Insulin in combination with pioglitazone prevents advanced cachexia in 256-Walker tumor-bearing rats: effect is greater than treatment alone and is associated with improved insulin sensitivity

BACKGROUND

Insulin (INS) resistance and hypoinsulinemia commonly observed in cancer-carrying, can contribute to cachexia. However, the effects of INS and INS sensitizers, such as pioglitazone (PIO), particularly when used in combination therapy, on cancer cachexia have not been evaluated sufficiently. We investigated the effects of INS and PIO, at various doses, either isolated or combined, on cachexia in Walker-256 tumor-bearing rats (TB rats).

METHODS

INS or INS + PIO were administered in TB rats, for 6 or 12 days, starting from the day of tumor cells inoculation.

RESULTS

INS at 18 or 27 U/kg (12-days treatment), but not 9 U/kg, reduced fat loss and slightly prevented weight loss. However, INS 18 U/kg + PIO 5, 10, 20, or 40 mg/kg (6 or 12-day treatment) reduced fat loss and markedly prevented weight loss but did not affect muscle wasting. While TB rats lost weight (37.9% in 12 days), TB rats treated with INS 18 U/kg + PIO 5 mg/kg showed pronounced weight gain (73.7%), which was greater than the sum (synergism) of the weight gains promoted by isolated treatments with INS 18 U/kg (14.7%) or PIO 5 mg/kg (13.1%). The beneficial effect of the INS 18 U/kg + PIO 5 mg/kg on weight loss was associated with improved INS sensitivity, as indicated by the higher blood glucose clearance constant (kITT), decreased levels of free fatty acids and triacylglycerols (INS resistance-inducing factors) in the blood, and increased expression of p-Akt (INS signaling pathway protein) in adipose tissue.

CONCLUSIONS

The combined treatment with INS 18 U/kg + PIO 5 mg/kg was more effective in preventing advanced cachexia in TB rats than each treatment alone, emerging as the best approach, considering the lower dosage and higher efficacy. This combination completely preserved adipose mass and markedly reduced weight loss through a synergistic mechanism linked to improved insulin sensitivity. These findings provide new insights into the importance of drug combinations in effectively combating fat loss in advanced cachexia.

Long-Term Follow-up of β-Transfusion-Dependent Thalassemia (TDT) Normoglycemic Patients with Reduced Insulin Secretion to Oral Glucose Tolerance Test (OGTT): A Pilot Study

Objective

To study the endocrine pancreas’ function in transfusion-dependent β-thalassemia (β-TDT) patients with a normal glucose tolerance test (NGT) and hypoinsulinemia. In addition, the prospective long–term follow-up using an annual oral glucose tolerance test (OGTT) to detect any abnormality of glucose metabolism.

Patients and methods

Seven β-TDT patients (mean age 22.4 ± 4.2 years) with NGT and inadequate insulin response (hypoinsulinemia) to OGTT were referred for a second opinion to an Italian Centre.

Results

The first-phase insulin response (FPIR), expressed as the sum of 1 and 3 minutes insulin, to intravenous glucose tolerance test (IVGTT), was between the 1^st and 3^rd percentile in two patients and between the 3^rd and 10^th percentile in five. The results were not associated with β-cell autoimmunity. After 43 ± 26 months (range 11 – 80 months) of follow-up, two patients developed impaired glucose tolerance (IGT), three both IGT and impaired fasting glucose (IFG) and two overt diabetes mellitus (DM). Interestingly, the patients who developed DM had, at baseline, the lowest value of the insulinogenic index (IGI: 0.08 and 0.25), defined as the ratio of the increment of plasma insulin to plasma glucose during the first 30 minutes after OGTT. Moreover, a significant correlation was found between the IGI at baseline and at follow-up in the patients who developed IGT with or without IFG (R= 0.927; P: 0.023). A significant reduction of Matsuda insulin sensitivity index (ISIM) and Insulin Secretion-Sensitivity Index-2 (ISSI-2) was documented in the study cohort at the diagnosis of IFG, IGT, and DM. There was a significant inverse correlation between ISSI-2 and area under the curve plasma glucose (AUC-PG).

Conclusions

These data demonstrated, for the first time, progressive deterioration in glucose homeostasis in β-TDT subjects with NGT and hypoinsulinemia and that the ISSI-2 index may be a valuable parameter to identify patients at high risk for developing glucose dysregulation.

An elderly diabetic patient with McArdle disease and recurrent rhabdomyolysis: a potential association with late hypoinsulinemia?

