Hypothyroidism affects dopamine D2 modulation of metabolism, body temperature, and breathing frequency in young female hamsters (1178.1)

Previous work from our laboratory showed that administration of 1 mg/kg bromocriptine (B), a D2 receptor agonist, stimulated body temperature, metabolism and ventilation in older hypothyroid females, but depressed these variables in older euthyroid female hamsters without affecting the expression of D2 receptors in various brain regions. This project investigated how hypothyroidism (induced by administration of propylthiouracil in drinking water) affected body temperature, ventilation and metabolism in young euthyroid and hypothyroid female hamsters following administration of vehicle and B. We hypothesized that the physiological responses of 2 month old females to B (1mg/kg) would be similar to those observed in older hypothyroid female hamsters. Results indicated that administration of 1 mg/kg B had little effect on breathing in young euthyroid and hypothyroid female hamsters. A higher dose, 3 mg/kg B, decreased body temperature and frequency of breathing in euthyroid hamsters, but stimulated metabolic rate and caused a post‐hypoxic frequency decline in hypothyroid hamsters. In conclusion, young female hypothyroid hamsters exhibited a lower sensitivity to B and also differences in frequency of breathing, body temperature and metabolic responses to B compared to previous responses observed in older hypothyroid female hamsters. Grant Funding Source : Supported by the UDiscover program at the University of South Dakota and APS STRIDE grant