刺激疑核对胰岛B细胞结构的影响

用3～4月龄灰色家兔9只,麻醉后于AP_(20),L_(1～1.6)处插入同心圆电极(H_(20)),用电子刺激器进行刺激.刺激后30min作电极位置的组织学检查,电极位于疑核的为实验组(6例),余为对照组(3例).分别采取实验组和对照组的胰腺作光镜和透射电镜观察.结果:刺激疑核后,胰岛的数量和其中的细胞密度有所增加,胰岛B细胞中的线粒体、核糖体和粗面内质网的数量增加,胰岛B细胞的超微结构表现出功能增强的结构相.     

疑核对细胞免疫机能调节作用的研究

实验用3～4月龄1.5～2.5kg灰色家兔22只,麻醉后于疑核内插入同心圆电极,在刺激前和刺激后采血检测PHA诱导的淋巴细胞转化率、T细胞百分率,并测定全血葡萄糖浓度;刺激疑核后0.5h,采6例胸腺组织作超微结构观察;刺激疑核后3.5h,采胸腺作石蜡切片ANAE阳性率检测。电极位置均作组织学检查。结果:刺激疑核后T细胞百分率、PHA诱导的淋巴细胞转化率持续升高(P<0.05);胸腺各部位ANAE阳性淋巴细胞百分率升高,胸腺后微静脉内淋巴细胞增多,均与对照组及非刺激对照组相差非常显著(P<0.005);胸腺髓质ANAE阳性淋巴细胞率与外周血液T细胞百分率相关显著;胸腺超微结构示上皮性网状细胞机能活跃,分泌旺盛,皮质处于分裂状态的淋巴细胞增多,髓质淋巴细胞活动能力增强。由此认为,疑核与外周细胞免疫存在机能联系,刺激疑核可引起细胞免疫机能增强。本实验还证明,刺激疑核引起血糖浓度降低,因而除神经途径外,疑核还通过体液途径调节免疫机能。实验结果提示,疑核可能是大脑皮层、下丘脑调节免疫机能的中继核。实验确定了疑核定位坐标是AP_(20～21),L_(1～1.5),H_(20～21)。     

疑核在大脑皮层参与免疫过程中的作用

实验用3～4月龄2.1～2.3kg健康青紫蓝家兔20只。麻醉后,5只刺激左侧大脑皮层,5只刺激右侧大脑皮层,10只损毁疑核后,刺激左侧大脑皮层。刺激前及刺激后不同时间采取血样,检测外周血T细胞百分率和PHA诱导的淋巴细胞转化率。结果:刺激左侧大脑皮层后,所测指标明显上升(P<0.01);而刺激右侧大脑皮层则无显著变化(P>0.05);损毁疑核后,刺激左侧大脑皮层时,所测T细胞百分率和PHA诱导的淋巴细胞转化率均无显著变化(P>0.05)。由此证明,左、右侧大脑皮层对细胞免疫具有分区调整现象,疑核可能是大脑皮层调整细胞免疫的中继站。     

疑核在针刺“足三里”调节机体细胞免疫中的作用

实验用3～4月龄健康家兔(体重2.0～2.5kg)15只。实验组兔经麻醉后固定于大脑立体定位仪上,于A P20-21、L1-1.5处埋置套管(H20-21),以微量注射器注入2%盐酸利多卡因0.5μL 阻断单侧疑核;对照组兔疑核未被阻断,其他处置同实验组。所有动物均电针“足三里”穴0.5 h,并于电针前和电针后即刻及0.5,1.0,1.5,2.0,2.5,3.0 h采血测定PHA诱导的淋巴细胞转化率、T细胞百分率及E-玫瑰花环形成率。结果,实验组兔的上述免疫指标在电针前,后无明显差异,而对照兔电针后的免疫指标显著高于电针前。由此认为,电针“足三里”穴可能通过神经-内分泌-免疫网络调节细胞免疫,而疑核是该调节环路中的一个重要的中继核团。     

