Vinodraj K
Nagendra Nayak I M
Rao J V
Mathai P
Chandralekha N
Nitasha B
Rajesh D
Chethan T K
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Comparison of the efficacy of liraglutide with pioglitazone on dexamethasone induced hepatic steatosis, dyslipidemia and hyperglycaemia in albino rats
K Vinodraj1, IM Nagendra Nayak1, J Vikram Rao1, Paul Mathai1, N Chandralekha1, B Nitasha1, D Rajesh1, TK Chethan2
1 Department of Pharmacology, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka, India
2 Department of Community Medicine, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka, India
Date of Submission 16-Oct-2014
Date of Acceptance 07-Feb-2015
K Vinodraj
Department of Pharmacology, K. S. Hegde Medical Academy, Deralakatte, Mangalore, Karnataka
Objectives: To evaluate the efficacy of liraglutide with pioglitazone for prevention of dexamethasone induced hepatic steatosis, dyslipidemia and hyperglycemia in Albino rats.
Materials and Methods: There were four groups of six rats each. First group received dexamethasone alone in a dose of 8 mg/kg intraperitoneally for 6 days to induce metabolic changes and considered as dexamethasone control. Second group received liraglutide 1.8 mg/kg subcutaneously 6 days before dexamethasone and 6 days during dexamethasone administration. Third group received pioglitazone 45 mg/kg orally 6 days before dexamethasone and 6 days during dexamethasone administration. Fourth group did not receive any medication and was considered as normal control. Fasting blood sugar, lipid profile, blood sugar 2 h after glucose load were measured. Liver weight, liver volume, and histopathological analysis were done.
Results: Dexamethasone caused hepatomegaly, dyslipidemia, and hyperglycemia. Both pioglitazone and liraglutide significantly reduced hepatomegaly, dyslipidemia and hyperglycemia (P < 0.01). Reduction of blood sugar levels after glucose load was significant with pioglitazone when compared with liraglutide (P < 0.01).
Conclusion: Liraglutide has comparable efficacy to pioglitazone in prevention of dexamethasone induced hepatomegaly, dyslipidemia and fasting hyperglycemia.
Keywords: Dexamethasone, hepatomegaly, hyperglycemia, liraglutide, pioglitazone, prevention
Vinodraj K, Nagendra Nayak I M, Rao J V, Mathai P, Chandralekha N, Nitasha B, Rajesh D, Chethan T K. Comparison of the efficacy of liraglutide with pioglitazone on dexamethasone induced hepatic steatosis, dyslipidemia and hyperglycaemia in albino rats. Indian J Pharmacol 2015;47:181-4
Vinodraj K, Nagendra Nayak I M, Rao J V, Mathai P, Chandralekha N, Nitasha B, Rajesh D, Chethan T K. Comparison of the efficacy of liraglutide with pioglitazone on dexamethasone induced hepatic steatosis, dyslipidemia and hyperglycaemia in albino rats. Indian J Pharmacol [serial online] 2015 [cited 2023 Jan 30];47:181-4. Available from: https://www.ijp-online.com/text.asp?2015/47/2/181/153426
Type 2 diabetes mellitus (T2DM) is occurring in pandemic proportions. Obesity and decreased levels of physical activity are contributing to the rise of T2DM worldwide. The precise mechanism by which obesity leads to insulin resistance and to T2DM is not completely known but it may be related to several biochemical factors such as abnormalities in free fatty acids, adipokines, leptin and other substances. [1]
Abnormalities such as reduced secretion of the incretin glucagon-like peptide 1 (GLP-1), hyperglucagonemia and raised concentrations of other counter-regulatory hormones also contribute to insulin resistance, reduced insulin secretion, and hyperglycemia in type 2 diabetes. [2] 11beta-hydroxysteroid dehydrogenases (11β-HSD1) regenerates cortisol amplifying its actions in liver, fat, and brain. Overexpression of this isozyme may contribute to the pathogenesis of the metabolic syndrome. [3] Obese humans and rodents show increased 11ί-HSD1 in adipose tissue. Transgenic mice overexpressing 11ί-HSD1 selectively in adipose tissue faithfully recapitulate metabolic syndrome. [4] Cushing's syndrome, characterized by endogenous glucocorticoid (GC) hormone excess, is associated with several systemic complications, including the impairment of glucose metabolism, which often becomes clinically manifest with the development of diabetes mellitus. [5] Increased prevalence of obesity, hypertension, T2DM, dyslipidemia and osteoporosis has been found in patients with adrenal incidentalomas. [6] Diabetes occurs as a consequence of an insulin-resistant state together with impaired insulin secretion, which are induced by GC excess. [7]
Numerous studies have documented a strong relationship between hepatic steatosis and insulin resistance. [8],[9] In addition, there are several reports about the association of hepatic steatosis and GCs. [10],[11] The effect of insulin sensitizers in nonalcoholic fatty liver disease in humans have been reviewed. It was observed from these studies that pioglitazone was more effective than metformin in hepatic steatosis. The study concluded that GLP-1 analogues such as liraglutide may be more worthy of a trial. [12]
Metformin and pioglitazone are the two insulin sensitizers used in commonly clinical practice. [13] Considering their adverse effect profiles, metformin is more acceptable than pioglitazone. Even then, there is a situation in practice for the use of pioglitazone either as an add on or as a substitute to metformin. [14] This is due to the difference in the mechanisms of action of metformin and pioglitazone. However, pioglitazone has several adverse effects, which limits its use. [15] There is a need for an alternative drug whose efficacy is comparable to pioglitazone. Hence, the present study was conducted to compare pioglitazone with liraglutide for GC induced metabolic abnormalities.
