Acetylcholine receptor, effect

Tattersall, J.E.H. (1992). The acetylcholine receptor effects of organophosphoras compounds and oximes. Plum. Exp. Toxicol. 11 559-60. 

Martyn JA, White DA, Gronert GA, Jaffe RS, Ward JM. Up-and-down regnlation of skeletal muscle acetylcholine receptors. Effects on nenromuscular blockers. Anesthesiology 1992 76(5) 822-43. 

The answer is e. (Murray, pp 505-626. Scriver, pp 4029-4240. Sack, pp 121-138. Wilson, pp 287-320.) The major problem in myasthenia gravis is a marked reduction of acetylcholine receptors on the motor endplate where cranial nerves form a neuromuscular junction with muscles. In these patients, autoantibodies against the acetylcholine receptors effectively reduce receptor numbers. Normally, acetylcholine molecules released by the nerve terminal bind to receptors on the muscle endplate, resulting in a stimulation of contraction by depolarizing the muscle membrane. The condition is improved with drugs that inhibit acetylcholinesterase. 

Antagonists of muscarinic acetylcholine receptors had widely been used since 1860 for the treatment of Parkinson s disease, prior to the discovery of l-DOPA. They block receptors that mediate the response to striatal cholinergic interneurons. The antiparkinsonian effects of drugs like benzatropine, trihexyphenidyl and biper-iden are moderate the resting tremor may sometimes respond in a favorable manner. The adverse effects, e.g., constipation, urinary retention, and mental confusion, may be troublesome, especially in the elderly. 

A G-protein-mediated effect has an absolute requirement for GTP. Reference has already been made to the requirement for GTP in reconstituting hormone-stimulated adenylate cyclase activity. A similar requirement can be demonstrated when the effector is an ion channel, such as the cardiac atrial inward-rectifier K+ channel which is activated following stimulation of the M2 muscarinic acetylcholine receptor. Thus, in the experiment illustrated in Figure 7.8, the channel recorded with a cell-... 

Nicotine increased DA levels both in vivo11,193 and in vitro. 94 196 Nicotine197 and its metabolites198 were found to both release and inhibit the reuptake of DA in rat brain slices, with uptake inhibition occurring at a lower concentration than that required for DA release. In addition, the (-) isomer was more potent than the (+) isomer.197 However, the effects of nicotine upon DA release and uptake were only apparent when brain slices were utilized because nicotine was unable to affect DA when a synaptosomal preparation was utilized.197 These results indicate that nicotine exerts its effects upon the DAT indirectly, most likely via nicotine acetylcholine receptors. This finding was supported by the results of Yamashita et al.199 in which the effect of nicotine on DA uptake was examined in PC 12 and COS cells transfected with rat DAT cDNA. Nicotine inhibited DA uptake in PC 12 cells that possess a nicotine acetylcholine receptor. This effect was blocked by the nicotinic antagonists hexamethonium and mecamylamine. Additionally, nicotine did not influence DA uptake in COS cells, which lack nicotinic acetylcholine receptors. 

Lukas, R. J. Effects of chronic nicotinic ligand exposure on functional activity of nicotinic acetylcholine receptors expressed by cells of the PC12 rat pheochromocytoma or the TE671/RD human clonal line. J. Neurochem. 56 1134, 1991. 

Marubio, L.M., Gardier, A.M., Durier, S. et al. Effects of nicotine in the dopaminergic system of mice lacking the alpha4 subunit of neuronal nicotinic acetylcholine receptors. Eur. J. Neurosci. 17 1329, 2003. 

Ke, L., Eisenhour, C., Bencherif, M., Lukas, R. Effects of chronic nicotine treatment on expression of diverse nicotinic acetylcholine receptor subtypes. I. Dose- and time-dependent effects of nicotine treatment. J. Pharmacol. Exp. Ther. 286 825, 1998. 

Ochoa, E., Chattopadhyay, A., McNamee, M. Desensitization of the nicotinic acetylcholine receptor Molecular mechanisms and effect of modulators. Cell Mol. Neurobiol. 9 141, 1989. 

Cosgrove, K., Ellis, S., Al-Tikriti, M. et al. Assessment of the effects of chronic nicotine on P2-nicotinic acetylcholine receptors in nonhuman primate using [I-123]5-IA-85830 and SPECT. Paper presented at the 66th Annual Scientific Meeting of the College on Problems of Drug Dependence, 2004, San Juan, Puerto Rico. 

List the side effects of imipramine that result from its blockade of muscarinic acetylcholine receptors. 

Xu et al. [5] described the effect of (z>)-penicillamine on the binding of several antiacetylcholine receptor monoclonal antibodies to the Torpedo acetylcholine receptor. Penicillamine is covalently incorporated into the acetylcholine receptor through SS exchange at the cysteine residues of the a-subunit, altering the antigenic structure of the receptor. This effect on the structure of the native receptor at the neuromuscular junction may be responsible for the establishment of the autoimmune response to the acetylcholine receptor in (i))-penicillamine-induced myasthenia gravis. Cysteine and penicillamine interact to form penicillamine-cysteine mixed disulfide complexes [6] ... 

Picciotto MR et al. Acetylcholine receptors containing the beta2 subunit are involved in the reinforcing properties of nicotine. Nature 1998 391(6663) 173—177. Popova NK et al. Altered behavior and alcohol tolerance in transgenic mice lacking MAO A a comparison with effects of... 

An even simpler protocol for performing nucleophilic substitutions (aminations) and Suzuki reactions in one pot was reported by the Organ group for the generation of a 42-member library of styrene-based nicotinic acetylcholine receptor (nAChR) antagonists (Scheme 6.21) [49]. After considerable experimentation, the authors found that simultaneous nucleophilic displacement and Suzuki coupling could be carried out very effectively by charging the microwave process vessel with the palladium catalyst (0.5 mol% palladium-on-charcoal), the boronic acid [R1B(OH)2], the... 

The answer is a. (Katzung, p 482.) Phenothiazines as a class and, in particular, the aliphatic phenothiazines are most likely to produce marked sedation. The mechanism of action for this effect is associated with its ability to block histamine and acetylcholine receptors. 

The answer is a. (Katzung, p 499.) Of the listed a n tide press ants, only amitriptyline, a tricyclic, causes adverse effects related to blockade of muscarinic acetylcholine receptors. Both trazodone and amitriptyline cause adverse effects related to a-adrenoreceptor blockade... 

The effect of Li+ upon the synthesis and release of acetylcholine in the brain is equivocal Li+ is reported to both inhibit and stimulate the synthesis of acetylcholine (reviewed by Wood et al. [162]). Li+ appears to have no effect on acetyl cholinesterase, the enzyme which catalyzes the hydrolysis of acetylcholine [163]. It has also been observed that the number of acetylcholine receptors in skeletal muscle is decreased by Li+ [164]. In the erythrocytes of patients on Li+, the concentration of choline is at least 10-fold higher than normal and the transport of choline is reduced [165] the effect of Li+ on choline transport in other cells is not known. A Li+-induced inhibition of either choline transport and/or the synthesis of acetylcholine could be responsible for the observed accumulation of choline in erythrocytes. This choline is probably derived from membrane phosphatidylcholine which is reportedly decreased in patients on Li+ [166],... 

---