Exercise may alleviate age-related spatial memory impairment by rescuing β-adrenergic receptor dysregulation via both G protein–dependent and β-arrestin–dependent mechanisms in rat hippocampus

Ageing, Cognitive Decline, and Effects of Physical Exercise: Complexities, and Considerations from Animal Models

“…Interestingly, six weeks of moderateintensity treadmill running ameliorated a decline in spatial learning in older-aged mice (18 months), but not in middle-aged (12 months), compared to younger adult mice (3 months) [87]. In conclusion, while physical exercise, both voluntary and involuntary, can improve spatial learning and memory in aged rodents [87,100], others have reported no effects of physical exercise on spatial learning [60,97]. While the reasons underlying these discrepancies are unknown, the exercise type and intensity as well as the inclusion of resistance is likely to play a role.…”

“…For example, both voluntary and involuntary exercise have been found to improve spatial learning in the MWM in older-aged rodents. However, studies have also reported no effects of both voluntary and involuntary exercise on spatial learning in the MWM in male and female older-aged rats [60,97]. Discrepancies in the exercise-induced changes in spatial learning may arise from the intensity of exercise.…”

“…Thus, this finding could be interpreted as an improvement in the general spatial navigation abilities (moving faster in the pool) rather than in spatial learning abilities (learning the platform location in the pool). Besides the beneficial effects of physical activity on spatial learning abilities during older age, studies have demonstrated that physical exercise, irrespective of being voluntary or involuntary, improved age-related spatial memory loss in rats [60,66,97,100] and mice [39,87,96].…”

“…Discrepancies in the exercise-induced changes in spatial learning may arise from the intensity of exercise. For instance, an extremely high intensity of a treadmill exercise protocol (30 m/min) [97] induced no change in learning abilities compared to that reported in studies where enhanced learning abilities through similar treadmill interventions were observed but at lower intensities [66,69,93,101]. The absence of an exercise-related improvement of learning abilities in aged rats may also be linked to the inclusion of resistance in the exercise regimen, as demonstrated by studies where forced swim exercise with resistance showed no impact on spatial learning [60].…”

“…Similarly, older-aged C57/BL mice (19 months) showed impaired spatial learning and memory compared to younger mice [ 96 ]. On the other hand, while older-aged Wistar rats (18 months) exhibited impaired spatial memory compared with younger animals (3 months), their spatial learning abilities were similar to the younger animals [ 97 ]. Individual differences in water maze performance also emerge with increasing age in rats, such that it is possible to distinguish age-impaired and age-unimpaired animals when large groups of animals are used [ 98, 99 ].…”