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1.
Background
The hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic adrenomedullary (SAM) system are the major stress-response pathways. Plasma adrenocorticotropic hormone (ACTH) represents HPA axis activity, while plasma catecholamines are used as markers of the SAM system. Salivary alpha amylase (AA), chromogranin A (CgA), and immunoglobulin A (IgA) are candidate markers of stress activation, although their role has not been established. The Uchida-Kraepelin (U-K) test is a questionnaire that requires intense concentration and effort, and has been used as a tool to induce mental stress. However, it is not clear whether or not the test is effective as a psychological/mental stressor. 相似文献2.
James P. Herman 《Cellular and molecular neurobiology》2018,38(1):25-35
Hindbrain neurons in the nucleus of the solitary tract (NTS) are critical for regulation of hypothalamo-pituitary-adrenocortical (HPA) responses to stress. It is well known that noradrenergic (as well as adrenergic) neurons in the NTS send direct projections to hypophysiotropic corticotropin-releasing hormone (CRH) neurons and control activation of HPA axis responses to acute systemic (but not psychogenic) stressors. Norepinephrine (NE) signaling via alpha1 receptors is primarily excitatory, working either directly on CRH neurons or through presynaptic activation of glutamate release. However, there is also evidence for NE inhibition of CRH neurons (possibly via beta receptors), an effect that may occur at higher levels of stimulation, suggesting that NE effects on the HPA axis may be context-dependent. Lesions of ascending NE inputs to the paraventricular nucleus attenuate stress-induced ACTH but not corticosterone release after chronic stress, indicating reduction in central HPA drive and increased adrenal sensitivity. Non-catecholaminergic NTS glucagon-like peptide 1/glutamate neurons play a broader role in stress regulation, being important in HPA activation to both systemic and psychogenic stressors as well as HPA axis sensitization under conditions of chronic stress. Overall, the data highlight the importance of the NTS as a key regulatory node for coordination of acute and chronic stress. 相似文献
3.
N. A. Prokopenko 《Neurophysiology》2012,43(6):487-493
We studied peculiarities of the autonomic reactions related to emotional experiences in persons with different characteristics
of their individuality. To model emotional states, tested subjects were proposed to mentally reproduce situations evoking
a sense of joy (positive emotions) and a feeling of grief (negative emotions). During such emotional tests, cardiointervalographic
(CIG) indices of the subjects were examined. The following properties of the individuality were taken into account: (i) extraversion/introversion
as the temperament parameter, (ii) externality/internality as a characteristic of the locus of psychological self-control,
and (iii) extrapunitivity/intropunitivity as a characterological feature manifested in frustration situations. Sympathico-parasympathic
influences were more powerful than central influences in regulation of the cardiorhythm in tested subjects with clearly “externally
directed” reactions to emotiogenic factors (extraverts, externals, and persons with an extrapunitive type of reaction). Vice versa, shifts of the autonomic balance toward activation of the sympathoadrenal link, relatively low efficacy of baroreflex regulation,
and strain of regulatory systems of the organism were observed at a high level of introversion in examined persons. Physiological
adaptation to the action of the various stressors, including the emotional ones, is realized mostly by the system cerebral
cortex – hypothalamus – hypophysis – adrenal cortex. In turn, the release of adrenalin by adrenal glands activates the reticular
formation and, via this structure, the hypothalamus and cerebral limbic system. Thus, it can be supposed that extraverts are
characterized by higher thresholds of the emotional sensitivity, which correspond to a higher threshold of activation of the
reticular formation and more intense inhibitory cortical influences upon subcortical formations. This is why extraverts manifest
weaker, in general, activation of the regulatory mechanisms of the cardiovascular system after the influence of extero- and
interoceptive stimuli, while in introverts such activation is more intense. 相似文献
4.
