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Hafez D Huang JY Huynh AM Valtierra S Rockenstein E Bruno AM Lu B DesGroseillers L Masliah E Marr RA 《The American journal of pathology》2011,178(1):306-312
Proteases that degrade the amyloid-β peptide (Aβ) are important in protecting against Alzheimer's disease (AD), and understanding these proteases is critical to understanding AD pathology. Endopeptidases sensitive to inhibition by thiorphan and phosphoramidon are especially important, because these inhibitors induce dramatic Aβ accumulation (~30- to 50-fold) and pathological deposition in rodents. The Aβ-degrading enzyme neprilysin (NEP) is the best known target of these inhibitors. However, genetic ablation of NEP results in only modest increases (~1.5- to 2-fold) in Aβ, indicating that other thiorphan/phosphoramidon-sensitive endopeptidases are at work. Of particular interest is the NEP homolog neprilysin 2 (NEP2), which is thiorphan/phosphoramidon-sensitive and degrades Aβ. We investigated the role of NEP2 in Aβ degradation in vivo through the use of gene knockout and transgenic mice. Mice deficient for the NEP2 gene showed significant elevations in total Aβ species in the hippocampus and brainstem/diencephalon (~1.5-fold). Increases in Aβ accumulation were more dramatic in NEP2 knockout mice crossbred with APP transgenic mice. In NEP/NEP2 double-knockout mice, Aβ levels were marginally increased (~1.5- to 2-fold), compared with NEP(-/-)/NEP2(+/+) controls. Treatment of these double-knockout mice with phosphoramidon resulted in elevations of Aβ, suggesting that yet other NEP-like Aβ-degrading endopeptidases are contributing to Aβ catabolism. 相似文献
3.
Neutral endopeptidase modulates tachykinin-induced increase in vascular permeability in guinea pig skin 总被引:4,自引:0,他引:4
I Iwamoto I F Ueki D B Borson J A Nadel 《International archives of allergy and applied immunology》1989,88(3):288-293
To determine the regulatory role of neutral endopeptidase (NEP) in the tachykinin-induced increase in vascular permeability, we examined the effects of NEP inhibitors and of other protease inhibitors on plasma extravasation induced by intradermal injection of substance P, neurokinin A, and neurokinin B in guinea pig skin. The three tachykinins induced plasma extravasation in concentration-dependent fashions. A significant NEP activity was found to be present in the guinea pig skin. The tachykinin-induced responses were increased by the NEP inhibitors phosphoramidon and thiorphan. However, other protease inhibitors, including a kininase II inhibitor, did not affect the response. We conclude that NEP modulates the tachykinin-induced increase in vascular permeability in the skin. 相似文献
4.
Newborn rats euthanized 24 h after birth were examined. The rats were born to females exposed to chronic hypobaric hypoxia
on days 14–19 of gestation. The index of nuclei labeled with3H-thymidine in the tracheal epithelium of newborn rats exposed to prenatal hypoxia was 3 times lower than in the control.
The LPO level was higher in posthypoxic animals than in intact rats. Prenatal hypoxia led to the suppression of antioxidant
defense in the lungs of newborn rats.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N
o
5, pp. 531–533, May, 1994 相似文献
5.
Yong-Di Zhou Joaquín M. Fuster 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1997,116(3):551-555
Studies have shown that in the monkey′s associative cerebral cortex, cells undergo sustained activation of discharge while
the animal retains information for a subsequent action. Recent work has revealed the presence of such ″memory cells″ in the
anterior parietal cortex (Brodmann′s areas 3a, 3b, 1, and 2) – the early stage of the cortical somatosensory system. Here
we inferred that, in a cross-modal visuo-haptic short-term memory task, somatosensory cells would react to visual stimuli
associated with tactile features. Single-unit discharge was recorded from the anterior parietal cortex – including areas of
hand representation – of monkeys performing a visuo-haptic delayed matching-to-sample task. Units changed firing frequency
during the presentation of a visual cue that the animal had to remember for making a correct tactile choice between two objects
at the end of a delay (retention period). Some units showed sustained activation during the delay. In some of them that activation
differed depending on the cue. These findings suggest that units in somatosensory cortex react to visual stimuli behaviorally
associated with tactile information. Further, the results suggest that some of these neurons are involved in short-term active
memory and may, therefore, be part of cross-modal memory networks.
Received: 24 March 1997 / Accepted: 8 May 1997 相似文献
6.
The number of neurons was counted in different functional neuronal complexes of the sensorimotor cortex in albino rats in
the control and at different times after clinical death caused by asphyxia. A decrease of the number of neurons from 2.5×106 in the control to 1.56×106 toward the 30th day of the postresuscitation period was found in the sensorimotor cortex. The complexes of small neurons
in the upper floor (layers II–IV) suffer badly, while the neurons of layer VI are damaged to a somewhat lesser degree and
the cells of layer V are minimally altered.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N
o
3, pp. 331–333, March, 1995
Presented by L. V. Poluektov, Member of the Russian Academy of Medical Sciences 相似文献
7.
