nicotinic

Examples of nicotinic in the following topics:

• Agonists, Antagonists, and Drugs

  • A nicotinic agonist is a drug that mimics, in one way or another, the action of acetylcholine (ACh) at nicotinic acetylcholine receptors (nAChRs).
  • Nicotinic acetylcholine receptors are receptors found in the central nervous system, the peripheral nervous systems, and skeletal muscles.
  • Nicotinic antagonist are mainly used for peripheral muscle paralysis in surgery, the classical agent of this type being tubocurarine, but some centrally acting compounds such as bupropion, mecamylamine, and 18-methoxycoronaridine block nicotinic acetylcholine receptors in the brain and have been proposed for treating drug addiction.
  • The nicotinic acetylcholine receptor agonist are gaining increasing attention as drug candidates for multiple central nervous system disorders such as Alzheimer's disease, schizophrenia, attention-deficit hyperactivity disorder (ADHD), and nicotine addiction.
  • In 2009 there were at least five drugs on the market that affect the nicotinic acetylcholine receptors.

• Parasympathetic Responses

  • The ACh acts on two types of receptors, the muscarinic and nicotinic cholinergic receptors.
  • When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on nicotinic receptors of postganglionic neurons.
  • Two different subtypes of nicotinic acetylcholine receptors with alpha and beta subunits.

• Peripheral Motor Endings

  • Acetylcholine diffuses into the synaptic cleft and binds to the nicotinic acetylcholine receptors located on the motor end plate.
  • Clinical Example: Myasthenia gravis is an autoimmune disorder in which circulating antibodies block the nicotinic acetylcholine receptors on the motor end plate of the neuromuscular junction.
  • Detailed view of a neuromuscular junction: 1) Presynaptic terminal; 2) Sarcolemma; 3) Synaptic vesicle; 4) Nicotinic acetylcholine receptor; 5) Mitochondrion.

• Transdermal Drug Administration

  • The highest-selling transdermal patch in the United States is the nicotine patch, which releases nicotine in controlled doses to help with cessation of tobacco smoking.

• Cholinergic Neurons and Receptors

  • At the same time, acetylcholine acts through nicotinic receptors to excite certain groups of inhibitory interneurons in the cortex, which further dampen cortical activity.
  • The result was also found in Alzheimer's disease patients and smokers after nicotine (an ACh agonist) consumption.

• Postganglionic Neurons

  • The sympathetic fibers: At the synapses within the ganglia, preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons.
  • The ACh acts on two types of receptors, the muscarinic and nicotinic cholinergic receptors.
  • Most transmissions occur in two stages: When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on nicotinic receptors of postganglionic neurons.

• Effects of Smoking

  • Although nicotine is a highly addictive drug, its effects on cognition are not as intense or noticeable as other drugs such as cocaine, amphetamines, or any of the opiates (including heroin and morphine).

• Excretion and Absorption

  • The most common mechanism of administration through the skin is the use of ointments or an adhesive patch, such as the nicotine patch or iontophoresis.

• Ionotropic and Metabotropic Receptors

  • The prototypic ligand-gated ion channel is the nicotinic acetylcholine receptor .

• Function and Physiology of the Spinal Nerves

  • Instead the presynaptic neuron releases acetylcholine to act on nicotinic receptors.
  • Acetylcholine is released from the axon terminal knobs of alpha motor neurons and received by postsynaptic receptors (nicotinic acetylcholine receptors) of muscles, thereby relaying the stimulus to contract muscle fibers.