脑室内注入TRH对大鼠肝脏无机磷代谢影响的核磁共振分析

采用在大鼠脑室内注入促甲状腺激素释放激素（Ｔｈｙｒｏｔｒｏｐｉｎｒｅｌｅａｓｉｎｇｈｏｒｍｏｎｅ,ＴＲＨ）,并利用３１Ｐ－核磁共振法测定活体大鼠肝脏中的含磷化学物质,并观察ＴＲＨ对肝脏无机磷代谢的影响,研究证明,ＴＲＨ通过中枢神经影响肝脏中无机磷的代谢。由侧脑室注入ＴＲＨ,使肝脏无机磷含量发生显著增加,此作用由于副交感神经的阻断剂阿托品的加入而消失,由此可以认为,ＴＲＨ是经由副交感神经而影响肝脏的代谢。     

脑室内注入TRH对大鼠肝脏无机磷代谢影响的核磁共振分析

采用在大鼠脑室内注入促甲状腺激素释放激素（ＴＲＨ）,并利用＾３１Ｐ－核磁共振法测定活体大鼠肝脏中的含磷化学物质,并观察ＴＲＨ对肝脏无机磷代谢的影响。研究证明,ＴＲＨ通过中枢神经影响肝脏中无机磷的代谢,由侧脑室注入ＴＲＨ,使肝脏无机磷含量发生显著增加,此作用由于副交感神经的阻断剂阿托品的加入而消失,由此可以认为,ＴＲＨ是经由副交感神经而影响肝脏的代谢。     

束缚浸水应激对大鼠肝胆汁分泌的影响及其作用机制的研究

目的：通过研究束缚浸水应激对大鼠肝胆汁分泌的影响,探讨其作用机制。方法：实验分6组（n=8）：A组：室温下单纯束缚＋生理盐水;B组：束缚浸水应激＋生理盐水;C组：室温下单纯束缚＋阿托品;D组：束缚浸水应激＋阿托品;E组：室温下单纯束缚＋酚妥拉明;F组：束缚浸水应激＋酚妥拉明。结果：与A组比较,B组肝胆汁分泌量显著减少（P〈0．05）,pH值显著升高（P〈0．01）;与A组比较,C组肝胆汁分泌量变化不明显,只有微量减少：E组与A组相对照肝胆汁分泌量无明显变化,但也有微量减少。与B组比较,D组肝胆汁分泌量有明显变化（P〈0．05）,肝胆汁pH无明显变化;F组与B组对照其肝胆汁分泌量有明显变化（P〈0．05）,肝胆汁pH无明显变化;D组与F组对照肝胆汁分泌量无明显变化,肝胆汁pH无明显变化。结论：束缚浸水应激对大鼠肝胆汁分泌有明显地抑制作用。浸水应激组肝胆汁的分泌量明显减少,肝胆汁的pH明显升高;迷走神经、交感神经在室温单纯束缚的情况下对肝胆汁的分泌影响较小,而在束缚浸水的情况下迷走神经、交感神经对肝胆汁的分泌有较显著的影响（P〈0．05）。     

慢性低氧性肺动脉高压鼠原代培养肺动脉平滑肌细胞内钙的检定

用共聚焦激光扫描显微镜观察经Ｆｌｕｏ－３／ＡＭ负荷的慢性低氧性肺动脉高压（ＨＰＨ）大鼠原代培养的肺动脉平滑肌细胞（ＰＡＳＭＣ）的形态与内游离Ｃａ２＋浓度的动态变化。结果表明：原代培养的（ＨＰＨ）大鼠的ＰＡＳＭＣ与正常大鼠相比,①细胞内游离Ｃａ２＋浓度增加,但其收缩性减弱;②随培养日数增加,咖啡因（Ｃａｆｅｉｎ）所致的细胞内储钙池－肌浆网的Ｃａ２＋释放作用逐渐减弱,直至消失;③血管紧张素Ⅱ（ＡＴ－Ⅱ）升高细胞内钙作用明显增强;④部分呈大红色细胞对多种缩血管物质敏感性增强。结果提示,ＨＰＨ大鼠的ＰＡＳＭＣ的内钙明显增加,其调节机制处于紊乱状态。     