Melissa A. Whidden Nataliya Kirichenko Zekai Halici Benedek Erdos Thomas C. Foster Nihal Tümer 《Biochemical and biophysical research communications》2011,408(3):H1205
Aging is associated with oxidative damage and an imbalance in redox signaling in a variety of tissues, yet little is known about the extent of age-induced oxidative stress in the sympathoadrenal system. Lifelong caloric restriction has been shown to lower levels of oxidative stress and slow the aging process. Therefore, the aims of this study were twofold: (1) to investigate the effect of aging on oxidative stress in the adrenal medulla and hypothalamus and (2) determine if lifelong 40% caloric restriction (CR) reverses the adverse effects of age-induced oxidative stress in the sympathetic adrenomedullary system. Adult (18 months) and very old (38 months) male Fischer 344 x Brown Norway rats were divided into ad libitum or 40% CR groups and parameters of oxidative stress were analyzed in the adrenal medulla and the hypothalamus. A significant age-dependent increase in lipid peroxidation (+20%, P < 0.05) and tyrosine nitration (+111%, P < 0.001) were observed in the adrenal medulla while age resulted in a reduction in the protein expression of key antioxidant enzymes, CuZnSOD (−27%, P < 0.01) and catalase (−27%, P < 0.05) in the hypothalamus. Lifelong CR completely prevented the age-induced increase in lipid peroxidation in the adrenal medulla and restored the age-related decline in antioxidant enzymes in the hypothalamus. These data indicate that aging results in a significant increase in oxidative stress in the sympathoadrenal system. Importantly, lifelong CR restored the age-related changes in oxidative stress in the adrenal medulla and hypothalamus. Caloric restriction could be a potential non-pharmacological intervention to prevent increased oxidative stress in the sympathetic adrenomedullary system with age. 相似文献
5.
Arline T. Geronimus Margaret T. Hicken Jay A. Pearson Sarah J. Seashols Kelly L. Brown Tracey Dawson Cruz 《Human nature (Hawthorne, N.Y.)》2010,21(1):19-38
We hypothesize that black women experience accelerated biological aging in response to repeated or prolonged adaptation to
subjective and objective stressors. Drawing on stress physiology and ethnographic, social science, and public health literature,
we lay out the rationale for this hypothesis. We also perform a first population-based test of its plausibility, focusing
on telomere length, a biomeasure of aging that may be shortened by stressors. Analyzing data from the Study of Women’s Health
Across the Nation (SWAN), we estimate that at ages 49–55, black women are 7.5 years biologically “older” than white women.
Indicators of perceived stress and poverty account for 27% of this difference. Data limitations preclude assessing objective
stressors and also result in imprecise estimates, limiting our ability to draw firm inferences. Further investigation of black-white
differences in telomere length using large-population-based samples of broad age range and with detailed measures of environmental
stressors is merited. 相似文献
6.
Fibromyalgia syndrome (FMS) is a prevalent musculoskeletal pain disorder characterized by diffuse pain and associated psychophysiological symptoms. Despite extensive research in the past 3 decades, the etiology and pathophysiology of FMS and effective treatment approaches are yet to be delineated. Recently, it has been suggested that FMS may be related to hypofunctional stress systems, particularly in the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis. Studies have demonstrated that patients with FMS exhibit lowered sympathoadrenal reactivity to stress. These findings seem to be consistent with the large volume of research indicating the inverse relationship between pain sensitivity and sympathetic reactivity. In this paper, we discuss the role of stress in the pain experience in general, stress in patients with FMS, and review the studies evaluating the ANS and HPA functions in response to various stressors. 相似文献
7.
8.
