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Acid-Sensing Ion Channels and Synaptic Plasticity: A Revisit
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
Ming-Gang Liu, Michael X. Zhu, Tian-Le Xu
Synaptic plasticity is a generic term that applies to short- or long-lasting experience- or activity-dependent changes in the efficacy or connection of synaptic transmission in the brain. It can be classified into both functional and structural aspects of synaptic plasticity. For the former, except for LTP and LTD, it also includes short-term plasticity (like paired-pulse facilitation or depression), depotentiaion86, metaplasticity (plasticity of synaptic plasticity)87, and homeostatic plasticity88 (scaling up or down of the synaptic strength in response to reduction or elevation of synaptic activity). For the latter, dendritic spines may undergo activity-dependent dynamic alterations in shape, size, density, or even composition during various behavioral tasks and/or synaptic stimulations84. To date, most studies have focused on the classical LTP, with much less emphasis placed on other forms of synaptic plasticity, although the possibilities that ASICs are equally important for depotentiaion (or metaplasticity) have not been fully excluded. It would be both necessary and exciting in future studies to test these possibilities.
Synapses
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The LTP and LTD mechanisms of the preceding discussion are believed to be a prelude to activity-dependent, structural changes in synapses that can last for years. The synapses mainly affected are those on characteristic, knob-shaped, outgrowths on dendrites known as dendritic spines (Figure 6.16). As can be seen from this figure, the spine shape can vary from stubby, to mushroom-like, to spindly with a thin and relatively long neck. The spine length varies between a fraction of a µm and few µms, the neck diameter being generally less than 0.1 µm, and the head volume ranging from 0.01 µm3 to 0.8 µm3. Spines are commonly found on the dendrites of most principal neurons in the brain. Neocortical and hippocampal pyramidal cells (Section 7.1) have tens of thousands of spines that may constitute up to about 40% of the total dendritic membrane area. Cerebellar Purkinje cells are believed to have more than 100,000 spines comprising about 75% of the total membrane area. It is estimated that more than 90% of excitatory synapses in the brain terminate on spines, with generally one synapse per spine on the spine head.
Neuronal Function
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Neurons are diverse in shape and size. A typical neuron has a cell body (or soma) with fibre-like processes called dendrites and axons emerging from it. The dendrites are branches that leave the cell body and receive information from adjoining neurons. The dendrites have knob-like extensions called dendritic spines. The cell body has an extensive system of rough endoplasmic reticulum containing basophilic granules (Nissl substance), which synthesize proteins. The dendritic spines, dendrites and soma receive information from other cells.
Gut dysbiosis impairs hippocampal plasticity and behaviors by remodeling serum metabolome
Published in Gut Microbes, 2022
Guoqiang Liu, Quntao Yu, Bo Tan, Xiao Ke, Chen Zhang, Hao Li, Tongmei Zhang, Youming Lu
The hippocampus, a key brain region involved in various sensory, emotional, and cognitive function, is highly susceptible to various damage.16 Previous studies have shown that the absence of gut microbiota affects the structure and function of the hippocampus.17,18 Therefore, we first analyzed whether early-life dysbiosis has an effect on dendritic spine morphogenesis. Compared with the control group, antibiotic-treated mice exhibited fewer apical dendritic spines with mature-appearing morphology (mushroom spine) in the dentate gyrus (DG) of the dorsal hippocampus Figure 4a and CA1 of the ventral hippocampus (FigureS2A), suggesting that a healthy early-life gut microbiota promotes spine maturation. Dendritic spines are highly dynamic neural structures, alterations in their morphology have been recognized as critical for synaptic plasticity and long-term memory.28 Next, we determined the effect of gut dysbiosis on hippocampal neurogenesis, which has been considered as a cellular model of anxiety29 and spatial memory.30 We used antibodies against 5-ethynyl-2’-deoxyuridine (EdU) and doublecortin (DCX) to label proliferation and neuronal differentiation of adult hippocampal progenitor cells. The number of cells positive for EdU, DCX, or double-labeled DCX-EdU cells decreases significantly after antibiotic intervention, revealing an impaired adult neurogenesis in antibiotic-treated mice compared with the controls (Figure 4b, FigureS2B).
The influence of hormonal contraception on depression and female sexuality: a narrative review of the literature
Published in Gynecological Endocrinology, 2022
Laura Buggio, Giussy Barbara, Federica Facchin, Laura Ghezzi, Dhouha Dridi, Paolo Vercellini
Estrogen receptors have been identified both intracellularly and on the cellular membrane [45]. Estrogen neurotrophic effects consist of a cascade of events that is well documented both in vivo and in vitro [46–48] and can be summarized in a three-step process [49]. Filopodial outgrowth is the earliest event and occurs within minutes of exposure. It’s followed by the development of stable dendritic spines that occurs lately [50] and, finally, by the stabilization of the spines. Estrogen-dependent induction of spine synapses is dependent on NMDA receptors [51], whereas spine stabilization is sustained by an estrogen-induced decrease in the GABAergic input [52]. Estrogen and progestogen interaction with GABA and glutamate receptors and their influence on synapse formation are likely correlated with their hypothesized neuroprotective effect. In ovariectomized animal models and in vitro experiments, estrogen treatment causes an increase in hippocampal levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and neurotrophin 3 (NT3) [53,54]. On the contrary, progesterone causes rapid downregulation of synaptogenesis, NGF, NT3 and BDNF levels when administered following estrogens [51,53,54].
Dynamic alteration of dendrites and dendritic spines in the hippocampus and microglia in mouse brain tissues after kainate-induced status epilepticus
Published in International Journal of Neuroscience, 2021
Lingling Xie, Tianyi Li, Xiaojie Song, Hong Sun, Jie Liu, Jing Yang, Wenjie Zhao, Li Cheng, Hengsheng Chen, Benke Liu, Wei Han, Chen Yang, Li Jiang
As major sites of excitatory synaptic input into the CNS, dendritic spines are strongly implicated in the mechanisms of plasticity and learning [6]. Furthermore, both clinical and experimental studies have indicated that epilepsy-related loss and structural injury of dendritic spines may be associated with cognitive deficits [7–9]. Recent evidence has confirmed the existence of communication between the microglia and neurons in epilepsy [10]. Activated microglia may exert different effects on brain function depending on the phase of epileptogenesis [11], and correct timing of the modulation of microglial phenotypes can improve the outcomes in epilepsy [12]; however, this requires further exploration. In addition, reports of the dynamic alteration in microglial types, their markers and changes in dendritic spines in the hippocampus of epileptic models at different time-points after acute status epilepticus (SE) are rare.