Background: The thyroid hormone derivative 3-iodothyronamine (T1AM), an endogenous biogenic amine, is a potent agonist of the G protein–coupled trace amine-associated receptor 1 (TAAR1). T1AM is present in rat brain, and TAAR1 is expressed in hypothalamic nuclei associated with the regulation of energy homeostasis.
Aim: The aim of this study was to determine the effects of T1AM on food intake in rodents.
Methods: We determined the effect of (i) intraperitoneal (i.p.) administration of T1AM on food intake, oxygen consumption (VO2) and locomotor activity in mice; (ii) intracerebroventricular (ICV) injection of T1AM on food intake in male rats; (iii) c-fos expression following ventricular administration of T1AM in male rats; and (iv) direct injection of T1AM into the arcuate nucleus (ARC) of male rats on food intake.
Results: (i) T1AM (4 nmol/kg) significantly increased food intake following i.p. injection in mice but had no effect on VO2 or locomotor activity. (ii) ICV administration of T1AM (1.2 nmol/kg) significantly increased food intake in male rats. (iii) Intraventricular administration of T1AM significantly increased c-fos expression in the ARC of male rats. (iv) Direct administration of T1AM (0.12, 0.4 and 1.2 nmol/kg) into the ARC of male rats significantly increased food intake.
Conclusion: These data suggest that T1AM is an orexigenic factor that may act through the ARC to increase food intake in rodents.