1. Introduction
Aging is associated with increased collagen deposition and decreased hepatic mitochondrial biogenesis [1, 2]. Increase in important regulators of Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α (PGC-1α) plays an important role in inhibiting ROS and mitochondrial biogenesis [3]. Aging can also affect the dynamics of mitochondria [4]. Mitochondrial dynamics involves the fission and fusion process. The most important fusion protein is MFn1 [5]. Some studies have shown that a decrease in MFn1 leads to an increase in collagen deposition [6]. Studies have shown that exercise can increase mitochondrial biogenesis [7]. Some studies have shown that resistance exercise causes collagen deposition in the heart [8]. On the other hand, studies have shown that vitamin C is effective in increasing collagen production [9]. Decreased mitochondrial biogenesis is one of the main factors in increasing the aging process and its related damage to body tissues, especially liver tissue. It can be controled by various methods such as exercise and consumption of antioxidants. The aim of this study was to evaluate the effect of exercise and vitamin C intake on PGC-1α, MFn1 and collagen deposition in older rats.

2. Materials and Methods
This is an experimental study conducted on 25 male Wistar rats with 24 weeks of age and 280-320 g of weight, randomly divided into 5 groups of 5 including young control, older exercise, older vitamin C, older exercise + vitamin C, and older control. In the exercise groups, 20 minutes of resistance exercise with ladders and weights were performed for 8 weeks, three days a week, each day for 20 min. In the groups receiving supplementation, daily liposomal vitamin C was administered by gavage per kg/ body weight.
Shapiro-Wilk test was used to evaluate the normality of data distribution. One-way ANOVA was used to examine the differences between groups, and Tukey’s post hoc test was used to determine the location of group differences. All analyses were performed in SPSS v. 22 software considering a significance the level of P<0.05.

3. Results
ANOVA results showed a significant difference between the groups in terms of PGC-1α expression (P=0.001). The results of post hoc test showed that the difference was between the older and young control groups where the level of PGC-1α was higher in the young control group (P=0.001), and also between the older control and older exercise + vitamin C groups where the older exercise + vitamin C group had a higher level of PGC-1α compared to the older control group (P=0.001). There was no significant difference between other groups.
ANOVA results also showed a significant difference between the groups in terms of MFn1 (P=0.001). The results of post hoc test showed that the difference was between the older and young control groups where the level of MFn1 was higher in the young control group (P=0.001). There was no significant difference between other groups.
ANOVA results also showed a significant difference between the groups in terms of collagen deposition (P=0.001). The results of post hoc test showed that that the young control, older exercise, older vitamin C, and older exercise + vitamin C had significantly different collagen deposition compared to the older control group (P=0.001). The difference was also significant between the older exercise + vitamin C and the older vitamin c groups, between the young control and the older vitamin c groups, and between the older exercise + vitamin C and the young control groups (P=0.001) (Figures 1, 2, 3, 4, 5 & 6). 













4. Conclusion
The purpose of this study was to evaluate the effect of exercise and vitamin C intake on collagen deposition and expression of PGC-1α and MFn1 in liver tissue of older rats. Our results showed that aging significantly reduced PGC-1α and MFn1 levels. Resistance exercise combined with vitamin C consumption significantly increased PGC-1α level, but MFn1 was not increased significantly. Resistance training and vitamin C consumption alone had no significant effect on PGC-1α and MFn1 in the older rats. Resistance exercise and vitamin C intake alone were effective in reducing collagen deposition, but their combination led to better results. Wenz et al. reported that an increase in PGC-1α leads to a decrease in muscle collagen deposition and a decrease in fibrosis [10]. Since resistance exercise combined with vitamin C increased PGC-1α, this possibility reduced calcium deposition.
There are few studies on the effects of exercise on mitochondrial dynamics, and the exact mechanism of controlling mitochondrial regeneration is unclear. Studies have shown that PGC-1α is involved in adaptation and response to exercise. Regulation of mitochondrial dynamics is influenced by intracellular metabolic regulators. PGC-1α is one of the most important regulators of energy metabolism and mitochondrial biogenesis, which is involved in mitochondrial regeneration by affecting fusion and fission. In this regard, some studies have shown that acute exercise increases the expression of mRNA and MFn1 protein levels in skeletal muscle, which is in line with the increase in PGC-1α [11]. Laboratory studies have shown that MFn1 expression is significantly reduced in muscle cells lacking PGC-1α [12], while increased expression of PGC-1α stimulates the expression of mRNA and MFn1 protein in cultured muscle cells [13]. Moreover, overexpression of PGC-1α and exercise-induced mitochondrial biogenesis are sensitive to cellular redox. Inhibition of Reactive Oxygen Species reduces the expression of PGC-1α and the expression of mitochondrial biogenesis genes controlled by PGC-1α [14].
Resistance training along with vitamin C consumption in older rats reduces collagen deposition in liver tissue and increases PGC-1α expression.