Pacák K 《Physiological research / Academia Scientiarum Bohemoslovaca》2000,49(Z1):S11-S17
New information has accrued from in vivo microdialysis studies about stress-related changes in norepinephrine concentrations in extracellular fluid of the paraventricular nucleus (PVN) and the activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Our data on the effects of lower brainstem hemisections show that paraventricular noradrenergic terminals are derived mainly from medullary A1 and A2 catecholaminergic cells. The activation of these cells contributes importantly to stress-induced noradrenergic activation in the paraventricular nucleus of conscious animals. The results from brainstem hemisection experiments also indicate that baseline levels and immobilization-induced increments in corticotropin-releasing hormone (CRH) mRNA expression in the PVN depend on ipsilaterally ascending medullary tract. Thus, the prevalent concept that stress-induced noradrenergic activation of the HPA axis depends mainly on activation of locus ceruleus noradrenergic neurons requires re-evaluation. Our new stress concepts favor stressor-specific activation of the HPA axis. The present data also suggest the existence of stressor-specific central pathways that differentially participate in the regulation of sympathoneuronal and adrenomedullary outflows as well as of the activity of the HPA axis. Furthermore, the results are inconsistent with a founding tenet of Selye's stress theory, the doctrine of nonspecificity, which defines stress as the nonspecific response of the body to any demand. We expect that future studies in this area will focus on further examination of the notion of stressor-specific patterns of central neurotransmitter release and elucidate the genetic bases of these patterns. 相似文献
9.
DeRosa MA Cryer PE 《American journal of physiology. Endocrinology and metabolism》2004,287(1):E32-E41
The relative contributions of the sympathetic nervous system and the adrenal medullae, the two components of the sympathoadrenal system, to the manifestations of hypoglycemia are largely unknown. We tested the hypothesis that the neurogenic symptoms of hypoglycemia are largely the result of sympathetic neural activation. To do so, we quantitated neurogenic symptoms, as well as norepinephrine (NE) kinetics and selected hemodynamic changes, during hyperinsulinemic euglycemic and stepped hypoglycemic clamps in 15 healthy control subjects (Controls) and four bilaterally adrenalectomized patients (ADX). Plasma epinephrine responses to hypoglycemia were virtually absent in ADX, as expected. Neurogenic symptom scores increased to higher values during the hypoglycemic compared with the euglycemic clamps in both Controls (P < 0.0001) (e.g., final scores of 7.8 +/- 1.2 vs. 3.0 +/- 0.7) and ADX (P < 0.0001) (e.g., final scores of 10.8 +/- 4.1 vs. 2.5 +/- 1.0). Plasma NE concentrations (P < 0.0001) and systemic NE spillover (P = 0.0007) increased during the hypoglycemic compared with the euglycemic clamps in Controls but not in ADX. Similarly, heart rate increased (P = 0.0104), diastolic blood pressure decreased (P = 0.0003), and forearm blood flow increased (P < 0.0001) during the hypoglycemic compared with the euglycemic clamps in Controls but not in ADX. These data indicate that the neurogenic symptoms of hypoglycemia are largely the result of sympathetic neural, rather than adrenomedullary, activation. They also suggest that the plasma NE and hemodynamic responses to hypoglycemia are largely the result of adrenomedullary, rather that sympathetic neural, activation. 相似文献
10.
Cells constituting the sympathoadrenal (SA) cell lineage originate from the neural crest and acquire a catecholaminergic fate
following migration to the dorsal aorta. Subsequently, SA cells migrate to sites widely dispersed throughout the body. In
addition to endocrine chromaffin and ”small intensely fluorescent” cells in adrenal glands and in extra-adrenal tissues such
as the paraganglia, this lineage also includes neurones located in sympathetic ganglia and in the adrenal gland. It is widely
assumed that these cells are all derived from the same precursors, which then differentiate along divergent pathways in response
to different external stimuli. During embryonic differentiation, SA cells lose some of their early traits and acquire other
distinguishing features. To help understand how the lineage diverges in terms of phenotype and function, this article examines
the cellular expression of a variety of ”marker” proteins that characterize the individuals of the lineage. In particular,
differences between adrenal medullary adrenergic and noradrenergic chromaffin cells in the expression of proteins, such as
the neural adhesion molecule L1, the growth-associated protein GAP-43 and molecules involved in the secretory process, are
emphasized. Factors that might differentially regulate such molecular markers in these cells are discussed.
Received: 29 December 1998 / Accepted: 1 April 1999 相似文献
11.
