Cells, Tissues and Organs
David Sturgeon in Introduction to Anatomy and Physiology for Healthcare Students, 2018
The final type of tissue is nervous tissue (not in the ‘worried’ sense). Nervous tissue comprises nerve cells (neurons) that generate, transmit and receive electrical impulses (action potentials), and supporting cells (glial cells) that nourish and protect the nerve cells. The two functions are often expressed as excitable and non-excitable. Nerve cells are highly specialised in their function and vary greatly in length. However, they still exhibit many of the same characteristics as other cells (e.g. nucleus, mitochondria, cytoplasm, etc.) and require oxygen and glucose to produce cellular energy (ATP). In this sense, they are susceptible to the same challenges as other, less-specialised cells and a few more besides. One interesting feature of ‘excitable’ neurons is that, for the most part, they are unable to undergo mitosis following maturation. Supporting cells, on the other hand, are capable of dividing mitotically and are essential for the maintenance of their more excitable neighbours. There are a number of different types of glial cells including astrocytes (cellular repair and clearance of neurotransmitters), microglia (clearance of cellular debris), oligodendrocytes and schwann cells (both produce an insulating material called myelin). However, we will look in much more detail at how neurons and glial cells work in Chapter 12.
Biological Basis of Behavior
Mohamed Ahmed Abd El-Hay in Understanding Psychology for Medicine and Nursing, 2019
Nervous tissue is composed of two types of cells: neurons and glial cells. Neurons are the primary type of cells whose function is to receive and transmit information. They are responsible for the computation and communication that the nervous system provides. Glial cells or glia play a supporting role for nervous tissue. Neurons are composed of: (1) a cell body that contains the nucleus and most of the cell’s biosynthetic machinery and keeps the cell alive; (2) branching tree-like fibers called dendrites, which extend from the cell body, collect information from other cells and send the information to the cell body; (3) an axon, which transmits information away from the cell body to other neurons or to the muscles and glands; and (4) specialized regions, at the end of axons, called synaptic buttons or synaptic endings, where communication with other nerve cells or special effector tissues (such as gland or muscle cells) is carried out (Figure 5.2).
Pharmacotherapy of Neurochemical Imbalances
Sahab Uddin, Rashid Mamunur in Advances in Neuropharmacology, 2020
Nervous tissue possesses a superior capability to expend some chemical substances for communication, fairly numerous from that of neurotransmitters, that is proscribed to specific neurons. These chemical substances are known as neurohormones, substances produced from neurosecretory cells of the nervous systems of vertebrates and invertebrates. Neurohormones have ability to travel to distant non-neuronal locations like endocrine messengers through blood and lymph. Unlike neurotransmitters, they are inactivated slowly and they are used by cells only once for the same action. Thus, neurohormones are the major mediators between nervous and non-nervous system (Scharrer, 1969). Yet, using this term is ambiguous because many times hypothalamic neurons also form synapses with central neurons. Cytochemical evidence indicates that the same substances that are secreted as hormones from the posterior pituitary, mediate transmission at these sites (Bloom, 2006).
Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma
Published in Ultrastructural Pathology, 2020
Evgeniya Yu. Kirichenko, Sehweil Salah M. M., Zoya A. Goncharova, Aleksei G. Nikitin, Svetlana Yu. Filippova, Sergey S. Todorov, Marina A. Akimenko, Alexander K. Logvinov
Despite the rarity of PXA, a large amount of data concerning the features of the cellular structure of this type of tumor has been accumulated. Nevertheless, the characteristics of intercellular communication in PXA are poorly studied. To date, only a few descriptions of desmosome-like contacts have been obtained.11,12 At the same time, the existence of gap junctions and half-channels, as well as the expression of their constituent proteins in astrocytic tumors, is an urgent topic in modern neurooncology.13–15 Gap junctions (GJ) are hexametric membrane pores, formed by connexins that directly connect cytoplasms of two cells. In nervous tissue, they can be formed either between neuronal cells16, or between astroglial and oligodendroglial cells.17 According to the modern data, GJs occupy a special place among the various types of intercellular contacts and serve as the key structural and functional component of metabolic homeostasis maintenance in the brain.18 The controversial role of GJ in astrocytic tumor pathogenesis has been investigated in a number of studies. On the one hand, GJ possesses such pro-oncogenic properties as tumor cells migration promotion19 and transmission of transforming signals from tumor to nonmalignant tissue.20 On the other hand, connexins proteins have been known for the antiproliferative activity.14
Lack of bombesin receptor-activated protein homologous protein impairs hippocampal synaptic plasticity and promotes chronic unpredictable mild stress induced behavioral changes in mice
Published in Stress, 2023
Xueping Yao, Xiaoqun Qin, Hui Wang, Jiaoyun Zheng, Zhi Peng, Jie Wang, Horst Christian Weber, Rujiao Liu, Wenrui Zhang, Ji Zeng, Suhui Zuo, Hui Chen, Yang Xiang, Chi Liu, Huijun Liu, Lang Pan, Xiangping Qu
Nervous tissue has a tremendous capacity of plasticity. In response to intrinsic or extrinsic stimuli neural networks change based upon synapse regulation and reorganization of circuitry. Psychosocial stressors or stressful life events have been shown to have profound effects on neural structure and function in susceptible individuals. For example, neuroplasticity hypothesis, which was proposed for understanding the mechanisms of the development of depression, incorporates the continually remodeling of key brain systems in response to various situations. It suggests that a disrupt or dysfunction of neural plasticity contributes to behaviors related to depression (Duman et al., 2016; B. Liu et al., 2017; Pittenger & Duman, 2008; Racagni & Popoli, 2008). Typical antidepressants may improve neuroplasticity through monoamine neurotransmitters’ stimulation of the postsynaptic monoamine receptors (Racagni & Popoli, 2008). In addition, other treatments such as psychotherapy, cognitive behavioral therapy and electroconvulsive shock treatment may also have therapeutic effects on depression through regulating neural plasticity in experimental animals (B. Liu et al., 2017).
Cerebrolysin: a multi-target drug for recovery after stroke
Published in Expert Review of Neurotherapeutics, 2018
Neuroprotective effects were the focus of early studies with Cerebrolysin. Cerebrolysin is a neuropeptide preparation that mimics the action of neurotrophic factors. These regulate normal physiological functioning as well as survival and regeneration of nervous tissue after injury. One of these early stroke studies was a randomized, double-blind, placebo-controlled trial (RCT) with 146 patients, published by Ladurner et al. [2]. This trial showed beneficial effects of Cerebrolysin (50 ml/day for 21 days) on motor function recovery and in cognitive performance, especially within the first 14 days, but missed significant treatment effects at Day 90 (Figure 1). This was explained by the rather mild baseline impairment, particularly spontaneous recovery, which was reflected by a Barthel Index (BI) of ≥85 at Day 90 in 66.2% of placebo patients.