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Acute inflammation and recovery in rats after intratracheal instillation of a 1-->3-B-glucan (zymosan a).

Authors
Young-SH; Robinson-VA; Barger-M; Porter-DW; Frazer-DG; Castranova-V
Source
J Toxicol Environ Health, A 2001 Oct; 64(4):311-325
NIOSHTIC No.
20032187
Abstract
Although endotoxin is a known potent stimulant of inflammatory responses, the magnitude of pulmonary response following exposure to various organic dusts does not always correlate with endotoxin content of the dusts alone. Other components, such as 1-->-3-b-glucans, derived from the inner cell wall of yeasts and fungi, have been implicated in organic dust toxic syndrome. However, animal studies report conflicting results concerning the inflammatory potency of 1-->-3-b-glucan. In this experiment, the pulmonary reaction of rats to 1-->-3-b-glucan (zymosan A) exposure was assessed. Male Sprague-Dawley rats were exposed via intratracheal instillation (IT) to zymosan A (dose range 0-5 mg/ kg body weight). Rats were sacrificed 1-7 d postexposure and the following pulmonary responses were monitored: (1) breathing frequency, (2) differential cell counts of bronchoalveolar lavage (BAL) cells, (3) chemiluminescence (CL) as a measure of alveolar macrophage activation, (4) nitric oxide production by alveolar macrophages, (5) albumin levels, and ( 6) lactate dehydrogenase (LDH) activity in the first acellular lavage fluid. Upon challenge with zymosan A, rats exhibited a dose-dependent pulmonary response at 1 d post IT that was significantly higher than the control level at a dose of 1-2.5 mg/ kg body weight for each of these pulmonary parameters. Post-IT enhancement of breathing frequencies and polymorphonuclear leukocytes (PMN) obtained by BAL both correlated very well with zymosan A concentration (r2 = .95 and .99, respectively). Elevation of albumin levels and LDH activity of the acellular BAL fluid also correlated (r2 = .80) with the dose of zymosan. The recovery from a single intratracheal administration of zymosan A (2.5 mg/ kg body weight) was monitored over 7 d. PMN and CL showed significant recovery from d 1 level by 3 d postexposure. Breathing frequencies and nitric oxide production showed significant recovery from d 1 level by 4 d postexposure. A good correlation (r2 = .8) between recovery of PMN in BAL, CL, or nitric oxide production and the days postexposure was observed.
Keywords
Acute-exposure; Animal-studies; Laboratory-animals; Laboratory-testing; Organic-dusts; Pulmonary-system; Exposure-levels
Contact
Shih-Houng Young, PhD, Engineering Control and Technology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, M/S 2027, Morgantown, 26505, USA
CODEN
JTEHD6
Publication Date
20011001
Document Type
Journal Article
Email Address
syoung@cdc.gov
Fiscal Year
2002
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
1528-7394
NIOSH Division
HELD
Source Name
Journal of Toxicology and Environmental Health, Part A: Current Issues
State
WV
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