蛙皮素的分布及其作用

<正> 近年来,由于免疫组织化学、放射免疫测定及电子显微镜等技术的广泛应用,使神经内分泌方面的研究进入一个新的阶段,成为当前神经科学发展的活跃领域。到目前,已相继在哺乳类和一些非哺乳类动物体内发现了多种肽类物质。它们对于机体的生理调节或病理改变都有着非常重要的作用。但对其中多数肽的了解还不十分深入。本文仅对蛙皮素的某些问题作一简要介绍。一、蚌皮素的概况蛙皮素(Bombesin,简作BBS)又称羚蟾素或羚蟾肽,它是由Anastasi等于1971年首先从两种欧州蛙的皮肤提取物中获得的。此后陆续发现在哺乳类和其它非哺乳类动物的神经     

蛙皮素及其受体和核因子-κB与肿瘤的关系

肿瘤的发生发展与多种内外因素有关。目前已发现,凋亡抑制和增殖能力增强是肿瘤发生的机制之一。蛙皮素及其受体和NF-κB共同的促增殖抗凋亡的特点,使其成为肿瘤研究中的热点。     

他汀类药物抗感染作用的研究进展

他汀类药物（statins）除有降脂作用外,还具有多效性,包括抗氧化、抗炎抗感染、免疫调节、改善血管内皮细胞功能和抑制血栓形成、稳定粥样硬化斑块等作用。目前对statins的抗微生物感染作用研究越来越多,包括实验室的研究和人群的流行病学研究,本文收集了statins抗细菌感染、抗病毒作用、抗真菌及其他微生物感染的实验室及流行病学证据并进行了分析。     

平面体温场的分类

在文献［１］的基础上，本文将平面体温场分成了九类     

体温对免疫功能的影响

体温对免疫功能的影响广州暨南大学医学院病理生理学教研室（５１０６３２）孙葳，陆大祥ＩｍｐａｃｔｏｆｔｅｍｐｅｒａｔｕｒｅｏｎｉｍｍｕｎｏｌｏｇｉｃｆｕｎｃｔｉｏｎＳｕｎＷｅｉ，ＬｕＤａ－ＸｉａｎｇＤｅｐａｒｔｍｅｎｔｏｆＰａｔｈｏｐｈｙｓｉｏｌｏｇｙ...     

番茄红素保护神经系统作用研究进展

番茄红素是一种类胡萝卜素,它广泛存在于番茄、石榴、木瓜等植物中,进入人体后,存在于睾丸、肾上腺、肝脏、脂肪组织、前列腺及卵巢等中,具有如抗肿瘤、抗炎症等的作用。随着社会的发展,神经系统疾病逐渐成为困扰人类健康的一大威胁。越来越多的证据表明,番茄红素通过多种机制对神经元有保护作用。本文就番茄红素对神经系统保护作用做一综述。     

CpG DNA的免疫学活性及其作用机理研究进展

近年发现含ＣｐＧ基序的ＤＮＡ或寡核苷酸具有许多免疫学活性,其活性的发挥与所含ＣｐＧ基序及其侧翼序吉构密切相关,作用机理波及胞内体内酸化、活性氧成份（ＲＯＳ）产生、ＮＦｋβ激活等过程。本文就有关ＣｐＧＤＮＡ或ＣｐＧＯＤＮ免疫学活性及其作用机理的近期的近期研究作一简述。     

新城疫病毒抗肿瘤作用及其机制研究进展

新城疫病毒(NDV)抗肿瘤作用早在50年代就有人提出,随着研究的不断深入和研究手段的不断提高,人们利用分子生物学和细胞生物学等先进技术对新城疫病毒及其修饰瘤苗的抗肿瘤作用进行了动物实验和临床I、Ⅱ期应用的研究,并取得了喜人的进展,本文即重点对NDV的抗肿瘤作用及机制进行综述.     

