Effects of Eight Weeks of Resistance Exercises on Expression of Neurotrophins and Trk Receptors in Alzheimer Model Male Wistar Rats

Abstract

This study aims to evaluate the effects of eight weeks of resistance exercises on expression of neurotrophins and Trk receptors in Alzheimer model male Wistar rats. For this purpose, 32 mature male Wistar rats with mean weights of 230 to 280 g were chosen and divided into Alzheimer and Sham groups. Rats in the Sham group received normal saline while rats in the Alzheimer group received STZ via intraventricular injection. These rats were then divided into the following four subgroups: 1. Resting Sham, 2. Exercising Sham, 3. Resting Alzheimer, and 4. Exercising Alzheimer. The two exercising rat subgroups, exercised three times a week for a period of eight weeks. A weight was attached to their tails and they had to carry this weight on a 26-step ladder in each cycle. Resting groups were handled every day to minimize the effects of stress level. At the end of the 8th week and 24 hours after the last exercise session (to avoid the effects of the last exercise session), the rats were put under deep anesthesia and scarified by head separation. Hippocampus tissues were precisely extracted and samples were sent to laboratory for molecular and cellular tests. In order to investigate gene expression, Quantitative RT-PCR was used. Results of the tests for comparing the means of BDNF, NT3, NGF, TrkA, and TrkB in two rat groups showed that with error levels of less than 5% and confidence of over 95%, there is a significant difference in the amounts of BDNF, NT3, NGF, TrkA, and TrkB between exercising rats and resting rats. These amounts were much higher in exercising Alzheimer rats group. Eight weeks of resistance exercises increased the expression of BDNF, NT3, and NGF genes as well as TrkA and TrkB receptors in Alzheimer model Wistar rats.

The Counter Effect of Exercise on Cisplatin-Induced Cognitive and Proliferation Impairments

“…Testing the changes in the levels of hippocampal proliferation markers is a supposedly suitable way of testing the effects of different variables on cognitive impairment, namely, memory and its many subtypes. Ki-67 is a direct proliferation marker found to be markedly reduced in the hippocampal samples of cisplatin-treated animals [ 32 ] and, on the other hand, increased in those given an exercise regimen [ 33 ]. In this study, we were able to support both findings concurrently where the total number of positive Ki-67 cells was higher among the exercise group in comparison to the cisplatin group, supporting the effect of exercise in protecting the hippocampal neurogenesis from cisplatin's toxic effects.…”

Associations between grip strength, brain structure, and mental health in > 40,000 participants from the UK Biobank

“…Skeletal muscle plays a crucial role in the production and secretion of many cytokines such as brainderived neurotrophic factor (BDNF) and insulin-like growth factor-1 [14], which are involved in neuronal survival, synaptic development, angiogenesis, learning, and neural plasticity [62]. Higher levels of these peptides have been correlated with greater physical fitness and increased GMV [58], and more importantly, studies showed that resistance activities could stimulate the release of BDNF and evoke neuroplastic changes in frontal and hippocampal regions, which may further translate into cognitive improvements [63][64][65]. Therefore, cytokine-induced alterations in GMV may represent a mechanism through which muscular fitness influences cognition and mental status, yet further research is needed [66].…”

The effects of resistance exercise on cognitive function, amyloidogenesis, and neuroinflammation in Alzheimer’s disease

“…Studies in animal models of AD have also shown the positive effects of RE on memory deficits and cognitive dysfunction (Table 1; Özbeyli et al, 2017;Liu et al, 2020;Pena et al, 2020;Jafarzadeh et al, 2021). Liu et al found that RE could improve cognitive function in AD mice by reducing amyloid load and tau pathology, and attenuating neuroinflammation.…”

“…Özbeyli et al (2017) showed that the improvement in working memory provided by RE may occur via oxidative stress and the antioxidant system. Another study by Jafarzadeh et al (2021) used a model of intraventricular injection of streptozotocin (STZ) in rats and observed that RE improved learning and memory, together with an increase in the expression of neurotrophic factors and their respective receptors. Although by different mechanisms, these studies showed improvements in memory and cognitive deficits in AD experimental models, and corroborate the results from studies with MCI patients.…”

“…RE applied in old animals or animal models of AD, using exercise programs lasting between 4 and 12 weeks, increased BDNF levels in the hippocampus (Özbeyli et al, 2017;Vilela et al, 2017;Jafarzadeh et al, 2021;Kim et al, 2021;Lee et al, 2022;Rahmati et al, 2022). Two of these studies also showed increased levels of exercise-induced NGF (Jafarzadeh et al, 2021;Rahmati et al, 2022) Frontiers in Neuroscience 04 frontiersin.org the brain of resistance-trained animals (Pena et al, 2020). Human studies investigating the effects of RE in the elderly population have indicated that programs with 12 weeks to 6 months of exercise increase peripheral BDNF levels (Roh et al, 2020;Deus et al, 2021;Castaño et al, 2022).…”