The Effect of Resistance Training and Date Pollen Extract on Bone Tissue Density and Osteoblast Cell Proliferation in Young Male Rats

One of the tissues that is affected by physical activity is bone. Bone is one of the tissues that needs to receive mechanical load to have normal function as a key factor in strengthening bone mass (2). Evidence shows that the mechanical load resulting from physical activity activates a set of proteins involved in the process of osteoblast activation and inhibits osteoclasts. One of these proteins is osteonectin. It is commonly used as a serum marker of osteoblastic bone formation and is believed to regulate minerals in the bone matrix, but now new genetic and pharmacological evidence also points to the hormonal role of this protein (5).Osteopointin, on the other hand, accounts for about 2% of non-collagenous bone proteins and is synthesized mainly by osteoblasts as well as bone-forming cells, bone cells and other hematopoietic cells in the bone marrow (7). Another important factor in the ossification process is ALP, a membrane-bound tetrameric enzyme found in the plasma membrane of osteoblasts. This substance plays an important role in the formation of osteoids and mineralization by degrading enzymes inhibiting minerals, pyrophosphate at alkaline pH (8).Also, due to their active phytochemical compounds, medicinal plants can affect the formation and destruction of bone tissue through various mechanisms. One of the plants used in traditional medicine for various therapeutic purposes is palm tree pollen. This plant is used to improve infertility and impotence in men and women. Phytochemical compounds such as estrone, α-amirin, triterpenoidal, saponins, flavonoids, estrone, estradiol and estriol are abundant in this plant (15). Therefore, the researcher seeks to answer the question whether resistance training and date pollen extract affect bone tissue density and osteoblast cell proliferation in young males?

For the present experimental study, 36 8-week-old male rats with a weight range of 220 20 20 g were purchased from the Pasteur Institute of Iran and randomly divided into 6 groups: 1) sham, 2) exercise, 3) palm pollen, 4) testosterone. 5) Exercise + palm pollen and 6) Exercise + Testosterone were divided. After one week of adaptation, groups 2, 4 and 6 performed resistance training for four weeks and five sessions per week. Groups 3 and 5 performed 100 mg / kg of date fertilization pollen five days a week. Gavage was also given. Groups 4 and 6 also received 2 mg / kg of testosterone propionate per week peritoneally. Finally, descriptive statistics, Shapiro-Wilk test, two-way analysis of variance and Benferroni post hoc using SPSS software at a significance level of p <0.05 were used for statistical analysis of data.

The results showed that resistance training and drug administration significantly increased osteocalcin gene expression, ALP concentration, ALP gene expression and osteopontin and osteogenesis of femoral bone tissue. Although the highest expression of osteocalcin gene was observed in the group of resistance training and date palm pollen or testosterone enanthate, but the interaction of these two interventions was not statistically significant. It was also found that resistance training (palm pollen and testosterone enanthate) significantly reduced serum ALP. The interaction of these two interventions on serum ALP concentration was significant. Simultaneous resistance training and medication enhanced the reducing effect of each intervention.

In this study, due to resistance training, osteocalcin, osteopontin, ALP, RUNX2 gene expression, ALP protein expression and osteogenesis were significantly increased. While serum ALP showed a significant decrease.The expression of bone matrix proteins, alkaline phosphatase, and osteocalcin appears to increase with the differentiation of osteoblasts, which may lead to bone mineralization and formation. Another reason for the increased expression of acetocalcin gene in this study can be explained by the change in cytokine changes caused by resistance training, especially interleukin-6. Much of IL-6 has been reported to be secreted into the bloodstream from muscle during physical activity, an increase that is essential for increasing physical function capacity. IL-6, on the other hand, triggers signals in osteoblasts to stimulate osteoclast differentiation and the secretion of the bioactive form of osteocalcin into the bloodstream. In general, an increase in interleukin-6 is necessary to increase circulating osteocalcin levels during physical activity (28).Another mechanism of increased expression of osteocalcin gene induced by resistance training in this study can be explained based on the effect of resistance training on oxidative stress. Evidence suggests that regular resistance training can increase antioxidant capacity and reduce oxidative stress (29). On the other hand, increasing oxidative pressure can reduce the process of osteoblast differentiation by activating apoptotic processes in bone (30).In the present study, resistance training increased the expression of osteopontin gene. Along with osteocalcin, acetaminophen is involved in the organization of the extracellular matrix, the coordination of bone cell interactions with the extracellular matrix, and the matrix minerals. Both proteins also play a structural role in bone and determine the tendency of bone to break. As a result, these proteins may regulate the structure and morphology of the entire bone and affect the mechanical properties of bone (36, 37). Like osteocalcin, the mechanical load resulting from resistance training appears to stimulate the expression of the osteopontin gene. It has been shown that the application of mechanical load on bone increases the periosteal of bone by increasing the activation of bone formation processes. In these conditions, mechanical load can stimulate both gene expression and ALP protein expression by activating adult osteoblasts and increase They become (26).On the other hand, date palm extract could increase the expression of the studied genes and the process of osteogenesis. The effect of date palm extract on increasing gene expression of osteocalcin, osteopontin, alkaline phosphatase and osteogenesis can be examined from two perspectives. The first view is the effect of this extract on the motility of LH followed by stimulation of testicular Leydig cells to produce and secrete circulating testosterone. Numerous studies have reported stimulation of testosterone secretion after induction of date palm pollen (45, 46).The view on the effect of date pollen extract on the process of outcomes measured in this study is the antioxidant and anti-inflammatory role of the compounds in this plant material (47, 48). As mentioned about the antioxidant and anti-inflammatory effect of physical exercise and its role on acetoblasts, increasing oxidative stress and inflammation has an inhibitory effect on the differentiation and proliferation of osteoblasts (30). Induction of date palm pollen extract in this way can develop the process of bone formation.