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141.
Our previously published studies are here reviewed detailing neuro-cnidocyte synapses, demonstrating putative neurotransmitter
substances, and identifying complex neural pathways in sea anemones. Synapses were traced to their contacts on nematocytes
and spirocytes by transmission electron microscopy of serial thin sections of tentacles. In five animals, cells containing
microbasic p-mastigophores had synapses with clear vesicles, whereas cells containing basitrichous isorhizas had synapses with dense-cored
vesicles, providing preliminary evidence for a selectivity of neurotransmitter types for different nematocysts. Either clear
or dense-cored synaptic vesicles were also present at neuro-spirocyte contacts. Antho-RFamide immunoreactivity occurred in
some anthozoan synaptic vesicles and immunogold labeling of serotonin was found at a neuro-spirocyte synapse. Neural pathways
included direct innervation of spirocytes by sensory cells, sequential neuro-neuro-spirocyte and neuro-neuro-nematocyte synapses
and reciprocal synapses involving axons of both sensory cells and ganglion cells. Such synaptic patterns resemble neuro-effector
pathways found in higher animals and lay to rest the independent effector hypothesis for cnidocyte discharge in tentacles
of sea anemones. 相似文献
142.
Regulation of neuronal plasticity in the central nervous system by phosphorylation and dephosphorylation 总被引:6,自引:0,他引:6
Neuronal plasticity can be defined as adaptive changes in structure and function of the nervous system, an obvious example
of which is the capacity to remember and learn. Long-term potentiation and long-term depression are the experimental models
of memory in the central nervous system (CNS), and have been frequently utilized for the analysis of the molecular mechanisms
of memory formation. Extensive studies have demonstrated that various kinases and phosphatases regulate neuronal plasticity
by phosphorylating and dephosphorylating proteins essential to the basic processes of adaptive changes in the CNS. These proteins
include receptors, ion channels, synaptic vesicle proteins, and nuclear proteins. Multifunctional kinases (cAMP-dependent
protein kinase, Ca2+/phospholipid-dependent protein kinase, and Ca2+/calmodulin-dependent protein kinases) and phosphatases (calcineurin, protein phosphatases 1, and 2A) that specifically modulate
the phosphorylation status of neuronal-signaling proteins have been shown to be required for neuronal plasticity. In general,
kinases are involved in upregulation of the activity of target substrates, and phosphatases downregulate them. Although this
rule is applicable in most of the cases studied, there are also a number of exceptions. A variety of regulation mechanisms
via phosphorylation and dephosphorylation mediated by multiple kinases and phosphatases are discussed. 相似文献
143.
Peter B. Garland 《Bioscience reports》1991,11(6):445-475
The concept of chemiosmotic systems arises from the pioneering work of Peter Mitchell on two fronts. One is concerned with the mechanisms by which molecules are transported across membranes which are generally barriers to such transport. These mechanisms are inevitably molecular, and are now yielding their secrets to a combination of structural protein chemistry and molecular biology. The other front is more physiological, and explores the functional relationships between metabolism and transport. Nevertheless, the two fronts form a continuum of mutally related structure and function. Chemiosmotic systems provide a hierarchy of complexity, starting from say a uniporter reconstituted in a chemically defined bilayer, and proceeding to greater complexity in mitochondria, chloroplasts, eukaryotic and prokaryotic cell membranes, and multicellular systems. Their relationship to medicine is profound, because they provide many opportunities for therapeutic intervention. In this paper I present an overview of chemiosmotic systems at different levels of complexity, both molecular and biological, of their involvements in pathology, and of possible pharmacological treatment or prevention of disease. 相似文献
144.
Levels of brain neurotransmitters and their metabolites, as well as concentrations of enzymes associated with their synthesis and metabolism, fluctuate during the day in patterns defined as circadian. The present study examined these rhythms in albino rats exposed to 60-Hz electric fields. Thirty-six animals were exposed to a 39 kV/m field for 4 weeks, 20 h/day, in a parallel-plate electrode system. A group of 36 sham animals was similarly handled and housed in a nonenergized exposure system. On the sampling day, animals were sacrificed at 4-h intervals throughout the 24-h day. Brains were removed, dissected, and kept frozen until chemically analyzed. The levels of biogenic amines and their acidic metabolites in the striatum, hypothalamus, and hippocampus were determined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD) methods. Repeated exposure to 60-Hz electric fields produced significant alterations in the diurnal rhythms of several biogenic amines: dihydroxyphenylacetic acid (DOPAC, the primary metabolite of dopamine in the rat) in the striatum, and norepinephrine, dopamine, and 5-hydroxyindoleacetic acid (5-HIAA; serotonin metabolite) in the hypothalamus. Levels of serotonin in the striatum and hypothalamus showed clear circadian patterns that was not affected by the field. No diurnal or field-related changes were observed in the hippocampal amines. 相似文献
145.
卒中后抑郁(post-stroke depression,PSD)是并发于脑血管病的一种情感障碍疾病,发病率高,预后差。重复经颅磁刺激(repetitive transcranial magnetic stimulation,r TMS)是通过磁场变化在大脑中产生感应电流来刺激皮层的非创伤性脑刺激技术,是临床上治疗PSD的一种重要非药物治疗方法,可以显著改善PSD患者的抑郁症状。但目前rTMS的作用机制不明确。本文总结了PSD治疗中有效的rTMS刺激方案,并结合PSD的单胺类神经递质相关致病假说及PSD的临床治疗手段,探索了rTMS通过对单胺类神经递质的调控参与PSD治疗的可能机制。rTMS刺激诱导的皮层单胺类递质释放增加、葡萄糖代谢上升、皮层兴奋性增加,提高了单胺类神经递质和脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)水平,进而引发前额叶抑制功能上升、与下游脑区连接改变、脑网络功能的调整,可能是rTMS治疗PSD的重要机制之一。 相似文献
146.
