Comparison of rats of the Fischer 344 and Long-Evans strains in their autonomic thermoregulatory response to trimethyltin administration.

The purpose of this study was to assess the effect of genetic strain on the acute and long-term thermoregulatory response to the neurotoxicant trimethyltin (TMT) in rats of the Long-Evans (LE) and Fischer 344 (FCH) strains. In one study basic thermoregulatory responses including colonic temperature (Tc), metabolic rate (MR), evaporative water loss (EWL), motor activity (MA), and thermal conductance (Cd) were measured in both rat strains at ambient temperatures (Ta) of 10, 28, and 37 degrees C. It was found that the LE rat has a significantly higher Tc when it is measured in their home cage. Because of its smaller body mass the FCH rat has a higher MR at all Ta values. The FCH rat also has a greater rate of EWL during exposure to a Ta of 37 degrees C. Following iv administration of 8.0 mg/kg TMT both rat strains become significantly hypothermic; however, the effect differed significantly between the strains. At 26-34 d after TMT exposure thermoregulatory responses at Ta values of 10-37 degrees C were generally similar to that of the saline controls. Overall, the LE and FCH strains of rat exhibit some distinct thermoregulatory differences in response to changes in Ta.