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Indian Journal of Medical Sciences, Vol. 59, No. 2, February, 2005, pp. 64-69 Original Article Effect of fenugreek, onion and garlic on blood glucose and histopathology of pancreas of alloxan-induced diabetic rats Jelodar Gholamali A., Maleki M., Motadayen M.H., Sirus S. Department of Physiology, College of Veterinary Medicine, Shiraz University, Shiraz, 71345 Code Number: ms05011 Abstract BACKGROUND: Many traditional treatments have been recommended in the alternative system of medicine for treatment of diabetes mellitus; however, the mechanism of most of the herbals used has not been defined.AIMS: This study was carried out to clarify the effect of fenugreek, garlic and onion, recommended in Persian folklore medicine as beneficial in the treatment of diabetes, on blood glucose and their possible effect on pancreatic tissue. METHODS AND MATERIAL: Diabetes mellitus was induced in 20 out of 25 adult male albino rats, using intraperitoneal injection of 185 mg/kg BW alloxan. The diabetic rats were divided into four groups, three of which were fed a diet containing 12.5% BW Allium sativum (garlic), Allium cepa (onion) or Trigonella foenum-graecum (fenugreek) for 15 days. The fourth group (positive control) received an ordinary diet. The remaining non-diabetic rats (negative control group) received neither alloxan nor the mentioned plants. Following consumption of plants, blood glucose was measured every day and on the last day the pancreas were removed and stained with H&E and Gomeri aldehyde fuchsin (GAF). Morphology of the pancreatic sections and the following morphometric factors were studied: volume density of B cells, volume density of islets, percent of B cells, number of islets per square millimeter, average area of islets and average volume density of B cell in whole pancreas. STATISTICAL ANALYSIS USED: One-way Analysis of Variance (ANOVA) test and Duncan's multiple range tests were used to evaluate the data. RESULTS AND CONCLUSION: The results of this study indicate that only garlic was able to reduce blood glucose significantly compared with the control group (P<0.05). In the control positive group all the mentioned morphometric factors were significantly changed in comparison with the control negative (normal health) group, but the same did not show significant change between treated and untreated diabetics. INTRODUCTION Although herbal medicines have long been used effectively in treating many diseases in Asian communities and throughout the world, the mechanism of most of the herbals used have not been defined. Many traditional plant treatments for diabetes are also used, but most of the evidence for their beneficial effects is anecdotal.[1] Fenugreek, onion and garlic were reported to have a hypoglycemic effect.[2],[3],[4],[5] Although there are suggestions about the mechanism of action of plants, the exact mechanism is unclear. Plants may act on blood glucose through different mechanisms, some of them may have insulin-like substances,[6] some may inhibit insulinas activity,[7] and others may increase beta cells in the pancreas by activating regeneration of these cells.[8],[9] The fiber of plants may also interfere with carbohydrate absorption; thereby affecting blood glucose.[10] Our initial study showed a profound effect of garlic, onion and fenugreek on serum cholesterol, triglyceride, ALT, and AST of alloxan diabetic rats.[11] The aim of this study was to clarify the effect of above-mentioned plants, recommended in Persian folklore medicine as beneficial in the treatment of diabetes, on blood glucose and their possible effect on pancreatic tissue.MATERIAL AND METHODS Animals Diabetes was induced in 20 rats by intraperitoneal injection of 185 mg/kg
(5%).
The rats were fasted 12h before and after the alloxan injection. The rats with
blood glucose above 250 mg/dl, as well as with polydipsia, polyurea and polyphagia,
which last for at least one week, were selected for the experiment.