高血压大鼠红细胞膜Ca~（2＋），Mg~（2＋）─ATP酶对Ca~（2＋）反应的变化及Mg~（2＋）的作用

本实验观察了正常及高血压大鼠红细胞膜Ｃａ２＋,Ｍｇ２＋－ＡＴＰ酶对不同浓度Ｃａ２＋及Ｍｇ２＋的反应。结果表明：（１）在自发性高血压大鼠（ＳＨＲ）,此酶最适反应的Ｃａ２＋浓度为１０－６ｍｏｌ／Ｌ;ＷＫＹ大鼠为１０－４ｍｏｌ／Ｌ;两肾一环型肾性高血压大鼠（ＲＨＲ）为１０－７ｍｏｌ／Ｌ,Ｗｉｓｔａｒ大鼠为１０－４ｍｏｌ／Ｌ,Ｃａ２＋高于以上各相应浓度时该酶活性受到抑制;（２）作为该酶激动剂的Ｍｇ２＋有其最适激活浓度,在ＷＫＹ大鼠、ＲＨＲ及Ｗｉｓｔａｒ大鼠均为４．５ｍｏｌ／Ｌ;（３）高浓度Ｍｇ２＋（３６．０ｍｏｌ／Ｌ）可以逆转高浓度Ｃａ２＋对该酶的抑制作用。以上结果表明,底物Ｃａ２＋浓度的变化对Ｃａ２＋,Ｍｇ２＋－ＡＴＰ酶的催化活性影响极大,该酶活性的促发及维持必须有适宜浓度的Ｍｇ２＋。高血压时此酶对Ｃａ２＋的敏感性增高,且Ｍｇ２＋对酶保护作用更为明显。本结果提示,胞内高浓度Ｃａ２＋不仅是高血压发生的原因之一,并可能与其发展及恶化有关。     

败血症大鼠肝细胞核Ca^2＋转运功能的改变

本实验观察败血症时肝细胞核钙转运的变化。早期败血症（结扎盲肠及穿刺后,９ｈ）大鼠肝细胞和肝细胞核钙含量分别增加２０％和３６％（Ｐ〈０．０５）。败血症大鼠肝细胞核Ｃａ＾２＋－ＡＴＰａｓｅ活性增加９４％（Ｐ〈０．０１）,核＾４５Ｃａ＾２＋转运显著增强（增加３２％,Ｐ〈０．０１）。核＾４５Ｃａ＾２＋转运与Ｃａ＾２＋－ＡＴＰａｓｅ活性呈明显正相关（ｒ＝０．９１４,Ｐ〈０．０１）。加入钙调素显著刺激而加入钙     

肝缺血再灌流损伤和复方丹参保护作用的实验研究

观察大鼠肝脏缺血后再灌流时酶组织化学及超微结构的变化,同时观察复方丹参的保护作用。结果显示：肝缺血２小时后再灌流３小时,肝ＳＤＨ、Ｍｇ２＋－ＡＴＰａｓｅ、Ｇ－６－Ｐａｓｅ的活性明显降低,ＬＤＨ、ＡＣＰ的活性明显增强。超微结构变化表现为肝细胞内线粒体肿胀、嵴断裂、空泡样变,粗面内质网颗粒明显减少,肝窦扩大、窦壁内皮细胞肿胀,胆小管扩张,微绒毛减少、断裂。复方丹参对肝细胞的缺血再灌流损伤有明显的保护作用     

兔迷走复合区内微量注射TRH对奥迪氏括约肌肌电的影响及？…

目的和方法：本工作旨在研究兔迷走复合区（ＤＶＣ）内ＴＲＨ对奥迪氏括约肌电的调节作用及外周途径。结果：（１）ＤＶＣ内注射ＴＲＨ（０．８ｎｍｏｌ,μｌ）后,慢波电位（ＳＷ）频率不变,但锋电位频率（ＦＳＰＳＯ）及幅度（ＡＳＰ－ＳＯ）,锋电位发生率（ＩＳＰ）明显增加。（２）ＤＶＣ内分别注射不同剂量ＴＲＨ（０．１３,０．２５,０．５０,０．８０,１．３０ｎｍｏｌ,１μｌ）后,各剂量ＴＲＨ均能引起ＦＳＰＳＯ增     

