MAPK信号通路参与调控大鼠腹腔巨噬细胞表达CRH

为了解终末巨噬细胞表达促肾上腺皮质激素释放激素(CRH)的胞内信号转导机制,明确丝裂原活化蛋白激酶(MAPK)信号通路与脂多糖(LPS)诱导的大鼠腹腔表达CRH的关系。我们利用体外培养的大鼠腹腔巨噬细胞,采用RT-PCR及ELISA方法观察MAPK信号通路中关键激酶特异性阻断剂(PD98059、SB203580、SP600125)对LPS诱导的CRH表达的影响。结果显示,LPS促进了大鼠腹腔巨噬细胞表达CRH,MAPK三条主要信号通路中关键激酶特异性阻断剂均剂量依赖性地抑制了LPS诱导的CRH表达。因此,我们认为LPS可以促进终末巨噬细胞表达CRH,而MAPK信号通路参与了该过程。     

CRH在中枢神经系统中的作用

通过对CRH的受体和结合蛋白的研究,发现CRH在中枢和外周均有分布,作用广泛,是一种重要的神经递质.它在神经内分泌调节、自律性、行为学、炎症反应和神经精神疾病中扮演了重要角色.随着对CRH研究的深入,CRH的临床意义也会愈加明显.     

精氨酸加压素翻转脂多糖引起大鼠发热及其对痛觉敏感性的影响

目的:研究外周给精氨酸加压素(AVP)对脂多糖(LPS)引起的大鼠发热和痛觉过敏的影响,以及与血清中IL-1β和PGE_2水平变化的关系。方法:实验用成年雄性SD大鼠,在23℃环境温度下,明暗时间各12 h。用无线遥测系统连续测量大鼠体核温度(Tc)、棕色脂肪温度(T_(BAT))和活动。10:00或11:30分别给大鼠腹腔注射LPS(50μg/kg)、AVP(10μg/kg)或V1a受体阻断剂(30μg/kg)。用ELISA法测定血清IL-1β和PGE_2的含量。用足底痛觉测试仪(Hargreaves test)测试大鼠热痛缩爪潜伏期的变化。结果:(1)腹腔注射LPS引起大鼠双相发热过程伴有痛觉过敏现象。(2)AVP能够翻转LPS引起的Tc和T_(BAT)升高反应,降低发热引起的痛觉敏感性。(3)外周给V1a受体阻断剂能提高LPS引起的发热反应,但不影响发热引起的痛觉敏感性变化。(4)AVP能抑制LPS引起的发热大鼠血液中IL-1β和PGE_2水平升高。结论:(1)外周给予AVP可通过抑制棕色脂肪产热以及降低血液中IL-1β和PGE_2的浓度而翻转LPS发热反应并降低发热伴随的痛觉敏感性升高现象。(2)内源性AVP也有限制LPS发热的作用,但可能不影响发热引起的痛觉阈值降低现象。     

中枢精氨酸加压素在大鼠CRH性发热机制中的作用

中枢精氨酸加压素在大鼠CRH性发热机制中的作用     

α—MSH对家兔ET性发热反应及脑腹中隔区AVP含量的影响

目的：研究脑腹中隔区精氨酸加压素（ＡＶＰ）在α－黑素细胞刺激素（αＭＳＨ）解热机制中的作用。方法：建立家兔ＥＴ性发热模型，观察侧脑室注射α－ＭＳＨ对家兔ＥＴ性发热反应及脑腹中隔区ＡＶＰ含量的影响。结果：（１）静脉注射ＥＴ（０３μｇ／ｋｇ）引起家兔明显的发热反应（Ｐ＜０００１），并增加脑腹中隔ＡＶＰ含量（Ｐ＜００５）；（２）静脉注射ＥＴ（０３μｇ／ｋｇ）３０ｍｉｎ后，侧脑室注射α－ＭＳＨ（２００ｎｇ／只），能明显抑制家兔发热反应，同时脑腹中隔区ＡＶＰ含量进一步显著增高（Ｐ＜０００１）；（３）侧脑室注射α－ＭＳＨ（２００ｎｇ／只）并不影响家兔正常体温，但增加脑腹中隔区ＡＶＰ含量（Ｐ＜００５）。结论：α－ＭＳＨ的解热作用可能部分是通过腹中隔ＡＶＰ增多来实现的，αＭＳＨ可能是引起发热时脑腹中隔区ＡＶＰ含量增加的一个重要因素。     

