The Effect of Eight-week High Intensity Interval Training with Hind Limb Suspension on the Level of GFAP and O4 in Glial and Neuronal Stem Cell of Male Rats

Nerve stem cell transplantation is one of the effective strategies for repairing nerve lesions. Oligodendrocytes are myelinated cells located in the central nervous system and are involved in the formation of myelin axons (8). Oligodendrocytes express O-A proteins, especially O4, which is a marker for the cell body and oligodendrocyte processes, during differentiation and maturation in the central nervous system (29). The results of some studies have shown that glial cells that express only O4 protein have the potential to become precursors of astrocytes and oligodendrocytes and can increase the growth stages in stem cells (29). Glial fibrillary acid protein (GFAP) is known as a specific marker for the identification of astrocytes in the central nervous system. This protein is the main cytoskeleton constituent of astrocytes (27) and plays an important role in maintaining, repairing and maintaining the white matter integrity of the central nervous system as well as the blood-brain barrier (35). The aim of this study was to compare the effect of High intensity interval training with hind limb suspension on the level of GFAP and O4 in glial and neuronal stem cell of male rats.

Twenty-four male wistar rats (body weight = 189.25 ± 5.71g.) were randomly divided into four groups: HIIT+HLS (n= 6), HIIT (n= 6), HLS (n= 6) or CON (n= 6). The exercise protocol was performed on a rodent treadmill for 6 weeks, 5 sessions per week. The rats were sampled and studied 24 h after last training session. Glial fibrillary acidic protein (GFAP) and monoclonal antibody O4 (O4) were analyzed before and after the training interventions.To suspend the lower limb, the animal's tail was first cleaned and dried using cotton and alcohol. Then two-thirds of the mouse tail was taped longitudinally from the beginning to the end third. Next, three pieces of kinesio-tape were placed transversely on the mouse tail, so that normal blood flow was not disturbed. We attached the upper end of the kinesio-tape to the suspension hook and then has been attached the hook to the cage movable bar chain so that the angle between the animal's chest and the floor of the cage is 30 degrees and the mouse legs do not come into contact with the floor of the cage. The suspension system, including a movable bar, pulley and hook, was mounted on top and on both parallel sides of the cage, allowing the animal to have full access to all parts of the cage by moving freely around a 360-degree axis. Data analysis was used using Shapiro-Wilk and Levine tests to investigate the natural distribution of data and homogeneity of variances and one-way and post-hoc Bonferroni statistics to test research hypotheses.

The results suggested that the percentage of changes in the amounts of fibrillary acidic protein of the cerebral hippocampus of the brain in the intense interval training group + group under the conditions of the hind legs compared to the control group showed a significant decrease (p≥0.001). Also, the percentage of changes in cerebral hippocampal glial fibrillary acid protein in the lower extremity suspension group increased significantly more than the control group (p≥0.001), but the percentage of changes in this protein in the intense interval training group compared to the group There was no significant difference in control (p≥1,000).The results of the data obtained from the percentage of changes in the O4 protein of the cerebral hippocampus of the groups showed that this change was significantly lower in the group of intense interval training with the conditions of the hind limb suspended than the control group (p≥0.001). Also, the percentage of O4 changes in the cerebral hippocampus in the lower extremity suspension group was significantly higher than the control (p≥0.001). In addition, the percentage of changes in the intense interval training group was not significantly different from the control group (p≥0.465).

The results of this study revealed that HIIT+HLS was being able to prevent damage to the cells of the central nervous system and direct the neural stem cells towards the production of neurons, astrocyte and oligodendrocyte.Mesenchymal stem cells are currently the main choice for cellular treatment of neuropsychiatric diseases. Mechanical stimuli have been reported to play a decisive role in the final fate of stem cells and their cell differentiation pathways, so that the path and flow of induced signals and activated factors determine cellular fate in time, position, and mediate an appropriate number (36). Studies have shown that the proliferation, differentiation, and cytoskeleton organization of stem cells are affected by microgravity and tend to produce neurons or nerve cells (31). Astroglia cells also act as neuronal stem cells and participate in neurogenesis. Evidence suggests a very important role for these cells during plasticity. These cells are involved in the neurogenesis of the adult mammalian brain in the ventricular region, and in the sub-granular region and the olfactory bulb. On the other hand, previous research has shown that lactate production during intense interval trainings and suspension of hind legs can play an important role in the development of oligodendrocytes and myelination, so that increasing lactate production as a substrate in myelination, and used by the nervous system. Considering this issue, it is possible to use this exercise mode in the condition of lower limb suspension as a treatment method or non-pharmacological supplement effective in neuromuscular disorders and other related diseases, to enhance fitness in athletes, improve injury and also prevention of adverse effects of being in weightlessness, especially on space missions.In general, the results show that intense interval training with hind leg suspension conditions had a greater effect on health and no damage to the hippocampus of the brain of a healthy male rat than other groups (intense interval, suspension or control group). Since no research has been done on the effect of intense interval training under the conditions of hind limb suspension on cellular changes in the hippocampus and human brain, judgment in this regard needs further study. Findings of this study may help in the rehabilitation process of people with neuromotor disorders, injured athletes, the elderly, sedentary people, as well as the conditioning program of athletes in various sports to adapt to the use of such exercises.