下丘脑-垂体-肾上腺皮质轴应激反应的中枢控制

应激反应是所有生物对紧张性事件的适应性反应,对生物的存活具有十分重要的意义。应激反应的主要特征是下丘脑－垂体－肾上腺皮质（ＨＰＡ）轴激活。ＨＰＨ轴激活的呆区控制十分复杂。海马参与整合感知的信息、解释环境信息的意义及定调行为反应和神经内分泌反应。杏仁核是应激性行为反应以及自主神经和神经内分泌反应的行旅地部位。下丘脑室６ 有直接激活ＨＰＡ轴的作用。负反馈机制、下丘脑局部回路和细胞因子也可能参与了调节Ｈ     

2-Deoxyglucose as a tool for analyzing the humoral component of the cardiovascular reaction to stress

Blood pressure (BP), heart rate (HR), adrenaline (A) and noradrenaline (NA) effects of 2-desoxyglucose (500 mg/kg i.v.) were studied in conscious chronically instrumented wistar rats. A and NA contents in the blood were estimated by HPLC with electrochemical detection. In 15-40 minutes after 2-DG administration it was 13-16-fold increase in A content, 1.7-1.9-fold increase in NA content. At the same time BP fell by 5 mm Hg and HR fell by 100 beats/min. Atropine blocked bradycardia but had no effect on BP. It is concluded that high levels of endogenous A during stress are not responsible for cardiovascular responses usually observed.     

Function of hypothalamic-pituitary-adrenocortical system in hypertensive rats of ISIAH strain

Functional activity of hypothalamic-pituitary-adrenocortical axis has been studied under control and restraint stress conditions in rats with inherited stress-sensitive arterial hypertension (ISIAH strain) and in normotensive WAG (Wistar Albino Glaxo) strain. The levels of hypothalamic CRH-mRNA (in control and 2 hrs stress), pituitary and plasma ACTH and plasma corticosterone (in control and after 5, 15 or 30 min of restraint stress), were evaluated. Hypothalamic CRH-mRNA level was found to be approximately the same in the control rats of both strains. In control conditions, the pituitary and plasma ACTH content in ISIAH rats was significantly lower whereas the corticosterone level in the plasma differed from each other in both strain. The restraint stress resulted in a statistically significant increase of the CRH-mRNA in ISIAH rats and not in the WAG rats. Moreover, in spite of the lower ACTH level in stressed ISIAH rats, the corticosterone blood plasma concentration in hypetensive rats was significantly higher. The data obtained confirm the idea that the stress-dependent hypertension might be related to an enhanced sensitivity of the main endocrine links involved in the stress response organization.     

Amphipod crustaceans as an important component of zoobenthos of the shallow Antarctic sublittoral

Benthic quantitative samples were taken in 1988 in the soft bottom sublittoral of Admiralty Bay (King George Island, South Shetlands) using a Tvärminne-type bottom sampler and SCUBA-diving technique at 7 successive stations situated at depths from 4 to 30 m.Dominant animal groups in terms of abundance were Amphipoda, Polychaeta and Bivalvia, whereas in terms of biomass Echinoidea were also dominant. Amphipod crustaceans clearly dominated the zoobenthos at depths from 10 to 25 m (the numerical share surpaising 60%) with maximal abundance of abt. 17 000 ind m^–2; in terms of biomass at specific depths amphipods occupied the 1st, 2nd or 3rd place with maximal biomass of abt. 100 g m^–2 where the maximal total biomass of zoobenthos reached 260 g m^–2 (10 m).Amphipoda were the most diversified group with some 35 taxa belonging to 14 families. Most species belonged to Eusiridae s.l. and Lysianassidae s.l. Dominant forms were Pontogeneiella brevicornis, Prostebbingia gracilis, Schraderia gracilis, Hippomedon kergueleni, Orchomenella cf. ultima, Cardenio paurodactylus and Paraphoxus rotundifrons.     

