RESUMO
OBJECTIVES: This study investigated the effects of glutamine administration on the expression of the heat-shock protein 72 (Hsp72) in the liver during sepsis. The role of heat-shock factor 1 (HSF-1) was analyzed for possible mechanisms to the phenomenon. METHODS: Male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). Heat-shock treatment was applied to the rats' whole body using an electric heating pad 24 h before CLP. Glutamine or saline was administered 1 h after initiation of sepsis by tail vein injection. The Hsp72 and HSF-1 expressions were detected using western blot analysis, and Hsp72 mRNA expression was measured using reverse transcription-polymerase chain reaction. RESULTS: The Hsp72 content noticeably increased in the livers of preheated rats supplied by glutamine 1 h after sepsis. However, no further synthesis of Hsp72 was found in septic livers or sham glutamine-treated livers. Hsp72, which was induced by preheating, decreased with time, whereas a large amount of Hsp72 could be detected by glutamine administration. Reverse transcription-polymerase chain reaction data indicated that Hsp72 mRNA could be detected only in the group treated with preheating and glutamine administration. The translocation of HSF-1 occurred significantly during sepsis in preheated and non-preheated rats. However, only the preheated group showed the phosphorylation in HSF-1. With the administration of glutamine, the nuclear accumulation of phosphorylated HSF-1 was observed to decline significantly 9 and 18 h after CLP when the Hsp72 mRNA became detectable. CONCLUSIONS: These results demonstrated that Hsp72 could be induced by glutamine in septic liver only if the liver was preconditioned by heat-shock response. The selective facilitating effect might depend on the accumulation of intranuclear phosphorylated HSF-1 caused by previous heat-shock treatment.
Assuntos
Glutamina/farmacologia , Proteínas de Choque Térmico HSP72/metabolismo , Resposta ao Choque Térmico/efeitos dos fármacos , Sepse/metabolismo , Animais , Western Blotting , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP72/genética , Fatores de Transcrição de Choque Térmico , Masculino , Fosforilação , RNA Mensageiro/metabolismo , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Sepse/genética , Fatores de Tempo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The blood-brain barrier (BBB) is a specialized structure in the central nervous system (CNS), which participates in maintenance of a state of cerebrospinal fluid homeostasis. The endothelial cells of the cerebral capillaries and the tight junctions between them form the basis of the BBB. Research has shown that destruction of the BBB is associated with diseases of the CNS. However, there is little research on how the BBB might be protected. In this study, we used a high osmotic solution (1.6 M D-mannitol) to open the BBB of rats and Evans blue dye as a macromolecular marker. The effect of heat shock treatment was evaluated. The results show that increased synthesis of heat shock protein 72 (Hsp72) was induced in the heated group only. BBB permeability was significantly less in the heat shock-treated group after hyperosmotic shock. The major tight junction proteins, occludin and zonula occludens (ZO)-1, were significantly decreased after D-mannitol treatment in the nonheated group, whereas they were preserved in the heated group. The coimmunoprecipitation studies demonstrated that Hsp72 could be detected in the precipitates of brain extract interacting with anti-ZO-1 antibodies as well as those interacting with anti-occludin antibodies in the heated group. We conclude that the integrity of tight junctions could be maintained by previous heat shock treatment, which might be associated with the increased production of Hsp72.