» Materials and Methods
Experimental Animal
Healthy adult rats of Wistar strain weighing around 240-270 g were used in the present study. The animals were housed in clean polypropylene cages and maintained in a well-ventilated temperature controlled (25°C ± 2°C) animal house with constant 12 h light\dark schedule. The animals were fed with standard rat pellet diet and clean drinking water was made available ad libitum. All animal procedures have been approved, and prior permission from the Institutional Animal Ethical Committee (IAEC) was obtained as per prescribed guidelines (KSHEMA/IAEC/42/2011).
A total of 24 rats were divided into four groups with six rats in each group. Body weight was checked for all groups on day 1, day 7 and on day 12.
First group received dexamethasone alone in a dose of 8 mg/kg intraperitoneally for 6 days to induce metabolic changes and considered as dexamethasone control
Second group received liraglutide 1.8 mg/kg subcutaneously 6 days before dexamethasone and 6 days during dexamethasone administration
Third group received pioglitazone 45 mg/kg orally 6 days before dexamethasone and 6 days during dexamethasone administration
Fourth group did not receive any medication and was considered as normal control.
Rats were fasted overnight; blood was collected by retro-orbital sinus puncture for fasting blood sugar (FBS), lipid profile and post prandial blood sugar (PPBS) (2 h after a glucose load of 2 g/10 ml/kg, i.p.). Rats were sacrificed by cervical dislocation. Liver was dissected out, liver weight, liver volume were measured. Livers were stored in 10% formalin and sent for histopathological analysis. The details of the study method are given in [Table 1].
Table 1: Study protocol
Data management was done in Excel after coding. Then the data was analyzed by using SPSS 17.0 (SPSS Inc. Released 2008. SPSS Statistics for Windows, Version 17.0. Chicago: SPSS Inc.). The values presented as mean ± standard division. Independent t-test was used to compare between two groups. ANOVA with Scheffe's post-hoc test was done for multiple comparisons. P <0.05 was considered as statistically significant.
Effect of Liraglutide on Blood Sugar Levels in Rats
The blood sugar levels of the four groups are presented in [Table 2]. A significant decrease in the FBS and PPBS levels were observed in the liraglutide and pioglitazone treated groups as compared to dexamethasone control group (P < 0.01). There was no significant difference in FBS in the liraglutide group as compared to pioglitazone group (P = 0.249). A corresponding significant decrease PPBS was observed (P < 0.01) in the pioglitazone group as compared with liraglutide group.
Table 2: Effect of liraglutide on blood sugar levels and lipids in rats (n=6 per group)
Effect of Liraglutide on Lipids
The lipid profile of the four groups is presented in [Table 2]. A significant decrease in the total cholesterol and triglyceride, and increase in high-density lipoprotein (HDL) levels were observed in liraglutide and pioglitazone treated groups as compared to dexamethasone control group (P < 0.01). The total cholesterol, triglyceride, and HDL levels in the liraglutide treated group was comparable to pioglitazone group (P = 0.058, P = 0.119, P = 0.269).
