Effects of garlic on myocardial dysfunction and plasma levels of nitric oxide, C-reactive protein and leptin hormone in diabetic rats

It is now accepted that allocin, the main biologically active compound in garlic, exhibits antioxidant activity. As well, garlic has been well known for its protective effects against cardiovascular disease. Diabetes mellitus is reported to be accompanied by severe oxidative stress. Since heart disease is the leading cause of death in diabetes, this study was carried out to determine the effect of garlic supplementation on cardiac performance as well as. on the cardiac responses to Badrenergic stimulation and on plasma levels of nitric oxide [NO], C-reactive protein [CRP] and leptin hormone in streptozotocin [STZ] diabetic rats. The study was carried out on 58 adult male albino rats, allocated into 4 groups: Group 1 included non-diabetic control rats [n = 12] that received a single i.p. injection of citrate buffer, in a volume equal to that used as solvent for STZ used to induce diabetes in the test groups. Group 2 included nondiabetic garlic-treated rats [n = 14], which were injected i.p. with garlic in a dose of 200 mg/kg/day, 6 days/week, for 1 month. Group 3 included diabetic rats [n = 15], diabetes being induced by a single i.p. injection of STZ in a dose of 40 mg/kg. Group 4 included diabetic garlic-treated rats [n = 17], that received a single dose of STZ as in group: and then treated with garlic in a dose of 200 mg/kg/day, given i.p., 6 days/week for 1 month. On the day of sacrifice, blood samples were taken from the aorta for estimation of plasma glucose, nitrate, CRP and leptin levels. Thereafter, the hearts were excised and subjected to in vitro cardiac studies to demonstrate the response of isolated hearts to isoproterenol [ISU] infusion. Hearts isolated from diabetic rats showed impairment of both intrinsic chronotropic and inotropic functions as shown by the diminished spontaneous beating rate [BR], peak developed tension [PT] and myocardial flow rate [MFR] together with prolonged time to peak tension [TPT]. Their response to the different doses of ISU stimulation was also diminished. Further, diabetes was found to be associated with increased plasma glucose, nitrate and CRP, with non significant change in plasma leptin level. Garlic administration to diabetic rats enhanced chronotropy, evidenced by increased BR, as well as inotropy as shown by the shortening of TPT. Garlic also caused significant reduction in blood glucose levels indicating its hypoglycemic effect, together with reduction of the elevated nitrate and CRP levels, yet no effect on leptin was detected. It can be concluded from the present study that diabetes caused impairment of cardiac functions, both basal and in response to ISU infusion. Moreover, the inflammatory effect of diabetes was manifested by the increase in CRP, whereas the high level of NO could be attributed to the oxidative stress induced iNOS activation. Garlic supplementation antagonized the diabetic adverse effects on cardiac functions through its cardioprotective, hypoglycemic, anti-inflammatory and antioxidant effects

Hematological and cardiac effects of excess zinc in rats

In this work administration of zinc sulphate at a dose of 20 mg/kg/day. 6 days/week for 4 successive weeks, resulted in significant decrease in RBCs count, hemoglobin content, hematocrit value and mean corpuscular hemoglobin concentration in zinc treated group compared to control group. Biochemical studies showed significant decrease in plasma triglyceride, and malondialdehyde levels in zinc treated group compared to control group. However, non significant difference was found between the two groups as regards plasma zinc level. ECG study demonstrated significant increase in heart rate [HR] in zinc treated group compared to control group. This was accompanied by shortening of QRS and prolongation in Q-Tc durations in zinc treated group compared to control group. In vitro study of isolated hearts perfused in a Langendorff preparation, significant increase in basal HR was shown in zinc treated group compared to control group. The maximal HR upon isoproterenol infusion [ISU], when expressed as percentage ratio from baseline values, showed significant decrease in zinc treated group compared to control group. As regards baseline peak tension [PT] and peak tension/left ventricular weight [PT/LV,], significant increase was found in zinc treated group compared to control group. Also, the PT maximal response upon ISU infusion, either absolute or upon correction of left ventricular weight, showed significant increase in zinc treated group. Significant shortening in baseline time to peak tension [TPT] and half relaxation time [l/2RT,] were noticed in zinc treated group compared to control group. However, basal myocardial flow rate [MFR] as well as MFR/L V showed non significant difference between the 2 studied groups. Post ischemic reperfusion responses showed non significant difference as regards HR between the 2 studied groups. The recovery of PT and PT/LV were significantly higher at 20, 25, and 30 minutes of reperfusion in zinc treated group compared to control group. As regard TPT reperfusion values, significant prolongation at 10 minute was noticed in zinc treated group compared to control group. However 1/2RT, MFR and MFR/LV reperfusion values, non significant differences were recorded between the two studied groups. From this study, it can be concluded that zinc administration at a dose of 20 mg/kg/day for 4 successive weeks, has a protective effect against the risk of atherosclerosis and oxidative stress in vivo. Also, zinc treatment maintained or even enhanced the intrinsic cardiac functions, both chronotropic and inotropic, and their responses to B-adrenergic stimulation. In addition, zinc proved to be a beneficial cardioprotective agent as it attenuated the detrimental effects of post-ischemia reperfusion on the myocardial contractility