Benjamin J. Cook G. Mark Holman Shirlee Meola 《Archives of insect biochemistry and physiology》1983,1(2):167-178
The musculature of the oviduct consists of an outer, irregular layer of longitudinal muscle and an inner layer of circular muscle. The four basic modes of activity—compression, segmentation, peristalsis, and reverse peristalsis—were evident in the isolated oviduct. These spontaneous events often occurred in an organized sequence. In fact eggs could be transported down the lateral oviducts by this myogenic activity once the sphincter between the common oviduct and vagina was severed. Myographic recordings were made of only the contractions of the longitudinal muscles. L-glutamate caused a distinct phasic contraction at 2.2 × 10?5 M. The response became larger and more complex as the concentration of the amino acid was increased. Acetylcholine (1.6 × 10?5 M) caused either a phasic or tonic response, or a combination thereof. By contrast, 5HT and tyramine simply increased the frequency of small phasic contractions, although in some preparations both monoamines caused an inhibition. The ecdysones, a juvenile hormone analogue (1 × 10?6 M), and prostaglandin E2 had no effect on oviduct activity. Initially high KCI solutions (162 mM) without Ca++ induced a strong contraction but subsequent additions failed to do so. However, when a high KCI solution (158 mM) with 2 mM Ca++ was added to the preparation the response was partially restored. Also the potent calcium antagonist Mn++ (2mM) can suppress spontaneous activity. 相似文献
147.
148.
《Developmental neurobiology》2017,77(9):1023-1037
The development of the neocortex requires the synergic action of several secreted molecules to achieve the right amount of proliferation, differentiation, and migration of neural cells. Neurons are well known to release neurotransmitters (NTs) in adult and a growing body of evidences describes the presence of NTs already in the embryonic brain, long before the generation of synapses. NTs are classified as inhibitory or excitatory based on the physiological responses of the target neuron. However, this view is challenged by the fact that glycine and GABA NTs are excitatory during development. Many reviews have described the role of nonhyperpolarizing GABA at this stage. Nevertheless, a global consideration of the inhibitory neurotransmitters and their downstream signaling during the embryonic cortical development is still needed. For example, taurine, the most abundant neurotransmitter during development is poorly studied regarding its role during cortical development. In the light of recent discoveries, we will discuss the functions of glycine, GABA, and taurine during embryonic cortical development with an emphasis on their downstream signaling. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1023–1037, 2017 相似文献
149.
Thomas I. Nathaniel Olajuyigbe Femi Adebobola Nathaniel 《Central European Journal of Biology》2006,1(2):249-262
Many studies have investigated different mechanisms of attack and defense in different species of higher brain animals including
cats, rats, rodents, mice, and even in some bird species. However, detailed comparative analysis has not been carried out
to understand the major similarities in the mechanisms of attack and defense across the different species of vertebrates.
Although there are differences, there are also significant similarities as well, which warrant comparative assessment. By
considering ethological ideas associated with the motivational defense system, we investigated the motor patterns of attack
and defense in cats and rats, using the “resident-intruder” experimental paradigm. Our results reveal specific similarities
and differences in the motor patterns of attack and defense in rats and cats. We discuss comparatively the mechanisms of attack
and defense across different species of vertebrates, focusing on motor patterns, neuromodulating factors, brains neural substrates,
and circuitry. 相似文献
150.
Dhanrajan M. Tiruchinapalli Marc G. Caron Jack D. Keene 《Journal of neurochemistry》2008,107(6):1529-1543
Growing evidence indicates that both seizure (glutamate) and cocaine (dopamine) treatment modulate synaptic plasticity within the mesolimbic region of the CNS. Activation of glutamatergic neurons depends on the localized translation of neuronal mRNA products involved in modulating synaptic plasticity. In this study, we demonstrate the dendritic localization of HuR and HuD RNA‐binding proteins (RBPs) and their association with neuronal mRNAs following these two paradigms of seizure and cocaine treatment. Both the ubiquitously expressed HuR and neuronal HuD RBPs were detected in different regions as well as within dendrites of the brain and in dissociated neurons. Quantitative analysis revealed an increase in HuR, HuD and p‐glycogen synthase kinase 3β (GSK3β) protein levels as well as neuronal mRNAs encoding Homer, CaMKIIα, vascular early response gene, GAP‐43, neuritin, and neuroligin protein products following either seizure or cocaine treatment. Inhibition of the Akt/GSK3β signaling pathway by acute or chronic LiCl treatment revealed changes in HuR, HuD, pGSK3β, p‐Akt, and β‐catenin protein levels. In addition, a genetically engineered hyperdopaminergic mouse model (dopamine transporter knockout) revealed decreased expression of HuR protein levels, but no significant change was observed in HuD or fragile‐X mental retardation protein RBPs. Finally, our data suggest that HuR and HuD RBPs potentially interact directly with neuronal mRNAs important for differentiation and synaptic plasticity. 相似文献