Investigation of effects of various quantities of yucca shidigera powder added to diets on plasma leptin, insulin, thyroid hormones and some biochemical parameters in rats.

Although, hypocholesterolemic, hypoglycemic, anti-inflammatory, and antiprotozoal effectsof saponin containing plants have been investigated largely, studies in their interactions withhormones playing a role in energy metabolism, are rare. The present thesis was carried out toinvestigate the effects of Yucca schidigera, which contains steroid saponin, on metabolichormon levels and certain biochemical parameters. Our study was carried out on 15 Sprague-Dawley rats, aged 2-3-months-old divided into 3 groups as a control and 2 study groups.While control group (CG) was fed with standard rat diet; 100 ppm Y. schidigera group (100ppm YS) was fed with standard rat diet + 100 ppm Y. schidigera powder (Sarsaponin 30®)whereas 200 ppm Y. schidigera group (200 ppm YS) was fed with standard rat diet + 200 ppmY. schidigera powder (Sarsaponin 30®) for 30 days ad libitum.In our study, plasma leptin level was elevated in both study groups compared to the CG group(p=0.000). Addition of Y. schidigera has elevated plasma insulin levels in both study groupscompared to that of CG (p=0.007). Except the plasma ST3 and ST4 levels in animals fed on100 ppm YS, all the thyroid hormon indicators in both study groups showed a statisticallysignificant drop compared to CG (TT3 (p=0,015), ST3 (p=0,021), TT4 (p=0,022) and ST4(p=0,019). Plasma glucose levels showed a statistically significant decrease in both studygroups (p=0,029). While in groups fed with Y. schidigera; plasma total cholesterol (p=0,000),triglyceride (p=0,000) and LDL (p=0,000) levels were statistically lower than the CG group;plasma HDL (p=0,002) level was found to be statistically high. Hundred ppm addition to dietcaused more drop in cholesterol level than that of 200 ppm YS addition. On the the otherhand, 200 ppm YS has decreased the plasma triglyceride and LDL levels more than that of100 ppm YS, albeit not at a significant amount. Our results show Y. schidigera added group ascausing an increase in plasma HDL levels. This result reported a HDL elevation, which differsfrom other studies reported HDL as unchanged. Plasma urea nitrogen level was determined tobe statistically low in study groups compared to the CG group (p=0,000). Plasma total proteinlevel was decreased without statistically in study groups compared to the CG (p=0,134); againnot statistically significant, β-carotene level was increased (p=0,366) and serum vitamin Alevel was dropped (p=0,693).The cause of the significant elevated plasma leptin levels are thought to be due to saponins,phenolic agents, fiber, resveratrol, and stilbenes. Because increase in insulin level cause bloodglucose to be stored as glycogen in liver and as fatty acid in fat tissues and thus elevating thefeed conversion ratio and productivity; hypoglycemic and hypocholestrolemic effects of Y.schidigera may be of use in suppressing the development of diabetes mellitus in pet animals.Elevated plasma HDL levels shown in our thesis present a different reference regarding therelated literature and may indicate an important support against atherosclerosis and othercardiovascular problems. Y. schidigera, attracting attention for its steroidal saponin content,may contribute to development of yield performance through binding of cholesterol andammoniac, inhibiting urease activity, and regulating nitrogen mechanism. Because Y.schidigera applied to the rations of the rats not reduced the protein absorption and digestionsignificantly, and slightly elevated the serum β-carotene levels, antioxidant status of it can beconsidered as positive effects.In conclusion, obtained data may contribute to methods of preventive medicine in preventingdigestive disorders and regulating energy metabolism and hormonal functions. Furthermore,while Y. schidigera is considered to be a new phytochemical nutrient for human being, it isalso thought to be a new ration component for animals.Key words: Yucca schidigera, Steroidal Saponin, Leptin, Insulin, Thyroid Hormones,Antioxidant, Fytochemicals.