gc-1-compound and Body-Weight

This study demonstrated a nanochannel membrane device (NMD) for controlled and sustained release of GC-1 in rats, in the context of the treatment of metabolic syndrome. Release profiles were established in vitro both with and without 5% labrasol for over 2 months. In vivo pharmacokinetic evaluation showed effective GC-1 plasma concentrations, which resulted in significant reductions in body weight after just one week of treatment when compared to the NMD releasing vehicle only (PBS). We also provided evidence that rats treated with NMD-GC-1 present sub-active thyroids and clear differences in the morphology of the epithelium and follicles as compared to the controls, while the heart showed changes in weight. Moreover, body temperatures remained stable throughout treatment, and glucose, pancreatic islet size, and liver histology appeared similar between the treated and control groups. Prolonged constant administration of GC-1 from the NMD proved to be a valid strategy to facilitate weight loss.

Topics: Acetates; Animals; Body Weight; Liver; Nanotechnology; Phenols; Rats; Rats, Inbred F344

Current drug therapies for obesity are ineffective, and existing treatments for lipid disorders can be further improved. Thyroid hormones affect both conditions, although currently available nonselective thyromimetics are not clinically useful for such treatment due to cardiac side effects. Recent studies suggest that thyroid hormone receptor subtype beta (TRbeta) selective agonists have a profile in which cholesterol can be reduced with minimal tachycardia. The purpose of this study was to determine whether modest (5-10%) increases in metabolic rate could also be observed with minimal tachycardia after TRbeta stimulation. For these studies, the TRbeta selective agonist, GC-1, was used to assess selectivity for lipid-lowering and metabolic rate changes relative to tachycardia. Studies in cholesterol-fed rats (7 d treatment) showed that GC-1 reduced cholesterol (ED(50) = 190 nmol/kg x d) approximately 30 times more potently than it induced tachycardia (ED(15) = 5451 nmol/kg x d). T(3) showed no potency difference between cholesterol lowering and tachycardia. GC-1 showed approximately 10-fold selectivity for increasing metabolic rate (ED(5) = 477 nmol/kg x d) relative to tachycardia compared with T(3), which showed no selectivity. In cynomolgus monkeys treated for 7 d, significant cholesterol-lowering and lipoprotein (a) reduction was noted for both T(3) and GC-1, whereas no tachycardia was observed for GC-1, unlike T(3). T(3) and GC-1 caused a significant (approximately 4%) reduction in body weight in these animals. Therefore, selective TRbeta activation may be a potentially usefully treatment for obesity and reduction of low density lipoprotein cholesterol and reduction of the atherogenic risk factor lipoprotein (a).

Topics: Acetates; Animals; Body Weight; Cholesterol; Cholesterol, Dietary; Dose-Response Relationship, Drug; Female; Heart Rate; Lipoprotein(a); Macaca fascicularis; Male; Phenols; Rats; Rats, Sprague-Dawley; Receptors, Thyroid Hormone; Triiodothyronine

Thyroid hormones influence the function of many organs and mediate their diverse actions through two types of thyroid hormone receptors, TRalpha and TRbeta. Little is known about effects of ligands that preferentially interact with the two different TR subtypes. In the current study the comparison of the effects of the novel synthetic TRbeta-selective compound GC-1 with T3 at equimolar doses in hypothyroid mice revealed that GC-1 had better triglyceride-lowering and similar cholesterol-lowering effects than T3. T3, but not GC-1, increased heart rate and elevated messenger RNA levels coding for the I(f) channel (HCN2), a cardiac pacemaker that was decreased in hypothyroid mice. T3 had a larger positive inotropic effect than GC-1. T3, but not GC-1, normalized heart and body weights and messenger RNAs of myosin heavy chain alpha and beta and the sarcoplasmic reticulum adenosine triphosphatase (Serca2). Additional dose-response studies in hypercholesteremic rats confirmed the preferential effect of GC-1 on TRbeta-mediated parameters by showing a much higher potency to influence cholesterol and TSH than heart rate. The preferred accumulation of GC-1 in the liver vs. the heart probably also contributes to its marked lipid-lowering effect vs. the absent effect on heart rate. These data indicate that GC-1 could represent a prototype for new drugs for the treatment of high lipid levels or obesity.

Topics: Acetates; Animals; Blotting, Northern; Body Weight; Dose-Response Relationship, Drug; Heart; Hemodynamics; Hypercholesterolemia; Hypolipidemic Agents; Hypothyroidism; Lipids; Male; Mice; Organ Size; Phenols; Rats; Rats, Sprague-Dawley; Receptors, Thyroid Hormone; RNA, Messenger; Thyroxine; Triiodothyronine