围产期患高发代谢病奶牛T_4、T_3、TSH、I含量动态变化的研究

试验以处于围产期的68头奶牛(以健康经产牛为对照组,患酮病、脂肪肝、胎衣不下牛为试验组)为研究对象,在奶牛产前第15,8,1天和产后第1,8,15,22天分别采集颈静脉血检测血清中甲状腺激素[四碘甲腺原氨酸(T4)和三碘甲腺原氨酸(T3)]、促甲状腺激素(TSH)、碘(I)的含量。结果表明:健康的经产牛围产期血清中T4、T3、TSH、I均呈现波浪式动态变化,最高值分别出现在产前第1天、产后第22天、产后第1天、产前第15天;TSH最低值出现在产前第15天,其他检测指标最低值出现在产后第1天。患酮病的奶牛和患脂肪肝的奶牛围产期处于缺碘状态,其产后甲状腺机能出现减退;患脂肪肝期间同时伴发甲状腺功能减退症;患胎衣不下的奶牛围产期碘含量低于正常值,其产犊前后伴发亚临床甲状腺功能减退症。数据统计结果显示:奶牛血清中T4与TSH、T3、I的相关系数分别为-0.749,0.535,0.691;T3与TSH、I的相关系数分别为-0.502,0.457。     

冷应激对雏鸡下丘脑-垂体-甲状腺轴的影响

越来越多的证据表明,应激能够激活下丘脑-垂体-甲状腺轴,进而影响促甲状腺激素释放激素(TRH)、促甲状腺激素(TSH)及甲状腺激素的合成与分泌。为了探明冷应激对雏鸡下丘脑-垂体-甲状腺轴的影响,以公雏鸡为实验动物,进行急性(0.25、1、3、6、12h与24h)与慢性(5、10d与20d)冷应激处理(12±1)℃,检测了雏鸡下丘脑TRH mRNA的表达水平,血清TSH、FT(3T3的游离形式)及FT(4T4的游离形式)的含量。结果表明:急性应激时,TRH mRNA的表达水平在各应激时间点均显著升高,TSH变化不明显,FT3开始无变化,在6h时突然降低,而后又显著升高,FT4开始变化不大,6h后显著升高;慢性应激时,TRH mRNA的表达水平与相应的对照组相比显著降低,TSH变化仍不明显,FT3呈上升趋势,而FT4呈下降趋势。这说明冷暴露可以使雏鸡下丘脑-垂体-甲状腺轴的激素分泌发生改变,而且不同程度的冷应激对同一激素也会产生不同的影响。     

缺硒对鸡甲状腺功能的影响

为了明确缺硒对甲状腺功能的影响,试验复制鸡硒缺乏的动物模型,测定与甲状腺功能密切相关的三碘甲腺原氨酸(T3)、四碘甲腺原氨酸(T4)、游离型三碘甲腺原氨酸(FT3)、游离型四碘甲腺原氨酸(FT4)、促甲状腺激素(TSH)和脑组织脱碘酶(5′-ID)的含量或活性变化。结果表明:在缺硒组鸡血清中,T3、T4含量及FT3、FT4含量均显著下降,TSH含量显著升高;在缺硒鸡的脑组织中,5′-ID的活性显著下降。     

疑核在下丘脑外侧区调节机体细胞免疫中的作用

实验用3～4月龄、1.5～2.5kg健康青紫蓝家兔16只,麻醉后固定于脑立体定位仪上.对其中11只刺激下丘脑外侧区;5只损毁疑核后,再刺激下丘脑外侧区.在刺激前和刺激后不同时间采血,检测外周血中T细胞百分率和PHA诱导的淋巴细胞转化率.结果:刺激下丘脑外侧区,能迅速提高外周血中的T细胞百分率,过一段时间,T细胞转化率也显著升高.而损毁疑核后再刺激下丘脑外侧区,外周血中T细胞百分率和淋巴细胞转化率均无显著变化.由此认为,下丘脑外侧区具有增强机体细胞免疫功能的作用,疑核是下丘脑外侧区调节机体免疫反应的中继核.     

