Exercise intensities modulate cognitive function in spontaneously hypertensive rats through oxidative mediated synaptic plasticity in hippocampus

Abstract

Oxidative damage in the brain may lead to cognitive impairments. There was considerable debate regarding the beneficial effects of physical exercise on cognitive functions because exercise protocols have varied widely across studies. We investigated whether different exercise intensities alter performance on cognitive tasks. The experiment was performed on spontaneously hypertensive rats (6 months at the established phase of hypertension) distributed into 3 groups: sedentary, low‐intensity exercise and high‐intensity exercise. Systolic blood pressure measurements confirmed hypertension in spontaneously hypertensive rats. In comparison to normotensive Wistar‐Kyoto rats, sedentary spontaneously hypertensive rats had similar escape latencies and a similar preference for the correct quadrant in the probe trial. Compared to the sedentary group, the low‐intensity exercise group had significantly better improvements in spatial memory assessed by Morris water maze. Low‐intensity exercise was associated with attenuated reactive oxygen species, as measured by dihydroethidine fluorescence and nitrotyrosine staining in the dentate gyrus of the hippocampus. This was coupled with increased numbers of neurons and dendritic spines as well as a significant upregulation of synaptic density. In contrast, the beneficial effects of low‐intensity exercise are abolished in high‐intensity exercise as shown by increased free radical levels and an impairment in spatial memory. We concluded that exercise is an effective strategy to improve spatial memory in spontaneously hypertensive rats even at an established phase of hypertension. Low‐intensity exercise exhibited better improvement on cognitive deficits than high‐intensity exercise by attenuating free radical levels and improving downstream synaptic plasticity.

The protective effects of Irbesartan in cognitive impairment in hypertension

“…In our research, old SHR rats were used to investigate hypertension-induced cognitive impairment, with WKY rats taken as the negative control, widely applied by previous studies [ 24 , 25 ]. In line with data presented by Yamada [ 26 ] and Lee [ 27 ], notably increased systolic blood pressure, decreased time of exploring the novel object in the ORT test, and elevated escape latency in the MWM test were observed in SHR rats. Following the administration of Irbesartan, the systolic blood pressure, time of exploring the novel object, and escape latency were markedly reversed in SHR rats, implying an alleviative property of Irbesartan on hypertension-induced memory and cognitive impairment in SHR rats.…”

The impact of aerobic and resistance training intensity on markers of neuroplasticity in health and disease

“…Exercise generates reactive oxygen species that can cause molecular damage. Reactive oxygen species-generation is exercise intensity-dependent in a way that low-vs. high-intensity chronic (long-term) exercise produces less reactive oxygen species (Lee et al, 2021;Radak et al, 2013). In addition, spatial memory, hippocampal neurogenesis and brain-derived neurotrophic factor levels changed independently of exercise intensity in rats (Okamoto et al, 2021) and the levels of key brain NP markers increased in the hippocampus without improving cognitive function (Constans et al, 2021).…”

Cognitive Fitness: Harnessing the Strength of Exerkines for Aging and Metabolic Challenges

“…While the specific effect of exercise intensity on CX3CL1 in the context of CI is not directly addressed in the available literature [ 99 ], the studies provide insights into the potential impact of exercise and related peptides on neuroinflammation and immune responses [ 90 , 95 , 99 ], which are relevant to the broader understanding of the topic. Further research specifically focusing on the relationship between exercise intensity, CX3CL1, and CI is warranted to draw more definitive conclusions.…”

“…Recent findings collectively suggest that exercise intensity can influence oxidative stress [ 138 ], and higher intensities of aerobic exercise would be the best in reducing oxidative stress [ 90 , 99 ].…”