Lewis rats display hyporesponsive hypothalamo-pituitary-adrenocortical (HPA) axes, overproduction of cytokines, and susceptibility to inflammatory disease. The Lewis corticotropin-releasing hormone (CRH) neurosecretory system contains normal numbers of vasopressin (VP)-deficient axon varicosities, but abnormally sparse VP-containing varicosities in the external zone of the median eminence, comp...

In order to elucidate the mechanism of thyroid hormone action on the ovary, direct effects of L-thyroxine (T4) or L-triiodothyronine (T3) on steroidogenic enzyme induction were investigated in vitro using a monolayer culture system of porcine granulosa cells obtained from small follicles. The cells were cultured in the absence or presence of porcine FSH (20ng/ml) for 6 days, with or without T4 ...

BACKGROUND A number of abnormalities has been identified among drug addicted users especially heroin addicts. However, there are a few studies to assess the opium effects on thyroid hormones. the aim of the present study is to investigate the effect of opium on the thyroid function tests. METHOD In this case-control, 50 male addicts, aged 20-50 years, with history of addiction to opium lastin...

Thyroid hormones play a critical role in the growth of many organs, especially the brain. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) interact with the thyroid pathway and may disturb neurodevelopment. This prospective study was designed to examine associations between maternal blood PBDEs and PCBs in early pregnancy and levels of thyroid hormones in maternal and...

The major product secreted by the thyroid is thyroxine (T4), whereas most of the biologically active triiodothyronine (T3) derives from the peripheral conversion of T4 into T3. The deiodinase enzymes are involved in activation and inactivation of thyroid hormones (THs). Type 1 and type 2 deiodinase (D1 and D2) convert T4 into T3 whereas D3 degrades T4 and T3 into inactive metabolites and is thu...

This study was conducted to examine the effects of thyme extract and probiotic on biological growth promoters. Therefore blood thyroid hormones (T3 and T4) concentration and growth hormone (GH) gene expression were measured. 108 one-day-old Ross male broiler were randomly allocated in 3 experimental treatments including: controlunsupplemented (CTRL), birds supplemented with Zataria multiflora e...

We developed and validated a non-invasive thyroid hormone measure in feces of a diverse array of birds and mammals. An I(131) radiolabel ingestion study in domestic dogs coupled with High Pressure Liquid Chromatography (HPLC) analysis, showed that peak excretion in feces occurred at 24-48h post-ingestion, with I(131)-labelled thyroid hormone metabolites excreted primarily as triiodothyronine (T...

Thyroid hormone production is regulated via pituitary thyrotropin (TSH) modulation of thyroxine (T4) prohormone secretion by the thyroid gland and regulation of active triiodothyronine (T3) production in peripheral tissues via metabolic events influencing activities of the iodothyronine monodeiodinase enzyme systems. Control at both levels is developmentally regulated and modified in serious no...

We studied the effect of thyroid hormone administration on responsivity of murine thyroid to exogenous thyrotropin (TSH) in order to explore the possibility that the thyroid gland might be directly inhibited by its own hormones. In the rat both L-thyroxine (T4) and 3,5,3'-L-triiodothyronine (T3) pretreatment inhibited TSH-induced thyroidal ornithine decarboxylase (ODC) activity in vivo in a dos...

The thyroid hormones (3,5,3',5'-tetraiodo-L-thyronine [L-T4]' and 3,5,3'triiodo-L-thyronine [L-T3]) have marked effects on the growth, development, and metabolic function of virtually all organ systems and tissues ofhuman beings and other higher organisms (1-3). L-T4 was one of the first hormones to be isolated and its structure determined (4-6). Several decades later L-T3 was identified in the...