Reverse 3,3',5'-triiodothyronine suppresses increase in free fatty acids in chickens elicited by dexamethasone or adrenaline.
Reverse triiodothyronine (rT3) displays hypometabolic properties and antagonizes the hypermetabolic effect of 3,5,3'-triiodothyronine (T3). Previous experiments revealed that exogenous rT3 enhanced free fatty acids (FFA) in heat-stressed pullets and in chickens infected with lipopolysaccharide from Escherichia coli. To gain more data concerning the action of rT3, its effect on lipaemia produced by two main stress hormones: glucocorticoids and catecholamines, has been investigated. Synthetic glucocorticoid [dexamethasone (Dex)] and adrenaline (Adr) were used in two experiments. The experiments differed in duration, i.e. 24 h (Dex) or 150 min (Adr), and frequency of rT3 injections, i.e. two (Dex) or single (Adr) injections. The doses of hormones were as follows: rT3: 14 microg 100 g body weight/ injection (subcutaneously): Dex: 5 mg/animal (subcutaneously) and Adr: 1 mg/animal (intramuscularly). Maximal increases in FFA of 230.5 and 227.5% were noted after 1.5 and 3 h, respectively, in birds treated with Dex. Reverse T3 almost completely suppressed the rise of plasma FFA elicited by Dex. The increase in Dex + rT3-treated fowl was only 30.4% (not significant in comparison to control). Adr increased FFA by a maximum of 89.1 % and treatment with rT3 (Adr + rT3 group) suppressed this FFA increase to 42.5%. The data obtained demonstrate that rT3 suppresses lipaemia induced by an exogenous glucocorticoid and adrenaline. This suppression was more pronounced in glucocorticoid-treated birds, where Dex produced a higher lipolytic response than Adr.
Bobek
S
S
Department of Animal Physiology, University of Agriculture, Kraków, Poland.
Sechman
A
A
Niezgoda
J
J
Jacek
T
T
D000818:Animals; D002645:Chickens; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism*; D006949:Hyperlipidemias / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology / Q000662:veterinary*; D007273:Injections, Intramuscular / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D011201:Poultry Diseases / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D014285:Triiodothyronine, Reverse / Q000008:administration & dosage / Q000494:pharmacology*
D005230:Fatty Acids, Nonesterified; D014285:Triiodothyronine, Reverse; D003907:Dexamethasone; D004837:Epinephrine