Abstract
This study was designed to investigate the effect of an extract of Zingiber officinale. Roscoe (Zingiberaceae) (ginger) on some hematologic values in alloxan-induced diabetic rats. Eighteen Sprague-Dawley rats were divided into three experimental groups: control, diabetic, and Z. officinale.–treated diabetic. At the end of the experimental period (3 weeks), animals in all three groups were fasted for 12 h and blood samples were taken for the determination of glucose levels, red blood cell (RBC) count, white blood cell (WBC) count, packed cell volume (PCV), hemoglobin (Hb) concentration, and platelet count. It was found that Z. officinale. treatment increased the lowered levels of RBC and WBC counts and PCV in diabetic rats (p < 0.05). However, the RBC count and PCV of the Z. officinale.–treated diabetic group were still lower than control. Z. officinale. treatment also decreased the elevated level of platelets and glucose concentration of diabetic rats (p < 0.05). It is therefore concluded that oral Z. officinale. treatment might decrease the diabetic-induced disturbances of some hematologic parameters in alloxan-induced diabetic rats.
Introduction
Diabetes mellitus is one of the most common metabolic disorders with a worldwide prevalence estimated to be 2.8% (Sarah et al., Citation2004). The increasing prevalence of diabetes mellitus in the world is a cause for concern. Diabetes mellitus leads to abnormalities in carbohydrate, protein, and lipid metabolism and increases the risk of developing atherosclerotic arterial disease by 2- to 6-fold (Sacks, Citation1997). It has been suggested that there is increased platelet activity and increased tendency for thrombus formation in diabetes. This is thought to be due to unbridling platelet hyperfunction secondary to loss of the restraining action of the anti-aggregating mechanisms such as inhibitory action of insulin and defective endothelial production of anti-aggregants nitric oxide (NO) and prostacyclin (PGI2) (Vinik et al., Citation2001; Arjomand et al., Citation2003).
Zingiber officinale. Roscoe (Zingiberaceae) is a spice plant (Grant & Kutz, Citation2000) and medicinal plant in which the rhizome is used as a natural remedy for a variety of illnesses. It has been shown that steam distillation of Z. officinale. rhizome produces ginger oil that contains zingiberene, shogaols, zingerone, and paranol (Goundarajan, Citation1982). Ginger oil has been shown to have antiemetic (Bluementhal, Citation2003), antidiabetic (Mascolo et al., 1987; Ahmed & Sharma, Citation1997), positive inotropic (Kolgayashi, Citation1998), analgesic (Bliddal et al., Citation2000), antitumor (Katiyar, 1986), and antimicrobial (Denyer et al., Citation1994) activities.
Because there is evidence that hematologic parameters are altered in diabetes mellitus (Glassman, Citation1993; Yenigun, Citation1997; Palmiari et al., Citation2001; Arjomand et al., Citation2003; Kamenov et al., Citation2003), this study was undertaken to determine whether or not Z. officinale. could restore altered hematologic parameters to normal.
Materials and Methods
Preparation of extract
Z. officinale. rhizomes were purchased from a local herb store at Ipata Market (Ilorin, Nigeria), authenticated by Mr. S.E. Adebayo of the Department of Plant Biology, University of Ilorin, and were washed and air-dried. A voucher specimen (A-214c) has been deposited in the departmental herbarium for future reference. The aqueous extract of Z. officinale. rhizome was prepared using the method described by Farida et al. (Citation1987), then filtered and the residue was discarded. The filtrate was subsequently evaporated to dryness. The resulting powder of the extract was stored in capped bottles until needed. The extract of Z. officinale. (5 g) was dissolved in 1000 mL distilled water to make a stock of 5 mg/mL.
Treatment of rats
Fifteen albino rats (Rattus norvegicus Muriadae.; Myers et al., 2006) weighing between 150 and 200 g and obtained from the Animal Breeding Unit of the Department of Biochemistry, University of Ilorin, were used for this study.
The rats were divided into three experimental groups (control, diabetic, and diabetic with Z. officinale. treatment), each containing five rats. At the start of the experiment, the animals in the latter two groups were injected intraperitoneally with 100 mg/kg of 10% alloxan (Sigma Chemical Co., St. Louis, MO, USA) dissolved in distilled water to induce diabetes. The control group was injected only with the same volume of isotonic NaCl as the diabetic groups received. Three days after alloxan injection, diabetes mellitus was confirmed by the demonstration of hyperglycemia (blood glucose ≥ 300 mg/dL). The rats were not treated with insulin at any time during the experiment. The diabetic Z. officinale.–treated group was given the aqueous extract of Z. officinale. at 400 mg/kg by oral cannula every day for 3 weeks after diabetes mellitus was confirmed. All animals were housed in plastic cages with stainless steel mesh cover under standard laboratory conditions (light period 6:30 a.m. to 7:00 p.m.; 25 ± 2°C; relative humidity 55%) with food and water freely available. They received humane care.