Domestication-related behavior as a factor for the long-term adaptation of the sheep hypothalamic-pituitary-adrenocortical system to social isolation

The reaction of the hypothalamic-pituitary-adrenocortical axis (HPA) to social isolation from the herd was studied in 45 ewes of the Altaian breed at the age of 12, 16, and 27 months. The animals belonged to either "wild" or "domesticated" phenotypes which contrasted in the character of feeding and defensive responses to a human. The basal corticoid level in animals of both behavioral phenotypes was similar. The corticosteroid reaction was absent in animals with the "domesticated" type of behavior, while it was significantly pronounced in animals with a clear-cut behavioral reaction of withdrawal from a human ("wild" phenotype) at different ages. Sheep of the "wild" type of behavior were not uniform in the rate of the age-dependent decrease in withdrawal and stress reactions: these reactions were stable in individuals of "conservative" phenotypes. Thus, the ontogenetic formation of the long-term adaptation of the HPA axis of sheep to isolation depends on genetically determined behavior and factors, which control correlated changes in feeding and defensive reactions in animals of the "wild" phenotype.     

The role of hormones of hypothalamic-pituitary-adrenocortical system in regulation of pain sensitivity

The review focuses on the role of hypothalamic-pituitary-adrenocortical system (HPAS) in regulation of pain sensitivity and discusses the mechanisms involved in this process. Analgesic effects of exogenous hormones of HPAS (corticotropin-releasing hormone (CRH), ACTH, glucocorticoids) have been shown in rats. It is mediated by both opioid and non-opioid mechanisms. Endogenous glucocorticoids produce development of analgesia mediated by non-opioid mechanisms. Analgesic effect of ACTH is mediated by both non-glucocorticoids mechanisms associated with endogenous glucocorticoids and opioid mechanisms. In contrast to ACTH, analgesic effect of CRH is mediated only by non-opioid mechanisms associated or dissociated with endogenous glucocorticoids. The neurons of midbrain periaqueductal gray matter may be involved in the analgesia induced by glucocorticoids.     

An electrophoretic component from the lens proteins of the Passeriformes as an important taxonomic characteristic

Zusammenfassung In Agarelektropherogrammen der Linsenextrakte von mehr als 80 untersuchten Passeriformes kommt stets eine charakteristische Komponente vor, welche wir wegen ihrer Regelmäßigkeit, genauen Umgrenzung und besonders stabilen Mobilität Typische Singvogel-Komponente (T S B C) genannt haben.In schwächerer Konzentration ist auch in den Linsenpherogrammen einiger anderer Ordnungen (Ciconiiformes, Falconiformes, Gruiformes, Strigiformes, Psittaciformes, Coraciiformes, Piciformes) eine Fraktion mit ähnlicher Mobilität und ferner fast die ganze Reihe der passeriformen Linsenproteine vorhanden. Weil die Ähnlichkeit zwischen solchen komplizierten Pherogrammen möglicherweise auf eine nähere Verwandtschaft hinweist, hat Verf. eine Übersicht der früheren taxonomischen Argumente, wie sie durch Autoren im Bereich der Anatomie, Osteologie, Myologie, Parasitologie und Biochemie vorgelegt wurden, gegeben und kurz besprochen.     

Nitrogen as an important detoxification factor to cadmium stress in poplar plants

To verify the important role of nitrogen in detoxifying plants from heavy metals in Populus, the influence of nitrogen and cadmium on growth, chlorophyll (Chl) synthesis, and the expression of the Glutamine synthetase gene (GS₂) were studied in poplar plants. Experiments were carried out in potted plants treated with (NH₄)₂CO₃, Cd(NO₃)₂, CdCl₂ and CdCl₂ plus (NH₄)₂CO₃. After treatment, plant height, biomass, chlorophyll content, the precursors content and GS₂ were investigated. Results showed that the plants treated with cadmium showed toxicity symptoms, decrease in growth and Chl content. Cd inhibited Chl synthesis seriously by blocking the site located on the steps between UrogenIII and Coprogen III. However, the plants treated with cadmium and nitrogen grew well without any toxicity symptoms. Nitrogen supplement can alleviate Cd inhibition on chlorophyll synthesis by unblocking the pathway. The results indicated that nitrogen can effectively alleviate cadmium toxicity to poplar plants.     