兔迷走复合区内微量注射TRH对奥迪氏括约肌肌电的影响及传出途径分析

目的和方法：本工作旨在研究免迷走复合区（ＤＶＣ）内ＴＲＨ对奥迪氏括约肌（ＳＯ）肌电的调节作用及外周途径。结果：（１）ＤＶＣ内注射ＴＲＨ（０．８ｎｍｏｌ,１μｌ）后,慢波电位（ＳＷ）频率不变,但锋电位频率（ＦＳＰＳＯ）及幅度（ＡＳＰＳＯ）、锋电位发生率（ＩＳＰ）明显增加．（２）ＤＶＣ内分别注射不同剂量ＴＲＨ（０．１３,０．２５,０．５０,０．８０,１．３０ｎｍｏｌ,１μｌ）后,各剂量ＴＲＨ均能引起ＦＳＰＳＯ增加。随注射剂量的增加,ＳＯ反应强度和持续时间均增加,呈现明显的剂量反应关系。（３）ＤＶＣ内注射ＴＲＨ兴奋ＦＳＰＳＯ的效应可被静脉注射阿托品（０．２ｍｇ／ｋｇ）或迷走神经切断完全阻断,但不能被静脉注射酚妥拉明（１．５ｍｇ／ｋｇ）、心得安（１．５ｍｇ／ｋｇ）或脊髓切断术所阻断。结论：ＤＶＣ内ＴＲＨ可能对ＳＯ肌电有重要的调节作用,这种作用是通过迷走神经及外周Ｍ受体介导。     

降钙素基因相关肽对大鼠分离的心肌细胞内游离Ca~（2＋）含量的影响

用荧光染色法观察了合成的大鼠降钙素基因相关肽（ＣＧＲＰ）对大鼠心肌细胞内游离Ｃａ￣（２＋）含量的影响。结果证明,ＣＧＲＰ能明显增加心肌细胞内Ｃａ￣（２＋）含量,小、中和大剂量（１０￣（－９）、１０￣（－８）、１０￣（－７）ｍｏｌ／Ｌ）的ＣＧＲＰ使Ｃａ￣（２＋）含量分别增加至２７６．８８±６．３１、３６４．９９７±１２．７０、５７６．３９７±１５ｎｍｏｌ／Ｌ与对照组（１３６．２８±７．２４ｎｍｏｌ／Ｌ）相比差异非常显著（Ｐ＜０．０１）,且随着ＣＧＲＰ剂量的增加而作用明显加强,呈现剂量—效应关系。３０μｍｏｌ／Ｌ的维拉帕米对ＣＧＲＰ所致的细胞内Ｃａ￣（２＋）增加有抑制作用,对小、中、大剂量ＣＧＲＰ作用的抑制率分别为４８％、４４％和１８％。我们推测,ＣＧＲＰ可能直接作用于心肌细胞。低浓度ＣＧＲＰ的正性肌力作用主要是促进Ｃａ￣（２＋）经Ｃａ￣（２＋）通道内流,使心肌细胞内Ｃａ￣（２＋）含量增加的结果。在大剂量ＣＧＲＰ的正性肌力作用中Ｃａ￣（２＋）内流也起到一定作用。     

Slow Penetration of Thyrotropin-Releasing Hormone Across the Blood-Brain Barrier of an In Situ Perfused Guinea Pig Brain

Transport of 3H-labelled thyrotropin-releasing hormone (TRH) across the blood-brain barrier was studied in the ipsilateral perfused in situ guinea pig forebrain. The unidirectional transfer constant (Kin) calculated from the multiple time brain uptake analysis ranged from 1.14 X 10(-3) to 1.22 X 10(-3) ml min-1 g-1, in the parietal cortex, caudate nucleus, and hippocampus. Regional Kin values for [3H]TRH were significantly reduced by 43-48% in the presence of an aminopeptidase and amidase inhibitor, 2 mM bacitracin, suggesting an enzymatic degradation of tripeptide during interaction with the blood-brain barrier. In the presence of unlabelled 1 mM TRH and 2 mM bacitracin together, a reduction of [3H]TRH regional Kin values similar to that obtained with 2 mM bacitracin alone was obtained . L-Prolinamide, the N-terminal residue of tripeptide, at a 10 mM level had no effect on the kinetics of entry of [3H]TRH into the brain. The data indicate an absence of a specific saturable transport mechanism for TRH presented to the luminal side of the blood-brain barrier. It is concluded that intact TRH molecule may slowly penetrate the blood-brain barrier, the rate of transfer being some three times higher than that of D-mannitol.     