BACKGROUND

McArdle disease is a myopathy caused by mutations in PYGM gene that is characterized by reduced or absent activity of myophosphorylase. Reports of patients with concomitant McArdle disease and diabetes are scarce. We report a case of a patient with a late diagnosis of McArdle disease and we postulate that symptoms may be related to hypoinsulinemia.

CASE PRESENTATION

This report describes the evolution of an elderly diabetic patient with confirmed diagnosis of McArdle's disease based on the absence of myophosphorylase activity in the analysis of muscle biopsy, and a homozygous mutation in the PYGM gene. The variant - Chr11: 64.525 (p. Asn168*fs) has not been previously described. The diagnosis of McArdle disease was confirmed after two episodes of rhabdomyolysis, at 77 and 81 years of age, as the symptoms were, until then, discrete. The "second-wind phenomenon" was not spontaneously reported, but it was confirmed when directly questioned. We postulate that the later episodes of rhabdomyolysis occurred because of a progressive decrease in insulin production with a consequent reduction in the uptake of blood glucose by muscle cells, thus compromising the cellular energy balance. To our knowledge, this is the first report of recurrent rhabdomyolysis in an elderly diabetic patient with genetically proven McArdle disease. Our initial attempt to reduce insulin resistance with metformin and pioglitazone was not effective, possibly because of inadequate insulinemia. However, an improvement was evident after the administration of low doses of intermediate-acting insulin.

CONCLUSIONS

In view of the patient's clinical evolution, we suggest the use of medication that reduces insulin resistance for patients with McArdle disease and type 2 diabetes, pre-diabetes or even normoglycemic metabolic syndrome.

Insulin: A Growth Hormone and Potential Oncogene

Both in vitro and in vivo experimental studies proved that insulin has an important anabolic role. This physiological function of insulin is reflected in its well documented involvement in protein metabolism and in acceleration of cell proliferation. Support for a growth promoting action of insulin is further provided by clinical studies that revealed that children with hypoinsulinemia have a decreased growth rate whereas, on the other hand, children with hyperinsulinemia have an accelerated growth. While it was initially assumed that the growth activities of insulin are facilitated via cross-talk with the closely related insulin-like growth factor-1 receptor (IGF-1R), it is now clear that the vast majority of these activities are mediated via direct interaction with the insulin receptor (IR). The present article provides an overview of the growth and proliferative actions of insulin, with an emphasis on a number of pathological conditions, including cancer.

Association between duration of obesity and severity of ovarian dysfunction in rat-cafeteria diet approach

Consumption of unhealthy, energy-dense palatable food during early age leads to obesity in children and the onset of obesity during childhood has a profound effect on the reproductive health of women. In this study, the mechanism underlying diet-induced obesity on ovarian dysfunction was studied by exposing rats to cafeteria diet (CAFD) for two different durations. For that purpose, 21-day-old female Sprague Dawley rats were fed ad libitum with a standard diet (control group) and a cafeteria diet (CAFD group) for a period of 20 weeks (20 W) and 32 weeks (32 W). We observed obesity, hyperglycemia, hyperlipidemia, hyperleptinemia and hypoadiponectinemia in CAFD fed groups. Hyperinsulinemia, hypergonadotrophism, hypertestosteronemia and hyperprogesteronemia were observed in the 20 W-CAFD group. Conversely, in the 32 W-CAFD group hypersecretion declined to hyposecretion. The levels of estradiol remained low during both time periods. The duration of estrous cycle was extended in the CAFD fed rats. The ovary weight was higher in the 20 W-CAFD fed rats but it was drastically reduced over a longer duration cafeteria diet feeding. In the 20 W-CAFD fed rats, the protein levels of LHR, StAR, CYP11A1, 3β-HSD and 17β-HSD were increased but FSHR and CYP19A1 levels were decreased in the ovary. On the other hand, gonadotropin receptor and the protein levels of steroidogenic enzymes were decreased in the ovary of 32 W-CAFD fed rats. We conclude that the duration of energy-dense diet consumption has differential regulatory mechanism in altering the ovarian steroid production. In 20 W-CAFD fed rats, hypergonadotropic condition was observed whereas, 32 W-CAFD consumption induced hypogonadotropic hypogonadism.

Novel murine model of congenital diabetes: The insulin hyposecretion mouse

AIMS/INTRODUCTION

Diabetic animal models have made an enormous contribution to our understanding of the etiology of diabetes and the development of new medications. The aim of the present study was to develop and characterize a novel, non-obese murine strain with spontaneous diabetes - the insulin hyposecretion (ihs) mouse.