Keith Johnson 《Journal of biological physics》2012,38(1):85-95
Water nanoclusters are shown from first-principles calculations to possess unique terahertz-frequency vibrational modes in
the 1–6 THz range, corresponding to O–O–O “bending,” “squashing,” and “twisting” “surface” distortions of the clusters. The
cluster molecular-orbital LUMOs are huge Rydberg-like “S,” “P,” “D,” and “F” orbitals that accept an extra electron via optical
excitation, ionization, or electron donation from interacting biomolecules. Dynamic Jahn–Teller coupling of these “hydrated-electron”
orbitals to the THz vibrations promotes such water clusters as vibronically active “structured water” essential to biomolecular
function such as protein folding. In biological microtubules, confined water-cluster THz vibrations may induce their “quantum
coherence” communicated by Jahn–Teller phonons via coupling of the THz electromagnetic field to the water clusters’ large
electric dipole moments. 相似文献
12.
We studied monosynaptic reflex discharges (MRD) recorded from the ventral roots (VR) of rats subjected to systemic administration
with thyroliberin, thyroxin, or 4-aminopyridine (4-AP). Under such conditions, in some of the experiments the MRD amplitude
reached values sufficient to excite non-active VR fibers. In these cases, immediately after the MRD peak had been reached,
abnormally increased responses (AIR) developed, whose amplitude was 2–2.5 times higher than the amplitude of highly facilitated
MRD. Proofs are presented that AIR reflect excitation of “neighboring” VR fibers, which were not involved in the reflex response,
and MRD plays the role of a “stimulus” exciting these fibers. Therefore, we demonstrate the possibility of transmission of
excitation from “active” to “silent” fibers within a nerve trunk under conditions of the development of “superreflexia”. This
state can be considered a model of excitation spreading via a non-synaptic pathway under conditions of hyperexcitability of
the CNS structures, in seizure states in particular.
neirofiziologiya/Neurophysiology, Vol. 32, No. 2, pp. 120–127, March–April, 2000. 相似文献
13.
Dynamin and Myosin Regulate Differential Exocytosis from Mouse Adrenal Chromaffin Cells 总被引:1,自引:0,他引:1
Neuroendocrine chromaffin cells of the adrenal medulla represent a primary output for the sympathetic nervous system. Chromaffin
cells release catecholamine as well as vaso- and neuro-active peptide transmitters into the circulation through exocytic fusion
of large dense-core secretory granules. Under basal sympathetic activity, chromaffin cells selectively release modest levels
of catecholamines, helping to set the “rest and digest” status of energy storage. Under stress activation, elevated sympathetic
firing leads to increased catecholamine as well as peptide transmitter release to set the “fight or flight” status of energy
expenditure. While the mechanism for catecholamine release has been widely investigated, relatively little is known of how
peptide transmitter release is regulated to occur selectively under elevated stimulation. Recent studies have shown selective
catecholamine release under basal stimulation is accomplished through a transient, restricted exocytic fusion pore between
granule and plasma membrane, releasing a soluble fraction of the small, diffusible molecules. Elevated cell firing leads to
the active dilation of the fusion pore, leading to the release of both catecholamine and the less diffusible peptide transmitters.
Here we propose a molecular mechanism regulating the activity-dependent dilation of the fusion pore. We review the immediate
literature and provide new data to formulate a working mechanistic hypothesis whereby calcium-mediated dephosphorylation of
dynamin I at Ser-774 leads to the recruitment of the molecular motor myosin II to actively dilate the fusion pore to facilitate
release of peptide transmitters. Thus, activity-dependent dephosphorylation of dynamin is hypothesized to represent a key
molecular step in the sympatho-adrenal stress response. 相似文献
14.
Inventory, differentiation, and proportional diversity: a consistent terminology for quantifying species diversity 总被引:1,自引:0,他引:1
Almost half a century after Whittaker (Ecol Monogr 30:279–338, 1960) proposed his influential diversity concept, it is time
for a critical reappraisal. Although the terms alpha, beta and gamma diversity introduced by Whittaker have become general textbook knowledge, the concept suffers from several drawbacks. First, alpha
and gamma diversity share the same characteristics and are differentiated only by the scale at which they are applied. However,
as scale is relative––depending on the organism(s) or ecosystems investigated––this is not a meaningful ecological criterion.
