Opiate participation in thyroid hormone regulation in domestic fowl

Administration of morphine sulfate (at 5 and 50 mg/kg) to immature domestic fowl lowered the circulating thyroxine (T4) concentration in a dose- and time-dependent manner. The inhibitory effect of morphine on T4 secretion was mediated via opiate receptors, since it was completely blocked in the presence of naloxone (50 mg/kg). The possibility that T4 secretion may be under tonic opioid inhibition was suggested by a stimulatory effect of naloxone on plasma T4 concentrations. Morphine sulfate (50 mg/kg) enhanced plasma triiodothyronine concentrations, an effect that was completely suppressed in the presence of naloxone. These results demonstrate differential effects of opiates on T4 and T3 concentrations and suggest that opiates tonically inhibit T4 release and accelerate its rate of peripheral monodeiodination.     

The relationship between anticonvulsant activity and receptor affinity of N-methyl-D-aspartate antagonists in epileptic fowl

The N-methyl-D-aspartate (NMDA) receptor antagonists [(3-(+/-)2-carboxypiperazin-4-yl)-propyl-l-phosphonic acid (CPP), +/- 2-amino-7-phosphonoheptanoic acid (2AP7), +/- 2-amino-5-phosphonovaleric acid (2AP5), D-alpha-aminoadipic acid (alpha AA), and +/- alpha, epsilon-diaminopimelic acid (DAP)] were tested for anticonvulsant activity in epileptic chickens. There was a high correlation between anticonvulsant potencies (ED50) and the affinity for the NMDA receptor measured by displacement of L-[3H]glutamate from synaptosomal membranes. The high seizure susceptibility is not due to abnormalities in the NMDA receptor as comparison of KD, Bmax and Ki values in synaptosomal preparations from epileptic and non-epileptic chickens indicated no differences in NMDA receptor binding receptor characteristics.     

恩平市生活饮用水与富碘食品中碘的调查及补碘现状分析

目的:调查恩平市生活饮用水与富碘食品中碘营养水平,并分析补碘的现状,为防治碘缺乏病提供重要的科学依据且为如何及科学补碘奠定基础。方法:对恩平市的居民生活饮用水中和含碘食品中的碘的含量进行调查,分别采用硫酸铈催化分光光度法和砷铈催化分光光度测定尿中碘的方法对居民生活饮用水中和富碘食品中的碘含量进行测量。结果:与碘水平正常的地区比较,恩平市的碘水平稍低,干海带是所有检测食品中碘含量最高的富碘食品,平均值约为1424.47mg/kg,同时恩平市现居民的碘水平基本达到正常,但是居民的碘营养的摄入存在均衡现象,综合性分析考虑我们认为主要与各个居民的身体情况差异、长期饮食差异等多项因素有关。结论:碘是人体的必需微量元素,在日常生活中我们要科学合理的补碘,减少甲状腺疾病的发生。     

Control of the Amount of Free Molecular Iodine in Iodine Germicides

Horseradish peroxidase has been used to generate iodine compositions that comprised principally free molecular iodine. The concentration of free molecular iodine in these enzyme-based compositions ranged from 44 to 63% of the thiosulphate titratable iodine; this is substantially higher than the corresponding value for the povidoneiodine preparation betadine. The biocidal efficacy of these compositions was proportional to the concentration of free molecular iodine. Iodine compositions with relatively low total iodine concentrations but high levels of free molecular iodine (20–175 ppm) killed Staphylococcus aureus and spores of Bacillus subtilis more rapidly than betadine. The effects of normal saline and these enzyme-based iodine compositions on the rate of epidermal regeneration in superficial swine wounds were comparable. These results suggest that an effective germicide containing a high level of molecular iodine need not be irritating or toxic.     

电位滴定法测定聚维酮碘栓中有效碘的含量

目的:建立电位滴定法测定聚维酮碘栓中有效碘的含量.方法:以硫代硫酸钠(0.1mol/L)为滴定液,用电位滴定法测定聚维酮碘栓中有效碘的含量.结果:有效碘质量在10.63～202.08mg范围内,与硫代硫酸钠滴定液呈良好的线性关系(r=0.9999),回收率为99.00%,精密度良好,重复性高,专属性好.结果:此方法简便、快捷、准确.     

Diamine oxidase activity and gamma-aminobutyric acid formation in medullary carcinoma of the thyroid

The formation of different metabolites from 14C-putrescine via oxidative deamination has been studied in patients with medullary carcinoma of the thyroid (MCT) and in control subjects. The neoplastic tissue from MCT patients produced in addition to delta 1-pyrroline, large quantities of GABA and some unidentified compound(s), whereas the formation of these metabolites in normal thyroid tissue was almost negligible. Plasma from patients with MCT contained higher diamine oxidase activity than plasma from control subjects, but there was a considerable overlap between the two groups. Determination of the as yet unidentified compound(s) could possibly become a sensitive tool in the diagnosis and follow-up of carcinomas associated with a high diamine oxidase activity.     

