1. Introduction
he high prevalence of liver disease in people with diabetes has already been reported. Although the exact mechanism of liver damage in diabetes is unclear, hyperglycemia increases glucose production by autooxidation of glucose, which leads to the destruction of liver cells, followed by the increase of alanine Aminotransferase (ALT), aspartate aminotransferase (AST) enzymes production from liver cells. According to reports, increased insulin level and resistance to this hormone leads to fibrosis and necrosis of hepatic lobules and the subsequent increase in ALT and AST enzymes. Oxidative stress, which causes the production of free radicals is also plays an important role in diabetes. Free radicals are highly toxic to cells, including the liver, and cause many side effects in the body. Exercises, including moderate-intensity aerobic exercise (reducing inflammation, oxidative stress, and the amount of fat in liver cells), and anti-diabetic drugs such as Stevia Rebaudiana have been suggested for fighting the negative effects of diabetes on the liver. Studies have shown that both leaf powder and extracted fibers from Stevia Rebaudiana have lowering effects on blood sugar and also play an important role in reducing liver damage. Therefore, it seems that the combination of Stevia herbal medicine and aerobic exercise can treat and prevent the progression of liver disease caused by diabetes and reduce the levels of transaminases.
2. Materials and Methods
In this study, 40 Wistar rats were studied. After overnight fasting (except for rats in the healthy control group), 32 rats with 50 mg/kg weight received intraperitoneal injection of Streptozotocin (STZ). 5 days after injection and by measurement of blood glucose using a glucometer, rats with blood glucose >300 mg/dl entered into the study. The remaining diabetic rats were randomly divided into 4 groups of diabetic control (n=7), diabetic + exercise (n=7), diabetic + Stevia (n=7) and diabetic + Stevia + exercise (n=7). Rats in the control and diabetic control groups did not have any particular activity during the experiments. The diabetic + exercise group performed aerobic exercise for 6 weeks (5 days per week). The diabetic + Stevia group received 250 mg/kg of Stevia extract orally (5 days per week, once a day). Rats in the diabetic + exercise+ Stevia group, while performing aerobic exercise, received 250 mg /kg of Stevia extract orally at the end of each exercise session for 5 days per week. After 6 weeks, the rats were anesthetized by intraperitoneal injection of a mixture of ketamine and xylazine, and then their blood samples were collected. Blood samples were centrifuged and their serums were prepared. Liver enzymes (ALT and AST) were measured using special kits. Aerobic exercise intensity was controlled using the treadmill. The exercise protocol was designed with increasing intensity based on ACSM principles (Table 1). 



Stevia extract was prepared by maceration (soaking). For statistical analysis, Shapiro-Wilk test, ANOVA and Tukey’s post hoc test were used.
3. Results
Table 2 presents the characteristics of samples mean serum levels of ALT and AST.



The results of ANOVA presented in Table 3 and Figure 1, indicated a significant difference between the mean ALT and AST levels in the five study groups (P=0.00).



Tukey’s Post Hoc test results in Table 4 indicates where the differences between the groups was reported. 



4. Conclusion
Stevia extract and aerobic exercise, either alone or in combination, cause a decrease in the number of damaging serum biomarkers in the liver of diabetic rats with streptozotocin. The reduction rate was more significant in the exercise group with the extract, which was probably achieved through hypoglycemic, antioxidant, and aerobic exercise. Therefore, it can be concluded that the use of stevia extract and aerobic training can have a double effect on reducing the risk of liver damage.
The dosage of stevia extract in this study is one of the limitations of the study. Stevia's hypoglycemic and antioxidant effects in people with diabetes likely depend on its dose; thus, further research in this area with different quantities of stevia dose can help better understand the results. It is suggested that in a similar study, the number of oxidative damage indices following stevia extract and exercise in diabetic rats should be investigated.
Overall, although being animals, the subjects were to be identified with human subjects. All of the results of this study showed that they effectively reduced the value of the currency. However, more biochemical researches should be done to use it.
Ethical Considerations
Compliance with ethical guidelines
All ethical principles were considered in this article. The participants were informed about the purpose of the research and its implementation stages; they were also assured about the confidentiality of their information; Moreover, They were allowed to leave the study whenever they wish, and if desired, the results of the research would be available to them.
Funding
This study was extracted from the PhD. thesis of first author approved by Islamic Azad University of Kermanshah Branch.
Authors' contributions
All authors contributed equally in preparing all parts of the research.
Conflicts of interest
The authors declare no conflict of interest


