Dose–Response Effect of Vibratory Stimulus on Synaptic and Muscle Plasticity in a Middle-Aged Murine Model

Abstract

Whole body vibration plays a central role in many work categories and can represent a health risk to the musculoskeletal system and peripheral nervous system. However, studies in animal and human models have shown that vibratory training, experimentally and/or therapeutically induced, can exert beneficial effects on the whole body, as well as improve brain functioning and reduce cognitive decline related to the aging process. Since the effects of vibratory training depend on several factors, such as vibration frequency and vibration exposure time, in this work, we investigated whether the application of three different vibratory protocols could modulate synaptic and muscle plasticity in a middle-aged murine model, counteracting the onset of early symptoms linked to the aging process. To this end, we performed in vitro electrophysiological recordings of the field potential in the CA1 region of mouse hippocampal slices, as well as histomorphometric and ultrastructural analysis of muscle tissue by optic and transmission electron microscopy, respectively. Our results showed that protocols characterized by a low vibration frequency and/or a longer recovery time exert positive effects at both hippocampal and muscular level, and that these effects improve significantly by varying both parameters, with an action comparable with a dose–response effect. Thus, we suggested that vibratory training may be an effective strategy to counteract cognitive impairment, which is already present in the early stages of the aging process, and the onset of sarcopenia, which is closely related to a sedentary lifestyle. Future studies are needed to understand the underlying molecular mechanisms and to determine an optimal vibratory training protocol.

Chronic whole body vibration ameliorates hippocampal neuroinflammation, anxiety-like behavior, memory functions and motor performance in aged male rats dose dependently

“…One study in young adult Sprague–Dawley rats showed that WBV (30 Hz and 4.5 mm amplitude, 30 min/day, 6 days/week for 8 weeks) was able to alleviate the level of microglia-activation induced by severe immobility stress 47 . Furthermore, vibration protocols characterized by variable terms of exposure time, frequency and recovery time (multiple series of 2–3 min long vibration exposure with 1–3 min recovery time and 45 or 90 Hz of frequency) revealed beneficial electrophysiological properties of the mouse hippocampus and muscle plasticity in the early onset of aging process 73 .…”

Whole Body Vibration Improves Brain and Musculoskeletal Health by Modulating the Expression of Tissue-Specific Markers: FNDC5 as a Key Regulator of Vibration Adaptations

“…Our previous studies have shown that vibratory training is an effective strategy to improve brain health and cognitive functions, as well as to counteract muscle atrophy and motor decline related to aging and/or a sedentary lifestyle [ 9 , 16 ]. In agreement, numerous studies over the last decades report among the main benefits of mechanical vibrations those affecting the musculoskeletal system, such as increased bone mass and muscle strength, as well as increased hormonal responses and improved cognitive abilities, anxious and depressive behavior, and neuromuscular adaptation [ 36 , 37 ].…”

“…Furthermore, WBV is currently used as a preventive tool for several diseases, such as osteoporosis, sarcopenia, and chronic low back pain, as well as for improving muscle function and joint stability [ 13 , 14 , 15 ]. In this context, we recently investigated the effects of WBV on skeletal muscle in a group of 12-month-old mice by light and electron microscopy, observing significant variations depending on the vibratory training protocol used [ 16 ]. Again, the most satisfactory results were observed in the group of animals subjected to the vibratory protocol characterized by the lowest frequency, shorter vibration exposure time, and longer recovery period between two consecutive sessions.…”

“…Again, the most satisfactory results were observed in the group of animals subjected to the vibratory protocol characterized by the lowest frequency, shorter vibration exposure time, and longer recovery period between two consecutive sessions. In contrast, a more stressful WBV protocol was correlated with a higher percentage of atrophic fibers, altered sarcomeric structures, and abundant interfibrillar fibrosis [ 16 ]. Similarly, Matsumoto and colleagues studied the effects of low-intensity WBV in 13-week-old mice undergoing tibial perforation, observing an improvement in bone healing induced by an increase in vascular growth [ 17 ].…”

Physical Exercise and Health: A Focus on Its Protective Role in Neurodegenerative Diseases

“…Surprisingly, the same WBV protocol administered to a group of 24-month-old animals resulted not only in a marked improvement in synaptic plasticity, but also in the disappearance of signs related to cognitive decline that characterized sedentary old mice [ 33 ]. Finally, beneficial effects of WBV training have also been observed in middle-aged mice, including an improvement in synaptic plasticity along with a significant increase in muscle fiber diameter and complete preservation of cellular ultrastructure, suggesting vibratory training as a valid strategy for delaying the onset of symptoms related to a sedentary lifestyle [ 34 ].…”