Blood collection
At the end of the experimental period (3 weeks), the animals in all three groups were fasted for 12 h. The rats were sacrificed by cervical dislocation, jugular vein was exposed and cut with a sterile scalpel blade, and the rats were bled into EDTA-coated specimen bottles. Plasma was obtained from a portion of the blood sample by centrifugation at 3000 rpm for 5 min. All plasma samples were stored in the refrigerator at 4°C before analysis.
Hematologic analysis
Blood glucose concentration was measured immediately by the glucose oxidase method (Yenson, Citation1986). All hematologic parameters were determine by an automated hematologic analyzer (SYSMEX KY-21; SYSMEX Corporation, Kobe, Japan), using whole blood sample.
Statistical analysis
The data were expressed as mean ± standard deviation (SD) and analyzed using analysis of variance (ANOVA). Student's t.-test was used to test for differences among means for which ANOVA indicated a significant (p ≤ 0.05) F ratio.
Results
Comparative hematologic values and blood glucose concentration of control and treatment groups are shown in .
Table 1.. Comparative hematologic values and serum glucose concentration of control and treatment groups.
Blood glucose concentration increased significantly from 97.27 ± 6.38 mg/dL in control group to 310.74 ± 36.52 mg/dL in diabetic rats (219%, p < 0.05, n = 5). Z. officinale. treatment decreased the elevated glucose concentration significantly to 187.42 ± 22.38 mg/dL (40%, p < 0.05, n = 5) in treated diabetic rats; however, their glucose concentration was still significantly higher (48%, p < 0.05, n = 5) than that of the control group. It was also found that the RBC and WBC counts and PCV decreased (RBC 7%, p < 0.05, n = 5; WBC 39%, p < 0.05, n = 5; PCV 6%, p < 0.05, n = 5) and platelet increased (23%, p < 0.05, n = 5) in diabetic rats. Z. officinale. treatment increased the lowered RBC and WBC counts and PCV in diabetic rats (RBC 9%, p < 0.05, n = 5; WBC 32%, p < 0.05, n = 5; PCV 11%, p < 0.05, n = 5). Z. officinale. treatment also decreased the elevated platelet count of diabetic rats to the normal level (17%, p < 0.05, n = 5). Neither an induced diabetic condition nor the administration of Z. officinale. produced any significant change in hemoglobin concentration.
Discussion
The current study indicated that Z. officinale. treatment might ameliorate some disturbed hematologic parameters in diabetic rats. It has been suggested that the occurrence of anemia in diabetes mellitus is due to the increased nonenzymatic glycosylation of RBC membrane proteins, which correlates with hyperglycemia (Kennedy & Baynes, Citation1984). Oxidation of these glycosylated membrane proteins and hyperglycemia in diabetes mellitus causes an increase in the production of lipid peroxidases resulting in hemolysis. There is impairment of deformability of RBCs and reduced RBC count in diabetes mellitus (Ernst & Matra, Citation1986). In this experiment, we did not measure the RBC membrane lipid peroxide levels in diabetic rats. However, Meral et al. (Citation2001) demonstrated that serum lipid peroxide level increased in diabetic rabbits. Thus, increased RBC count of Z. officinale.–treated rats could be due to the lowered lipid peroxide level in RBC membrane leading to a decreased susceptibility of RBCs to hemolysis. Because nonenzymatic glycosylations of membrane proteins correlate with hyperglycemia (Kennedy & Baynes, Citation1984), it might be said that Z. officinale. produced its effect by decreasing the elevated glucose concentration in Z. officinale.–treated rats. However, further studies are required. Such studies should include measurement of RBC fragility and serum folic acid, iron, cobalt, vitamin B12, and calcium levels to demonstrate the exact mechanism of action of Z. officinale. on increased RBC count of diabetic rats.
White blood cells are involved in body defense against infection (Ganong, Citation1999). It has been suggested that the body's defense mechanism against infection is disturbed due to the disturbed WBC function in diabetes (Yenigun, Citation1997). In this experiment, we demonstrated that Z. officinale. increased the lowered WBC to control levels. This result indicates that Z. officinale. treatment might also increase the defense mechanism of the body against infections in diabetic rats.
Alloxan-induced diabetes increased the platelet count whereas Z. officinale. treatment decreased it to control level. The increased platelet count in diabetic rats was probably due to loss of the restraining action of anti-aggregating mechanisms of insulin and defective endothelial production of NO and PGI2 (Vinic et al., Citation2001). It may also be due to accumulation of products of advanced glycosylation, which reduced membrane fluidity of platelets and contributes to platelet hyperfunction (Winocour et al., Citation1992). In the current study, it was found that the platelet count decreased and also blood glucose decreased in Z. officinale.–treated rats. Therefore, decreased platelet count could be due to normalized blood glucose in these rats.
It is concluded that oral Z. officinale. treatment might reduce the (diabetic-induced) disturbances of hematologic parameters in alloxan-induced diabetic rats.
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