References

1. Tappy L, Minehira K. New data and new concepts on the role of the liver in glucose homeostasis. Current Opinion in Clinical Nutrition & Metabolic Care. 2001; 4(4):273-7. [DOI:10.1097/00075197-200107000-00005] [PMID]
2. Cameron NE, Gibson TM, Nangle MR, Cotter MA. Inhibitors of advanced glycation end product formation and neurovascular dysfunction in experimental diabetes. Annals of the New York Academy of Sciences. 2005; 1043:784-92. [DOI:10.1196/annals.1333.091] [PMID]
3. De Marco R, Locatelli F, Zoppini G, Verlato G, Bonora E, Muggeo M. Cause-specific mortality in type 2 diabetes. The Verona Diabetes Study. Diabetes Care. 1999; 22(5):756-61. [DOI:10.2337/diacare.22.5.756] [PMID]
4. Venditti P, Napolitano G, Barone D, Di Meo S. Effect of training and vitamin E administration on rat liver oxidative metabolism. Free Radical Research. 2014; 48(3):322-32. [DOI:10.3109/10715762.2013.867959] [PMID]
5. Domingueti CP, Dusse LMSA, das Graças Carvalho M, de Sousa LP, Gomes KB, Fernandes AP. Diabetes mellitus: the linkage between oxidative stress, inflammation, hypercoagulability and vascular complications. Journal of Diabetes and its Complications. 2016; 30(4):738-45. [DOI:10.1016/j.jdiacomp.2015.12.018] [PMID]
6. Ajayi OB, Odutuga A. Effect of low-zinc status and essential fatty acids deficiency on the activities of aspartate aminotransferase and alanine aminotransferase in liver and serum of albino rats. Die Nahrung. 2004; 48(2):88-90. [DOI:10.1002/food.200300316] [PMID]
7. Soochan D, Keough V, Wanless I, Molinari M. Intra and extra-hepatic cystadenoma of the biliary duct. Review of literature and radiological and pathological characteristics of a very rare case. BMJ Case Reports. 2012. [DOI:10.1136/bcr.01.2012.5497] [PMID] [PMCID]
8. von Känel R, Abbas CC, Begré S, Gander M-L, Saner H, Schmid J-P. Association between posttraumatic stress disorder following myocardial infarction and liver enzyme levels: A prospective study. Digestive Diseases and Sciences. 2010; 55(9):2614-23. [DOI:10.1007/s10620-009-1082-z] [PMID]
9. Tanné F, Gagnadoux F, Chazouilleres O, Fleury B, Wendum D, Lasnier E, et al. Chronic liver injury during obstructive sleep apnea. Hepatology. 2005; 41(6):1290-6. [DOI:10.1002/hep.20725] [PMID]
10. Harris EH. Elevated liver function tests in type 2 diabetes. Clinical Diabetes. 2005; 23(3):115-9. [DOI:10.2337/diaclin.23.3.115]
11. Lawlor DA, Sattar N, Smith GD, Ebrahim S. The associations of physical activity and adiposity with alanine aminotransferase and gamma-glutamyltransferase. American Journal of Epidemiology. 2005; 161(11):1081-8. [DOI:10.1093/aje/kwi125]
12. Agarwal A, Nallella KP, Allamaneni SS, Said TM. Role of antioxidants in treatment of male infertility: an overview of the literature. Reproductive Biomedicine Online. 2004; 8(6):616-27. [DOI:10.1016/S1472-6483(10)61641-0]
13. Oh S, Tanaka K, Warabi E, Shoda J. Exercise reduces inflammation and oxidative stress in obesity-related liver diseases. Medicine and Science in Sports and Exercise. 2013; 45(12):2214-22. [DOI:10.1249/MSS.0b013e31829afc33] [PMID]
14. Johnson NA, Sachinwalla T, Walton DW, Smith K, Armstrong A, Thompson MW, et al. Aerobic exercise training reduces hepatic and visceral lipids in obese individuals without weight loss. Hepatology. 2009; 50(4):1105-12. [DOI:10.1002/hep.23129] [PMID]
15. Kawanishi N, Yano H, Mizokami T, Takahashi M, Oyanagi E, Suzuki K. Exercise training attenuates hepatic inflammation, fibrosis and macrophage infiltration during diet induced-obesity in mice. Brain, Behavior, and Immunity. 2012; 26(6):931-41. [DOI:10.1016/j.bbi.2012.04.006] [PMID]
16. Gutierrez-Grobe Y, Ponciano-Rodríguez G, Ramos MH, Uribe M, Méndez-Sánchez N. Prevalence of non alcoholic fatty liver disease in premenopausal, posmenopausal and polycystic ovary syndrome women. The role of estrogens. Annals of Hepatology. 2010; 9(4):402-9. [DOI:10.1016/S1665-2681(19)31616-3]
17. Devries MC, Samjoo IA, Hamadeh MJ, Tarnopolsky MA. Effect of endurance exercise on hepatic lipid content,enzymes, and adiposity in men and women. Obesity (Silver Spring). 2008; 16(10):2281-8. [DOI:10.1038/oby.2008.358] [PMID]
18. Barzegarzadeh-Zarandi H, Dabidy-Roshan V. [Changes in some liver enzymes and blood lipid level following interval and continuous regular aerobic training in old rats (Persian)].  Journal of Shahrekord Uuniversity of Medical Sciences. 2012; 14(5):13-23. http://journal.skums.ac.ir/article-1-1334-en.html