Thyrotropin-releasing hormone in the dorsal vagal complex stimulates pancreatic blood flow in rats

Central administration of thyrotropin-releasing hormone (TRH) enhanced pancreatic blood flow in animal models. TRH nerve fibers and receptors are localized in the dorsal vagal complex (DVC), and retrograde tracing techniques have shown that pancreatic vagal nerves arise from the DVC. However, nothing is known about the central sites of action for TRH to elicit the stimulation of pancreatic blood flow. Effect of microinjection of a TRH analog into the DVC on pancreatic blood flow was investigated in urethane-anesthetized rats. After measuring basal flow, a stable TRH analog (RX-77368) was microinjected into the DVC and pancreatic blood flow response was observed for 120 min by laser Doppler flowmetry. Vagotomy of the several portions, or pretreatment with atoropine methyl nitrate or N(G)-nitro-l-arginine-methyl ester was performed. Microinjection of RX-77368 (0.1-10 ng) into the left or right DVC dose-dependently increased pancreatic blood flow. The stimulation of pancreatic blood flow by RX-77368 microinjection was eliminated by the same side of cervical vagotomy as the microinjection site or subdiaphragmatic vagotomy, but not by the other side of cervical vagotomy. The TRH-induced stimulation of pancreatic blood flow was abolished by atropine or N(G)-nitro-l-arginine-methyl ester. These results suggest that TRH acts in the DVC to stimulate pancreatic blood flow through vagal-cholinergic and nitric oxide dependent pathways, indicating that neuropeptides may act in the specific brain nuclei to regulate pancreatic function.     

Thyrotropin-Releasing Hormone and Its Analog MK-771 Increase the Cerebroventricular Perfusate Content of Dihydroxyphenylacetic Acid

The effects of thyrotropin-releasing hormone (TRH) and its synthetic analog, pyro-2-aminoadipyl-histidyl-thiazolidine-4-carboxamide (MK-771), were determined on the efflux of dihydroxyphenylacetic acid (DOPAC) collected from push-pull cannulae chronically implanted into the lateral cerebral ventricles of rats. Intracerebroventricular and intraperitoneal injections of both peptides increased the efflux of DOPAC. These results suggest that TRH and MK-771 increase the activity of dopaminergic neurons that terminate in periventricular regions.     

Effects of thyrotropin-releasing hormone (TRH) microinjected into various brain areas of conscious and pentobarbital-pretreated rabbits

Thyrotropin releasing hormone (TRH) was administered intracerebrally into various brain regions of conscious and pentobarbitalnarcotized rabbits. In conscious animals tachypnea was observed after TRH administration into all brain regions investigated. Behavioral excitation was most pronounced after TRH administration into the cerebral cortex, caudate nucleus and hypothalamus. Hyperthermia was produced only after hypothalamic injections of TRH. In pentobarbital-narcotized rabbits TRH exerted analeptic activity (shortening of narcosis) regardless of the brain area injected, although some quantitative differences were observed. These results indicate that the analeptic effect of TRH may be initiated from various areas of the brain.     

TRH dissociates the aggressivity of vegetative and motor phenomena induced by carbachol in the cat

In these experiments interaction of thyrotropin releasing hormone (TRH) and carbachol injected into the cerebral ventricles of unanaesthetized cats has been investigated. Intracerebroventricular (i.c.v.) carbachol as well as i.c.v. TRH produced emotional behaviour, autonomic and motor phenomena. The most impressive feature of i.c.v. carbachol was the aggressive behaviour, whereas that of i.c.v. TRH the autonomic changes. In cats treated with i.c.v. TRH, the aggressive behaviour, but the autonomic and motor changes of i.c.v. carbachol was potentiated. Since there is evidence that carbachol acts mainly on muscarinic M-2 receptors, the potentiation by TRH of aggressive behaviour, but not the autonomic and motor changes induced by carbachol could indicate heterogeneity of central muscarinic M-2 receptors.     