α-helical CRH(9-41)与消炎痛联用对家兔内毒素性发热的解热作用

目的：观察促皮质激素释放激素（ＣＲＨ）受体拮抗剂α－ｈｅｌｉｃａｌＣＲＨ（９－４１）与消炎痛联用对家兔内毒素（ＥＴ）性发热的影响。方法：静脉给药,用ＷＲＹ－Ｂ型微机热原测温仪测定家兔的结肠温度。结果：（１）静脉注射消炎痛（５ｍｇ／ｋｇ）明显抑制家兔ＥＴ（０２μｇ／ｋｇ）性发热,５ｈ发热反应指数（ＴＲＩ５）显著降低（Ｐ＜００５）。（２）静脉注射ＥＴ（０２μｇ／ｋｇ）引起家兔体温明显双相性升高（双相热）,提前５ｍｉｎ静脉注射α－ｈｅｌｉｃａｌＣＲＨ（９－４１）（２５μｇ／ｋｇ）显著抑制家兔ＥＴ性发热,且双相热第一峰消失,第二峰明显降低。（３）α－ｈｅｌｉｃａｌＣＲＨ（９－４１）与消炎痛联合用药显著抑制家兔ＥＴ性发热,其解热效果显著超过两者单独用药。半剂量消炎痛（５ｍｇ／ｋｇ）和α－ｈｅｌｉｃａｌＣＲＨ（９－４１）联用解热组与全剂量消炎痛（１０ｍｇ／ｋｇ）解热组比较,ＴＲＩ５无显著差别（Ｐ＞００５）。结论：ＣＲＨ可能参与ＥＴ性双相热的形成抑制。ＣＲＨ受体拮抗剂与化学解热剂消炎痛联用可能是一种高效低毒的解热措施     

内源性精氨酸加压素在索曼引起的大鼠体温降低中的作用

目的:探讨内源性精氨酸加压素是否参与索曼引起的降温过程。方法:用数字体温计测量大鼠的体温,每次间隔60 min,观察了腹腔注射AVP V₁受体阻断剂(30 μg/kg)对皮下注射索曼(60 μg/kg)引起大鼠降温效应的影响,以及给索曼后2 h血浆中AVP含量的变化。结果:给索曼后可引起明显的体温降低,在给药后7 h体温恢复到基线水平。AVP V₁受体阻断剂能明显阻断索曼的降温效应。在给索曼后2 h血浆中AVP浓度明显提高。结论:实验结果证明内源性AVP参与索曼引起的降温过程。     

前庭功能锻炼对运动病大鼠血浆应激相关激素水平的影响

 目的：探讨前庭功能锻炼对运动病大鼠接受旋转刺激后血浆应激相关内分泌指标的变化,进一步阐明激素与运动病的内在联系。方法：旋转刺激72只雌性SD大鼠,根据大鼠条件性味觉厌恶程度判断其运动病敏感性。用放射免疫分析法测定血浆皮质酮、促肾上腺皮质激素（ACTH）、促肾上腺皮质素释放激素（CRH）和精氨酸加压素（AVP）水平,观察旋转刺激对血浆激素水平的影响。接着,进行前庭功能锻炼1个月,等大鼠对运动病产生耐受后,再观察旋转刺激对血浆激素水平的影响。结果：（1）大鼠经过1个月的前庭功能锻炼后,糖精水厌饮行为完全被抑制,说明达到了习服的效果;（2）旋转刺激可引起大鼠血浆皮质酮、ACTH和AVP水平升高（P<0.05或P<0.01）,但经前庭功能锻炼后,旋转刺激对皮质酮的升高作用明显减弱;（3）不敏感组大鼠血浆皮质酮、ACTH、CRH和AVP的水平均高于敏感组,尤其是旋转刺激后的皮质酮、ACTH水平与CRH的基础水平（P<0.05或P<0.01）。并且,经过前庭功能锻炼,皮质酮、ACTH与CRH的基础水平在2组均高于前庭功能锻炼前（P<0.05或P<0.01）,AVP基础水平也有一定程度的升高。结论：（1）给大鼠进行前庭功能锻炼可以达到习服的目的,抑制运动病的发生;（2）大鼠运动病敏感性的个体差异可能与血浆应激相关激素基础水平的高低相关。     

下丘脑[Ca^2＋]i,cAMP在家兔EGTA性发热机制中的作用

用６０只新西兰兔分两部分进行实验。（１）用１２只制备下丘脑细胞悬液，在离体条件下，应用Ｆｕｒａ－２荧光指示剂测定细胞内Ｃａ＾２＋浓度（Ｃａ＾２＋］ｉ）。结果表明，用ＥＧＴＡ络合神经细胞外Ｃａ＾２＋而降低细胞外Ｃａ＾２＋浓度时，下丘脑神经细胞（［Ｃａ＾２＋］ｉ）明显降低（Ｐ＞０．０１）；相反，增加细胞外Ｃａ＾２＋浓度，则［Ｃａ＾２＋］ｉ明显增高（Ｐ＞０．０１）。（２）用４８只家兔分４组，分别向侧脑室     