犬眠宝异氟醚麻醉及手术对犬血浆中T3、T4影响

为了观察犬眠宝注射麻醉和异氟醚吸入麻醉对经历去势术犬血浆中甲状腺激素T3、T4的影响,试验将20只实验犬随机均分为犬眠宝注射麻醉组(Q组)和异氟醚吸入麻醉组(I组),每组10只。两组分别进行犬去势术,术中进行麻醉监测,并采静脉血,用放射性免疫法(RIA),检测血浆的含量,测定血浆中的T3、T4。试验结果表明,犬眠宝、异氟醚麻醉及手术对犬血浆中T3、T4的影响具有相似之处,均表现为术中升高,术后持续降低直至48h恢复到麻醉前水平。     

地衣芽孢杆菌对热应激公兔精液品质及激素水平的影响

选择体质量基本一致、性欲旺盛的健康公兔25只,设常温对照组、热应激对照组(饲喂配合日粮)和热应激试验1~3组(分别在配合日粮中添加地衣芽孢杆菌500,1 000,1 500mg/kg),热应激温度控制在33~35℃。测定采食量和体质量;采用动物精子测定仪检测精液品质;放射免疫法测定血浆FSH、LH、TSH、T、T_3、T_4含量。结果显示:日粮中添加1 000mg地衣芽孢杆菌采食量除第10,15天显著高于热应激对照组外,其他日期差异不显著;体质量略高于热应激对照组,较常温对照组低;对采精量无明显影响,10d后精子密度和精子活力极显著低于常温对照组,极显著高于热应激对照组,精子畸形率明显降低;对血浆FSH影响不明显,能提高热应激公兔前20d血浆LH和TSH浓度,提高血浆睾酮(T)和T_3、T_4含量。结果表明:在公兔日粮中添加1 000mg/kg地衣芽孢杆菌能够短期缓解热应激,提高精液品质,有升高血浆LH、TSH、T、T_3、T_4浓度的作用,并对地衣芽孢杆菌的添加量有剂量依赖性。     

二狼山白山羊遗传性甲状腺肿发病机理及诊断研究——Ⅲ.甲状腺功能测定

本实验对内蒙古二狼山白山羊遗传性甲状腺肿(Inherited goitre,IHG)杂合子羊进行了甲状腺吸~(131)碘率测定;对IHG纯合子羊和杂合子羊进行了血清总T_3(TT_3)、总T_4(TT_4)、反T_3(rT_3)、游离甲状腺激素指数(FTI)以及促甲状腺激素(TSH)等甲状腺功能参数测定.结果表明,IHG杂合子羊的甲状腺吸~(131)碘率及吸~(131)碘速率降低(P<0.01);IHG纯合子羊和杂合子羊的血清TT_3、TT_4、FT_3I及FT_4I均显著降低(P<0.05或P<0.01),而TSH显著升高(P<0.01).据此认为,这些甲状腺功能参数(特别是TT_3和FT_3I)的改变,是山羊IHG的生化表型特征,可用于IHG基因群体中杂合子携带羊的检出.     

Effects of trimethoprim-sulfadiazine on thyroid function of horses

Trimethoprim-sulfadiazine was administered to horses in a randomized, placebo controlled study to determine the effects of potentiated sulfonamides on thyroid function in normal horses. The treatment group included eight horses that received trimethoprim-sulfadiazine mixed with molasses orally at 30 mg/kg once daily for eight weeks. The control group included 8 horses that received an oral placebo (flour mixed with molasses) once daily for the same period. Thyroid function was evaluated prior to initiation of treatment and after 8 weeks of treatment. Serum concentrations of total and free triiodothyronine (T3), total and free thyroxine (T4), and thyroid stimulating hormone (TSH) were determined at rest and after a thyrotropin-releasing hormone (TRH) stimulation test. There was no detectable difference between treatment and control groups.     

Thyrotropin stimulation test--new perspective on value of monitoring triiodothyronine

Thyrotropin (thyroid stimulating hormone; TSH) stimulus to thyroid cells of horses and dogs resulted in increased serum triiodothyronine (T3) concentrations that were detected earlier than those of thyroxine (T4). Doubling of the base-line T3 values in horses was detected 0.5 hours after injection of 5 IU of TSH IV, with peak response of 5 times base-line value detected 2 hours after injection. Doubling of T4 values in horses was noticed between 2 and 3 hours, with the peak response of 2.4 times base-line value at 4 hours after injection of TSH. Doubling of base-line T3 values in dogs in response to 0.2 IU TSH/kg of body weight (IV-5 IU maximum dose) was noticed at 1 hour, whereas T4 response doubled between 1.5 and 2 hours. Peak release of T3 and T4 in response to TSH in dogs had not developed by 4 hours; however, the percentage increase over base-line values was greater for T3 than T4 at early sampling time points, and this response has resulted in an increased T3/T4 ratio in hypothyroid dogs. Thus, in both dogs and horses, these studies indicated that T3 response to TSH could be used as a measure of thyroid function at earlier time intervals after TSH administration than one measures T4 response.     

