Effects of @entity6448 on thyroid status in XXXX .

@entity1375 @entity6449 @entity137 @entity26 @entity1955 @entity6448 @entity35 @entity1954
Treatment of @entity35 with toxic doses of @entity6448 ( @entity6449 ) results in reduction in feed intake, body weight, serum @entity1955 (T4) and @entity1954 (T3) concentrations, resting heart rates, and body temperatures. Some of these effects resemble changes characteristic of @entity1375 . Therefore the effects of @entity6449 on functional thyroid status were examined to relate changes in thyroid status with signs of @entity6449 @entity137 . In the present study, the dose-related effects of @entity6449 on plasma thyroid hormone concentrations and a number of indices of thyroid status were investigated and compared with signs of @entity6449 @entity137 . Young adult male @entity35 were given single intraperitoneal doses of @entity6449 (20, 40, or 80 mg/kg), and subsequent changes were evaluated 7 days after dosing. Decreases in body weight and feed intake were used as measures of @entity6449 @entity137 and ranged from minimal to severe. Plasma T4 concentrations and free thyroxine index were drastically reduced at all doses, and these changes were mimicked by pair feeding only at the high dose of @entity6449 (80 mg/kg). Plasma T3 concentrations were not affected by @entity6449 treatment, whereas pair feeding at the high-dose level (80 mg @entity6449 /kg) resulted in a significant reduction (ca. 50% from unlimited-fed control) in T3. Although @entity6449 caused a dose-dependent decrease in thyroid gland weight which was not completely paralleled by pair feeding, thyroid histology was unremarkable. @entity6449 treatment resulted in a small decrease in basal metabolic rate (8% at 80 mg @entity6449 /kg). A greater reduction (ca. 18%) in basal metabolic rate was observed in vehicle-treated controls pair-fed to @entity35 of the 80 mg @entity6449 /kg dose group. Thermogenesis, as measured by @entity26 consumption and body core temperatures, was not greatly affected by @entity6449 treatment, and these changes were paralleled by pair feeding. Reductions in plasma T4 concentration and free thyroxine index at a low dose of @entity6449 (20 mg/kg) indicate that @entity6449 -induced hypothyroxinemia can be dissociated from its overtly toxic effects (i.e., severe hypophagia and body weight loss) observed at higher doses. The results obtained here suggest that despite alterations in plasma thyroid hormone levels there is no consistent pattern of effects on functional thyroid status which could explain the overt @entity137 of @entity6449 .
