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Reduced central c‐fos expression and febrile response to repeated LPS injection into periodontal tissue in rats
Author(s) -
Tedeschi Valéria Pontelli Navarro,
Dias Mirela Barros,
Branco Luiz Guilherme Siqueira
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1360-d
Subject(s) - lipopolysaccharide , immunohistochemistry , hypothalamus , saline , medicine , endocrinology , c fos , anesthesia , chemistry , gene expression , biochemistry , gene
Systemic injection of repeated doses of Escherichia coli lipopolysaccharide (LPS) results in attenuation of the febrile response, i.e. endotoxin tolerance, which has been fairly well characterized in rats. In the present study, we tested the hypothesis that endotoxin tolerance also occurs after repeated local injection of LPS in the periodontal protection tissue. Male Wistar rats were giving a gingival intra‐pouch injection of saline or LPS at dose of 100 microg/kg in 3 consecutive days with 24 h intervals. Body core temperature (Tb) was measured with a miniature datalogger. Another group of rats were used for Fos immunohistochemistry 3 h after the injections in both non‐tolerant and tolerant animals. In day 1 we observed a biphasic febrile response after LPS injection. The increase in Tb started about 1.5 h after LPS injection and lasted 5 h. In day 2 this response was attenuated and in day 3 the febrile response was completely abolished. These data indicate that rats do develop endotoxin tolerance after LPS administration in the oral cavity. Moreover, immunohistochemistry detected a reduction in LPS‐induced c‐fos expression in the subnucleus caudalis of spinal trigeminal nucleus and in the preoptic area of the hypothalamus in tolerant animals compared with non‐tolerant animals, indicating that the endotoxin tolerance may be locally mediated in the periodontal protection tissues of rats. Financial support: FAPESP.