Effect of diet induced obesity and treatment on feed intake, body weight and BMI
In this study there was significant higher food intake in both free diet of HFD and HSD during 4th, 6th and 8th wk (Figure 1) and 10th &12th wk (Figure 2) compared to control diet and this is may be due to HFD causing hyperphagia which similar to human cafeteria diet . The mechanisms for how saturated fat and sugar-based beverages contribute to human obesity are clearly in rats on an HF choice diet, plasma leptin concentrations and proopiomelanocortin mRNA increased and neuropeptide Y mRNA decreased .
Dietary fat possesses a number of characteristics that may contribute to its overconsumption. Both palatability and energy density were contribute to fat hyperphagia and reduced satiation signaling accompanying HFD consumption which could contribute to overconsumption and often leads to obesity. Although HF adaptation promotes short-term overconsumption of a high-energy food (i.e., reduced satiation), it also appears to offer a vital influence in the control of energy metabolism. Long-term HFD eating may promote excessive short-term energy intake by reducing sensitivity to the satiating properties and thus consume more food .
Rats fed high-saturated fat had both hyperglycaemia and hyper-triacylglycerolemia, the same as our model while rats fed high n-3 PUFA only had hyperglycaemia. In this concern various forms of dietary fat differentially change the expression of neuropeptide genes involved in energy homeostasis .
Higher feed intake in HSD may be due to hyperphagia induced by sucrose which affect appetite centers in hypothalamic neuropeptids Y, (NPY) and proopinne melanocortin (POMC) both receive information about nutritional status and level of energy storage through insulin and leptin signaling mediated by specific receptor located POMC and NPY neurons. Sucrose consumption increase calories intake through up regulation of hypothalamic CB1 mRNA and down regulation of NPY mRNA . Also consumption of sucrose solution results in high body weight gain through activation of hunger signals and depression of satiety signals which support our results.
The current data showed significant increase in body weight and BMI especially in the 8th wk in HFD and HSD (Figure 3 &4). Giving of HFD through canula showed significant increase in body weight in accordance with Akiyama et al. .
Increased BW and BMI may be due to increase caloric intake resulting in more adipose tissue deposition than starch diet this result varies between researches due to sex, age, strain. Furthermore HSD appear to induce mitochondrial dysfunction in adipose tissue, which may be related to greater weight gain and metabolic impairment [19, 20].
Garcinia ameliorated feed intake (Figure 2) and significantly decreased BW and BMI (Figure 3&4). These effects of HCA in Garcinia achieved by increasing release/availability of 5 hydroxy tryptamine, or serotonin, also enhance serotonin uptake in the brain . Serotonin, a neurotransmitter implicated in the regulation of eating behavior, appetite control and weight management by curbing appetite, reduction of food intake and inhibiting body fat biosynthesis .
Effect of diet induced obesity and treatment on lipid profiles
HFD and HSD significantly increased TC, TG and LDL levels in comparison with control group (Table 1). These findings may be owed to high fat from beef tallow induced hypercholesterolemia . Dietary sucrose significantly produced hypertriglyceridemia across rats' life span that had free food access or were calorie restricted and may be due to increased secretion of TG and decreased its catabolism . HSD induces hepatic synthesis of TG from glucose and transport it to blood through VLDL and stored in adipose tissue.
There were significant and positive correlation between increased level of LDL and oxidative stress which was demonstrated by high level of MDA (P = 0.02 r = 0.94) (Table 4) and high MDA from lipid peroxidation causing oxidative stress which generally result in increase oxidation of LDL.
Garcinia treatment produces decrement in LDL, TG and TC serum levels. These findings occur as a result of inhibiting effect of hydroxy citric acid on ATP citrate lyase, an enzyme which catalyses extramitochondrial cleavage of citrate to oxaloacetate and acetyl COA. The produced acetyl COA is used in fatty acid synthesis, TC and TG synthesis. The current data suggested that Garcinia has hypolipidemic action causing significant hypocholesterolemic and hypotriglycerdemic effect.
