Elsevier

Regulatory Peptides

Volume 179, Issues 1–3, 10 November 2012, Pages 33-38
Regulatory Peptides

[d-Leu-4]-OB3, a synthetic peptide amide with leptin-like activity, augments the effects of orally delivered exenatide and pramlintide acetate on energy balance and glycemic control in insulin-resistant male C57BLK/6-m db/db mice

https://doi.org/10.1016/j.regpep.2012.08.006Get rights and content

Abstract

The escalation predicted for the incidence of both type 2 diabetes mellitus and obesity has prompted investigators to search for additional pharmacotherapeutic approaches to their treatment. Two of these approaches, combination pharmacotherapy and utilization of leptin-related bioactive synthetic peptides as anti-diabetes/anti-obesity agents, were used in the present study. Exenatide or pramlintide acetate was reconstituted in dodecyl maltoside (DDM) in the absence or presence of [d-Leu-4]-OB3, and delivered orally by gavage to insulin-resistant male C57BLK/6-m db/db mice twice daily for 14 days. Body weight gain, food and water intake, blood glucose, and serum insulin levels were measured. Mice given DDM alone for 14 days were 19.7% heavier than they were at the beginning of the study, while oral delivery of exenatide or [d-Leu-4]-OB3 in DDM reduced body weight gain to only 13.9% and 11.5%, respectively, of initial body weight. Mice receiving exenatide and [d-Leu-4]-OB3 were 4.2% lighter than they were at the beginning of the study. In another study, Intravail® treated control mice gained 38.2% of their initial body weight, while mice receiving pramlintide acetate or [d-Leu-4]-OB3 were only 26.8% and 25.4% heavier, respectively, at the end of the study, Co-administration of pramlintide acetate and [d-Leu-4]-OB3 did not further enhance the effect of pramlintide acetate on body weight gain. Food intake was reduced by exenatide, pramlintide acetate, and [d-Leu-4]-OB3 alone, and co-delivery with [d-Leu-4]-OB3 did not induce a further decrease. Water intake was not affected by exenatide, pramlintide acetate, or [d-Leu-4]-OB3 alone, but co-delivery of exenatide or pramlintide acetate with [d-Leu-4]-OB3 resulted in a significant reduction in water intake. Oral delivery of exenatide or pramlintide acetate in DDM significantly lowered blood glucose levels by 20.4% and 30.2%, respectively. Co-delivery with [d-Leu-4]-OB3 further reduced blood glucose by 38.3% and 50.5%, respectively. A concentration-dependent increase in serum insulin was observed in response to increasing concentrations of exenatide, and [d-Leu-4]-OB3 slightly reduced the insulin response to exenatide at all concentrations tested. Increasing concentrations of pramlintide acetate alone did not elevate serum insulin, and when given in combination with [d-Leu-4]-OB3, serum insulin levels fell below those of DDM-treated control mice. Our data indicate that (1) exenatide and pramlintide acetate, currently administered by subcutaneous injection, can be given orally in DDM; (2) the bioactivity of exenatide and pramlintide acetate is retained following oral delivery in DDM; and (3) the effects of exenatide and pramlintide acetate on energy balance and glycemic control can be enhanced by co-administration with [d-Leu-4]-OB3, a synthetic peptide amide with leptin-like activity.

Highlights

► Oral delivery of exenatide and pramlintide acetate in Intravail® is feasible. ► Oral exenatide and pramlintide in Intravail® is biologically active. ► [d-Leu-4]-OB3 enhances the effects of exenatide and pramlintide acetate.

Introduction

The World Health Organization has estimated that the number of children and adults with diabetes mellitus type 2 will rise to 366 million by 2030, and in 2035, approximately 300 million persons will be obese [1], [2]. The link between obesity and type 2 diabetes is strong; obesity has been found to contribute to approximately 55% of all cases of type 2 diabetes [3]. Additional factors which contribute to increasing the risk of type 2 diabetes include age-related impairment of pancreatic beta cells [4], high-fat diet [5] low levels of physical activity [6], and environmental toxins [7]. This combination of lifestyle and genetic factors, as well as an association of type 2 diabetes mellitus with a number of medical conditions such as hypertension [8], hyperlipidemia [9], and cancer [10], [11] has made the clinical management of type 2 diabetes a changing and challenging task.

