title: Low-frequency transcranial magnetic stimulation is beneficial for enhancing synaptic plasticity in the aging brain.
abstract: In the aging brain, cognitive function gradually declines and causes a progressive reduction in the structural and functional plasticity of the hippocampus. Transcranial magnetic stimulation is an emerging and novel neurological and psychiatric tool used to investigate the neurobiology of cognitive function. Recent studies have demonstrated that low-frequency transcranial magnetic stimulation (≤1 Hz) ameliorates synaptic plasticity and spatial cognitive deficits in learning-impaired mice. However, the mechanisms by which this treatment improves these deficits during normal aging are still unknown. Therefore, the current study investigated the effects of transcranial magnetic stimulation on the brain-derived neurotrophic factor signal pathway, synaptic protein markers, and spatial memory behavior in the hippocampus of normal aged mice. The study also investigated the downstream regulator, Fyn kinase, and the downstream effectors, synaptophysin and growth-associated protein 43 (both synaptic markers), to determine the possible mechanisms by which transcranial magnetic stimulation regulates cognitive capacity. Transcranial magnetic stimulation with low intensity (110% average resting motor threshold intensity, 1 Hz) increased mRNA and protein levels of brain-derived neurotrophic factor, tropomyosin receptor kinase B, and Fyn in the hippocampus of aged mice. The treatment also upregulated the mRNA and protein expression of synaptophysin and growth-associated protein 43 in the hippocampus of these mice. In conclusion, brain-derived neurotrophic factor signaling may play an important role in sustaining and regulating structural synaptic plasticity induced by transcranial magnetic stimulation in the hippocampus of aging mice, and Fyn may be critical during this regulation. These responses may change the structural plasticity of the aging hippocampus, thereby improving cognitive function.
authors.affiliation: Department of Human Anatomy, Hebei Medical University, Shijiazhuang, Hebei Province, China.
authors.forename: Zhan-Chi
authors.initials: ZC
authors.lastname: Zhang
authors.affiliation: Department of Otorhinolaryngology, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Luan
authors.affiliation: Second Surgical Department, Qinghe Public Hospital of Hebei Province, Xingtai, Hebei Province, China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Xie
authors.affiliation: Department of Human Anatomy, Hebei Medical University, Shijiazhuang, Hebei Province, China.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Geng
authors.affiliation: Department of Neurology, First Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China ; Hebei Key Laboratory for Brain Aging and Cognitive Neuroscience, Shijiazhuang, Hebei Province, China.
authors.forename: Yan-Yong
authors.initials: YY
authors.lastname: Wang
authors.affiliation: Department of Human Anatomy, Hebei Medical University, Shijiazhuang, Hebei Province, China ; Hebei Key Laboratory for Brain Aging and Cognitive Neuroscience, Shijiazhuang, Hebei Province, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
keywords: aging; brain-derived neurotrophic factor; cognitive function; hippocampus; neural regeneration; neuroplasticity; neurotrophic factor; non-invasive brain stimulation; transcranial magnetic stimulation