Effect of HFD, HSD and treatment on kidney function
Lifestyle factors and diet play a role in the development of kidney disease in several stages including, progress of obesity and the metabolic syndrome and occurrence of obesity-related glomerulopathy.
HFD and HSD caused significant elevation in serum creatinine a specific indicator of glomerular function and urea level (Table 1) owing to consumption of HFD and HSD which result in metabolic syndrome marked by obesity, hyperlipidemia and associated with oxidative stress and nitric oxide inactivation by reactive oxygen species (ROS) and diminish NO bioavailability  which leading to renal dysfunction, characterizing by high level of creatinine and blood urea nitrogen .
Using HFD (32%) for 10 wk, about one-half develop obesity and mild hypertension, oxidative stress and impaired renal function. Also hydroxynonenal protein adducts in the kidney were highly increased, indicating oxidative stress in the renal tissue .
In obese subject, increased serum creatinine was to be observed suggesting that obesity caused elevation in renal function test and produce proteinuria, concomitantly with other risk factors such as hypertension, diabetes and dyslipidemia .
Obesity is recently acknowledged as an important independent risk factor for kidney disease. This risk is probably explained by renal intracellular lipid accumulation . Also metabolic disorders in obesity associated with high blood pressure, poor glycemic control, dyslipidemia and smoking were considering risk factor for susceptibility of chronic renal disease (CRD). Glomerular hypertension and endothelial dysfunction were regarded as common mechanism of CRD rennin-angiotensin system.
Renal triglyceride accumulated in obese rats accompanied by hypoalbuminemia and elevated blood urea nitrogen. Dysregulated gene expression may result in increased renal collagen cross-linking and lipid accumulation, that may be associated with development of nephropathy in the animal model of type 2 diabetes and obesity .
Feeding HFD to rat resulted in macroscopical and microscopical changes in kidney weight, total kidney volume, changes in medulla and cortex, glomerulus, proximal and distal convoluted tubules .
Visceral and renal fat accumulation through consumption of a HFD leads to marked renal sympathetic activation, which is related to increased responsiveness to central sympathoexcitatory effects of leptin that contributes to the development of hypertension .
Insulin resistance and increased sympathetic nerve activity were implicated in development of glomerular hypertension and endothelial dysfunction . Furthermore hyperinsuliemia induced by obesity cause relaxation of afferent arterioles leading to hyperfiltration of gloumerulus and renal damage , which explained the defect in renal functions in our model of HFD and HSD.
Garcinia treatment enhances renal function as a result of HCA-SX derived from Garcinia cambogia (HCA-SX, Super CitriMax) which attenuated the increased oxidative stress biomarker through reducing lipid peroxidation (MDA) and declining lipid profiles and level of oxidized LDL which generally improved kidney function .
Effect of diet induced obesity and treatment on blood glucose level
Obesity and type 2 diabetes mellitus is correlated with each other, in our experiment significant hyperglycaemia occurred due to HFD (Table 2), which resulted from free fatty acid release from adipose tissue causing peripheral and hepatic insulin resistance initiating T2DM. Furthermore, FFA impair muscle uptake of glucose by competitive inhibition [ &].
HSD has no significant effect on blood glucose level, that result was in accordance with Fukuchis et al.  who reported that rats fed a sucrose diet for 4 wks had significantly larger visceral fat pads and hypertriglyceridemia, however, neither plasma glucose nor insulin levels were significantly higher, while hyperglycemia and insulin resistance occur after 20 wks of feeding HSD.
Relationship between renal disorder and obesity in HFD group was confirmed by hyperglycemia, insulin resistance, decreased production of renal NO and increased oxidative stress which implicated in progression of diabetic nephropathy .
Garcinia significantly improved the hyperglycemia, in HFD, by declining insulin resistance , in this concern Garcinia could be used for management of diabetes, by increasing metabolic pathway via rising glucose oxidation through improving insulin action; also Garcinia promotes glycogenesis and lipid oxidation.