Alpha and gamma diversity can instead be grouped together under the term “inventory diversity.” Out of the three levels proposed
by Whittaker, beta diversity is the one which receives the most contradictory comments regarding its usefulness (“key concept”
vs. “abstruse concept”). Obviously beta diversity means different things to different people. Apart from the large variety
of methods used to investigate it, the main reason for this may be different underlying data characteristics. A literature
review reveals that the multitude of measures used to assess beta diversity can be sorted into two conceptually different
groups. The first group directly takes species distinction into account and compares the similarity of sites (similarity indices,
slope of the distance decay relationship, length of the ordination axis, and sum of squares of a species matrix). The second
group relates species richness (or other summary diversity measures) of two (or more) different scales to each other (additive
and multiplicative partitioning). Due to that important distinction, we suggest that beta diversity should be split into two
levels, “differentiation diversity” (first group) and “proportional diversity” (second group). Thus, we propose to use the
terms “inventory diversity” for within-sample diversity, “differentiation diversity” for compositional similarity between
samples, and “proportional diversity” for the comparison of inventory diversity across spatial and temporal scales.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Anya Plutynski 《Biology & philosophy》2008,23(3):363-381
There have been two different schools of thought on the evolution of dominance. On the one hand, followers of Wright [Wright
S. 1929. Am. Nat. 63: 274–279, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; 1934. Am.
Nat. 68: 25–53, Evolution: Selected Papers by Sewall Wright, University of Chicago Press, Chicago; Haldane J.B.S. 1930. Am.
Nat. 64: 87–90; 1939. J. Genet. 37: 365–374; Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have defended the view that
dominance is a product of non-linearities in gene expression. On the other hand, followers of Fisher [Fisher R.A. 1928a. Am.
Nat. 62: 15–126; 1928b. Am. Nat. 62: 571–574; Bürger R. 1983a. Math. Biosci. 67: 125–143; 1983b. J. Math. Biol. 16: 269–280;
Wagner G. and Burger R. 1985. J. Theor. Biol. 113: 475–500; Mayo O. and Reinhard B. 1997. Biol. Rev. 72: 97–110] have argued
that dominance evolved via selection on modifier genes. Some have called these “physiological” versus “selectionist,” or more
recently [Falk R. 2001. Biol. Philos. 16: 285–323], “functional,” versus “structural” explanations of dominance. This paper
argues, however, that one need not treat these explanations as exclusive. While one can disagree about the most likely evolutionary
explanation of dominance, as Wright and Fisher did, offering a “physiological” or developmental explanation of dominance does
not render dominance “epiphenomenal,” nor show that evolutionary considerations are irrelevant to the maintenance of dominance,
as some [Kacser H. and Burns J.A. 1981. Genetics 97: 639–666] have argued. Recent work [Gilchrist M.A. and Nijhout H.F. 2001.
Genetics 159: 423–432] illustrates how biological explanation is a multi-level task, requiring both a “top-down” approach
to understanding how a pattern of inheritance or trait might be maintained in populations, as well as “bottom-up” modeling
of the dynamics of gene expression. 相似文献
16.
E. M. McLachlan 《Neurophysiology》2007,39(4-5):251-258
The discharge of vasoconstrictor pathways arising in the CNS is largely unmodified as it passes through the sympathetic ganglia
to the vasculature. The underlying synaptic events have been revealed by intracellular recordings from sympathetic paravertebral
ganglion cells in the course of ongoing and reflex activity in anesthetized animals, first made in Skok’s Laboratory in Kyiv
(Ukraine). Each preganglionic neuron diverges to contact a number of post-ganglionic neurons, on each of which several pre-ganglionic
inputs converge. However, only suprathreshold “strong,” or “dominant” synapses are effective in transmitting the CNS signals.
