PRESENCE OF THE STRESS-INDUCIBLE FORM OF HSP-70 (HSP-72) IN NORMAL RAT COLON

The expression of heat shock proteins (hsp) is probably one of the mos t primitive mechanisms of cellular protection from stress. Pathogens s uch as viruses and bacteria have recently been found to induce the hea t shock gene expression. In the present study hsp-72, the stress-induc ible form of hsp-70, was detected by Western blotting in samples from rat distal colon (DC), proximal colon (PC), and terminal ileum (TI), b ut was not found in proximal small bowel (PSB) or other organs (liver, kidney, spleen, heart, and brain) of unstressed animals. The signal i ntensity of hsp-72 in colon (DC>PC>TI>PSB) correlates qualitatively wi th the presence of normal gut microflora. hsp-72 was also observed in DC, to a lesser extent in PC, but not in TI or PSB of bacteria-free or antibiotic-treated rats. Inflammatory states induced by the intraveno us administration of endotoxin (1 mg/kg), the subcutaneous injection o f zymosan (1 g/kg) or by cecal ligation and puncture (sepsis) failed t o increase the hsp-72 levels in rat colon or other organs. These resul ts demonstrate that hsp-72 is expressed in normal rat colon. However, the induction of hsp-72 expression may not be due solely to the presen ce of resident bacteria in the gut, but instead, may be the result of a more complex process.