内源性精氨酸加压素在昼光期大鼠紧张性体温调节中的作用

目的: 探讨内源性精氨酸加压素(AVP)在昼光期大鼠紧张性体温调节中的作用及其机制。方法: 使用成年雄性SD大鼠,在22 ℃环境温度下,明暗时间各12 h,同步无线遥测体核温度(Tc)和棕色脂肪(BAT)温度。上午10:00给大鼠腹腔注射AVP(10 μg/kg)或精氨酸加压素V_1a(AVP V_1a)受体阻断剂(30 μg/kg)。用酶联免疫吸附测定法,分别检测昼光期和暗光期大鼠血浆中AVP浓度。给AVP 60 min 后测定血清中甘油三酯、游离脂肪酸和甘油浓度变化。给予AVP后间隔10 min 记录大鼠的理毛活动。结果: (1)在昼光期中AVP V_1a受体阻断剂能够升高Tc和BAT温度。(2)在昼光中Tc和BAT温度处于低温期时,血浆中AVP水平则明显提高。(3)腹腔注射AVP引起Tc快速降低时,伴有BAT温度明显降低和大鼠的理毛行为明显增加。(4)AVP可以降低血清游离脂肪酸与甘油浓度,提高血清甘油三酯的浓度。结论: (1)内源性AVP通过AVP V_1a受体参与昼光期大鼠紧张性体温调节过程,因为在昼光期中不仅血浆AVP浓度明显高于暗光期,而且AVP V_1a受体阻断剂也能明显升高Tc和BAT温度。(2)AVP能降低BAT温度、血中游离脂肪酸和甘油浓度,提高理毛活动,证明AVP引起低温的机制可能与抑制脂肪分解、降低BAT产热和提高散热反应有关。     

α-MSH对EGTA发热的作用

目的：观察α－ＭＳＨ对ＥＧＴＡ发热反应的作用及其可能机制。方法：建立ＥＧＴＡ发热模型；在离体条件下，应用Ｆｕｒａ－２荧光指示剂测定细胞内Ｃａ２＋浓度（［Ｃａ２＋］ｉ）；体外培养下丘脑神经细胞。结果：α－ＭＳＨ能明显抑制ＥＧＴＡ性发热反应（Ｐ＜０．０１）；ＥＧＴＡ可以降低下丘脑神经细胞［Ｃａ２＋］ｉ水平（Ｐ＜０．０１），但α－ＭＳＨ不影响正常下丘脑神经细胞［Ｃａ２＋］ｉ及ＥＧＴＡ对下丘脑神经细胞［Ｃａ２＋］ｉ的作用（Ｐ＞０．０５）；ＥＧＴＡ可刺激体外培养的下丘脑神经细胞释放ＣＲＨ（Ｐ＜０．０５），而α－ＭＳＨ能抑制ＥＧＴＡ的这种作用（Ｐ＜０．０５）。结论：α－ＭＳＨ抑制中枢发热介质ＣＲＨ的产生可能是降低ＥＧＴＡ发热反应的主要机制之一；中枢ＣＲＨ的产生和释放增加可能是ＥＧＴＡ性发热的一个重要因素。     

Immunoreactivity of hypothalamo-neurohypophysial neurons which secrete corticotropin-releasing hormone (CRH) and vasopressin (Vp): immunocytochemical evidence for a correlation with their functional state in colchicine-treated rats

Summary The specific immunoreactivity of neurons containing corticotropin-releasing hormone (CRH) or vasopressin (Vp) was studied both centrally, in the parvocellular division of the paraventricular nucleus, and distally, in the external median eminence. Control rats were compared with adrenalectomized rats and with animals supplemented with corticosterone or dexamethasone, either without additional treatment, or 24, and 48 h after an intraventricular injection of colchicine. In all groups of animals, colchicine induced a progressive and parallel decrease in both CRH and Vp immunoreactivity within the axons of the external median eminence. A semi-quantitative estimation of this axonal immunostaining showed that the decrease was clearly correlated with the axons' releasing activity according to the different functional states of the adrenocorticotropic system. Increased rates of hormonal release induced by adrenalectomy could be seen in the accelerated depletion of axonal immunoreactivity whereas corticosteroid supplementation had the opposite effect. Correspondingly, the progressive intensification of the CRH and Vp immunoreactivity within the perikarya following colchicine treatment was further markedly enhanced in adrenalectomized rats and diminished after corticosteroid supplementation. Taken together, these data suggest that in these neurons, perikaryal hormone synthesis may be closely related to the releasing activity of the axon terminals. They further point to appropriate colchicine treatment as useful tool for evaluating the functional state of CRH and Vp neurons of the parvocellular paraventricular nucleus under various experimental conditions.     

