Selective thyroid hormone receptor-beta activation: a strategy for reduction of weight, cholesterol, and lipoprotein (a) with reduced cardiovascular liability.
Few treatments for obesity exist and, whereas efficacious therapeutics for hyperlipidemia are available, further improvements are desirable. Thyroid hormone receptors (TRs) regulate both body weight and cholesterol levels. However, thyroid hormones also have deleterious effects, particularly on the heart. The TR beta subtype is involved in cholesterol lowering and possibly elevating metabolic rate, whereas TR alpha appears to be more important for control of heart rate (HR). In the current studies, we examined the effect of TR beta activation on metabolic rate and HR with either TR alpha 1-/- mice or the selective TR beta agonist KB-141 in mice, rats, and monkeys. 3,5,3'-triiodi-l-thyronine (T3) had a greater effect on increasing HR in WT than in TR alpha-/- mice (ED15 values of 34 and 469 nmol/kg/day, respectively). T3 increased metabolic rate [whole body oxygen consumption (MVO2)] in both WT and TR alpha-/- mice, but the effect in the TR alpha 1-/- mice at the highest dose was half that of the WT mice. Thus, stimulation of MVO2 is likely due to both TR alpha and -beta. T3 had equivalent potency for cholesterol reduction in WT and TR alpha-/- mice. KB-141 increased MVO2 with selectivities of 16.5- and 11.2-fold vs. HR in WT and TR alpha 1-/- mice, respectively. KB-141 also increased MVO2 with a 10-fold selectivity and lowered cholesterol with a 27-fold selectivity vs. HR in rats. In primates, KB-141 caused significant cholesterol, lipoprotein (a), and body-weight reduction (up to 7% after 1 wk) with no effect on HR. TR beta-selective agonists may constitute a previously uncharacterized class of drugs to treat obesity, hypercholesterolemia, and elevated lipoprotein (a).
Grover
Gary J
GJ
Metabolic and Cardiovascular Drug Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute, Pennington, NJ 08534, USA. groverg@bms.com
Mellström
Karin
K
Ye
Liu
L
Malm
Johan
J
Li
Yi-Lin
YL
Bladh
Lars-Göran
LG
Sleph
Paul G
PG
Smith
Mark A
MA
George
Rocco
R
Vennström
Björn
B
Mookhtiar
Kasim
K
Horvath
Ryan
R
Speelman
Jessica
J
Egan
Donald
D
Baxter
John D
JD
D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects; D002784:Cholesterol / Q000097:blood*; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D017270:Lipoprotein(a) / Q000097:blood*; D008252:Macaca fascicularis; D051379:Mice; D018345:Mice, Knockout; D010647:Phenyl Ethers / Q000494:pharmacology*; D010648:Phenylacetates / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011988:Receptors, Thyroid Hormone / Q000819:agonists* / Q000378:metabolism; D037021:Thyroid Hormone Receptors alpha / Q000172:deficiency / Q000235:genetics; D037042:Thyroid Hormone Receptors beta; D014284:Triiodothyronine / Q000494:pharmacology; D015431:Weight Loss / Q000187:drug effects*
D000924:Anticholesteremic Agents; D002791:Cholesterol, Dietary; C478108:KB 141; D017270:Lipoprotein(a); D010647:Phenyl Ethers; D010648:Phenylacetates; D011988:Receptors, Thyroid Hormone; D037021:Thyroid Hormone Receptors alpha; D037042:Thyroid Hormone Receptors beta; D014284:Triiodothyronine; D002784:Cholesterol