Effect of Caloric Restriction on Lipoprotein Lipase Expression in Adipose Tissue of Ovariectomized Rats

Objective: Study the adipose tissue distribution and the associated metabolic dysfunction in ovariectomized rats. We will also investigate the role of lipoprotein lipase gene expression on adipose tissue distribution and compare the possible protective effect of estradiol replacement low caloric diet. Material and Methods: Adult female albino rats were randomly divided into Group I (Control-sham operated); Group II: Ovariectomized (OVX); Group III: Ovariectomized + estradiol therapy (OVX+E2) and Group IV: Ovariectomized + hypocaloric diet (OVX+D). Six weeks after ovariectomy, animals were weighed and blood samples were collected. Animals were sacrificed and subcutaneous and visceral adipose tissue depots were dissected. Visceral fat depot was weighed. Plasma estradiol; lipid profile (cholesterol-TGs-HDL-LDL); glucose and insulin levels were measured. HOMA-insulin resistance index was calculated. Lipoprotein lipase gene expression was measured in subcutaneous and visceral adipose tissue. Results: Our results revealed that ovariectomy caused a significant rise in body weight, visceral fat depot weight, plasma glucose, plasma insulin, HOMA-IR index, plasma cholesterol, TGs and LDL levels and a significant decline in plasma HDL level relative to control group. This effect was reduced by estradiol treatment and low caloric diet. Corresponding values in estradiol and low caloric diet groups showed a non significant difference for all parameters except for plasma TGs level which was significantly elevated in low caloric diet group. Our results also revealed that LPL gene expression level showed a non significant difference in OVX + E2 and OVX + D group compared to OVX group. On the other hand, estradiol injection, low caloric diet could significantly lower LPL gene expression in VAT compared to OVX group. Caloric restriction LPL gene expression in VAT showed a significant elevation while in SCAT showed a non significant difference compared to estradiol group. Conclusion: Estradiol replacement and low caloric diet both have a protective effect against the increase in body weight, visceral adiposity and metabolic complications observed after ovariectomy. Thus, we can recommend low caloric diet as a safe substitute for HRT which was reported to have additional consequences including hormone-dependent cancer.