Effects of rose bengal on serum levels of thyroid hormones and thyroid peroxidase activity in male mice

The thyrotoxic effect of Rose bengal (RB) (4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein disodium salt; Food Red No. 105) was examined in male (C57BL/6N X C3H/N) F1 mice. They were given drinking-water containing RB at levels of 0 (control), 0.125 and 0.250% for 2 weeks. The effect resulted in decreases in serum levels of 3,5,3'-triiodothyronine (T3) and thyroxine (T4), and slight increases in serum 3,3',5'-triiodothyronine (rT3) levels and thyroid weight, but no difference in the values for the body-weight gain, serum thyroid stimulating hormone (TSH) levels and thyroid peroxidase (TPO) activities. However, the in vitro inhibitory effect of RB on TPO activity was observed by addition of RB to the TPO-catalyzed guaiacol oxidation. These results suggest that RB might have weak goitrogenic properties, inhibiting the peripheral conversion of T4 to T3 and/or inhibiting TPO to lead a decrease of T4 and T3 formation.     

Monoamine oxidase activity and triiodothyronine biosynthesis in human cultured thyroid cells.

1. The proposal that monoamine oxidase (MAO) is a source of peroxide in thyroid hormone biosynthesis has been examined by use of isolated cultured human thyroid cells which retain the ability to secrete triiodothyronine (T3) in response to thyroid stimulating hormone (TSH). 2. The results demonstrated the presence of MAO A and B in human thyroid cells which oxidized 5-hydroxytryptamine and 2-phenylethylamine, respectively, and were selectively inhibited by the MAO inhibitors clorgyline and (-)-deprenyl. 3. Addition of propylthiouracil to the culture system induced a 61% reduction in TSH-stimulated T3 secretion, indicating that the bulk of such secretion apparently derives from de novo iodothyronine synthesis. 4. The MAO A and B substrate, tyramine, was ineffective in stimulating T3 secretion. 5. The selective MAO inhibitors, clorgyline and (-)-deprenyl, alone and in combination, and in the presence and absence of tyramine, failed to inhibit basal as well as TSH-stimulated T3 secretion in cultured human thyrocytes. 6. It is therefore apparent that even though thyroid MAO A and B enzyme reactions result in the generation of H2O2, this H2O2 does not seem to play a significant role in T3 biosynthesis.     

An improved thyroid hormone reporter assay to determine the thyroid hormone-like activity of amiodarone, bithionol, closantel and rafoxanide

A number of environmental chemicals have been reported to exhibit thyroid hormone-like activity. Since thyroid hormones play a crucial role in development, it is important to identify chemicals in the environment that are capable of endocrine disruption of thyroid hormone homeostasis. In order to detect thyroid hormone-like activity, the growth of pituitary cell lines has been commonly used as a sensitive marker, albeit with limited specificity to thyroid hormones. Reporter gene assays using the thyroid hormone responsive element (TRE) connected to the luciferase reporter gene have also been developed. Thus far however, this type of assay appears to have limited sensitivity compared to cell growth assays. In the present study, we developed a highly sensitive TRE reporter gene assay by using a pituitary cell line, MtT/E-2, and by culturing cells in a serum-free medium. Our assay was developed in order to detect T3 activity at a concentration of 10⁻¹¹ M. This assay identified thyroid hormone-like activity from the antiarrhythmic drug, amiodarone, and from three anti-parasitic drugs, bithionol, closantel and rafoxanide, all commonly used in veterinary medicine. Thyroid hormone-like activity of these compounds was further confirmed by the induction of BCL3 gene expression in MtT/E-2, which is known to be regulated by thyroid hormones. Our improved assay was proved to be a sensitive tool for assessing thyroid hormone-like activity of environmental chemicals.     

Modulation in vitro of monoamine oxidase activity by thyroid hormones

Experiments in vitro using whole rat brain homogenate revealed that l-thyroxine (T₄) and l-triiodothyronine (T₃) can increase indoleacetic acid (IAA) formation from the oxidative deamination of tryptamine. This effect was dependent upon (a) the homogenate concentration, (b) the hormonal concentration, (c) temperature and (d) pre-incubation of the hormones with the homogenate prior to the addition of trypatime. For T₄, the extent of the increase in IAA production was correlated with the specific activity of the particular homogenate under test but no such correlation existed with T₃. The influence of the thyroid hormones was shown to occur at the monoamine oxidase (MAO) step and appears to be mediated indirectly so as to increase MAO activity. The nature of the interaction is reversible but the precise mechanism(s) involved have not been elucidated. It is postulated that the thyroid hormones and/or their metabolites either suppress an endogenous inhibitor or function to dissociate aggregated MAO. A similar augmentation of IAA production was found in the liver, less in the kidney, and only slight increases were obtained in the heart. Thus, a degree of organ selectivity exists. The present finding describe a new effect of the thyroid hormones which may be of importance in the modulation of monoamine metabolism.     

Modeling the anxiety-depression continuum hypothesis in domestic fowl chicks

Anxiety and depression are currently classified as separate clinical syndromes despite considerable similarities in their symptoms, pathophysiological substrates and response to treatment interventions. An alternative hypothesis views anxiety and depression along a temporal continuum, a construct that the current research attempts to model in a preclinical setting. In experiment 1, socially raised domestic fowl chicks separated from conspecifics demonstrated a pattern of distress vocalizations that sequentially models anxiety-like and depressive-like states. In addition, administration of the benzodiazepine anxiolytic chlordiazepoxide and the tricyclic antidepressant imipramine provided pharmacological validation for the model in that they were capable of dissociating the anxiety-like and depressive-like states. In experiment 2, corticosterone levels were quantified across the isolation test session to provide convergent validity to the model. These findings fit well with the human clinical literature on the anxiety-depression continuum perspective, and suggest the consideration of a nosology that emphasizes the inter-relatedness of these clinical states rather than their boundaries.