Nicotinic cholinergic syndrome

Nicotinic cholinergic syndrome. Stimulation of nicotinic receptors at autonomic ganglia activates both parasympathetic and sympathetic systems, with unpredictable results. Excessive stimulation frequently causes depolarization blockage. Thus, initial tachycardia may be followed by bradycardia, and muscle fasciculations may be followed by paralysis. (Examples nicotine in addition, the depolarizing neuromuscular blocker succinyl-choline, which acts on nicotinic receptors in skeletal muscle.)... 

This chapter deals with botulinum toxin type A (BOTOX) in the treatment of strabismus, blepharospasm, and related disorders. Botulinum toxin type A (BOTOX) has been used to treat strabismus, blepharospasm, Meige s syndrome, and spasmodic torticollis. By preventing acetylcholine release at me neuromuscular junction, botulinum toxin A usually causes a temporary paralysis of the locally injected muscles. The variability in duration of paralysis may be related to me rate of developing antibodies to me toxin, upregulation of nicotinic cholinergic postsynaptic receptors, and aberrant regeneration of motor nerve fibers at me neuromuscular junction. Complications related to this toxin include double vision (diplopia) and lid droop (ptosis). 

Fiedler JL, Epstein CJ, Rapoport SI, Caviedes R, Caviedes P (1994) Regional alteration of cholinergic function in central neurons of trisomy 16 mouse fetuses, an animal model of human trisomy 21 (Down syndrome). Brain Res 658 27-32 Flores CM, Rogers SW, Pabreza LA, Wolfe BB, Kellar KJ (1992) A subtype of nicotinic cholinergic receptor in rat brain is composed of alpha 4 and beta 2 subunits and is up-regulated by chronic nicotine treatment. Mol Pharmacol 41 31-37 Freedman R, Hall M, Adler LE, Leonard S (1995) Evidence in postmortem brain tissue for decreased numbers of hippocampal nicotinic receptors in schizophrenia. Biol Psychiatry 38 22-33... 

Mixed cholinergic syndrome. Because both nicotinic and muscarinic receptors are stimulated, mixed effects may be seen. The pupils are usually miotic (of pinpoint size). The skin is sweaty, and peristaltic activity is increased. Fasciculations are a manifestation of nicotinic stimulation and may progress to muscle weakness or paralysis. (Examples organophos-phate and carbamate insecticides and physostigmine.)... 

Since completion of this manuscript, a number of reviews have appeared covering various aspects of Parkinsonism such as the use [557], mode of action [558], metabolism [559], and side-effects [560, 561] of L-dopa and the antagonism of its effects by pyridoxine [562], Other useful sources include general accounts of Parkinsonian therapeutics [563-565], the role [558, 566] and distribution [567] of dopamine in the central nervous system, and the pharmacology and biochemistry of 6-hydroxydopamine [567, 568]. Furthermore, there appear to be two forms of Parkinsonism, one more refractory to nicotine than the other [569], and it is significant that nicotine is a known cholinergic tremorogen and produces a Parkinsonian syndrome in animals [8]. 

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