الفهرس 
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Abstract
The present study was conducted to evaluate the effect of dietary zinc and chromium supplementation on rats with diabetic nephropathy. Male albino rats (n=30) weighing 180±5g were divided into two main groups; first group: negative control (n=6) was fed on standard diet, and the second group: diabetic rats (n=24). Diabetes was induced by a single intraperitonial injection of STZ (40mg/kg body weight).
This group of rats was divided equally to four groups as follows:
group (1): Rats were fed on basal diet only, “negative control”.
group (2): Diabetic rats were fed on basal diet only, “Positive control”.
group (3): Diabetic rats were fed on basal diet supplemented with zinc carbonate by (0.5%) diet.
group (4): Diabetic rats were fed on basal diet supplemented with chromium picolinate by (0.5%) diet .
group (5): Diabetic rats were fed on basal diet supplemented with both zinc carbonate by (0.5%) diet plus chromium picolinate by (0.5%) diet.
Each rat was weighed at the initial and the end of experiment and feed intake also was recorded daily, respectively. Atthe end of the experimental period (6 weeks), rats weresacrificed and blood samples were collected thencentrifuged to obtain serum. Biochemical analysis ofserum minerals (Zn,Cr), glucose and insulin serumwere determined. Some organs such as liver, kidney , spleen , heart and lung were carefully removed from each rat , cleaned from the adhesive matter then weighted for the determination of organs to body weight percent.
The obtained results could be summarized as follow:
1. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Body Weight (BWG%) and Feed Intake( FI) Efficiency Ratio (FER)inRats with Diabetic Nephropathy:
All groups fed on diet supplemented with zinc, chromium and thier mixture had significant increase in BWG% compared with the control negative group except the group ingested the mixture (group 5 ), showed reduction in the BWG% compared with the control negative group . Data in the same table revealed that best body weight gain percent was seen when rats were ingested diet supplemented with chromium at 0.5 % level with mean value of 16.33±1.30 (group 4 ).
Concerning food intake (FI) , it has been shown that it was increased as a result of diabetic induction (group 2 ) with mean value of 24 g . Athough food intake for rats ingested diet supplemented with a mixture of zinc and chromium was high ( 24 g ) , but the BWG % was reduced significantly compared with the positive control group suffering from diabetes .
On the other hand, feed efficiency ratio (FER), it has been shown that there was non significant increase in the levels of FER of the group 3 and group 4 compared to the control positive group (group 2 ) . however , rats fed on the mixture (group 5 ) had significant decrease in the level of FER compared to the control positive group (group 2). Also , there is a significant (P<0.05) decrease in the level of FER for the group of rats ingested the mixture compared with the groups had chromium supplementation in the diet .
2. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Blood Glucose Level and Insulin Activity and Glycated Haemoglobinin Rats with Diabetic Nephropathy:
Glucose concentration in the blood increased significantly as a result of diabetic induction (group 2 ) compared with the normal rats (group 1 )
When rats were ingested diets supplemented with zinc , chromium separately or as a mixture , their blood glucose levels were reduced significantly in all tested groups compared with the positive control group.
It could be observed that insulin level was reduced significantly as a result of diabetic induction (group 2) . When rats were fed on diets supplemented with the tested minerals separately or as a mixture , their insulin concentration in the blood were increased significantly , compared with the positive control group.
The best result for insulin activity was seen when rats were fed on diet supplemented with zinc and chromium as a mixture (group 5 ).
Concerning glycated haemoglobin (HbA1c) concentration in serum , results show that the normal rats had 4.26±0.272 % . However , this percent was increased when rats were become diabetic with mean value of 7.50±0.360 % , significantly( positive control group) (group 2). Results illustrated that zinc , chromium and their mixture reduced the elevated concentrations of HbA1c at all tested levels gradually , with the best reduction when rats were ingested the diet supplemented with the mixture of zinc and chromium with mean value of 5.06±0.088 % .
It could be concluded from our results that diets supplementation reduced the elevated level of glucose as well as glycated haemoglobin in the serum of all tested groups. However, increased the activity of insulin .
3. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Kidney Functions in Rats with Diabetic Nephropathy:
The induction of diabetes nephropathy (control positive) caused significant (P≤0.05) increase in the levels of urea, uric acid, creatinine and blood urea nitrogen (BUN) compared with the normal control rats (negative group). Data revealed significant (P≤0.05) decrease in the mean values of urea, uric acid, creatinine and BUN when rats were fed on zinc, chromium and their mixture, compared with the control positive group.
It is clear from our results that there were non significant differences in the levels of urea, uric acid and creatinine in the blood among tested groups fed on zinc , chromium and their mixture in the diet .
4. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Liver Functions inRats with Diabetic Nephropathy:
When rats were become diabetic the control positive group showed significant (P≤0.05) increase in the levels of serum Aspartate aminotransferase (AST) concentration, Alanin aminotransferase (ALT) concentration and alkaline phosphatase (ALP) compared with the normal control (negative group) . Rats were fed on basal diet supplemented with zinc, chromium and their mixture had significant (P≤0.05) decrease in the mean value of serum levels of AST compared with the control positive group There was non significant differences in the activity of AST between group of rats ingested diet supplemented with zinc (group3)and the other had chromium (group 4 ) . However, there was significant (P<0.05) reduction in the AST activity when rats were ingested the tested two minerals as a mixture (group5) compared with the other tested groups .
Also , there was a significant (P≤0.05) decrease in levels of ALT activity when rats were fed on diet supplemented with zinc, chromium and their mixture compared with the control positive group .The best result was seen when rats were fed on the diet supplemented with the mixture of zinc and chromium.
Data in the concerning the ALP concentration in serum showed the same trend . When rats were become diabetic the level of ALP was increased significantly compared with normal rats (negativegroup).
The concentration of ALP in all tested groups were reduced as a result of ingesting diets supplemented with zinc, chromium or their mixture .
5. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Relative Organs Weight % in Rats with Diabetic Nephropathy:
Results revealed that liver relative weight % was increased significantly as a result of diabetic induction (group2), compared with the normal control rats. when rats were fed diets supplemented with chromium the liver relative weight % was reduced and become close to the normal rats . Also, rats fed on a diet supplemented with the mixture of zinc and chromium improved the liver relative weight % to the normal value .
Concerning relative kidney weight%, there was a significant increase in kidney relative weight % when rats become diabetic ( group 2 ) . However, kidney relative weight % was reduced when rats were fed on zinc in the diet . On the contrary, the relative weight of kidney was increased when rats were ingested chromium in the diet then it was reduced when they had the mixture of zinc and chromium as a mixture in the diet significantly ( p ≤ 0.05 ).
the spleen relative weight %, from the results the spleen weight was increased significantly when rats become diabetic. The best result was seen when rats were ingested zinc and chromium in the diet as a mixture.
Concerning heart relative weight %, the organ weight was not affected by the treatment. However, it was decreased significantly when diet was introduced with the mixture of zinc and chromium.
6. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Serum Lipid Profile in Rats with Diabetic Nephropathy:
Feeding rats on the control positive group diet caused significant (P≤0.05) increase in the levels of triglyceride (TG) and total cholesterol (TC) compared with the control negative group. Rats were fed on basal diet supplemented with zinc, chromium, and their mix had significant (P≤0.05) decrease in the mean value of TG compared with the control positive group. In addition, significant (P≤0.05) decrease in the levels of TC was observed in the groups fed on zinc, chromium and their mixture compared with the control positive group.
Rats fed diets supplemented with zinc , chromium and their mixture reduced the elevated levels of TG . However, there were non significant differences in levels of TG among all tested groups. Also, there were non significant differences in serum TC among the groups of fed zinc, chromium and their mixture.
The highest decrease in the levels of TC was recorded in the group fed on the mixture of (zinc and chromium) compared with the other treated groups. But, the highest decrease in the level of TG was recorded in the chromium group compared with the other treated groups.
High density lipoprotein cholesterol (HDL-C) levels were increased significantly when rats were fed diets supplemented with zinc , chromium and their mixture . However, its concentration was decreased significantly when rats were become diabetic.
The results in the same table showed that control positive group )2( showed significant (P≤0.05) increase in the levels of LDL-C and VLDL-C compared with the control negative group. The diet supplementation to the rat groups had significant (P≤0.05) decrease in the levels of LDL-C and VLDL-C compared with the control positive group. Whereas, rats fed on zinc, chromium and their mixture had significant (P≤0.05) increase in the levels of HDL-C compared with the control positive group. The results indicated non significant differences in levels of LDL-C in zinc group, chromium group and the mix group. Likewise, there were non significant differences in levels of VLDL-C and HDL-C among all the treated groups.
The highest decrease in the level of LDL-C was found at the mix group. But, the highest decrease in the level of VLDL-C was found at chromium group. Moreover, the highest increase in the level of HDL-C was recorded at the mix group.
7. Effect of Dietary Zinc, chromium Supplementation and their Mixture on Serum level of chromium and zinc of Rats with Diabetic Nephropathy:
Serum elements (Zn and Cr) concentrations were significantly (P<0.05) decreased as a result of STZ injection (group 2) compared with the negative control normal rats ( group 1).
When rats were ingested diets supplemented with zinc , chromium separately or as a mixture , their serum level of chromium were increased significantly, compared with the positive control group (group 2).
The best result for chromium was seen when rats were fed on diet supplemented with zinc and chromium as a mixture (group 5 ).
serum level of zinc, It could be observed that serum level of zinc was reduced significantly as a result of diabetic induction (group 2) . When rats were fed on diets supplemented with the tested minerals separately or as a mixture, their serum level of zinc were increased significantly, compared with the positive control group .
The best result for zinc was seen when rats were fed on diet supplemented with zinc and chromium as a mixture (group5)