The importance of corticosterone in mediating restraint-induced weight loss in rats

I. J. Scherer, P. V. Holmes, R. B.S. Harris. The importance of corticosterone in mediating restraint-induced weight loss in rats. PHYSIOL BEHAV 00 (0) 000-000, 2010. Rats restrained for 3 h/day for 3 days (RR) lose weight and do not return to the weight of non-restrained controls once restraint has ended. This study tested the importance of restraint-induced corticosterone release in mediating the change in body weight by injecting ADX rats with 2.0 mg corticosterone/kg before each restraint to replicate the restraint-induced surge in circulating corticosterone. Restrained adrenalectomized (ADX) rats injected with corticosterone had the same initial weight loss as intact restrained rats, whereas corticosterone injection in non-restrained ADX rats and restraint of ADX rats injected with saline each produced only half as much initial weight loss. Sustained weight loss, measured for 14 days after the end of RR, was the same for restrained intact rats and restrained ADX rats injected with corticosterone whereas restrained ADX rats injected with saline achieved the same weight gain as their controls. Corticosterone injections had no effect on weight gain of non-restrained intact rats. In situ hybridization showed that corticotropin releasing factor (CRF) mRNA expression in the paraventricular nucleus of the hypothalamus (PVN) was increased by the same degree in ADX rats and restrained intact rats and was not modified by corticosterone injections. There was no significant effect of restraint, ADX or corticosterone injection on PVN arginine vasopressin (AVP) mRNA expression. These data indicate that a surge in corticosterone causes sustained weight loss in ADX rats through a mechanism that can be compensated for in intact rats and is independent of changes in PVN CRF or AVP mRNA expression.     

Expression of mRNA for corticotropin-releasing hormone and vasopressin in the hypothalamus and amygdala of rats after administration of narcogenic

Male Wistar rats received intraperitoneal injections of physiological saline (control), phenamine, fentanyl, ethanol, sodium ethaminal, or dexamethasone in increasing concentrations for 4 days. Forced administration of these drugs provided gradual load of the organism and prevented the development of tolerance. Such approach is extensively used for the development of drug addiction or several manifestations of this state. Expression of corticotropin-releasing hormone mRNA in the amygdala was maximum after administration of dexamethasone (0.46 arb. units vs. β-actin), but was much lower in experiments with sodium ethaminal and fentanyl (0.07 and 0.037 arb. units, respectively). In the hypothalamus, enhanced mRNA expression was observed after injection of sodium ethaminal, ethanol, and fentanyl (0.8, 0.37, and 0.039 arb. units, respectively). Phenamine did not increase mRNA expression in the amygdala and hypothalamus. Expression of vasopressin mRNA was not detectable in brain structures of animals from various groups. Our results indicate that the hypothalamic reinforcement system provides a similar response to narcogens, whereas the extended amygdala includes elements of both reinforcement and stress reactivity. Translated From Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 146, No. 9, pp. 292–296, September, 2008     

Agmatine attenuates stress- and lipopolysaccharide-induced fever in rats

Physiological stress evokes a number of responses, including a rise in body temperature, which has been suggested to be the result of an elevation in the thermoregulatory set point. This response seems to share similar mechanisms with infectious fever. The aim of the present study was to investigate the effect of agmatine on different models of stressors [(restraint and lipopolysaccharide (LPS)] on body temperature. Rats were either restrained for 4 h or injected with LPS, both of these stressors caused an increase in body temperature. While agmatine itself had no effect on body temperature, treatment with agmatine (20, 40, 80 mg/kg intraperitoneally) dose dependently inhibited stress- and LPS-induced hyperthermia. When agmatine (80 mg/kg) was administered 30 min later than LPS (500 microg/kg) it also inhibited LPS-induced hyperthermia although the effect became significant only at later time points and lower maximal response compared to simultaneous administration. To determine if the decrease in body temperature is associated with an anti-inflammatory effect of agmatine, the nitrite/nitrate levels in plasma was measured. Agmatine treatment inhibited LPS-induced production of nitrates dose dependently. As an endogenous molecule, agmatine has the capacity to inhibit stress- and LPS-induced increases in body temperature.     

