Neurotransmitters receptor binding

Key Words Serotonin3 receptor 5-hydroxytryptamine3 receptor Cys-loop receptor ligand-gated ion channel ionotropic receptor neurotransmitter binding site. 

A 17 amino acid long peptide sequentially related to opioid peptides in particular dynorphin A. OFQ/N is inactive at the 5, k, and p opioid receptors, but binds to its own NOP receptor (formerly ORL-1, for opioid receptor like-1). In contrast to opioid peptides, OFQ/N has no direct analgesic properties. OFQ/N is the first example for the discovery of a novel neurotransmitter from tissue extracts by using an orphan receptor as bait. Centrally administered in rodents, OFQ/N exerts anxiolytic properties. OFQ/N agonists and antagonists... 

Synaptic vesicles mediate the release of small molecules other than classical neurotransmitters and neuropeptides. Of these, zinc and ATP are the best characterized. NMDA and GABA receptors contain binding sites for zinc, and zinc exerts a direct effect on... 

For each neurotransmitter in the autonomic nervous system, list the neurons that release it and the type and location of receptors that bind with it... 

ACh regulates the cortical arousal characteristic of both REM sleep and wakefulness (Semba, 1991, 2000 Sarter Bruno, 1997, 2000). Medial regions of the pontine reticular formation (Figs. 5.2 and 5.7) contribute to regulating both the state of REM sleep and the trait of EEG activation. Within the medial pontine reticular formation, presynaptic cholinergic terminals (Fig. 5.1) that release ACh also are endowed with muscarinic cholinergic receptors (Roth et al, 1996). Autoreceptors are defined as presynaptic receptors that bind the neurotransmitter that is released from the presynaptic terminal (Kalsner, 1990). Autoreceptors provide feedback modulation of transmitter release. Autoreceptor activation... 

Neurotransmitter/Receptor Binding. At this point, the neurotransmitter chemical is free in the synapse (extracellular fluid) and drifts (diffuses) in all directions. Some of the neurotransmitter molecules float across the synapse and bind to receptors on the surface of the adjacent nerve cell. Each neurotransmitter has its own unique three-dimensional shape and binds with certain receptors but not others. The binding between a neurotransmitter and a receptor is similar to fitting a key into a lock. When the neurotransmitter binds the receptor, the signal has been passed to the neighboring nerve cell. This is the process of neurotransmission. 

Negative Feedback. Some of the neurotransmitter diffuses back to the surface of the nerve cell that released it. There are also receptors that tit the neurotransmitter here. When a neurotransmitter binds a receptor (called an autoreceptor) at the axon terminal of the nerve cell that released it, it tells the nerve cell that there s plenty of neurotransmitter already in the synapse. So don t release anymore This process is called negative feedback and is analogous to the way a thermostat works in your home to control room temperature. 

Information transfer between two nerves in the brain occurs at synaptic junctions, across which chemical messengers (neurotransmitters) diffuse. The neurotransmitter binds to a receptor on the postsynaptic neurone, changing its membrane potential. If the membrane potential decreases, this either initiates an action potential or increases the likelihood that a further depolarisation, from stimulation by another nerve, will initiate an action potential. Such a neurotransmitter is described as excitatory. In contrast, if it increases the membrane potential, it reduces the likelihood of initiation of an action potential, such a... 

This rather cumbersome name indicates that the neurotransmitter binds a receptor that directly affects an ion channel, i.e. the neurotransmitter binds to one of the proteins that constitute the channel (Chapter 5, see Figure 5.4). 

Neurotransmitters bind to their receptors with high affinity but low potency, whereas peptides bind with very high affinity and high potency. 

Fast-acting, class 1 (ionotropic) receptors. The neurotransmitter binds to the receptor protein and within milliseconds leads to a change in the permeability of the associated ion channel, allowing the influx of ions such as Ca ", Na", K", or Cl . 

Acetylcholine (ACh) is an example of an endogenous neurotransmitter that binds to more than one receptor type, the nicotinic acetylcholine receptor (nAChR) which preferentially binds nicotine and the muscarinic receptor which binds muscarine, a mushroom alkaloid. The latter is a G protein-coupled receptor while the nACh receptor is an excitatory ligand-gated ion channel that transports Na-i- ions. Nicotinic cholinergic receptors are found in the CNS, autonomic ganglia, and at the neuromuscular junction of skeletal muscles. They are a possible target for anaesthetics. 

The most popular OTC sleep aids are those that contain antihistamines such as diphenhydramine or doxylamine (Table 3.1). As noted in Chapter 1, nerve cells in the brain communicate with each other by secreting chemicals called neurotransmitters. One such neurotransmitter that regulates sleep is histamine. When histamine is released by a nerve cell, it diffuses over to the target nerve cell and binds to specialized proteins called receptors located on the outer surface of the nerve cell. These receptors are specially designed to bind only histamine, and when they do, the target nerve cell will become either activated or deactivated. In the brain, histamine serves the function of keeping us awake, and when drugs such as antihistamines are taken, they block the ability of histamine receptors to bind histamine. 

Ca2+ is released from the endoplasmic reticulum in response to hormones or neurotransmitters binding to cell-surface receptors. 

It should now be clear that neurotransmission does not end when a neurotransmitter binds to a receptor or even when ion flows have been altered or second messengers have been created. Events such as these all start and end within milliseconds to seconds following release of presynaptic neurotransmitter (Fig. 1 —13)-The ultimate goal of neurotransmission is to alter the biochemical activities of the... 

FIGURE 2—12. Second messengers are intracellular chemicals produced when some neurotransmitters bind to their receptors. Such receptors are capable of converting the binding information of their neurotransmitter into the synthesis of these second messengers. 

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