Olive Leaf Extract Elevates Hepatic PPARαmRNA Expression and Improves Serum Lipid Profiles in Ovariectomized Rats

Abstract

We hypothesized that olive leaf extract might alleviate dyslipidemia resulting from estrogen deficiency. Serum lipid profile and mRNA expression of the related genes in the liver and adipose tissue were analyzed after providing olive leaf extract (200 or 400 mg/kg body weight; n = 7 for each group) to ovariectomized rats for 10 weeks. After 10 weeks' administration, the rats in the olive leaf extract-administered groups showed significantly lower levels of serum triglyceride and verylow-density lipoprotein (VLDL)-cholesterol compared with the rats in the control group, whereas the administration of olive leaf extract did not significantly change the elevated low-density lipoprotein cholesterol levels. In addition, administration of high dose of olive leaf extract significantly decreased the liver triglyceride and increased serum estradiol levels. mRNA expressions of peroxisome proliferator-activated receptor alpha (PPAR a) and acyl-CoA oxidase (ACO) were not affected by ovariectomy, however, administration of olive leaf extract significantly increased both PPAR a and ACO mRNA expression. Expression of adiponectin mRNA in adipose tissue was significantly decreased in the ovariectomized control group. Rats administered lowdose olive leaf extract showed significantly elevated adiponectin mRNA expression compared with rats in the ovariectomized control group. Even though dose-dependent effects were not observed in most of the measurements, these results suggest that genes involved in lipid metabolism may be regulated by olive leaf extract administration in ovariectomized rats.

Olive Leaf (<b><i>Olea europaea L. folium</i></b>): Potential Effects on Glycemia and Lipidemia

“…In a study supporting these results, it was found that daily 20 mL olive leaf extract supplementation given to 29 healthy male participants changed expression level of early growth response protein 1, cyclooxygenase-2, and inhibitor of DNA binding 3 genes in peripheral blood mononuclear cells [47]. A study conducted with ovariectomized rats showed that olive leaf extract supplementation at the doses of 200 or 400 mg/kg body weight decreased serum triglyceride level particularly at high doses [48]. Furthermore, it was determined that 1-10 µg/mL concentration of oleuropein and hydroxytyrosol extracts inhibited ROS and protected cardiomyocytes against toxicity and carbonyl stress induced by 4-hydroxynonenal [13].…”

“…Potential effects of olive leaf on lipid metabolism and inflammation emerge by means of metabolic pathways and inflammationrelated genes [13,[47][48][49][50]. In a study supporting these results, it was found that daily 20 mL olive leaf extract supplementation given to 29 healthy male participants changed expression level of early growth response protein 1, cyclooxygenase-2, and inhibitor of DNA binding 3 genes in peripheral blood mononuclear cells [47].…”

Potential Health Benefits of Olive Leaf

“…Ayrıca yüksek dozda zeytin yaprağı ekstresi alımının serum östradiol seviyesini anlamlı ölçüde arttırdığı belirtilmiştir. 34 24 tavşan üzerinde yapılan başka bir çalışmada yüksek yağlı diyet verilen ve oleuropein destekli normal diyet verilen tavşanlara 6 haftalık bir ça-lışma sonucunda serum trigliserid, total kolesterol, LDL ve HDL düzeyi ile malonaldehit seviyeleri karşılaştırılmıştır. Aynı zamanda 6 haftanın sonunda aterosklerotik lezyonlar ve intima kalınlı-ğına bakılmıştır.…”

Peroxisome Proliferator-Activated Receptor α in Lipid Metabolism and Atherosclerosis

“…It is suggested that fenofibrate significantly decreases VLDL secretion in male Wistar Unilever rats fed the diets containing fructose [78]. Exposure of ovariectomized rats to olive leaf extract for 10 weeks has been shown to lower plasma VLDL-cholesterol (VLDL-C) levels by upregulating PPARα mRNA expression [79]. In a Brazilian elderly population, C allele of PPARα is associated with lower plasma VLDL-C levels as compared to G allele, indicating a protective role for the PPARα C allele in reducing cardiovascular disease risks [80].…”