The nitric oxide pathway is an important modulator of stress-induced fever in rats

Psychological stress evokes a number of physiological responses, including a rise in body temperature (T(b)), which has been suggested to be the result of an elevation in the thermoregulatory set point, i.e., a fever. This response seems to share similar mechanisms with infectious fever. A growing number of studies have provided evidence that nitric oxide (NO) has a modulatory role in infectious fever, but no report exists about the participation of NO in stress fever. Thus, the present study aimed to verify the hypothesis that NO modulates stress fever by using restraint stress as a model. To this end, we tested the effects of the non-specific NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) or its inactive enantiomer N(G)-nitro-D-arginine methyl ester (D-NAME) on colonic T(b) of restrained or unrestrained rats. A rapid increase in T(b) was observed when animals were submitted to restraint. Intravenous (i.v.) injection of L-NAME at a dose (10 mg/kg) that caused no change in T(b) when administered alone significantly attenuated the elevation in T(b) elicited by stress, indicating that the NO pathway may mediate stress fever. Moreover, intracerebroventricular (i.c.v.) L-NAME (250 microg/microl) caused a rise in T(b) of euthermic animals and enhanced stress fever, supporting that NO in the central nervous system (CNS) leads to a reduction in T(b) and, therefore, this is unlikely to be the site where NO may mediate stress fever. Taken together, these data indicate that the NO pathway plays an important role in modulating restraint stress-induced fever in rats.     

Structure and dynamics of adrenal mitochondria following stimulation with corticotropin releasing hormone

The mitochondria of rat adrenals were investigated qualitatively and quantitatively in different functional states of the adrenal cortex. Following stimulation of the animals with corticotropin releasing hormone (CRH), the corticosterone serum levels reached a maximum 1 hour after stimulation with CRH. The amount of inner mitochondrial membrane within the zona fasciculata increased showing a biphasic time course, with a first maximum 2 hours and a second maximum 8 hours after stimulation. In contrast, a significant rise of mitochondrial volume occurred only 24 hours after CRH stimulation. Therefore, the dense vesicularization of mitochondrial cristae may constitute an early process to enhance the steroidogenic capacity of these cells. Within cells of the transition zone between zona glomerulosa and zona fasciculata, we could depict a special type of mitochondria with characteristic crescent-like cristae only seen after stimulation with CRH. This type of mitochondria may represent an intermediate form between mitochondria of zona glomerulosa and zona fasciculata underlining the impressive transformational capacity of adrenocortical mitochondria. After hypophysectomy, zona fasciculata cells contained mitochondria with tubular inner membranes, representing a hypofunctional state. In contrast, the hypofunctional state after hypophysectomy and the hyperfunctional state after stimulation of the adrenal cortex via CRH injection did not appear to correlate with the morphology of mitochondria from the zona reticularis and adrenal medulla.© Willey-Liss, Inc.     

Secretion of growth hormone and thyroid-stimulating hormone in patients with dementia

We studied the growth hormone (GH) response to GH-releasing hormone (GHRH) and the thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) in four groups of patients with dementia and examined whether GH and TSH secretion is altered in patients with Alzheimer's disease. The four groups included those with Alzheimer's disease (n=28), parkinsonism with dementia (n=10), progressive supranuclear palsy with dementia (n=10), and dementia of vascular origin (n=28). The results showed no differences among the four groups in GH response to GHRH (12.2 ± 2, 10.7 ± 2, 8.9 ±1.1, and 9.9 ± 1.9 g/ml, respectively); there was no correlation between GH response to GHRH and sex, stage of the disease, or cerebral atrophy. The proportion of patients with exaggerated, normal, or lower GH response was similar in the four groups. There were also no differences among the groups in terms of TSH response to TRH (9.2 ±0.9, 11.1 ± 1, 11.1 ± 1, and 10.3 ± 1 mU/ml, respectively), nor was there a correlation between TSH response to TRH and sex, stage of the disease, cerebral atrophy, or GH response to GHRH. The proportion of those with exaggerated, normal, or lower TSH response was similar in the four groups. Cerebrospinal somatostatin levels were similar in Alzheimer's disease and vascular dementia patients. These findings indicate that neither GH response to GHRH nor TSH response to TRH provides a useful diagnostic adjunt in Alzheimer's disease patients.Abbreviations AD Alzheimer's disease - PD parkinsonism with dementia - PSP progressive supranuclear palsy - VD dementia of vascular origin - GH growth hormone - GHRH growth hormone releasing hormone - TRH thyrotropin releasing hormone - TSH thyroid stimulating hormone Correspondence to: J.M. Gomez