The effects of different iodide availabilities on thyroid function during development in Japanese quail

Japanese quail (Coturnix japonica) were used to study the effects of different egg iodide (I) availabilities on thyroid function during development. Low (less than 50 micrograms 1/kg feed in the maternal diet) and high (1200 micrograms 1/kg feed) I availability were compared to control levels (800 micrograms 1/kg feed), a standard supplementation for game bird feed. We measured thyroid gland content of I, triiodothyronine (T3) and thyroxine (T4), plasma concentrations of T3 and T4, hepatic 5' monodeiodinase (5'-D) activity, and the response of the thyroid gland to thyrotrophin (TSH) stimulation. Embryos, on day 14 of the 16.5-17 day incubation period, and 1-day chicks were used for most studies but thyroid gland hormone content and plasma hormone concentrations were determined for more stages. With high I, thyroidal I content was elevated but thyroidal T4 and T3 were not different from controls. Plasma T3 and T4, the thyroid gland response to TSH stimulation, and hepatic 5'-D activity did not differ between control and high I. Reduced body weight occurred with high I. In general, thyroid gland weight was not altered, but some high I birds exhibited thyroid hypertrophy and altered thyroid gland function. With low I availability, thyroid gland contents of I and T4 were reduced but thyroidal T3 content was maintained. The thyroid gland response to TSH stimulation, plasma thyroid hormone concentrations, and the developmental patterns of plasma thyroid hormones, hepatic 5'-D activity, body weight and thyroid weight were not different between control and low I groups. Developing Japanese quail exhibit excellent ability to adjust thyroid function over a wide range of I availabilities. Regulation appears to occur at the level of thyroid hormone synthesis in the thyroid gland, which allows most aspects of thyroid dynamics to remain unchanged in the maintenance of circulating thyroid hormone concentrations.     

松麦粉对蛋鸡生产性能及血清T3、T4水平的影响

选取130日龄罗曼褐壳蛋鸡180羽,随机分为2组,每组90羽,对照组饲喂基础日粮,试验组饲喂基础日粮+2%松麦粉,研究其对蛋鸡生产性能及甲状腺功能的影响.试验期间每天记录产蛋数,每10 d每组随机取鸡蛋30枚逐一称重;于150、210 d每组随机取鸡6羽,解剖取甲状腺称重;心脏采血、分离血清,测定T3、T4水平.结果表明试验组蛋重显著高于对照组(P＜0.05);甲状腺重无显著差异;T3、T4水平和T3/T4值显著低于对照组(P＜0.05).结果表明,日粮添加松麦粉可显著提高蛋鸡的生产性能,降低T3、T4水平.     

Comparison of thyroid analytes in dogs aggressive to familiar people and in non-aggressive dogs

A cross-sectional study was performed in order to examine the association between canine aggression to familiar people and serum concentrations of total thyroxine (TT4), free thyroxine (fT4), thyroxine autoantibodies (T4AA), total triiodothyronine (TT3), free triiodothyronine (fT3), triiodothyronine autoantibodies (T3AA), thyroid stimulating hormone (TSH), and thyroglobulin autoantibodies (TgAA). The subjects were 31 dogs historically aggressive to familiar people and 31 dogs with no history of aggression. Behavioral evaluation and physical examination were completed for each dog in addition to a complete blood count, serum chemistry panel, TT4, fT4 by equilibrium dialysis, TT3, fT3, TgAA, T3AA, and T4AA. Significant differences were found between the two groups with respect to only T4AA, which was increased in the aggressive group, but the concentrations for both groups were within the normal reference range. There were no differences between the two groups in the thyroid analytes most commonly measured by veterinary practitioners evaluating thyroid function in dogs. The results of this study revealed no significant difference between aggressive and non-aggressive dogs in the thyroid concentrations most commonly used to diagnose canine hypothyroidism.     

