Induction of heat shock protein in interdental cells by hyperthermia

The effect of hyperthermia on induction of the 72 kilodalton (kDa) heat shock protein (HSP72) was examined in interdental cells of the guinea pig cochlea. After being immersed in a water bath of either normal body temperature (37 degrees C, control condition) or 43 degrees C (hyperthermic condition), animals were killed either 0, 1, 2, 6, or 18 hours later. Cochlear sections were incubated with a monoclonal antibody raised against HSP72 and relative staining densities were quantified with a light microscopic image analysis system. Optical densities of the interdental cell region of animals receiving hyperthermia treatment were significantly greater than those of animals in the control group. Further analysis revealed that levels of HSP72 immunoreactivity began increasing by 1 hour after hyperthermia and continued to increase thereafter, to reach maximal levels at 6 hours. The maximal levels were maintained for the rest of the experiment--18 hours. The results indicate that hyperthermia leads to an increase in the synthesis of HSP72 in guinea pig interdental cells.