Effect of Liraglutide on Liver Weight and Liver Volume
An increase in the liver weight and liver volume was seen in the dexamethasone group as compared to normal control group. A significant decrease in the liver weight and liver volume was observed in the liraglutide and pioglitazone treated groups as compared to dexamethasone control group (P < 0.01). No significant difference was observed in as in liver weight and liver volume in the liraglutide treated group as compared to pioglitazone group (P = 0.324, P = 0.085) [Table 3].
Table 3: Effect of liraglutide on liver weight, liver volume, and body weight in rats (n=6 per group)
Effect of Liraglutide on Body Weight
The body weights of four groups are presented in [Table 3]. There was a weight loss seen in dexamethasone group as compared to normal control group on day 12. A significant increase in the body weight was observed in the liraglutide and pioglitazone treated groups as compared to dexamethasone control group (P < 0.01). The body weight in the liraglutide treated group was comparable to pioglitazone group (P = 0.028).
Histopathological Observations
The normal control group rats showed normal hepatocytes. The dexamethasone treated group showed an increase in the size of hepatocytes, cytoplasm is vesicular to clear. Fat deposition was observed. The hepatocytes in rats treated with pioglitazone and liraglutide were smaller in size and had reduced fat deposition compared with dexamethasone treated group [Figure 1].
Figure 1: Histopathological changes of rat liver tissue (H and E, ×40). (a) Hepatocytes in normal control group. (b) Hepatocytes in Dexa treated group showing fat deposition pushing the nucleus to the periphery. (c and d) Hepatocytes showing reduced fat deposition in pioglitazone and liraglutide treated rats respectively
Glucocorticoids are implicated in the pathogenesis of metabolic syndrome and its manifestations like T2DM, dyslipidemia, and hepatic steatosis. Several studies have been done in animals using GCs to induce hepatic steatosis, [16] hyperlipidemia [17] and hyperglycemia. [18] As all the features of metabolic adverse effects are produced by insulin resistance induced by GCs, they can be prevented by using insulin sensitizers. [19]
Glucagon-like peptide 1 receptor agonists were shown to be useful in preventing features of insulin resistance. [20] The aim of the present study is to evaluate the efficacy of the GLP1 receptor agonist liraglutide in preventing the metabolic adverse effects produced by the use of large doses GCs and compare the same with that of pioglitazone.
Once-daily injections of liraglutide in mice exposed to corticosterone for five consecutive weeks improved glucose control by enhancing glucose clearance and slowed progression towards obesity and ectopic fat deposition in liver. [21] Liraglutide decreased accumulation of lipids in liver thereby reducing its weight by improving insulin sensitivity in rats having hepatic steatosis induced by a diet high in fat that also contained trans-fat and high-fructose corn syrup (ALIOS diet). [22] Administration of liraglutide prevented hypoadiponectinemia induced increases in plasma insulin, free fatty acids, triglycerides and total cholesterol. Liraglutide also attenuated hypoadiponectinemia-induced deterioration in peripheral and hepatic insulin sensitivity and alterations in key regulatory factors implicated in glucose and lipid metabolism via regulating gene and protein expression. [23] Liraglutide enhanced insulin sensitivity in normal glucose tolerance states as well as in insulin-resistant states by activating AMP-activated protein kinase in male Wistar rats. [24] This action of liraglutide is similar to that of metformin in insulin resistant states.
In our study liraglutide was as effective as pioglitazone in reducing the dyslipidemia, hepatic steatosis, and fasting hyperglycemia. However, pioglitazone was more effective in reducing blood glucose levels after the glucose load. Liraglutide prevented both the increase in liver weight and decrease in body weight caused by dexamethasone administration, which is in accordance with earlier studies. [25] We have not studied the effect of liraglutide in reversing the metabolic changes induced by GCs, which is the limitation of this study.
Dexamethasone used in high doses might lead to the development of Insulin resistance leading to various complications. Prophylactic treatment with liraglutide could significantly prevent the development of insulin resistance and associated complications.
The authors acknowledge sincere thanks to the Department of Pharmacology (K.S Hegde Medical Academy), Nitte University Central Research Laboratory and the staff of animal house for the facilities granted for the research work.
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Mells JE, Fu PP, Sharma S, Olson D, Cheng L, Handy JA, et al. Glp-1 analog, liraglutide, ameliorates hepatic steatosis and cardiac hypertrophy in C57BL/6J mice fed a Western diet. Am J Physiol Gastrointest Liver Physiol 2012;302:G225-35.
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[Figure 1]
[Table 1], [Table 2], [Table 3]
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