Effects of hyper‐ and hypothyroidism on the development and proliferation of testicular cells in prepubertal rats

Thyroid hormones are important in the development and regulation of testes. This study was conducted to determine the effects of hyper‐ and hypothyroidism on testicular development in prepubertal rats aged 20–70 days. Weaning male rats (20 days old) until day 70 age were randomly divided into four groups: control, hyperthyroid (hyper‐T), hypothyroid (hypo‐T) and hypothyroid treated with thyroxine (T4) (hypo‐T+T4). The results indicated that thyroid hormones caused a significant effect in body and testis weights, and food and water consumption. In addition there were changes in serum concentrations of tri‐iodothyronine, T4, thyroid stimulating hormone (TSH) and testosterone. Histomorphology showed a significant decrease in seminiferous tubule diameter in hyper‐T compared to the other groups. Leydig cell numbers showed a significant elevation in hyper‐T but not in hypo‐T groups. Immunostaining indicated that TSH receptor (TSHR), thyroid hormone receptors α/β (TRαβ) and proliferating cell nuclear antigen (PCNA) have the roles in testicular development. Our findings suggest that hyper‐ and hypo‐thyroidism regulate testicular cell proliferation and spermatogenesis in prepubertal rats, indicating that expression of TSHR, TRαβ and PCNA may be regulated by thyroid hormones that are involved in testicular development; and that the administration of T4 to the hypo‐T+T4 group leads to an improvement in the testicular condition.     

Effects of racing and training on serum thyroid hormone concentrations in racing Greyhounds.

OBJECTIVES: To determine the effects of racing and training on serum thyroxine (T4), triiodothyronine (T3), and thyroid stimulating hormone (TSH) concentrations in Greyhounds. ANIMALS: 9 adult racing Greyhounds. PROCEDURE: Serum thyroid hormone concentrations were measured before and 5 minutes after a race in dogs trained to race 500 m twice weekly for 6 months. Resting concentrations were measured again when these dogs had been neutered and had not raced for 3 months. Postrace concentrations were adjusted relative to albumin concentration to allow for effects of hemoconcentration. Thyroid hormone concentrations were then compared with those of clinically normal dogs of non-Greyhound breeds. RESULTS: When adjusted for hemoconcentration, total T4 concentrations increased significantly after racing and TSH concentrations decreased; however, there was no evidence of a change in free T4 or total or free T3 concentrations. Resting total T4 concentrations increased significantly when dogs had been neutered and were not in training. There was no evidence that training and neutering affected resting TSH, total or free T3, or free T4 concentrations. Resting concentrations of T3, TSH, and autoantibodies against T4, T3, and thyroglobulin were similar to those found in other breeds; however, resting free and total T4 concentrations were lower than those found in other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Except for total T4, thyroid hormone concentrations in Greyhounds are affected little by sprint racing and training. Greyhounds with low resting total and free T4 concentrations may not be hypothyroid.     

Investigation of thyroid function in dogs treated with the tyrosine kinase inhibitor toceranib

Tyrosine kinase inhibitors are widely utilized in veterinary oncology for the treatment of mast cell and solid tumours. In man, these drugs are associated with thyroid dysfunction: however, to date only one study has investigated this in dogs. The aim of this study was to prospectively assess thyroid function in a group of dogs with cancer receiving toceranib. Thirty‐four dogs were prospectively enrolled at two referral hospitals into two groups; those receiving toceranib with prednisolone and those receiving toceranib alone. Total thyroxine (TT4) and thyroid stimulating hormone (TSH) was monitored at regular time points during treatment. Follow‐up data was available for 19 dogs. Overall, 12 incidences of elevated TSH occurred but none of these dogs had concurrent low TT4 concentrations. There was a significant difference in median TSH at week six compared with baseline. Hypothyroidism was not diagnosed in any patient during the study period. Patient drop‐out was higher than anticipated which prevented the assessment of longer term toceranib administration on thyroid function. Toceranib therapy was not associated with hypothyroidism in this study but did result in elevations in TSH which confirms what has been previously reported. Toceranib should be considered to cause thyroid dysfunction in dogs and monitoring is advised.