Radiation adaptive response as a stress reaction of a cell

The published data on the primary changes that occur in human peripheral blood lymphocytes after small dose irradiation in vitro (SDI), as well as relation between these changes and the adaptive response mechanism (increase of radioresistance of lymphocytes after SDI) have been analyzed. The author has come to a conclusion in favor of the absence among the revealed primary changes of any traces of a specific inducible mechanism that protects a cell from exterior influences and elevates cell radioresistance. The changes in cell radioresistance following the SDI comprise only an insignificant part of all the changed characteristics. There are large numbers of mechanisms by which radioresistance changes and they are poorly studied at that. The author speculates that the adaptive response isn't a specific radiobiological protective phenomenon, but it is rather a type of the cell stress reaction that is evoked by external influences. Signals that trigger transition to a state of stress, as well as the signals to implement adaptive functions, thus restoring the normal state, can be represented, for example, by increased concentrations of reactive oxygen species, and most likely by as yet unknown metabolic changes. An irradiated cell transfers into the state of stress and mobilizes all possible ways to increase resistance to any damaging effects, radiation including. What particular way of increasing radioresistance will be used depends on the genotype, experiment conditions, etc. The consequences of stress could cause more rapid cell division, malignant transformations and increased stability of malignization, hormesis and many other things.     

Oxidative stress as a component of chromium-induced cytotoxicity in rat calvarial osteoblasts

It has been documented that medical prosthetic alloys release metal ions into surrounding tissues and cause cytotoxicity, but the mechanisms remain undefined. In that regard the cellular oxidative stress may be a common pathway in cellular responses to metal ions. The objective of this study was to approach the hypothesis that oxidative stress mediates chromium-induced cytotoxicity in rat calvarial osteoblasts. Osteoblasts were exposed to different concentrations of Cr⁶⁺ or Cr³⁺ (5–20 μM) in the presence or absence of the antioxidant N-acetyl-cysteine (NAC; 1–5 mM). Cellular viability, differentiation, and intracellular ultrastructural alterations were evaluated by MTT assay, alkaline phosphatase (ALP) activity assay, and transmission electron microscopy. Cellular oxidative stress was evaluated by intracellular reactive oxygen species (ROS) production. ROS production was monitored by the oxidation-sensitive fluorescent probe 2′7′-dichlorofluorescin diacetate (DCFH-DA). A time- and concentration- dependent increased cytotoxicity, time-dependent increased intracellular ROS production were indicated on exposure to Cr⁶⁺. Pretreatment of osteoblasts with 1–5 mM NAC afforded dose-dependent cytoprotective effects against Cr⁶⁺-induced cytotoxicity in osteoblasts. NAC decreased the level of intracellular ROS induced by Cr⁶⁺, too. While Cr³⁺ and NAC did not have any significant effects on osteoblasts (5–20 μM). These results suggest that oxidative stress is involved in Cr⁶⁺-induced cytotoxicity in osteoblasts, and NAC can provide protection for osteoblasts against Cr⁶⁺-induced oxidative stress. Cr³⁺ (5–20 μM) have no significant cytotoxicity in osteoblasts based on the results of this study.     

Serum bank as a component of system of biological safety

The concept of biological safety foresees prevention of potential and real biological hazard at different biorisk levels. In consideration are approaches for creation of a global monitoring, control and prognosis system of socially significant and dangerous infectious diseases with help of informative passported blood sera collection. The basic criteria of effective functioning of serum bank and computer base of the epidemiological data are the subject of discussion in a scope of update WHO requirements. Also new analytical systems for blood sera testing on the basis of protein microchip technology are discussed.     

