Plasma hormone levels in growth-retarded rats with dorsomedial hypothalamic lesions

Rats with lesions in the dorsomedial hypothalamic nuclei (DMNL rats) are hypophagic and growth-retarded. Since previous work had shown normal plasma growth hormone and insulin levels in DMNL rats we investigated the diurnal patterns of these and other hormones involved in growth. Trial 1: Rats received electrolytic DMNL or sham operations (SCON). The DMNL rats exhibited no differences from SCON rats in plasma triiodothyronine (T₃), growth hormone (GH), insulin and somatomedin (SM) concentrations, Trial 2: kainic acid, a neurotoxin, was used for lesion production. Again, DMNL rats showed no deficiencies in plasma levels of T₃, GH or insulin. Trial 3: In this experiment, diurnal hormone profiles were assessed. The GH profile and mean 24-hour secretion of both DMNL and SCON groups did not differ significantly. Both groups exhibited a diurnal release of T₃, with the DMNL rats showing slightly higher levels. Plasma insulin rose after dark, i.e., at the onset of feeding, in SCON but not in DMNL rats; the later have a previously reported disrupted feeding rhythm. Glucose patterns were in keeping with insulin profiles. Controls showed a normal plasma corticosterone rhythm whereas DMNL rats had an altered pattern. The data suggest that deficiencies in the principal anabolic and growth-promoting hormones cannot be responsible for the retarded growth of DMNL rats.     

Effects of triiodothyronine and fluoxetine on 5-HT1A and 5-HT1B autoreceptor activity in rat brain: regional differences

The thyroid hormone triiodothyronine (T3) augments and accelerates the effects of antidepressant drugs. Although the majority of studies showing this have used tricyclics, a few studies have shown similar effects with the selective serotonin re-uptake inhibitor (SSRI) fluoxetine. In this study we investigated the effects of fluoxetine (5 mg/kg), T3 (20 μg/kg) and the combination of these drugs, each administered daily for 7 days, on serotonergic function in the rat brain, using in vivo microdialysis. Fluoxetine alone induced a trend towards desensitization of 5-HT_1A autoreceptors as shown by a reduction in the effect of 8-OH-DPAT to lower 5-HT levels in frontal cortex, and desensitized 5-HT_1B autoreceptors in frontal cortex. The combination of fluoxetine and T3 induced desensitization of 5-HT_1B autoreceptors in hypothalamus. Since there is evidence linking hypothalamic function and depression, we suggest that this effect may partly account for the therapeutic efficacy of the combination of an SSRI and T3.     

Effect of thyroid hormone on protein turnover in cultured cardiac myocytes

Since systemic actions of thyroid hormone increase cardiac work, direct effects of T3 on myocardial protein turnover may be obscured in the intact animal. For this reason, the effects of T3 on synthesis and degradation of cellular protein were measured in replicate cultures of cardiac myocytes obtained from chick embryos. During the first 3 days of exposure, 10(-8) M T3 increased the fractional rate of protein synthesis 10% to 16% and the fractional rate of cell growth 20% to 40% with no change in protein degradation. During the fourth and fifth days of 10(-8) M T3 exposure, fractional synthesis rates in T3 cultures increased 15% to 19% but fractional degradation rates also increased 17% to 29% so that growth rates in T3 cultures fell to control levels. Similar changes in myocardial protein turnover have occurred in response to T3 treatment in intact animals. T3 treatment caused a disproportionately large increase in the rate of myosin heavy chain turnover when compared to total cellular protein and actin. This may be related to the change in amounts of myocardial isomyosins occurring in response to thyroid hormone treatment.     

Triiodothyronine stimulates45Ca-accumulation via synthesis of insulin-like growth factor-I in cultures of osteoblast-like cells

We examined the effects of triiodothyronine (T₃) on⁴⁵Ca-accumulation into extracellular matrix in osteoblast-like MC3T3-El cells cultured for 7-week period, which was considered to be long enough to develop calcification. T₃ increased⁴⁵Ca-accumulation into sodium dodecyl sulfate-insoluble, EDTA-extractable materials cultures of MC3T3-El cells in a dose-dependent manner in the range between 10 pM and 10 nM. Contrary to the stimulatory effect on⁴⁵Ca-accumulation, T₃ inhibited DNA synthesis in MC3T3-El cells dose dependently between 10 pM and 10 nM. T₃ stimulated the secretion of insulin-like growth factor-I (IGF-I) dose dependently between 0.1 nM and 10 nM in MC3T3-El cells cultured for 7 weeks. Antibodies to IGF-I suppressed the⁴⁵Ca-accumulation induced by T₃ almost to the control level. These results strongly suggest that T₃ stimulates⁴⁵Ca-accumulation via synthesis of IGF-I in osteoblast-like cells.     

Regional thyroid hormone levels in rat brain

Levels of T₄ and T₃ were measured in half-brain and seven brain regions. Although thyroid hormones were distributed throughout the brain, T₄ levels were highest in cerebellum and thalamus. The highest T₃ levels were observed in the thalamus and lowest levels were found in olfactory bulb, hypothalamus, and amygdala.     

江苏省某戒毒所男性吸毒人员甲状腺激素水平及影响因素研究

目的 了解吸毒人群促甲状腺激素（TSH）、三碘甲状腺原氨酸（T3）、甲状腺素（T4）、游离三碘甲状腺原氨酸（FT3）以及游离甲状腺素（FT4）的异常情况及影响因素。方法 2018年6－8月于江苏省某戒毒所招募788名男性吸毒人员进行一对一的问卷调查并采集静脉血进行甲状腺功能5项激素项目的检测。结果 调查结果显示,江苏省某戒毒所男性戒毒人员的血清T3、T4、FT3、FT4以及TSH的异常率分别为4.57%、1.27%、0.51%、0.38%和0.89%。HCV感染是该人群发生T3异常的影响因素（OR=8.52,95% CI：2.36～30.74,P=0.001）,且血清T3（P<0.001）和T4（P=0.048）水平随着HCV病毒载量的升高而升高。结论 HCV感染是男性吸毒人员发生血清T3水平异常的影响因素。因此,在对吸毒人群进行健康教育时应增加甲状腺相关的知识,对感染HCV的男性吸毒人员还应加强甲状腺功能的监测。     

血清3,5,3'-三碘甲腺原氨酸化学发光定量免疫分析方法的建立

目的 建立血清3,5,3'-三碘甲腺原氨酸(T3)化学发光定量免疫分析方法.方法 采用固相竞争法,96孔微孔板包被T3抗体,辣根过氧化物酶标记T3,鲁米诺为发光底物,建立T3化学发光定量免疫分析方法.结果 本方法的线性范围为0.5 ～8.0ng/mL;分析灵敏度为0.18ng/mL;批内变异系数为4.4％ ～6.6％,批间变异系数为5.5％～10.6％;回收率为90.0％～113.3％;高值T3血清样品经系列倍比稀释后的测定值与稀释度呈线性关系,相关系数为0.9922;与T4、γT3的交叉率分别为0.35％、0.54％;与罗氏电化学发光分析法的测定值具有较好的相关性.结论 本方法具有分析灵敏度高、特异性好和操作简便快速的特点,适用于临床检测和科研应用.