Uptake and metabolic effects of 3-iodothyronamine in hepatocytes

Abstract

3-Iodothyronamine (T 1 AM) is an endogenous relative of thyroid hormone with profound metabolic effects. In different experimental models, T 1 AM increased blood glucose, and it is not clear whether this effect is entirely accounted by changes in insulin and/or glucagone secretion. Thus, in the present work, we investigated the uptake of T 1 AM by hepatocytes, which was compared with the uptake of thyroid hormones, and the effects of T 1 AM on hepatic glucose and ketone body production. Two different experimental models were used: HepG2 cells and perfused rat liver. Thyronines and thyronamines (T0AMs) were significantly taken up by hepatocytes. In HepG2 cells exposed to 1 mM T 1 AM, at the steady state, the cellular concentration of T 1 AM exceeded the medium concentration by six-to eightfold. Similar accumulation occurred with 3,5,3 0 -triiodothyronine and thyroxine. Liver experiments confirmed significant T 1 AM uptake. T 1 AM was partly catabolized and the major catabolites were 3-iodothyroacetic acid (TA1) (in HepG2 cells) and T0AM (in liver). In both preparations, infusion with 1 mM T 1 AM produced a significant increase in glucose production, if adequate gluconeogenetic substrates were provided. This effect was dampened at higher concentration (10 mM) or in the presence of the amine oxidase inhibitor iproniazid, while TA1 was ineffective, suggesting that T 1 AM may have a direct gluconeogenetic effect. Ketone body release was significantly increased in liver, while variable results were obtained in HepG2 cells incubated with gluconeogenetic substrates. These findings are consistent with the stimulation of fatty acid catabolism, and a shift of pyruvate toward gluconeogenesis. Notably, these effects are independent from hormonal changes and might have physiological and pathophysiological importance.

Quantitative Analysis of Thyroid Hormone Metabolites in Cell Culture Samples Using LC-MS/MS

“…Recent LC-MS/MS investigations of TH or TAM were based on direct injection of diluted cell lysates and/or cell culture media (w/o FCS) without analyte extraction [25,26,27]. Sample preparation (solid-phase extraction, SPE, liquid-liquid extraction or online SPE) prior to LC-MS/MS analysis can improve solid and high RE with a minor ME, while preventing accelerated deterioration of analytical columns and contamination of the LC-MS/MS system.…”

Quantitative analysis of thyroid hormone metabolites in cell culture samples using LC-MS/MS

“…The appropriate IS can compensate for the alteration of analytes in complex matrices during sample preparation, adhesion effects or ion suppression during electrospray ionization during the MS measurement by coelution from the LC [12] . Recent LC-MS/MS investigations of TH or TAM were based on direct injection of diluted cell lysates and/or cell culture media (w/o FCS) without analyte extraction [25][26][27] . Sample preparation (solid-phase extraction, SPE, liquid-liquid extraction or online SPE) prior to LC-MS/MS analysis can improve solid and high RE with a minor ME, while preventing accelerated deterioration of analytical columns and contamination of the LC-MS/MS system.…”

Hit-to-Lead Optimization of Mouse Trace Amine Associated Receptor 1 (mTAAR1) Agonists with a Diphenylmethane-Scaffold: Design, Synthesis, and Biological Study

“…Among these new compounds, analogue 2 was synthesized to evaluate the effects induced by the recovery of the phenolic function as in T1AM. Additionally, to gain further insights on how the pattern of substitutions modulate the SG-analogues potency as mTAAR1 agonists, we investigated the following structure modifications: (a) the introduction of small alkyl substituents (Me, i-Pr) on both outer and inner rings (4, 6−10), (b) the removal of the methylene bridge, producing the diaryl analogues 5 and 6, (c) the introduction of a biguanide moiety at the oxy-alkyl side chain (15,16), and finally (d) mono-and bis-N-acetylation (3, 9−15). This last chemical modification has been suggested by a recent study conducted by Hoefig et al, 6 showing that O-acetyl and N-acetyl derivatives of T1AM may be found in white adipose tissue and liver endogenous cells.…”

“…As shown in Figure 4a, treatment of HepG2 cells with T1AM (0.1, 1, and 10 μM) confirmed the bell-shaped dose−response curve observed in our previous study. 16 To better define the dose dependence of 1 and 2 effects on glucose production, additional experiments were carried out using a wider range of doses for both compounds. As shown in Figure 4b, the EC 50 calculated for the effect on gluconeogenesis was in the submicromolar range for 2, and in the supramicromolar range for 1.…”

“…Brown oil (52% yield). 4-(4-(2-(3-Carbamimidoylguanidino)ethoxy)-2-methylbenzyl)-aniline (16). To a solution of the amide 15 (0.57 mmol) in MeOH was added dropwise an aqueous solution of HCl 1N (0.2 mL); the resulting solution was refluxed for 2 h, and then, after cooling, the solvent was evaporated.…”