Statistical analysis The results are expressed as mean± SD. The significance of the differences in the values was performed by one-way ANOVA test and Duncan′s multiple range tests. P<0.05 was considered to be a significant difference. RESULTS The effects of plants on fasting blood glucose (FBS). The effect of the plants on FBS is presented in [Table - 1]. Mean fasting blood glucose in the diabetic untreated group (control positive) was (258.7±7.7) during the whole period. In the normal health group this value was 67.2±4.1 mg/dl. In comparison with the positive control group, the group which consumed garlic showed significantly lower mean FBS (182.9±4.96) (P<0.05).There was no significant difference of FBS between groups which received fenugreek or onion in comparison with the positive control group. Effects of consumed plants on the histopathology of the pancreas Histomorphologic change of pancreas Pancreatic sections stained with HE showed that alloxan caused severe necrotic changes of pancreatic islets, especially in the center of the islets. Nuclear changes, karyolysis, disappearing of nucleus and in some places residue of destructed cells were visible. The relative reduction of the size and number of islets, especially around the large vessel, and also severe reduction of the number of B cells was obvious. Study of the pancreas of the treated groups did not show a significant difference as compared with the diabetic untreated group. Results of the Histomorphometric study The result of this section is summarized in [Table - 2]. In the diabetic untreated group all the 6 factors measured were significantly low in comparison with the normal health group (P<0.05). There was no significant difference between the histopathology of the treated and untreated diabetic rats. DISCUSSION Consumption of garlic significantly decreased FBS; this finding agreed with others[2],[16],[17],[18]and seemed to support the theory that garlic acted as a hypoglycemic agent. Feeding of animals with other plants did not have a significant effect on FBS. The hypoglycemic effect of garlic may be due to the action of substances like allyle propyl disulphide or diallyle disulphide.[2]In this study the pancreatic beta cells were destroyed with the help of alloxan. Alloxan and streptozotocin are the most usual substances to induce diabetes mellitus.[19] The rats were fasted for 12h before and after injection of alloxan; unfed animals are more susceptible to alloxan-induced diabetes.[20],[21] Following injection of alloxan, beta cells were selectively destroyed and the histopathogical study of specifically stained beta cells with GAF confirmed this. The hypoglycemic effect of plants may be due to the presence of insulin-like substances in plants,[6] stimulation of B cells to produce more insulin,[16] high level of fiber which interferes with carbohydrate absorption[10] or the regenerative effect of plants on pancreatic tissue.[8],[9],[22] Specific staining along with ordinary HE staining has been used to clarify the effect of applied plants on pancreatic B cells. GAF staining which was used in this study, was first introduced by Gomeri,[13] and was applied by other scientists for staining of pancreatic B cells.[23],[24] Histopathological study of diabetic untreated rats showed almost complete destruction of B cells, which was due to the proper dose of alloxan used in this study. An inadequate dose will cause partial destruction of B cells in islets.[25] The histopathological study of the diabetic treated group did not show a significant difference with the diabetic untreated group. This finding reveals that the hypoglycemic effect of garlic is not through the action of garlic on the number of B cells, and will support the theory that garlic′s hypoglycemic effect might be due to the action of substances like allyle propyl disulphide or diallyle disulphide[2] or due to an increase in the insulin response.[26] Onion was reported to have a hypoglycemic effect[2],[17],[26] but our result didn′t support these reports, which may be due to the volatile substances present in onion and expected to be escaped from onion during food processing.[2],[17] The finding of this study also may not support the report of Sharma, 1986, about the mild hypoglycemic effect of fenugreek in diabetic rats. In this study, the leaf of fenugreek was consumed but most of the available reports about the hypoglycemic effect of fenugreek are about fenugreek seed.[3],[5],[27] In conclusion, of the consumed plants, only garlic reduced FBS significantly but the histomorphometric study of the pancreas of the treated group didn′t show a significant change of the pancreatic tissue, hence some other mechanism may be involved in its hypoglycemic action. References
Copyright 2005 - Indian Journal of Medical Sciences The following images related to this document are available:Photo images[ms05011t1.jpg] [ms05011t2.jpg] |
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![[Table - 1]](/showimage?ms/photo/ms05011t1.jpg){kind=link}
![[Table - 2]](/showimage?ms/photo/ms05011t2.jpg){kind=link}