1. Effects of endosulfan, malathion and carbaryl on circulating T4, T3 and T3/T4 ratio in the freshwater catfish, C. batrachus have been studied during reproductively active phases, i.e. vitellogenic and post-vitellogenic phases of its annual reproductive cycle. 2. Endosulfan provoked a significant increase in T4 and a decrease in T3 as well as the T3/T4 ratio. 3. Malathion decreased T3 and T3/...

The contribution of L-thyroxine (T4) to nuclear thyroid receptor occupancy was studied in GC cells incubated with concentrations of 3,5,3'-triiodo-L-thyronine (T3) and T4 that resulted in free iodothyronine levels similar to those in serum of euthyroid rats. T4 accounted for 5.4-10% of the occupied receptors: T3 derived from T4 [T3(T4)] and T3 added to medium accounted for the remainder of rece...

t4 and t3, two major hormones of thyroid gland, are responsible for regulation of “basal metabolism” in the body. thyroid function is regulated primarily by variation in the pituitary tsh. in this study, about four hundred individuals were considered from four iranian populations. they were selected randomly in their cities; shiraz, mashhad, rasht, and ilam. essential family information was ask...

To study the protective effects of maternal thyroxine (T4) and 3,5,3'-triiodothyronine (T3) in congenital hypothyroidism, we gave pregnant rats methimazole (MMI), an antithyroid drug that crosses the placenta, and infused them with three different doses of T4 or T3. The concentrations of both T4 and T3 were determined in maternal and fetal plasma and tissues (obtained near term) by specific RIA...

In order to determine the frequency of thyroxine (T4) toxicosis and study the possibility of usefulness for differentiation between thyrotoxic Graves' disease and destructioninduced thyrotoxicosis, the serum concentrations of T4, triiodothyronine(T3), reverse T3 (rT3), and T4-binding globulin (TBG) and the values of T3-uptake and radioactive iodine uptake (RAIU) were measured, and free, T4 inde...

The main objective of this study was to characterize nuclear T3 and T4 binding in the developing rat brain. More specifically, we sought to determine (a) whether T3 and T4 bind to the same nuclear receptor, (b) whether there are multiple forms of nuclear T3 or T4 receptors, and (c) whether the above parameters are similar in nuclei of cerebral hemispheres and cerebellum of developing rat brain....

We have studied whether, or not, tissue-specific regulatory mechanisms provide normal 3,5,3'-triiodothyronine (T3) concentrations simultaneously in all tissues of a hypothyroid animal receiving thyroxine (T4), an assumption implicit in the replacement therapy of hypothyroid patients with T4 alone. Thyroidectomized rats were infused with placebo or 1 of 10 T4 doses (0.2-8.0 micrograms per 100 gr...