterically activates pyruvate carboxylase activity and flux, and that this phenomenon explains its acute, transcription-independent effect to acutely stimulate hepatic gluconeogenesis in vivo (unpublished results). In addition, using PINTA analysis it has been shown that glucagon stimulates hepatic mitochondrial oxidation through calcium signaling in awake mice, and that this process can be exploited by short-term continuous glucagon treatment leading to two-fold increases in hepatic mitochondrial fat oxidation, which in turn results in large reductions in hepatic steatosis and marked improvements in glucose tolerance through reversal of hepatic insulin resistance in a high fat fed rat model of non alcoholic fatty liver.

Hypothesis:

1. A physiological increase in plasma glucagon concentrations will promote a significant increase in rates of hepatic mitochondrial oxidation in healthy humans.
2. A physiological increase in plasma glucagon concentrations will promote a significant increase in rates of hepatic pyruvate carboxylase flux in healthy humans.
3. A physiological increase in plasma glucagon concentrations will promote a significant increase in rates of 13C4 β-hydroxybutyrate turnover (hepatic ketogenesis) in healthy humans.

Study Design - Clinical Plan:

The effects of a physiological increase in plasma glucagon on rates of hepatic mitochondrial oxidation and pyruvate carboxylase flux will be examined in 12 healthy participants (ages 21-65) using Positional Isotopomer NMR Tracer Analysis (PINTA) (Perry et al. Nature Communication 2017). Briefly rates of hepatic mitochondrial oxidation and hepatic pyruvate carboxylase flux will be assessed in 12 healthy overnight fasted participants by PINTA after a three-hour infusion of glucagon or saline. The glucagon infusion will be designed to increase peripheral and portal vein plasma glucagon concentrations 3-4 fold. The effects of a physiological increase in plasma glucagon on rates of hepatic ketogenesis will also be assessed using an infusion of 13C4 β-betahydroxybutyrate (Perry et al. Cell Metabolism 2017).

Rates of hepatic pyruvate carboxylase flux /citrate synthase flux by PINTA: Participants (n=12) will be studied by PINTA under 2 conditions: 1) following an overnight fast and a 3 hour saline infusion (Control), 2) following an overnight fast and a 3 hour glucagon infusion. Briefly, after collection of baseline blood samples a 3 hour infusion of tracers as described below will be started. Relative rates of pyruvate carboxylase to citrate synthesis flux will be assessed using a constant infusion of [3-13C] lactate and rates of glucose production will be measured using an infusion of [2H7]glucose (Perry et al. Nature Communication 2017). Rates of hepatic ketogenesis will be measured using a constant infusion of [3C β-hydroxybutyrate as previously described (Perry et al. Cell Metabolism 2017).

Whole body energy expenditure and the respiratory quotient will be assessed by indirect calorimetry.

Study Design

• Study Type: Interventional (Clinical Trial)
• Actual Enrollment: 15 participants
• Allocation: N/A
• Intervention Model: Single Group Assignment
• Intervention Model Description: Each participant will participate in two studies: one without and one with a 3 hour infusion of glucagon during the PINTA study
• Masking: None (Open Label)
• Primary Purpose: Basic Science
• Official Title: The Effect of Glucagon on Rates of Hepatic Mitochondrial Oxidation and Pyruvate Carboxylase Flux in Man Assessed by Positional Isotopomer NMR Tracer Analysis (PINTA)
• Actual Study Start Date: May 22, 2019
• Estimated Primary Completion Date: December 6, 2023
• Estimated Study Completion Date: December 6, 2025

Arms and Interventions

Arm	Intervention/treatment
Experimental: Glucagon; Participants will receive glucagon or saline during the PINTA study	Drug: Glucagon; PINTA study with or without glucagon; Other Name: hormone study

Outcome Measures

Primary Outcome Measures :

1. Rates of Hepatic Glucose production [ Time Frame: 5 Hours ]
   Rates of fasting glucose production will be measured using D7 glucose
2. Rates of Hepatic Mitochondrial Oxidation [ Time Frame: 5 hours ]
   Rates of pyruvate carboxylase flux and citrate synthesis flux will be assessed using GC/MS and NMR analyses of plasma glucose 13C enrichments after the [3-13C]lactate infusion
3. Rates of Hepatic Ketogenesis [ Time Frame: 5 hours ]
   Assessment of hepatic acetyl CoA content will be estimated from rates of hepatic ketogenesis following the 13C beta-hydroxybutyrate infusion

Eligibility Criteria

• Ages Eligible for Study: 21 Years to 65 Years (Adult, Older Adult)
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Criteria

Inclusion Criteria:

• Healthy
• Normal body weight (BMI<28 Kg/m2)
• Non smoking
• Taking no medications except birth control

Exclusion Criteria:

• Any systemic or organ disease
• Smoking
• Taking any drug or medications other than birth control (women)

Contacts and Locations

Locations

United States, Connecticut

Yale Hospital reserach Unit / YCCI

New Haven, Connecticut, United States, 06520

Sponsors and Collaborators

Yale University

Merck Sharp & Dohme Corp.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

• Principal Investigator: Kitt F Petersen, MD; Professor

More Information

• Responsible Party: Yale University
• ClinicalTrials.gov Identifier: NCT03965130
• Other Study ID Numbers: 0209020997; 1R01DK113984-01 ( U.S. NIH Grant/Contract ); 1R01DK124272-01 ( U.S. NIH Grant/Contract )
• First Posted: May 28, 2019
• Last Update Posted: July 20, 2020
• Last Verified: July 2020

Individual Participant Data (IPD) Sharing Statement:

• Plan to Share IPD: No
• Plan Description: Final data to be shared with study sponsor

• Studies a U.S. FDA-regulated Drug Product: Yes
• Studies a U.S. FDA-regulated Device Product: No

Keywords provided by Yale University:

Hepatic Glucose Metabolism; Hepatic Mitochondrial Oxidation; PINTA; Glucagon

Additional relevant MeSH terms:

Pinta; Treponemal Infections; Gram-Negative Bacterial Infections; Bacterial Infections; Skin Diseases, Bacterial; Spirochaetales Infections; Skin Diseases, Infectious; Infection; Skin Diseases; Glucagon; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Physiological Effects of Drugs; Gastrointestinal Agents