Document Detail


Neurotoxic mechanism of cinnabar and mercuric sulfide on the vestibulo-ocular reflex system of guinea pigs.
MedLine Citation:
PMID:  12011485     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cinnabar, a naturally occurring mercuric sulfide (HgS), has been combined with Chinese herbal medicine as a sedative for more than 2000 years. To date, its neurotoxic effect on the vestibulo-ocular reflex (VOR) system has not been reported. By means of a caloric test coupled with electronystagmographic recordings, the effect of commercial HgS and cinnabar on the VOR system of guinea pigs was studied. HgS or cinnabar was administered orally (1.0 g/kg) to Hartley-strain guinea pigs once daily for 7 consecutive days. A battery of electrophysiological, biochemical, and histopathological examinations were performed. The results showed that HgS induced a 60% caloric response abnormality (40% caloric hyperfunction and 20% hypofunction), whereas the abnormal responses appeared to be more severe (six out of six) in the cinnabar group. The Hg contents of whole blood and cerebellum were increased and correlated to their neurotoxic effects on the VOR system, indicating that both insoluble HgS and cinnabar could be absorbed from the gastrointestinal tract and distributed to the cerebellum. Although the vestibular labyrinth revealed no remarkable change under light microscopy, loss of Purkinje cells in the cerebellum was detected, and the enzymatic Na(+)/K(+)-ATPase activity of cerebellum (a higher inhibitory center of the VOR system) was significantly inhibited by HgS and cinnabar. Moreover, cerebellar nitric oxide (NO) production was increased significantly. Hence, we tentatively conclude that the increased Hg contents in the cerebellum following oral administration of HgS and cinnabar were responsible, at least in part, for the detrimental neurotoxic effect on the VOR system. Potentially, decreasing Na(+)/K(+)-ATPase activity and increasing NO production within the cerebellar regulatory center are postulated to mediate this VOR dysfunction caused by the mercurial compounds and cinnabar.
Authors:
Yi-Ho Young; Jiunn-Jye Chuu; Shing-Hwa Liu; Shoei-Yn Lin-Shiau
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Toxicological sciences : an official journal of the Society of Toxicology     Volume:  67     ISSN:  1096-6080     ISO Abbreviation:  Toxicol. Sci.     Publication Date:  2002 Jun 
Date Detail:
Created Date:  2002-05-15     Completed Date:  2002-10-10     Revised Date:  2010-09-17    
Medline Journal Info:
Nlm Unique ID:  9805461     Medline TA:  Toxicol Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  256-63     Citation Subset:  IM    
Affiliation:
Department of Otolaryngology, National Taiwan University Hospital, No. 1 Section 1, Jen-Ai Road, Taipei, Taiwan.
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MeSH Terms
Descriptor/Qualifier:
Administration, Oral
Animals
Caloric Tests
Cerebellar Cortex / drug effects,  enzymology,  pathology
Drugs, Chinese Herbal*
Electrophysiology
Guinea Pigs
Mercury / metabolism
Mercury Compounds / administration & dosage,  toxicity*
Nitric Oxide / metabolism
Purkinje Cells / drug effects,  pathology
Reflex, Vestibulo-Ocular / drug effects*,  physiology
Sodium-Potassium-Exchanging ATPase / antagonists & inhibitors,  metabolism
Temporal Bone / drug effects,  pathology
Chemical
Reg. No./Substance:
0/Drugs, Chinese Herbal; 0/Mercury Compounds; 10102-43-9/Nitric Oxide; 19122-79-3/cinnabar; 7439-97-6/Mercury; EC 3.6.3.9/Sodium-Potassium-Exchanging ATPase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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