The thyroid hormone derivative 3-iodothyronamine increases food intake in rodents.
BACKGROUND
The thyroid hormone derivative 3-iodothyronamine (T(1)AM), an endogenous biogenic amine, is a potent agonist of the G protein-coupled trace amine-associated receptor 1 (TAAR1). T(1)AM is present in rat brain, and TAAR1 is expressed in hypothalamic nuclei associated with the regulation of energy homeostasis.


OBJECTIVE
The aim of this study was to determine the effects of T(1)AM on food intake in rodents.


METHODS
We determined the effect of (i) intraperitoneal (i.p.) administration of T(1)AM on food intake, oxygen consumption (VO(2)) and locomotor activity in mice; (ii) intracerebroventricular (ICV) injection of T(1)AM on food intake in male rats; (iii) c-fos expression following ventricular administration of T(1)AM in male rats; and (iv) direct injection of T(1)AM into the arcuate nucleus (ARC) of male rats on food intake.


RESULTS
(i) T(1)AM (4 nmol/kg) significantly increased food intake following i.p. injection in mice but had no effect on VO(2) or locomotor activity. (ii) ICV administration of T(1)AM (1.2 nmol/kg) significantly increased food intake in male rats. (iii) Intraventricular administration of T(1)AM significantly increased c-fos expression in the ARC of male rats. (iv) Direct administration of T(1)AM (0.12, 0.4 and 1.2 nmol/kg) into the ARC of male rats significantly increased food intake.


CONCLUSIONS
These data suggest that T(1)AM is an orexigenic factor that may act through the ARC to increase food intake in rodents.
Dhillo
W S
WS
Department of Investigative Medicine, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
Bewick
G A
GA
White
N E
NE
Gardiner
J V
JV
Thompson
E L
EL
Bataveljic
A
A
Murphy
K G
KG
Roy
D
D
Patel
N A
NA
Scutt
J N
JN
Armstrong
A
A
Ghatei
M A
MA
Bloom
S R
SR
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D001679:Biogenic Amines / Q000008:administration & dosage*; D001921:Brain / Q000187:drug effects*; D004435:Eating / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013970:Thyronines / Q000008:administration & dosage*
C487948:3-iodothyronamine; D001679:Biogenic Amines; D013970:Thyronines