Immunohistochemical localization of TRH in rat CNS: comparison with RIA studies

The localization of thyrotropin releasing hormone (TRH) in rat brain determined by use of avidin-biotin immunoperoxidase histochemistry was compared with the distribution and quantitation by radioimmunoassay (RIA). Male Sprague-Dawley rats received intracisternal injections of 100 micrograms of colchicine or saline and were sacrificed 24 hours later. Brains were either perfused with lysine-periodate fixative and processed for TRH immunohistochemistry or were dissected into 9 brain regions for TRH RIA. In colchicine pretreated rats. TRH immunoreactive perikarya were observed only in nuclei of the hypothalamus and brain stem. No cell body staining was observable in non-colchicine treated rats. With the exception of the olfactory bulb, brain regions exhibiting dense TRH staining contained high concentrations of TRH as measured by RIA. Colchicine pretreatment did not alter the concentration of TRH in most brain regions, however, there was a significant increase in brain stem TRH content 24 hours following colchicine administration. These findings indicate that immunohistochemical localization of TRH corresponds well with endogenous concentrations of TRH determined by RIA.     

Regional Dissociation of Cyclic AMP and Inositol Phosphate Formation in Response to Thyrotropin-Releasing Hormone in the Rat Brain

The present study was undertaken to define effects of thyrotropin-releasing hormone (TRH) on formation of cyclic AMP (cAMP) and inositol phosphates (IPs) in rat brain regions. The brain of male Wistar rats was dissected into seven discrete regions, and each region was sliced. The slices were incubated in Krebs-Henseleit glucose buffer containing varying doses of TRH. TRH caused a significant and consistent increase in cAMP level, but not in formation of IPs, in the hypothalamus, striatum, and midbrain. TRH stimulated formation of IPs in the cerebellum, where the tripeptide did not change the cAMP level. In contrast, formation of neither cAMP nor IPs was affected by TRH in the cortex, hippocampus, or pons-medulla. These data suggest that TRH possesses two distinct types of brain intracellular signaling systems, which vary with brain regions.     

Central respiratory stimulation produced by thyrotropin-releasing hormone in the cat

Thyrotropin-releasing hormone (TRH) was administered intracerebroventricularly and it's effects on respiration were evaluated in the alpha-chloralose anesthetized cat. Respiratory activity was measured using a Fleisch pneumotachograph to monitor tracheal airflow. TRH (0.28-28 nmol) caused an elevation in respiratory minute volume which was due to an increase in respiratory rate with no effect on tidal volume. The site of TRH-induced tachypnea was in the hindbrain as both injections into the cisterna magna and the fourth ventricle produced similar effects. No changes in respiratory activity were seen when TRH injection was restricted to the lateral and third ventricles (forebrain). Furthermore, systemic administration of TRH (28 nmol) produced no significant respiratory effects. The active analogue, [3-Me-His2]-TRH (2.7 nmol) produced the same respiratory effects as TRH. The inactive analogue, TRH free acid (28-280 nmol), caused no significant change in respiratory activity. The data suggest that TRH interacts with a specific receptor in the hindbrain of the cat to affect respiration.     

Neuroanatomical dissociation of thyrotropin-releasing hormone induced shaking behavior and thermogenic mechanisms

To more clearly characterize the neuroanatomical substrates mediating thyrotropin-releasing hormone (TRH) induced shaking and antagonism of pentobarbital hypothermia, TRH was microinjected into 140 individual sites of the rat forebrain and brainstem. Previously determined threshold dosages of 10 ng TRH for the temperature response and 50 ng TRH for the shaking response were used. A clear distinction in regional sensitivity between the two TRH-induced effects was observed. The shaking response was most consistently observed with microinjection of TRH into the floor of the 4th ventricle and the periventricular posterior diencephalon, including the posterior hypothalamus and rostral periventricular grey. In contrast, the temperature response was most effectively induced by TRH administered in the interpeduncular nucleus and the rostral preoptic region located medial to, and including the diagonal band of Broca. The sensitivity of some brain areas to nanogram doses of TRH supports the possibility that TRH may have a physiological function in the initiation of shaking behavior and/or thermogenesis. If such a function does exist, the brain regions identified in this study as most sensitive to exogenous TRH are likely neuroanatomical substrates for endogenous TRH.