Effect of a Single Dose of Triiodothyronine on the Uptake of (Methyl-¹⁴C) Choline into Chick Liver Phospholipids

Abstract

The effects of a single dose of 3,3'-5-triiodothyronine (T3) on the uptake of (methyl-14C) choline into liver phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) were studied in chicks as a function of time up to 6 h after injection of the radioactive precursor. In all cases, chicks received the T3 dose intraperitoneally 5 h before injection of the labelled compound. T3 enhances the incorporation of 14C-choline into liver PC, showing a biphasic response; the main uptake occurs between 2 and 3 h after administering the precursor. A smaller but significant hormone-dependent increase in incorporation of the labelled compound is observed in the case of LPC. Lipid P associated to PC and LPC remains constant throughout the experiment, and does not vary with hormone treatment. It is suggested that T3-injection increases, either directly or through other metabolic processes, PC and LPC turnover in chick liver cells.

A Study of the Hepatic Lipids during Chick Embryo Development Effect of Triiodothyronine

“…The effects of thyroid hormones on rat and chick liver lipidic metabolism has been studied by different authors in our laboratory (Arrondo et al, 1978;Paino et al, 1981;Marino et al, 1984;Perez et al, 1984), which suggest a hormone-dependent activation of lipid metabolism.…”

Increased Phospholipid Methylation and Glycogen Phosphorylase Activation after a Single Dose of Dexamethasone in Mouse Liver

“…The activities of glycogen phosphorylase a and glycogen synthase a were measured directly on the liver homogenate, in normal, hormonal-treated and/or adrenalectomized mice, by standard methods: phosphorylase a activity was determined in the presence of 1 mM caffeine by the release of inorganic phosphate from glucose-1-phosphate according to the method of Hue et al (1975); the glycogen synthase â activity was assayed by the method of De Wulf et al Analysis of lipids and radioactivity determinations. Lipids were extracted by blending the livers with chloroform: methanol: hydrochlorid acid 12.5 N (200: loo:1) in a Potter-Elvehjem homogenizer as previously described (Marino et al, 1984). Samples (100 iii) were applied to 20 cm t.l.…”