Ursolic acid regulates aging process through enhancing of metabolic sensor proteins level

Abstract

We previously reported that Ursolic Acid (UA) ameliorates skeletal muscle performance through satellite cells proliferation and cellular energy status. In studying the potential role of the hypothalamus in aging, we developed a strategy to pursue UA effects on the hypothalamus anti-aging proteins such as; SIRT1, SIRT6, PGC-1β and α-Klotho.

In this study, we used a model of aging animals (C57BL/6). UA dissolved in Corn oil (20 mg/ml) and then administrated (200 mg/Kg i.p injection) to mice, twice daily for 7 days. After treatment times, the mice perfused and the hypothalamus isolated for preparing of tissue to Immunofluorescence microscopy.

The data illustrated that UA significantly increased SIRT1 (∼3.5 ± 0.3 folds) and SIRT-6 (∼1.5 ± 0.2 folds) proteins overexpression (P< 0.001). In addition, our results showed that UA enhanced α-Klotho (∼3.3 ± 0.3) and PGC-1β (∼2.6 ± 0.2 folds) proteins levels (P < 0. 01). In this study, data were analyzed using SPSS 16 (ANOVA test).

To the best of our knowledge, it seems that UA through enhancing of anti-aging biomarkers (SIRT1 and SIRT6) and PGC-1β in hypothalamus regulates aging-process and attenuates mitochondrial-related diseases. In regard to the key role of α-Klotho in aging, our data indicate that UA may be on the horizon to forestall diseases of aging.

Introduction

Ageing is characterized by the gradual and overall loss of various physiological functions, leading to the end of lifespan [1]. Researchers have now uncovered an area in the brain about the size of an almond in humans that wields powerful control over the body’s aging process [2]. The hypothalamus is a critical anatomical site in which cells monitor changes in energy status of the body and trigger responses aimed at maintaining metabolic homeostasis as well as controls a number of hormones that influence development, growth, metabolism and reproduction [3]. Previous research has also shown that an unhealthy hypothalamus can lead to disorders associated with aging such as glucose intolerance and hypertension [1]. It has been reported that many aspects of aging are controlled by the hypothalamus. They excitingly declared that, it in addition to the increase longevity, enhancing of Sirt1 protein levels might also one day be a strategy to combat neurodegenerative diseases associated with aging [4].

With regard to the role of small molecules in enhancing of sirtuin activities, including Caloric Restriction (CR) mimetics and NAD⁺ derivatives, which promising strategies to ameliorate age-related diseases [5]. Hence, according to our previous study; UA, a triterpenoid compound which found in apple peels and has many biological effects such as; anti-diabetic, anti-inflammatory, anti-HIV and hepatoprotective [6], led to decrease in cellular energy status, up-regulating of Sirt1 and PGC-1α genes overexpression [7]. Furthermore, rejuvenating effects of UA on the skeletal muscle tissue through satellite cells proliferation, enhancing of myoglobin protein level, switching of fiber typing toward fast-oxidative IIA and neomyogenesis [7] made a new avenue to appraise metabolic sensor proteins as like as Sirt1 and Sirt-6 in hypothalamus. Besides, based on the critical role of hypothalamus in maintaining of energy homeostasis and crosstalk between peripheral organs and the central nervous system and because of Glucose, lipids and amino acids are metabolized in the mitochondria and defects in mitochondrial function may contribute to nutrient over load causing cellular damage as typically associated with obesity, insulin resistance, cardiovascular disease, neurodegeneration or accelerated aging [8]. Accordingly, we devised an experiment to evaluate Peroxisome­-proliferator­-activated­-receptor γ coactivator 1 beta (PGC­-1β) which regulates mitochondrial biogenesis and function through its coactivating effects on specific nuclear receptors [9]. Finally, we examined an anti-aging hormone as well, α-Klotho, which restrains the aging-like phenotypes [10].

Consequently, in this survey we used aged-mice C57BL/6 and evaluated UA on the metabolic sensor proteins. Due to the prominent role of hypothalamus in managing of aging process, our decision was to appraise the anti-aging biomarkers with Immunofluorescence (IF) microscopy, a robust and broadly applicable method generally used by researchers to assess both the localization and endogenous expression levels of proteins of interest.