The role of hormones of hypothalamic-pituitary-adrenocortical system in analgesic effect of corticotropin-releasing hormone

The role of hypothalamic-pituitary-adrenocortical system (HPAS) in analgesic effect induced by central or systemic corticotrophin-releasing hormone (CRH) was studied on anaesthetized male rats. Blockade of the HPAS functional activity by hydrocortisone in pharmacological dose one week before the experiment was used as approach to investigate the contribution of the HPAS hormones in CRF-induced analgesia. Elimination of the hormones rise in the blood plasma by hydrocortisone resulted in decrease of analgesic effect induced by systemic CHR and complete disappearance of analgesic effect induced by central CRH. The results suggest that CRH-induced elevation of pain threshold is provided by two components: 1) depending on the HPAS hormones after central and systemic injection of CHR; 2) not depending on the HPAS hormones after systemic injection of CHR.     

Effect of pentoxifylline on endothelaemia and hypothalamic-pituitary-adrenocortical axis activation in female rats under stress exposure

Endothelial dysfunction may belong to negative consequences of stress exposure accompanied by activation of several stress systems including the hypothalamic-pituitary-adrenocortical (HPA) axis. The present experiments were aimed at testing the hypotheses that i) immobilization (IMO) stress results in sustained increase in endothelaemia for 24 h and that ii) pentoxifylline, a drug with endothelium protective properties, attenuates the rise in endothelaemia and HPA axis activation in female rats as shown previously in males. Circulating endothelial cells increased immediately after the IMO for 2 h, returned back to control levels at 12 h and increased again at 24 h. Stress-induced rise in adrenocorticotropic hormone (ACTH) and corticosterone levels was particularly high immediately after the IMO. Pretreatment with pentoxifylline (20 mg/kg subcutaneously for 7 days) attenuated the rise in endothelaemia and adrenal corticosterone measured at 24 h following IMO. Plasma levels of ACTH and proopiomelanocortin gene expression in the anterior pituitary were not affected by pentoxifylline treatment. The present results indicate that IMO stress in female rats induces a biphasic rise in endothelaemia early at the time of stress exposure and than 24 h thereafter. Based on these data and our previous study we can conclude that intensive stress has a negative influence on endothelial cells in both sexes and no gender differences seem to be present in the protective action of pentoxifylline.     

Phases of the initial reaction of the sympatho-adrenal system to stress

Changes in the content and ratio of catecholamines, their precursors and metabolites in canine blood and tissues during the initial period of stress have been studied. A sharp increase in tissue adrenaline (A) and dopamine (DA) and a decrease in tissue noradrenaline (NA); decline in blood A and rise in blood NA; inhibition of monoamine oxidase activity and a fall in metanephrine and normetanephrine blood and tissue level have been demonstrated in the first phase of reaction developing right after exposure to stress. A sharp synchronous rise in A, NA and DA and a parallel increase in their metabolic intensity towards oxidative deamination and O-methylation have been found in the second phase of reaction that develops in 60 sec. The first phase of the reaction has been designated as dissociation phase of sympathoadrenal secretory synthetic activity, and the second phase was termed the phase of synchronous system activation.     

Glycine: An important potential component of spinal shock

Amino acid neurotransmitters (AANTs) play a major role in maintenance of muscle tone. Abnormal AANT concentrations are associated with hyper- or hypotonic states. Flaccidity from spinal shock commonly occurs after spinal cord injury (SCI) and may be associated with changes in AANT concentrations. Ischemic SCIs created in the lumbar region of rabbits by intraaortic balloon occlusion produced spastic or flaccid injuries. Microdialysis sampling of AANTs from the injured segmental structures was done 3 days after SCI. Evoked potentials were used to monitor spinal cord stability. No significant changes in AANT levels occurred in the spastic or flaccid group after 4 hour sampling. However, flaccid animals had baseline glycine levels 2–3 times higher (p<0.001) than spastic animals or controls. High concentrations of the inhibitory AANT glycine is associated with flaccidity following SCI, or spinal shock, but not spasticity. Glycinergic compounds directed toward suppression of excess muscle tone deserve further study.