抗真菌药作用机理的研究进展

目前投入使用的抗真菌药物归为5大类：多烯类、唑类、吗啉类、丙烯胺类及一组不相关的化合物类。可能某一类药有其独特的作用机理，而两类或两类以上的药物可能有相同的作用机理，也许某种药物有多种不同的作用机制，这些都将在以下几方面给予阐述。     

Effect of bombesin on thermoregulation of the rabbit

Injections of bombesin (BOM, 125, 250 and 500 ng) into the preoptic/anterior hypothalamus caused dose-related decreases of threshold temperatures for metabolic cold defence, cutaneous vasomotor tone and respiratory rate, combined with a reduced sensitivity of these thermoregulatory effectors in response to core temperature changes induced at thermoneutral or warm ambient conditions. Intracisternal (i.c.) injections of BOM (250 ng) produced qualitatively identical thermoregulatory effector changes in response to core temperature changes. Injections of BOM into the posterior hypothalamus did not affect body temperature control. Increased locomotor behavior, licking and grooming was elicited, however, from all injection sites. The results explain the prevailing hypothermic effect of BOM as the consequence of the concerted decrease in threshold temperatures and gains of all autonomic thermo-regulatory effectors and suggest the activation of warm inputs, relative to cold inputs, at the hypothalamic level as the underlying mechanism. Direct or indirect inhibition of the intrinsic hypothalamic system involving thyrotropin-releasing hormone (TRH) and consequent deactivation of central noradrenergic pathways known to generate the entire autonomic pattern of cold defence might be involved in the neuro-humoral changes resulting in hypothermic effects of centrally applicated BOM.     

Effect of p-chlorophenylalanine on thermoregulation in unrestrained rats

p-Chlorophenylalanine (PCPA), a serotonin depletor, was used to investigate thermoregulation of unrestrained unanesthetized rats exposed to warm (approximately 32 degrees C) and cold (approximately 3 degrees C) environments. PCPA (300 mg/kg, ip) was administered approximately 48-96 h prior to the experimental trials. After 60 min of warm exposure, PCPA-treated rats had a significantly smaller increase in mean tail temperature (3.05 degrees C) and a greater increase in mean core temperature (1.47 degrees C) than did the control rats (6.13 and 1.20 degrees C, respectively) as measured via chronically implanted thermistors. A noninvasive method, infrared photography, was also used to monitor skin temperatures following heat exposure. Changes were qualitatively similar to those seen with thermistors, although differences between control and PCPA-treated groups were not statistically significant. During cold exposure, thermistor measurements indicated that the decrease in mean core temperature of the PCPA-treated rats (0.62 degrees C) did significantly differ from that of the controls (1.11 degrees C), whereas tail temperatures did not. These data confirm other studies implicating serotonin in the thermoregulation of rats. In particular, these results show that in a warm environment, PCPA may alter, albeit subtly, peripheral vasodilation in unrestrained rats.     

Effect of plasma volume on thermoregulation in the dog

Panting thresholds, plasma volume (PV) changes and cardiac filling pressure were studied during thermal dehydration in control, water deprived (WD) and hypovolemic (PEG) dogs. WD and PEG dogs showed a delayed panting threshold, apparently due to hypovolevoia. Initiation of heat stress however resulted in a transient plasma expansion in all dogs. Cardiac filling pressure did not change.Permanent address: Dept. of Physiology, Haddassah School of Medicine and Dental Medicine, The Hebrew University, Jerusalem, Israel.     

β-Endorphin: Effect on thermoregulation in aged monkeys

In previous experiments small doses of the opiate morphine produced greater hyperthermia in aged than in younger sub-human primates. To test whether this augmented response is due to enhanced sensitivity of CNS opioid receptors with age. β-endorphin (0.625–5 μg), an endogenous opioid peptide, was injected into the lateral cerebral ventricle (ICV) of young (<9 years) and aged (>9 years) squirrel monkeys. Significantly greater hyperthermias developed in the older primates after each dose. In the aged monkeys, all but the smallest dose increased core temperature about 1.5°C within 1 hr after injection. Mean rectal temperature in the y younger animals rose 0.5–0.7° after all but the largest dose (1–1.5°C rise). Both groups maintained an elevated body temperature after central β-endorphin throughout the 5 hr recording period. 1.25 μgβ-endorphin given ICV in a hot environment (30°C) caused greater hyperthermia in older animals. This dose given in the cold (18°C) caused large changes in temperature of the aged monkeys, either hyperthermia or marked decreases, whereas the young primates developed only moderate rises in body temperature. The same dose of morphine sulfate (1.25 μg) ICV produced similar changes in core temperature in the two age groups in each ambient temperature. These results indicate that: (1) stimulation of CNS opioid receptors influences thermoregulation and (2) aging increases responsiveness to such stimulation.     