Effect of diet induced obesity and treatment on G6PD activity
G6PD activities were significantly decreased in HFD (Table 2). These findings may be due to hyperglycemia with HFD caused activation of protein kinase A and subsequent increased phosphorylation and inhibition of G6PD activity and hence decreased NADPH which therefore led to increased oxidative stress . G6PD activity and accordingly NADPH level was significantly decreased in diabetic nephropathy.
Our data show that hyperglycaemia during HFD can reduce G6PD activity. Conversely, G6PD insufficiency can promote oxidative stress and impairment of insulin secretion by beta cells. It is suggested that reduced G6PD activity and HFD can aggravate each other, and HFD could be aetiologically associated with reduced G6PD activity.
Lipid peroxidation was significantly increased, while G6PD activity was decreased in HFD group. Oxidative stress due to increased oxidant production and/or decreased antioxidant activity is a critical underlying mechanism. The principal intracellular reductant is NADPH whose production is mainly dependent on G6PD activity.
There was significant increase in G6pD activities in HSD and HSD+G groups p ≤ 0.05 compared with control (Table 2) which may be attributed to metabolic alteration produced from sucrose rich diet, among these changes increased level of G6PD which is the first enzyme of hexose monophsphate pathway and induction of G6pD in paranchymal cells that support the escalating needs for NADPH for synthesis of fatty acids .
Effect of diet induced obesity and treatment on adipose tissue
Our data indicated significant increases in mesenteric, perirenal and epididymal adipose tissues in HFD and HSD group (Table 2). HFD increases the weight of different fat depots resulting in significant decrease in OB-Rb mRNA level .
Adipose tissue functions as an endocrine organ, secreting hormones/cytokines (e.g., leptin) which may trigger renal sodium retention by activating the renin-angiotensin. Furthermore, excess perirenal and visceral adipose tissue may physically compress the kidneys, increasing intrarenal pressures and tubular reabsorption. Ultimately, continuous obesity causes renal structural alteration, glomerular hypertrophy and occasionally focal segmental glomerulosclerosis .
HCA, an active ingredient of Garcinia, reduces food consumption probably by diverting fatty acids and carbohydrates that would have become fat in the liver into hepatic glycogen . This metabolic alteration may send a signal to the brain that result in rising serotonin level concomitant with a reduced appetite. Moreover, using Garcinia causes dispersion of fat which facilitate action of lipase on adipose tissue , suppresses body fat accumulation , inhibit cytoplasmic lipid accumulation and regulates adipogenesis, so eliminates body fat.
Effect of diet & treatment on renal catalase activity
Renal catalase activity was significantly increased in HFD and HSD (Table 3). These findings occur in response to oxidative stress and important to balance the elevated ROS resulting from the activation of biochemical pathway leading to increased level of ROS and increased lipid peroxidation, producing oxidative stress . Increased catalase activity was indicative of elevated ROS and consequently higher oxidative stress.
The increment in renal catalase and MDA offer better understanding and evidence for the relation between obesity and oxidative stress where increased ROS levels generally stimulate antioxidant system as a compensated defense mechanism and are an important trigger for insulin resistance. Some researchers reported that when exposure of alpha cells of pancreas to diabetogenic substance there was increase of catalase activety .
Renal catalase activity reduced after using Garcinia, suggesting the role of HCA-SX to attenuate the increase in oxidative stress, via decreasing feed intake, indicating the antioxidant effect of Garcinia.
Effect of diet induced obesity and treatment on serum and renal MDA
HFD and HSD generated significant increase in blood and renal levels of MDA compared to control group, while Garcinia, significantly decreased levels of serum MDA and renal MDA compared with HFD and HSD group(Table 3) as result of HCA-SX that inhibit ATP citrate lyase which catalyse extramitochondrial cleavage of citrate to oxaloacetate giving acetyl COA which used in fatty acid synthesis, suggesting that Garcinia has hypolipidemic action and reduces MDA in kidney, so HCA improves lipid peroxidation .
Feeding HFD and HSD raised LDL, TC, TG and renal lipid peroxidation (MDA) level which affect on the kidney because MDA act as tissue toxicant metabolites. These changes were monitored by increased level of urea and creatinine, whereas using Garcinia as antiobesity agent decreased TC, LDL and improved kidney function.
