Neurotransmission process

This reuptake pump takes an active part in the neurotransmission process, which begins with the firing of the presynaptic neuron and release of neurotransmitter (Fig. 2—23). The neurotransmitter diffuses across the synapse, binds its neurotransmitter receptors selectively, and triggers all the subsequent events that translate that chemical message into another neuronal impulse in the postsynaptic neuron, activate postsynaptic genes, and regulate various cellular functions in the target neuron. The neurotransmitter then diffuses off its receptor and can be destroyed by enzymes or transported back into the presynaptic neuron. 

Finally, altering the rates of synthesis of enzymes that can either create or destroy neurotransmitters can also affect the amount of chemical neurotransmitter available for neurotransmission and thereby alter the chemical neurotransmission process itself. 

The enzymes most important in the neurotransmission process are those that make and destroy the neurotransmitters. Thus, precursors are transported into the neuron with the aid of an enzyme-assisted transport pump and converted into neurotransmitters by a series of neurotransmitter-synthesizing enzymes (Figs. 1—7 through 1— 9). Once synthesis of the neurotransmitter is complete, it is stored in vesicles, where it stays until released by a nerve impulse. In the vesicle, the neurotransmitter is also protected from enzymes capable of breaking it down. Once released, however, the neurotransmitter is free not only to diffuse to its receptors for synaptic actions but also to diffuse to enzymes capable of destroying the neurotransmitter or to the reuptake pump already discussed above and represented in Figures 2-20 through 2-24. 

In the neurotransmission process, the first event is the firing of the presynaptic neuron which releases neurotransmitter. True or False. 

Cholinesterases, e.g., acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholi-nesterase (BChE, EC 3.1.1.8), are serine hydrolases that break down the neurotransmitter acetylcholine and other choline esters [5]. In the neurotransmission processes at the neuromuscular junction, the cationic neurotransmitter acetylcholine (ACh) is released from the presynaptic nerve, diffuses across the synapse and binds to the ACh receptor in the postsynaptic nerve (Fig. 1). Acetylcholinesterase is located between the synaptic nerves and functions as the terminator of impulse transmissions by hydrolysis of acetylcholine to acetic acid and choline as shown in Scheme 4. The process is very efficient, and the hydrolysis rate is close to diffusion controlled [6, 7]. 

Ossowska K (1993) Disturbances in neurotransmission processes in aging and age-related diseases. Pol J Pharmacol 45 109-131. 

Dopamine is a neurotransmitter that has long been of interest to both chemists and neuroscientists. For instance, a loss of dopamine-containing neurons or its transmission is related to a number of illnesses and conditions including Parkinson s disease and schizophrenia. It is therefore of interest to perform quantitative and qualitative determination of dopamine in the extracellular fluid in animals in order to gain an understanding of the neurotransmission processes. Such a study will also aid in correlating neurochemistry with behaviour. 

Among the catecholamines, dopamine has long been of interest to both chemists and neuroscientists. It is one of the most important neurotransmitters and is ubiquitous in the mammalian central nervous system[5]. It modulates many aspects of brain circuitry in a major system of the brain including the extra pyramidal and mesolimbic system, as well as the hypothalamic pituitary axis[6]. It also plays a crucial role in the functioning of the central nervous, cardiovascular, renal and hormonal systems[4], A loss of dopamine containing neurons or its transmission is also related to a number of illnesses and conditions including Parkinson s disease, schizophrenia, motivational habit, reward mechanisms and the regulation of motor functions and in the function of the central nervous, hormonal and cardiovascular system[5,18,19]. It is therefore of interest to measure dopamine in the extracellular fluid in animals to order to monitor neurotransmission processes and correlate neurochemistry with behavior[19]. 

Sodium is a chemical element, and as such, caimot be synthesised by the body. It is, therefore, an essential nutrient that must be provided by the diet. Sodium is required by the body for several important biological functions including regulation of osmotic pressure within individual compartments of the body, active transport of many essential nutrients into cells, as well as in neurotransmission processes. 

The next important milestone will probably be the access to a high resolution experimental structure of GPCRs. However, these static pictures might not even be sufBcient to provide scientists with definitive answers on receptor-hgand interaction since recent studies have already demonstrated the importance of the kinetic parameters for the neurotransmission process and the extraordinary complexity of this system. 

To date, two types of major depression have been postulated. The first is often referred to as endogenous or melancholic depression. In this type of major depression, symptoms of depressed mood are related directly to internal biologic factors such as neurotransmitter dysfunction (Kaplan Sadock, 1990 Tierney et al., 1997). Electroconvulsive therapy (ECT), referred to historically as shock treatments, is often considered an endogenous treatment. Here, direct (biologic) stimulation of the neurotransmission process is the treatment strategy. Similar to ECT, antidepressant medications also are successful in lifting endogenous depression, with the major difference that they affect the neurochemical pathways chemically rather than electrically (Maxmen Ward, 1995). 

Although molecular imaging with PET has detected abnormalities in regional cerebral metabolism and some parts of the neurotransmission process, they do not provide a comprehensive picture of brain manifestations in autism. For example, SPECT imaging with technetium Tc-99m hexamethylpropyleneamine oxide did not reveal specific abnormalities in patients with autism, although many different abnormalities were found. 

This section presents method of numerical determination of diflfiision D and friction C coefficients of Brownian particles from velocity (VACF) and force (FACF) autocorrelation functions in molecular dynamic simulations. Electrostatic parameters of particles in simulation were obtained using modem DFT methods of quantum chemistry. The calculations were carried out with PCS (Patch Clamp Simulation) program package, designed for simulation of neurotransmission processes, using Brownian and molecular dynamic methods, with GPU acceleration support, based on NVIDIA CUBA. 

Catecholamines and indolamines are present in the central nervous system and different physiological and behavioral functions of the brain are based on these chemical messengers. These species are actively involved in the neurotransmission processes of the CNS. Neurosecretion is associated with the metabolic activities which occur in the brain. These metabolic processes stimulate pH fluctuations in the CNS. Thus, secretion of neurotransmitters is accompanied with endogenous species such as protons or ascorbate ions which alter the behavior of redox-active chemical messengers, e.g., catecholamines and indolamines. ... 

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