Effect of substance P on thermoregulation parameters during different cooling modes

The modulatory effect of ionophoretic application of substance P to the skin on the formation of the cold-triggered thermal protection reactions depends on the rate of cooling. During rapid cooling substance P enhances heat production, while during slow cooling it promotes constriction of skin blood vessels aimed at reduction of heat emission. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 6, pp. 643–645, June, 2006     

Effect of physical restraint on the limits of thermoregulation in telemetered rats

Physical restraint of rodents is needed for nose-only exposure to airborne toxicants and is also used as a means of psychological stress. Hyperthermia is often observed in restrained rats, presumably as a result of impairments in heat dissipation. However, such a hyperthermic response should be dependent on the prevailing ambient conditions. To understand how ambient temperature (T(a)) affects the thermoregulatory response to restraint, core temperature (T(c)) and heart rate (HR) were monitored by telemetry in rats subjected to 1 h of physical restraint while T(a) was maintained at 14-30 °C in 2 °C increments. The T(c) of unrestrained rats was unaffected by T(a). During restraint, T(c) was elevated at ambient temperatures with the exception of 14 °C, at which the rats became mildly hypothermic. There was an inverse relationship between T(a) and HR in both unrestrained and restrained rats; however, HR was significantly elevated in restrained rats at all ambient temperatures except 22 and 24 °C. Heat loss from the tail, estimated from T(c) and tail skin temperature, was markedly reduced at all but the highest ambient temperatures in restrained rats. The data suggest that the T(a) limits of normothermia are narrowed in the restrained rat. That is, between 16 and 20 °C, the rat maintains a relatively stable T(c) that is slightly elevated above that of the unrestrained rat. At ambient temperatures above or below this range, the rat shows signs of hyperthermia and hypothermia, respectively. In contrast, the limits of normothermia for unrestrained rats range from 14 (or lower) to 30 °C. Overall, the ideal T(a) for restrained rats appears to be 20 °C and no higher than 22 °C for the thermoregulatory system to maintain a regulated T(c) in rats well adapted to physical restraint.     

Effect of heating & cooling the hypothalamus on behavioral thermoregulation in the pig

1. Pigs were trained to push a switch with their snouts in order to obtain a short burst of infra-red heat on the skin.

2. When the preoptic region of the hypothalamus was cooled by means of an implanted thermode, the rate at which the heaters were turned on increased at environmental temperatures ranging from 0 to 25° C. At 30 and 35° C cooling sometimes had no effect.

3. The preoptic region was warmed either by means of a thermode or using radio-frequency heating from implanted electrodes. Warming the preoptic region decreased the rate at which the infra-red heaters were turned on, but the effect was not as obvious as the increases observed during cooling.

4. Pigs placed in a cold or neutral environment did not learn to push a switch in order to obtain radio frequency heating of the preoptic region.

     

Homodimeric forms of bombesin act as potent antagonists of bombesin on Swiss 3T3 cells.

Two Lys3-bombesin dimers were prepared by crosslinking epsilon-amino groups Lys3-bombesin with noncleavable (glutaraldehyde) and cleavable [dimethyl-3,3'-dithiobispropionimidate (DTBP)] crosslinkers. The dimers were purified by HPLC ion-exchange chromatography and were shown to have retained immunoreactivity with an anti-bombesin monoclonal antibody directed against the C-terminal binding region of bombesin. The glutaraldehyde cross-linked bombesin dimer specifically inhibited binding of 125I-GRP to its receptor on Swiss 3T3 cells. Bombesin, at 0.6-60 nM induced mitogenesis in quiescent Swiss 3T3 cells, whereas, incubation of cells with the glutaraldehyde bombesin dimer at concentrations up to 124 nM did not. In competition assays, the bombesin dimer exhibited a dose dependent inhibition of bombesin-induced mitogenic activity and intracellular Ca++ mobilization. The bombesin dimer was 100 to 1000-fold more potent than D-Phe12Leu14-bombesin and D-Phe12bombesin, respectively, in inhibiting bombesin-induced mitogenesis on quiescent Swiss 3T3 cells. Similarly, the DTBP-bombesin dimer was not mitogenic to Swiss 3T3 cells, however, cleavage of the disulfide crosslinker with DTT of cell bound DTBP dimer restored mitogenic activity. Finally, the glutaraldehyde bombesin dimer also inhibited growth of bombesin receptor positive H345 SCLC cells in vitro. These findings suggest that the dimeric forms of bombesin are potent antagonists of bombesin.