Not unexpectedly, therapies for the management of diabetes and obesity that have been based on behavioral and nutritional modification have had only partial and temporary benefits. At the same time, a large number of existing pharmacotherapeutics have shown only limited efficacy, generated serious health risks, or have been withdrawn from clinical use [12], [13], [14], [15]. These events have catalyzed an intensified search for new approaches for the management of diabetes and obesity. One such approach is combination therapy utilizing existing FDA-approved drugs, currently used as the standard of care to treat diabetes mellitus in the clinic, with new anti-obesity/anti-diabetes drug candidates [16]. We have incorporated this strategy into the present study. In the following report, we describe the effects of oral delivery of two commonly used anti-diabetes medications normally given by injection, exenatide and pramlintide acetate, either alone or in combination with [d-Leu-4]-OB3 [17], an orally bioavailable anti-diabetes/anti-obesity peptide drug candidate, on energy balance and glycemic control in genetically obese C57BLK/6-m male db/db mice.

Section snippets

Housing

Six-week-old (+/− 3 days) male C57BLK/6-m db/db mice were obtained from Jackson Laboratories (Bar Harbor, ME, USA). The animals were housed three per cage in polycarbonate cages fitted with stainless steel wire lids and air filters, and supported on ventilated racks (Thoren Caging Systems, Hazelton, PA, USA) in the Albany Medical College Animal Resources Facility. The mice were maintained at a constant temperature (24 °C) with lights on from 07:00 to 19:00 h, and allowed food and water ad libitum.

Effects on body weight gain

The effects of oral delivery (by gavage) of exenatide in DDM, either alone or in combination with [d-Leu-4]-OB3, on body weight gain in male db/db mice are described in Fig. 1A and Table 1. Mice given DDM alone for 14 days were 19.7% heavier than they were at the beginning of the study, while mice receiving exenatide alone were only 13.9% heavier. Mice given [d-Leu-4]-OB3 gained only 11.5% of their initial body weight. When exenatide and [d-Leu-4]-OB3 were given together, the mice lost 4.2% of

Discussion

The therapeutic potential of naturally occurring peptide and protein drugs in the treatment of human disease has long been recognized. These drugs frequently offer high potency and selectivity, and are generally free of chemical toxicity [23]. Because they are metabolized to naturally occurring amino acids in the gastrointestinal tract, as are the proteins ingested as food, peptide and protein drugs do not evoke xenobiotic metabolic responses, a major source of small molecule drug toxicity [24].

Acknowledgments

The authors thank Zachary Novakovic and Xiaolan Ding for their expert technical assistance, and Aegis Therapeutics for providing the Intravail® reagent. This research was supported by a grant from the Willard B. Warring Memorial Fund.

References (44)

  • Centers for Disease Control, Prevention (CDC)

    Prevalence of overweight and obesity among adults with diagnosed diabetes – United States, 1988–1994 and 1999–2002, MMWR

    Morb Mortal Wkly Rep

    (November 2004)
  • L. Jack et al.

    Aging Americans and diabetes

    Geriatrics

    (2004)
  • J.C. Lovejoy

    The influence of dietary fats on insulin resistance

    Curr Diab Rep

    (2002)
  • F.B. Hu

    Sedentary lifestyle and risk of obesity and type 2 diabetes

    Lipids

    (2002)
  • I.A. Lang et al.

    Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults

    JAMA

    (2008)
  • V. Lyssenko et al.

    Clinical risk factors, DNA variants, and the development of type 2 diabetes

    N Engl J Med

    (2008)
  • J.C. Lovejoy

    The influence of dietary fat on insulin resistance

    Curr Diab Rep

    (2002)
  • J.A. Johnson et al.

    Diabetes and cancer (1): evaluating the temporal relationship between type 2 diabetes and cancer incidence

    Diabetologia

    (2012)
  • A.G. Renehen et al.

    Diabetes and cancer (2): evaluating the impact of diabetes on mortality in patients with cancer

    Diabetologia

    (2012)
  • A.M. Lincoff et al.

    Pioglitazone and risk of cardiovascular events in patients with type 1 diabetes mellitus

    JAMA

    (2007)
  • D.J. Graham et al.

    Risk of acute myocardial infarction, stroke, heart failure, and death in elderly medicare patients treated with rosiglitazone or pioglitazone

    JAMA

    (2010)
  • M. Fujita et al.

    Cytotoxicity of troglitazone through PPARγ-independent pathway and p38 MAPK pathway in renal cell carcinoma

    Cancer Lett

    (2011)
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