甲状腺素与硫尿嘧啶处理第13天鸡胚对其生长发育的影响——Ⅰ.血清甲状腺激素含量及体重的变化

本文应用放射免疫方法,研究了不同甲状腺功能状态下,小鸡出壳前后,血清甲状腺激素含量和体重的变化.结果表明:在孵化中期即可检测出鸡胚血清中 T_4、T_3、rT_3的含量,并分别在孵化的第12,17,19天升到峰值,然后迅速下降.甲状腺素处理第13天鸡胚可使其血清T_4、T_3、rT_3平均含量稍有降低(p>0.01),而硫尿嘧啶却使血清 T_4、T_3含量短暂降低后,有较大升高(p<0.01),同时 rT_3含量也升高。T_4、T_3峰值时间推迟.上述处理对小鸡出壳前后体重无显著影响.     

Effect of thyroid hormone supplementation on survival of euthyroid dogs with congestive heart failure due to systolic myocardial dysfunction: a double-blind, placebo-controlled trial

Nineteen euthyroid dogs of 12 breeds with echocardiographic signs of dilated cardiomyopathy (DCM) and radiographic and clinical signs of congestive heart failure (CHF) were evaluated in a randomised, double-blind, and placebo-controlled study. The dogs received either thyroxine or placebo as an adjunct to digoxin, furosemide and propranolol. The group assignment of individual dogs and serum concentrations of thyroid hormones remained unknown to owners and investigators during the entire study period. Dogs were evaluated clinically and with electrocardiography (ECG), thoracic radiography, echocardiography and measurement of total thyroxine (tT4) and thyroid stimulating hormone (TSH) before beginning of the trial, and then one week, 2 months, 6 months and yearly after initial examination, and, when applicable, at the time of euthanasia. End-point of the study was euthanasia (n = 17) due to severe congestive heart failure or sudden death (n = 2). Survival times ranged from 17 to 1030 days (median 187 days) in the placebo group, and from 18 to 1000 days (median 73 days) in the treatment group. There was no statistically significant difference in survival times between the treatment group and the placebo group (p = 0.46). Post mortem and histopathologic examinations revealed the attenuated wavy fiber type of DCM in 11 dogs, and myocardial infarcts, arteriosclerosis and chronic valvular disease in one dog. In conclusion, there was a wide range in survival times of dogs treated with digoxin, furosemide and propranolol. Adding thyroid hormones to the treatment did not significantly influence survival.     

Thyroid gland development in Senegalese sole (Solea senegalensis Kaup 1858) during early life stages: A histochemical and immunohistochemical approach

A key to success in the culture of marine fish species is the mass production of high quality fry, a process largely dependent on successful first feeding and normal development and growth of fish larvae. In this regard it is important to examine the structural and functional development of the endocrine system (pituitary, thyroid, interrenal glands) during early ontogeny of marine fish. Particularly, the thyroid hormones, thyroxine (T₄) and triiodothyronine (T₃), influence numerous metabolic processes, such as growth, differentiation, metamorphosis, reproduction, respiration, migratory behaviour, central nervous system activity, seasonal adaptation, etc. Therefore the aim of this study was to describe the development of the thyroid gland and the ontogeny appearance of the thyroid hormones in Solea senegalensis larvae by means of histological and immunohistochemical techniques. The first thyroid follicle was present at 4 days-post-hatch (dph) coinciding with first feeding. During metamorphosis (12–20 dph) the follicles increased in both number and size, and by 30 dph presented the same characteristics as that seen in adult fish. Tissue immunostaining of both thyroid hormones decreased during the endogenous larvae development to nearly undetectable levels at the completion of yolk-sac absorption. During larvae exogenous phase, T₃ and T₄ immunostaining was first detected by 6 dph and an increase of specific staining for both hormones was detected between 12 and 20 dph, during metamorphosis phase.     

Thyroxine-induced alterations in the testis and seminal vesicles of air-breathing catfish, Clarias gariepinus

Effect of experimentally induced thyroxine overdose on the testis and seminal vesicles was studied in the air-breathing catfish, Clarias gariepinus during the preparatory and the pre-spawning phase. The present study revealed a marked reduction in testosterone level in serum, testis and seminal vesicles (SV). Histological examination showed a considerable reduction in the number of spermatozoa/spermatids in the seminiferous tubular lumen as well as depletion of fluid in the loculi of SV. SDS-PAGE analysis of SV fluid proteins demonstrated a significant decrease in the level of a ~27 kDa protein in thyroxine treated fishes. Evidences are presented here to indicate that thyroid hormone plays a role in regulating testis and SV function in catfish. T.N. Jacob and J.P. Pandey contributed equally     

甲状腺素与硫尿嘧啶处理第13天鸡胚对其生长发育的影响——Ⅱ.脑中甲状腺激素含量及脑重量的变化

本文应用放射免疫方法研究了不同甲状腺机能状态下,小鸡出壳前后,脑中甲状腺激素含量和脑重量的变化.结果表明:在孵化第10天的鸡胚脑中即可检测出 T_4,T_3含量,然后逐渐上升,分别在孵化第14,17天达到峰值,此后逐渐下降.3星期内小鸡 T_4,T_3平均含量分别变化于4.3～26ng/mg,0.29～1.2ng/mg 之间.脑中 rT_3含量较低,因而检测不出.在孵化第13天的受精蛋中注入甲状腺素(200ng/枚),可使脑中 T_3/T_4比值减小;而注射硫尿嘧啶(200μg/枚)却使之增加.上述处理,对小鸡出壳前后脑的增重无显著影响.     