Estrogen replacement therapy in OVX-STNx rats and its nephroprotective role against progression of renal failure

Inspite of estrogen replacement therapy being extensively used in clinical and experimental studies without renal impairment, there are no long-term studies concerning estrogen replacement in chronic renal failure. This study was performed to explore whether estrogen has a nephroprotective role against progression of renal failure. This study was carried out on 41 adult female albino rats, that were allocated into 3 groups; Group 1 [n = 10] sham-operated rats, that received the solvent [sesame oil] and used as control group, Group II [n = 17], ovariectomized-subtotal nephrectomized rats [OVX-STNx] without treatment, that received the solvent, group III [n = 14], OVX-STNx rats treated with estrogen, subcutaneous [s.c.] at a dose of 30 micro g/kg/day for 10 weeks, started on the second day after ovariectomy. Mean Blood pressure was measured on the day of sacrifice. Blood urea nitrogen [BUN], serum creatinine, malondialdehyde [MDA] and platelet aggregation were estimated. Kidneys were excised and examined histologically. The results of the present study showed that untreated OVX-STNx rats showed significant elevation in mean blood pressure compared to treated OVX-STNx rats [129 +/- 2.2 versus 97 +/- 3.2 mmHg]. The untreated OVX-STNx rats showed significant elevation in BUN and serum creatinine levels compared to sham-operated rats [85.9 +/- 4.0 versus 19.4 +/- 1.6 mg/dl; and 2.6 +/- 0.13 versus 0.16 +/- 0.02 mg/dl, respectively], while, the treated OVX-STNx group showed significant reduction in BUN and serum creatinine levels, compared to untreated OVX-STNx group [24.8 +/- 1.6 versus 85.9 +/- 4.0 mg/dl; and 0.38 +/- 0.04 versus 2.6 +/- 0.13 mg/dl, respectively]. In addition, serum MDA level was elevated in untreated OVX-STNx group compared to sham-operated and to treated group [6.6 +/- 0.4 versus 3.6 +/- 0.3 and 4.8 +/- 0.3 /micro mol/L, respectively]. Also, ADP-stimulated platelet aggregation showed significant reduction in untreated OVX-STNx group in comparison to sham-operated and to treated group [46.8% +/- 2.6 versus 76.5% +/- 1.8 and 65.1% +/- 3.6 respectively]. Histological examination of the remnant kidney models in untreated OVX-STNx group showed a picture of focal glomerulosclerosis, this finding was minimally seen in treated OVX-STNx group

Chromium, the natural lipid-modulating therapy, protects the rat myocardium against ischemic-reperfusion hazards

This study was carried out on 20 male albino rats weighing 200-250 grams each. They were divided into 2 groups: Group I [n = 10], used as control; Group II [n = 10], chromium supplemented rats at a dose of 20 micro g/ rat/day for 12 weeks. After that, blood samples were collected for estimation of serum triglycerides [TG], total cholesterol [TC], high density lipoprotein-cholesterol [HDL-C] as well as fasting glucose and insulin levels. This was followed by ischemia-reperfusion of isolated hearts. After 30 minutes of reperfusion, the hearts were sent for histopathological examination, LDL-cholesterol [LDL-C] and HDL/total cholesterol ratio were also calculated. The results of this study showed that chromium supplementation induced significant reduction in the levels of serum glucose, insulin, TG, LDL-C and TC accompanied by a significant increase in HDL-C and HDL-C/TC ratio. Chromium supplemented hearts, also showed better recovery of myocardial activity at different periods of reperfusion compared to control hearts in the form of a significant increase in heart rate [HR], peak tension [PT] and myocardial flow rate [MFR] as well as an insignificant reduction in time to peak tension [TPT] and half relaxation time [1/2RT]. Histopathological examination of hearts showed a clear picture of ischemia in control hearts compared to chromium supplemented hearts. We can conclude that chromium supplementation can protect the rat myocardium against ischemic-reperfusion hazards and this may be due to promoting the healthy blood lipid level and reducing fasting insulin levels which may reflect enhancement of tissue sensitivity to insulin