19. Osawa T, Kato Y. Protective role of antioxidative food factors in oxidative stress caused by hyperglycemia. Annals of the New York Academy of Sciences. 2005; 1043(1):440-51. [DOI:10.1196/annals.1333.050] [PMID]
20. Stickel F, Schuppan D. Herbal medicine in the treatment of liver diseases. Digestive and Liver Disease. 2007; 39(4):293-304. [DOI:10.1016/j.dld.2006.11.004] [PMID]
21. Ghosh N, Ghosh R, Mandal V, Mandal SC. Recent advances in herbal medicine for treatment of liver diseases. Pharmaceutical Biology. 2011; 49(9):970-88. [DOI:10.3109/13880209.2011.558515] [PMID]
22. Shivanna N, Naika M, Khanum F, Kaul VK. Antioxidant, anti-diabetic and renal protective properties of Stevia rebaudiana. Journal of Diabetes and its Complications. 2013; 27(2):103-13. [DOI:10.1016/j.jdiacomp.2012.10.001] [PMID]
23. Kim H-J, Park JY, Oh SL, Kim Y-A, So B, Seong JK, et al. Effect of treadmill exercise on interleukin-15 expression and glucose tolerance in zucker diabetic fatty rats. Diabetes & Metabolism Journal. 2013; 37(5):358-64. [DOI:10.4093/dmj.2013.37.5.358] [PMID] [PMCID]
24. Yildirim Ö, Büyükbingöl Z. Effect of cobalt on the oxidative status in heart and aorta of streptozotocin-induced diabetic rats. Cell Biochemistry and Function. 2003; 21(1):27-33. [DOI:10.1002/cbf.995] [PMID]
25. Thompson WR, American College of Sports Medicine. ACSM’s guidelines for exercise testing and prescription. 8^th ed. Philadelphia: Lippincott Williams & Wilkings; 2010. https://books.google.com/books/about/ACSM_s_Guidelines_for_Exercise_Testing_a.html?id=6NcjAQAAMAAJ
26. Moradi Peynevandi K, Sharifi M, Behmanesh M. [Effects of methyl jasmonate, on stevioside & rebaudioside A content and expression of the ent-Kaurenoic acid 13-hydroxylase gene in Stevia rebaudiana Bert. In vitro (Persian)]. Journal of Plant Biology. 2014; 6(21):99-110. https://ijpb.ui.ac.ir/article_18942.html?lang=en
27. Kalailingam P, Sekar AD, Samuel JSC, Gandhirajan P, Govindaraju Y, Kesavan M, et al. The efficacy of Costus igneus rhizome on carbohydrate metabolic, hepatoproductive and antioxidative enzymes in streptozotocin-induced diabetic rats. Journal of Health Science. 2011; 57(1):37-46. [DOI:10.1248/jhs.57.37]
28. Singh PK, Baxi D, Banerjee S, Ramachandran AV. Therapy with methanolic extract of Pterocarpus marsupium Roxb and Ocimum sanctum Linn reverses dyslipidemia and oxidative stress in alloxan induced type I diabetic rat model. Experimental and Toxicologic Pathology. 2012; 64(5):441-8. [DOI:10.1016/j.etp.2010.10.011] [PMID]
29. Assaei R, Mokarram P, Dastghaib S, Darbandi S, Darbandi M, Zal F, et al. Hypoglycemic effect of aquatic extract of Stevia in pancreas of Diabetic rats: PPARγ -dependent regulation or antioxidant potential. Avicenna Journal of Medical Biotechnology. 2016; 8(2):65-74. [PMID] [PMCID]
30. Komissarenko NF, Derkach AI, Kovalyov IP, Bublik NP. Diterpene glycosides and phenylpropanoids of Stevia rebaudiana Bertoni. Rast Research. 1994; 1(2):53-64.
31. Shukla S, Mehta A, Bajpai VK, Shukla S. In vitro antioxidant activity and total phenolic content of ethanolic leaf extract of Stevia rebaudiana Bert. Food and Chemical Toxicology. 2009; 47(9):2338-43. [DOI:10.1016/j.fct.2009.06.024] [PMID]
32. Venkateswarlu V, Kokate CK, Rambhau D, Veeresham C. Antidiabetic activity of roots of Salacia macrosperma. Planta medica. 1993; 59(5):391-3. [DOI:10.1055/s-2006-959715] [PMID]
33. Ananthan R, Latha M, Ramkumar KM, Pari L, Baskar C, Bai VN. Modulatory effects of Gymnema montanum leaf extract on alloxan-induced oxidative stress in Wistar rats. Nutrition. 2004; 20(3):280-5. [DOI:10.1016/j.nut.2003.11.016] [PMID]
34. Straznicky NE, Lambert EA, Grima MT, Eikelis N, Nestel PJ, Dawood T, et al. The effects of dietary weight loss with or without exercise training on liver enzymes in obese metabolic syndrome subjects. Diabetes, Obesity and Metabolism. 2012; 14(2):139-48. [DOI:10.1111/j.1463-1326.2011.01497.x] [PMID]
35. Mikami T, Sumida S, Ishibashi Y, Ohta S. Endurance exercise training inhibits activity of plasma GOT and liver caspase-3 of mice [correction of rats] exposed to stress by induction of heat shock protein 70. Journal of Applied Physiology. 2004; 96(5):1776-81. [DOI:10.1152/japplphysiol.00795.2002] [PMID]