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Evaluation of Water and Its Contaminants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
Toxic effects from anatoxin-a progress very rapidly because it acts directly on the nerve cells (neurons) as a neurotoxin. The progressive symptoms of anatoxin-a exposure are loss of coordination, twitching, convulsions, and rapid death by respiratory paralysis. The nerve tissues which communicate with muscles contain a receptor called the nicotinic acetylcholine receptor. Stimulation of these receptors causes a muscular contraction. The anatoxin-a molecule is shaped so it fits this receptor, and in this way it mimics the natural neurotransmitter normally used by the receptor, acetylcholine. Once it has triggered a contraction, anatoxin-a does not allow the neurons to return to their resting state, because it is not degraded by cholinesterase which normally performs this function. As a result, the muscle cells contract permanently, the communication between the brain and the muscles is disrupted, and breathing stops (Figure 3.40).657,658
Amplification Possibilities with Neuroreceptor-Based Biosensors
Published in Richard P. Buck, William E. Hatfield, Mirtha UmañA, Edmond F. Bowden, Biosensor Technology Fundamentals and Applications, 2017
The nicotinic acetylcholine receptor exists in at least three conformations: 1) conformation 1 with two molecules of acetylcholine bound to the alpha subunits (channel does not open), 2) conformation 2 with the same molecules bound (channel opens), and 3) conformation 3 with one or two molecules of acetylcholine bound but with different binding affinities than in 1 or 2 (channel does not open) (28). Whether such conformational changes will occur or be a problem with this receptor as part of a biosensor and whether such conformational changes occur with other types of neuroreceptors remains to be tested experimentally.
Effects of short-term sub-lethal diazinon® exposure on behavioural patterns and respiratory function in Clarias batrachus: inferences for adaptive capacity in the wild
Published in Chemistry and Ecology, 2022
Shubhajit Saha, Azubuike V. Chukwuka, Dip Mukherjee, Kishore Dhara, Aina O. Adeogun, Nimai Chandra Saha
The strong positive association between mucus secretion and loss of balance and average opercular movement within 48hrs of exposure to diazinon, indicates that the exhibition of loss of balance and increased opercular movement across exposure concentrations was explainable by the hypersecretion of mucus. While these observations are like stress responses observed during the 24 h exposure, the increased average opercular movement in elevated concentrations highlights the onset of respiratory distress due to cholinergic toxicity. This indicates the onset of the intermediate toxicity phase which is often marked by respiratory distress due to paralysis of respiratory muscles [65]. From the 72 h exposures correlogram, the positive relationship between average opercular movement showed strong positive association with erratic swimming movement indicating that with increased exposure time, erratic movements become more emphasised and rigorous due to the onset of respiratory distress. The strong positive association between AOM and erratic swimming behaviour highlights the post cholinergic phase. The muscular seizures and paralysis which precede death of the organism are the hallmark of excessive stimulation of nicotinic acetylcholine receptors at the neuromuscular junction [72].
Experimental and computational analysis of N-methylcytisine alkaloid in solution and prediction of biological activity by docking calculations
Published in Molecular Physics, 2022
Fanny C. Alvarez Escalada, Elida Romano, Silvia Antonia Brandán, Ana E. Ledesma
Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate fast chemical neurotransmission at the neuromuscular junction and have various signalling characters in the central nervous system; human α4β2 is a nicotinic receptor of nicotinic subtype mostly abundant in the brain [41]. Nicotine is a plant alkaloid responsible for the addictive properties of tobacco; it binds with high affinity to the nicotinic acetylcholine receptors α4β2nAChRs and acts as a full agonist. Research works find new use of nAChR partial agonists for the treatment option by smoking cessation, such as cytosine, which diminishes nicotine support and reduces the pleasure from smoking [42]. To evaluate the basis for affinity binding and eventually identify the structural elements, supporting the receptor selectivity of the NMC to nAChRs receptor, we have structurally characterised complexes of that molecule with acetylcholine-binding protein (Ac-AChBP, PDB:4BQT) and human α4β2 nAChR (PDB: 5KXI) receptors. Full details, showing the ligand position in the binding site with NMC docked into each complex, are provided in Figure 6.
Carob extract attenuates brain and lung injury in rats exposed to waterpipe smoke
Published in Egyptian Journal of Basic and Applied Sciences, 2018
Mona Abdel-Rahman, Amira A. Bauomy, Fatma Elzahraa H. Salem, Mona Ahmed Khalifa
From the present results, it is clear that DA content is decreased after 2 weeks in brainstem of rats exposed to waterpipe smoke. The primary target for nicotine in the central nervous system is the α4β2 nicotinic acetylcholine receptor, which when activated by nicotine binding, results in the release of DA in the brain's “reward center” and provides the positive reinforcement observed with cigarette smoking [34].