MATERIALS AND METHODS

During the development of the ICGN.B6-Tns2WT strain as the control for the ICGN-Tns2nph congenital nephrotic strain, diabetic mice were discovered and named ihs mice. Intraperitoneal insulin tolerance test, oral glucose tolerance test and an insulin secretion experiment by the pancreas perfusion system were carried out on ihs mice. The pancreatic islets were examined histologically, and the mRNA expression of pancreatic β-cell-specific genes or genes associated with monogenic diabetes was examined by RT-qPCR.

RESULTS

The ihs mice showed several distinctive diabetes-related characteristics: (i) the onset of diabetes was observed only in the male mice; (ii) there were no differences in insulin content between the ihs and control mice; (iii) impaired insulin secretion was elicited by glucose, potassium chloride and sulfonylureas; (iv) there was a significant reduction of relative β-cell volume with no signs of inflammation or fibrosis; (v) they showed a normal glycemic response to exogenous insulin; and (vi) the mice were not obese.

CONCLUSIONS

The ihs mouse provides a novel murine model of congenital diabetes that shows insulin secretion failure. This model allows not only an analysis of the progression of diabetes, but also the identification of unknown genes involved in insulin secretion.

Co-ingestion of carbohydrate with leucine-enriched essential amino acids does not augment acute postexercise muscle protein synthesis in a strenuous exercise-induced hypoinsulinemic state

Strenuous exercise following overnight fasting increases fat oxidation during exercise, which can modulate training adaptation. However, such exercise induces muscle protein catabolism by decreasing blood insulin concentrations and increasing amino acid oxidation during the exercise. Leucine-enriched essential amino acids (LEAAs) enhance muscle protein synthesis (MPS) at rest and after exercise. However, it remains to be clarified if the co-ingestion of carbohydrate with LEAAs induces an additional increase in MPS, particularly in a hypoinsulinemic state induced by strenuous exercise. Eight-week-old male Sprague–Dawley rats were made to perform strenuous jump exercise (height 35 cm, 200 jumps, 3-s intervals), after which they ingested distilled water and 1 g/kg LEAAs with or without 1 g/kg of glucose. The fractional synthesis rate was determined by measuring the incorporation of l-[ring-²H₅]-phenylalanine into skeletal muscle protein. Immediately after the exercise, plasma insulin concentration was significantly lower than that at the basal level. Co-ingestion of glucose with LEAAs alleviated the reduction in plasma insulin concentration, while LEAA ingestion alone did not. LEAA administration with or without glucose led to a higher MPS compared with water administration (P < 0.05). However, the co-ingestion of glucose with LEAAs did not induce further increases in MPS compared with LEAA ingestion alone. Thus, the co-ingestion of glucose with LEAAs does not additionally increase MPS under a strenuous exercise–induced hypoinsulinemic state when glucose is co-ingested with a dose of LEAAs that maximally stimulates MPS.

Disruption of the Golgi protein Otg1 gene causes defective hormone secretion and aberrant glucose homeostasis in mice

Background

Concerted hormone secretion is essential for glucose homeostasis and growth. The oocyte testis gene 1 (Otg1) has limited information in mammals before. Human OTG1 has been identified as an antigen associated with cutaneous T cell lymphoma, while worm Otg1 is recently reported to be a vesicle trafficking regulator in neurons. To understand the physiological role of Otg1 and its potential relation to hormone secretion, we characterized a mutation caused by the piggyBac transposon (PB) insertion in mice.

Results

Oocyte testis gene 1 encodes a Golgi localized protein that is expressed with a broad tissue distribution in mice. The PB insertion effectively blocks Otg1 expression, which results in postnatal lethality, growth retardation, hypoglycemia and improved insulin sensitivity in mice. Otg1 mutants exhibit decreased levels of insulin, leptin and growth hormone in the circulation and reduced hepatic IGF-1 expression. Decreased expression of Otg1 in pituitary GH3 cells causes reduced grow hormone expression and secretion, as well as the traffic of the VSVG protein marker.

Conclusions

Our data support the hypothesis that Otg1 impacts hormone secretion by regulating vesicle trafficking. These results revealed a previously unknown and important role of Otg1 in hormone secretion and glucose homeostasis in mammals.

Electronic supplementary material

The online version of this article (doi:10.1186/s13578-016-0108-4) contains supplementary material, which is available to authorized users.