Evidence of the Presence of Thyroid Hormones in Achatina fulica Snails

ABSTRACT The objective of this study was to identify thyroid hormones and to examine their putative site of synthesis in Achatina fulica snails. For this purpose, radioimmunoassays were performed for T3 and T4 before and after long starvation with or without hemolymph deproteinization. Sodium/iodide symporter activity in vivo was analyzed through 125I administration with and without KClO4 pretreatment. Only T4 was detected, and its concentration decreased due to starvation or deproteinization. However, high-performance liquid chromatography analysis also showed the presence of T2 and T3 apart from T4, but rT3 was not detected in the A. fulica hemolymph. The sodium/iodide symporter activity was greater in cerebral ganglia than digestive gland, but KClO4 treatment did not inhibit iodide uptake in any of the tissues analyzed. Altogether, our data confirm for the first time the presence of thyroid hormones in A. fulica snails and suggest their participation in the metabolism control in this species, although the putative site of hormone biosynthesis remains to be elucidated

The effect of acute exercise session on thyroid hormone economy in rats

The hypothalamic-pituitary-thyroid axis is affected by acute exercise, but the mechanisms underlying thyroid function changes after exercise remain to be defined. The aim of this study was to elucidate the effects of a session of acute exercise on the treadmill at 75% of maximum oxygen consumption on thyroid function of rats. Male Wistar rats were divided into five groups: control (wtihout exercise), and killed immediately after (0 min) or 30, 60, and 120 min after the end of the exercise session. A significant increase in serum tri-iodothyronine (T-3) occurred immediately after the exercise, with a gradual decrease thereafter, so that 120 min after the end of the exercise, serum T-3 was significantly lower than that in controls. Total thyroxine (T-4) increased progressively reaching values significantly higher than that in the control group at 120 min. T-3/T-4 ratio was significantly decreased 60 and 120 unit after the exercise, indicating unpaired T-4-to-T-3 conversion. Liver type 1 deiodinase activity (D1) significantly decreased at 60 and 120 min, while pituitary D1 increased progressively from 30 to 120 min after the exercise, and thyroid D1 was increased only immediately after the end of the exercise. Brown adipose tissue (BAT) type 2 deiodinase activity (D2) was significantly lower at 30 min, but pituitary D2 remained unchanged. No change in serumn thyrotropin was detected, while serum corticosterone was significantly higher 30 unit after the exercise. Our results demonstrate that decreased liver D1 and BAT D2 might be involved in the decreased T-4-to-T-3 conversion detected after an exercise session on the treadmill

Evidence of the Presence of Thyroid Hormones in Achatina fulica Snails

<div><p>ABSTRACT The objective of this study was to identify thyroid hormones and to examine their putative site of synthesis in Achatina fulica snails. For this purpose, radioimmunoassays were performed for T3 and T4 before and after long starvation with or without hemolymph deproteinization. Sodium/iodide symporter activity in vivo was analyzed through 125I administration with and without KClO4 pretreatment. Only T4 was detected, and its concentration decreased due to starvation or deproteinization. However, high-performance liquid chromatography analysis also showed the presence of T2 and T3 apart from T4, but rT3 was not detected in the A. fulica hemolymph. The sodium/iodide symporter activity was greater in cerebral ganglia than digestive gland, but KClO4 treatment did not inhibit iodide uptake in any of the tissues analyzed. Altogether, our data confirm for the first time the presence of thyroid hormones in A. fulica snails and suggest their participation in the metabolism control in this species, although the putative site of hormone biosynthesis remains to be elucidated.</p></div

Hypothyroidism in the adult rat causes incremental changes in brain-derived neurotrophic factor, neuronal and astrocyte apoptosis, gliosis, and deterioration of postsynaptic density

Background: Adult hypothyroidism is a highly prevalent condition that impairs processes, such as learning and memory. Even though tetra-iodothyronine (T4) treatment can overcome the hypothyroidism in the majority of cases, it cannot fully recover the patient's learning capacity and memory. In this work, we analyzed the cellular and molecular changes in the adult brain occurring with the development of experimental hypothyroidism. Methods: Adult male Sprague-Dawley rats were treated with 6-propyl-2-thiouracil (PTU) for 20 days to induce hypothyroidism. Neuronal and astrocyte apoptosis were analyzed in the hippocampus of control and hypothyroid adult rats by confocal microscopy. The content of brain-derived neurotrophic factor (BDNF) was analyzed using enzyme-linked immunosorbent assay (ELISA) and in situ hybridization. The glutamatergic synapse and the postsynaptic density (PSD) were analyzed by electron microscopy. The content of PSD proteins like tyrosine receptor kinase B (TrkB), p7

Primer sequences.

<p>Primer sequences.</p

Baseline hemodynamic parameters.

<p>Baseline hemodynamic parameters.</p

Post-ischemic hemodynamic parameters.

<p>Post-ischemic hemodynamic parameters.</p