الفهرس 
• Introduction and Aim of the WorkOnly 14 pages are availabe for public view
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Abstract
PYY is produced by the intestinal L-cells, the highest tissue concentrations of PYY are found in distal segments of the gastrointestinal tract, although it is present throughout the gut. Previous studies found that the role of Pancreatic polypeptide family including NPY, and PYY in obesity development and its metabolic changes is controversial due to different routes of administration, multiple receptor involvement with antagonistic effects, and different experimental animals used. Therefore, this study was designed to:
• Investigate the effect of intraperitoneal injection of a potent Y2 receptor agonist; Peptide Tyrosine Tyrosine (PYY3-36) on high fat diet (HFD) induced obesity in adult albino rats of both sexes as well as in ovariectomy induced obesity and its metabolic abnormalities.
• Study the role of NPY in the pathogenesis of either type of obesity by measuring hypothalamic NPY concentration in the rats of the different groups.
• Studying gender differences in the development of HFD induced obesity and the role of pancreatic polypeptides in either sex.
Results:
- The results of the present study revealed that ovariectomy was accompanied with a significantly higher body weight than the sham operated control group from two weeks after ovariectomy till the end of the study. This was accompanied with a significantly higher food intake, lee index, weight of gastrocolic omentum fat (GCOF), serum TC, LDL-c, glucose, leptin and hypothalamic concentration of NPY with a significant lower serum level of HDL-c and TGs.
- The results of the present study revealed that HFD caused a significant higher food intake in the first and second weeks then lowered significantly at the end of the fourth and fifth weeks in obese non-treated groups as compared to control groups. This was accompanied with a significantly higher body weight, lee index, serum TC, TGs, LDL-c, glucose, leptin and weight of GCOF with significant lower serum HDL-c level and hypothalamic NPY concentration.
- The results of the present study revealed that Peripheral administration of PYY 3-36 after induction of obesity in both HFD and OVX rats significantly lowered food intake, body weight, lee index, GCOF weight, hypothalamic NPY, serum leptin and glucose as compared to control groups.
- Concerning the gender difference, in control non treated groups, food intake, body weight, GCOF weight, serum leptin and hypothalamic NPY concentration were significantly higher in males than females associated with significantly lower serum level of HDL-c.
- In the present study, concerning HFD groups, body weight, GCOF weight, lee index, serum leptin, TC, TGs and glucose were significantly higher in males than females.
- In HFD treated groups, the body weight, GCOF weight, serum glucose, TC and TGs were still significantly higher in males than females in the present study.
In conclusion
1- Peripheral PYY3-36 administrations reduced food intake, body weight gain and serum glucose in HFD obese rats of both sexes or in ovariectomized obese female rats. These findings suggest that targeting the PYY system may offer a new therapeutic strategy for obesity management and its metabolic abnormalities.
2- Hypothalamic NPY positively correlates with food intake and obesity development in either type of obesity.
3- Male rats feeding high caloric diet are more vulnerable to gain weight and metabolic disturbances than females. Sex hormone differences are probably the contributing factors with male hormones predisposing to, and female hormones protecting from obesity (obesity follow ovariectomy). The effect of sex hormones could be mediated through hypothalamic NPY.
4- HFD initially stimulated and finally reduced food intake in spite of the gain in weight and metabolic disorder. This probably reflects the hazards of the high caloric value of fatty diet irrespective of the reduced amount.
5- Any single line of obesity treatment (e.g. PYY3-36 administration) will partially but not absolutely correct obesity in the presence of continuous HFD intake. Therefore, diet regimen is a must with other lines of management.