High urinary corticoid/creatinine ratios in cats with hyperthyroidism

Measurement of the urinary corticoid : creatinine (C : C) ratio provides an assessment of cortisol secretion over a period of time. Therefore, this test is a very sensitive measure of adrenocortical function. The stress of the diagnostic procedure and nonadrenal disease may increase the urinary C : C ratio. In addition, diseases such as hyperthyroidism may influence the metabolic clearance of cortisol. To evaluate the effect of thyroid hormone excess, urinary C : C ratios were measured in 32 cats with hyperthyroidism and 45 healthy household cats. In 7 cats, urinary C : C ratios were measured both before and after treatment for hyperthyroidism. With data from the healthy cats, the reference range for the urinary C : C ratio was determined to be 8.0 to 42.0 X 10(-6). The urinary C : C ratios in the cats with hyperthyroidism (median, 37.5 x 10(-6); range, 5.9-169.5 x 10(-6)) were significantly (P = .001) higher than those in the healthy cats (median, 16 x 10(-6); range, 4.8-52.5 x 10(-6)). In 15 cats with hyperthyroidism, the urinary C : C ratios exceeded the upper limit of the reference range. Treatment for hyperthyroidism led to a marked decrease in urinary C : C ratios. The results of this study demonstrate that the urinary C : C ratio may be abnormally high in cats with hyperthyroidism, probably because of increased metabolic clearance of cortisol and activation of the pituitary-adrenocortical axis by disease. Although the clinical features of hyperthyroidism and hyperadrenocorticism in cats are different, hyperthyroidism should be ruled out when cats are suspected of hyperadrenocorticism on the basis of abnormally high urinary C : C ratios.     

Effects of thyroid hormone on myocardial T-type calcium channels at mRNA and protein levels in rats

AIM: To observe the effect of thyroxine on the expression of T-type calcium channels Cav3.1, Cav3.2 and Cav3.3 in rat myocardium, and to explore the possible biological mechanism between the changes of the expression of T-type calcium channels and the arrhythmia in hyperthyroid heart disease. METHODS: Healthy SD rats (n=20) were randomly divided into normal control group (n=10) and hyperthyroid heart disease group (n=10). The animal model was established by intraperitoneal injection of levothyroxine for 35 d. The contents of T3 and T4 in serum, the heart-to-body weight ratio, the diameter of cardiac myocytes and electrocardiograph were measured to evaluate hyperthyroid heart disease. Moreover, the mRNA and protein expression levels of T-type calcium channels in the myocardium were measured by RT-PCR, immunohistochemistry and Western blot. RESULTS: After intraperitoneal injection of levothyroxine for 35 d, compared with the normal control group, the serum contents of T3 and T4, the heart-to-body weight ratio and the diameter of cardiac myocytes were significantly increased in hyperthyroid heart disease group (P<0.05), and arrhythmia occurred in hyperthyroid heart disease group. By immunohistochemistry and Western blot, the protein expression of Cav3.1 increased significantly (P<0.05), while the protein expression of Cav3.2 decreased significantly (P<0.01). However, no change of the Cav3.3 protein was observed. The results of RT-PCR were the same as immunohistochemistry and Western blot. CONCLUSION: Thyroxine promotes the expression of Cav3.1 in the myocardium but inhibits the expression of Cav3.2 at mRNA and protein levels, which might be involved in arrhythmia in hyperthyroid heart disease.     

Raf-1 is dually down regulated by p,p′-DDE via reduced thyroid hormone and activated ERK

Raf-1 is the best characterized member of the mammalian raf family. The raf-1 kinase has many important physiological functions but its regulation is complex. 1,1-Dichloro-2,2 bis(p-chlorophenyl) ethylene (p,p′-DDE), a major and important metabolite of organochlorine pesticide DDT, is a widespread environmental pollutant. Previous studies have reported that p,p′-DDE influences the MAPK pathway, but little details are known regarding how the raf-1 activity is influenced and regulated by p,p′-DDE in those events. And here, we used 20 male rats that received different doses of p,p′-DDE (0, 20, 60, 100 mg/kg b.wt) every other day by intraperitoneal injection for 10 days. Results showed that the raf-1 mRNA and protein expressions showed significant down-regulation. The thyroxine (T4) level and the protein kinase C alpha (PKCα) mRNA expression declined, but the raf kinase inhibitory protein (RKIP) up regulated. In addition, the p,p′-DDE-induced oxidative stress resulted in declines of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) activities. The elevations of ERK mRNA level and phosphorylated ERK protein expression were also observed. Taken together, these results suggest that the raf-1 is dually down regulated by p,p′-DDE via two pathways. One pathway is that the p,p′-DDE exposure elevates RKIP level by decreasing T4 and PKCα level, and the increased RKIP eventually down regulates the raf-1. The other is that the p,p′-DDE exposure activates the ERK by oxidative stress, and the activated ERK down regulates the raf-1 through the negative feedback phosphorylation.