A number of reports suggested that ROS overproduction in the kidneys , heart and arteries , was involved in obesity-induced hypertension. However, the role of ROS and NO in the kidney has not been clarified.
The current data showed that TG positively correlated significantly with renal MDA (P = 0.01 and r = 0.96) and catalase (P = 0.003 and r = 0.98) as indicators of oxidative stress, while negatively correlated with renal NO, (P = 0.04 and r = -0.90) (Table 4) suggesting an association between renal lipid peroxidation and obesity associated nephropathy. Furthermore, oxidative stress was increased in HFD and HSD groups as MDA level and catalase activity were increased, while NO level was decreased.
Effect of diet induced obesity & treatment on serum and renal NO level
HFD and HSD significantly decreased serum and renal NO compared with control group (Table 3). Obesity associated with hyperglycemia is a key factor that contributes to the development of diabetes-related microvascular disease both cyclooxygenase1 and cyclooxygenase2 and play a key role in the regulation of cardiovascular function, this increment resulted in rise of oxidative stress and reduction in NO generation in microvessels endothelial cells , suggesting that NO deficiency may contribute to renal vascular congestion and the renal dysfunction progression.
NO synthetase activity in the HFD group was decreased associated with diminished L-arginine transportation . Also adipose tissue has a role in secreting factor that impairs endothelial dependent dilatation via inhibition of NO synthase mediating NO production . Consequently, Garcinia that decreased TG results in replenish of NO level to normal.
NO signalling, which is involved in the regulation of food intake and insulin signalling, is altered in obesity and diabetes. It was suggested that hyperglycaemia impairs glucose and insulin regulation of NO production which occur through AMP-activated protein kinase .
Our data showed negative correlation between renal NO with renal MDA (P = 0.046 and r = -0.88) and renal catalase (P = 0.005 and r = -0.97) as indicator for oxidative stress in kidney tissues (Table 4). These are considering novel data of our known, suggesting that renal oxidative stress associated with lower renal NO initiating glomerular vasoconstriction and favour nephropathy.
We found that NO negatively correlated with MDA and hence its inactivation by ROS and functional NO deficiency in our model. So enhanced ROS-mediated inactivation and sequestration of NO which may contribute to the reduction of bioactive NO in obesity and hypertriglyceridemia.
NO plays an important role in the regulation of renal blood flow to the renal medulla and in the tubular regulation of sodium excretion. Rats fed HFD, resulted in decrease in serum and renal NO production (Table 3), indicating that obese rats are more liable to develop hypertension. Furthermore, HFD -induced defects in NO production may promote the salt-sensitivity of blood pressure, which appears to require more NO to maintain blood pressure during a salt challenge .
NO decreased in HFD and HSD, initiate vasoconstriction that affect the kidney and using methods for controlling obesity generate increased levels of NO and improving state of the involved organs that apparent in our results due to action of NO as vasodilator via using Garcinia.
Physical activity as a method of management of obese person prevent cardiovascular disease by increasing NO production and lessening NO inactivation , which could be comparable with our model of Garcinia used as antiobesity drugs.
Our rat's model was developed obesity and hyperglycemia by 12 wks on HFD and HSD diet. They also developed hypercholesterolemia, profound hyper-triglyceridemia, high urea and creatinine, and renal function disorders. Furthermore, serum NO production was decreased, and homogenates from kidney demonstrated reduced NO. Our data offer novel insights into potential mechanisms of renal dysfunction, oxidative stress and NO in obesity and demonstrate the efficacy of HCA-SX in renal protection and weight management.
Collectively, feeding HFD and HSD to rats resulted in significant elevating in BW, BMI, feed intake, adipose tissue, blood levels of glucose, TG, TC, LDL, MDA and catalase activity while significantly, decreased serum and renal NO levels in our model. All of these parameters implicated in renal disorders, consequently produce adverse effect on kidney, while administration of Garcinia improves these changes as, HCA-SX attenuates the increase in oxidative stress so improves lipid peroxidation which is cytotoxic by reducing free-radical production and by increasing nitric oxide production/availability.