Strong synapses differ from the other subthreshold “weak,” or “accessory” inputs: (a) excitatory synaptic currents are >1
nA in their amplitude, (b) 3 to ≈>30 times more quanta of acetylcholine are released, (c) pre-synaptic Ca2+ entry through channels resistant to all-known antagonists triggers acetylcholine release, and (d) post-synaptic Ca2+ entry boosts and prolongs the nicotinic current. While the majority of postganglionic neurons have only one strong input,
a proportion receives two or, rarely, three such inputs. In cells with multiple strong inputs, an equivalent number of discrete
Ca2+ currents can be evoked at distinct foci electrically distant from the soma, suggesting that each strong input has a unique
dendritic association with a cluster of Ca2+ channels. When strong preganglionic inputs are destroyed, residual weak synapses sprout and rapidly restore the suprathreshold
connections. While much remains to be discovered about how strong synapses are established, their high safety factor ensures
the wide and secure distribution of vasoconstrictor command signals from the CNS.
Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 294–301, July–October, 2007. 相似文献
17.
Y Maruyama A Kawano S Okamoto T Ando Y Ishitobi Y Tanaka A Inoue J Imanaga M Kanehisa H Higuma T Ninomiya J Tsuru H Hanada J Akiyoshi 《PloS one》2012,7(7):e39375
Background
Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.Principal Findings
We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.Conclusions
These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors. 相似文献18.
Psychosocial stress plays a major role in the etiology and the course of mental disorders that often show an altered activation
of the hypothalamus–pituitary–adrenal (HPA) axis. The Trier Social Stress Test (TSST) reliably activates the HPA axis and
reflects real life stress exposure. However, habituation may confound the results of clinical trials that apply TSST. The
present study investigates the cortisol response after repeated psychosocial stress induction with short-term and long-term
intervals between repeated testing sessions. Forty-one healthy subjects were exposed to the TSST four times with an interval
of 24 h between the first and the second testing session (t1 and t2). The 3rd and the 4th testing session (t3 and t4) were
also separated by a 24-hour interval whereas there were 10 weeks between t2 and t3. A significant decrease in the salivary
cortisol responses was noticed from testing session t1 to t2 as well as from testing session t3 to t4. By contrast, there
were no differences in the HPA axis reactivity between testing session t2 and t3. Our results demonstrated the habituation
of the HPA axis to a standardized psychosocial stress test when testing was repeated after 24 h. By contrast, a renewed challenge
with a ten-week-interval in-between activated the HPA axis in a similar manner as before. It is suggested that studies designed
to investigate the HPA axis activity under repeated psychosocial stress conditions should apply the TSST three times in order
to separate habituation from intervention effects. 相似文献
19.
On the occasion of the first international workshop on systems radiation biology we review the role of cell renewal systems
in maintaining the integrity of the mammalian organism after irradiation. First, 11 radiation emergencies characterized by
chronic or protracted exposure of the human beings to ionizing irradiation were “revisited”. The data provide evidence to
suggest that at a daily exposure of about 10–100 mSv, humans are capable of coping with the excess cell loss for weeks or
even many months without hematopoietic organ failure. Below 10 mSv/day, the organisms show some cellular or subcellular indicators
of response. At dose rates above 100 mSv/day, a progressive shortening of the life span of the irradiated organism is observed.
To elucidate the mechanisms relevant to tolerance or failure, the Megakaryocyte–thrombocyte cell renewal system was investigated.
A biomathematical model of this system was developed to simulate the development of thrombocyte concentration as a function
of time after onset of chronic radiation exposure. The hematological data were taken from experimental chronic irradiation
studies with dogs at the Argonne National Laboratory, USA. The results of thrombocyte response patterns are compatible with
the notion of an “excess cell loss” (compared to the steady-state) in all proliferative cell compartments, including the stem
cell pool. The “excess cell loss” is a function of the daily irradiation dose rate. Once the stem cell pool is approaching
an exhaustion level, a “turbulence region” is reached. Then it takes a very little additional stress for the system to fail.
We conclude that in mammalian radiation biology (including radiation medicine), it is important to understand the physiology
and pathophysiology of cell renewal systems in order to allow predicting the development of radiation induced lesions. 相似文献
20.
下丘脑-垂体-肾上腺皮质轴应激反应的中枢控制 总被引:53,自引:0,他引:53
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 相似文献