K. N. Dudkin V. K. Kruchinin I. V. Chueva 《Neuroscience and behavioral physiology》1997,27(2):153-158
The effect of intracortical perfusion with the glutamate agonist NMDA on visual recognition and short-term memory, as well
as on the responses of visual cortex neurons, were studied in rhesus macaques. A microdialysis technique was used in combination
with multichannel microelectrode recording of single cortical cells in the immediate vicinity of the dialysis tube in a behavioral
experiment in which the monkey had to solve a task involving delayed visual differentiation of stimuli of different colors.
NMDA altered the characteristics of recognition in monkeys. The duration of information storage in short-term memory was increased
significantly (2–4-fold), and there was a significant reduction in the motor response time for all delay periods. These changes
were accompanied by a significant rearrangement of neuron activity in the visual cortex at all stages of the behavioral task.
At different stages of the task, 70–85% of the neurons showed 2–5-fold increases in activity, while 6–20% showed reductions
in activity. These results demonstrate an involvement of visual cortex glutaminergic structures in the processes of visual
recognition and short-term memory, as well as a nootropic effect obtained by intracortical administration of NMDA.
Laboratory for the Regulation of Brain Neuron Function (Director M. O. Samoilov), I. P. Pavlov Institute of Physiology, Russian
Academy of Sciences, St. Petersburg. Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 81, No. 5, pp. 23–30,
May, 1995. 相似文献
8.
N. N. Karamysheva 《Neuroscience and behavioral physiology》2012,42(4):347-352
In the sensorimotor cortex of rabbits with a formed cryptic (subthreshold) focus of excitation in the CNS, the spike frequencies
of neurons responding to light stimulation were significantly lower (p = 0.01) than the spike frequencies of neurons not responding to light. Similar findings were obtained in the visual cortex
of intact rabbits. In this case too, the spike frequencies of neurons responding to stimulation were significantly lower (p = 0.01) than the spike frequencies of neurons not responding to light stimulation. In both intact rabbits and rabbits with
a cryptic focus of excitation formed in the CNS, 36 % of neurons in the sensorimotor cortex responded to light stimuli not
specific to this area. In the sensorimotor cortex of rabbits with a cryptic focus of excitation formed in the CNS, as compared
with intact rabbits, there were significantly more (p = 0.01) cells responding to light stimuli with latent periods of less than 100 msec and significantly fewer (p = 0.02) responding to light stimuli with latencies of 200–300 msec. In the visual cortex of rabbits with a formed cryptic
focus of excitation in the CNS, as compared with intact rabbits, significantly fewer (p = 0.01) neurons responded to light stimuli with latent periods of 50–100 msec. 相似文献
9.
Tyul'kova EI Semenov DG Vataeva LA Belyakov AV Samoilov MO 《Bulletin of experimental biology and medicine》2011,151(3):275-277
Ca2+-mediated signal transduction of group I metabotropic glutamate receptors (ImGluR) was studied in the brain of young (15 days)
and old rats (90 days) exposed to severe hypobaric hypoxia on gestation days 14–16. Changes in the concentration of bound
intracellular Ca2+ (Ca2+ response) were evaluated after repeated application of a selective ImGluR agonist 3,5-dihydroxyphenylglycine (DHPG) to cultured
brain slices. Primary application of DHPG for 2 min induced a negative Ca2+ response in slices from 15-day-old intact animals, while repeated application caused a positive response. In slices from
90-day-old control animals, both responses were negative. In slices from rats of both age groups subjected to severe prenatal
hypobaric hypoxia, both responses were mainly positive, but short-term negative components were present in adult animals.
Our results suggest that severe hypobaric hypoxia changes the balance between the two constitutive signal pathways triggered
by ImGluR (inosine triphosphate and diacylglycerol pathways). This procedure is followed by the increased influx of extracellular
Ca2+ (as compared to Ca2+ release from the intracellular stores). This imbalance is particularly pronounced at the early stage of ontogeny. 相似文献
10.
We sought to confirm the identity of the tachykinin receptor subtype that mediates plasma extravasation in the rat trachea, and assess the respective contributions of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) in regulating this tachykinin-induced response. To achieve these aims, we determined the relative potencies of several natural tachykinins and receptor-selective synthetic agonists, both before and after inhibiting NEP with phosphoramidon and ACE with captopril. We also determined the effects of these peptidase inhibitors, and the NK-1 receptor antagonist L-703,606, on the plasma extravasation produced by capsaicin, which releases tachykinins endogenously from sensory nerve endings. We found that the rank order of potency for producing plasma extravasation in the rat trachea was NK-1 receptor agonist ([Sar9, Met(O2)11] SP)>substance P>neurokinin A> neurokinin B. The NK-2 ([Nle10]NKA (4–10)) and NK-3 ([MePhe7]NKB) receptor agonists were without effect. We observed no change in the relative potencies of these peptides after giving rats phosphoramidon or captopril, which suggests that the different peptide potencies are not simply the consequence of different rates of enzymatic degradation. Nevertheless, the responses to substance P and neurokinin A were clearly potentiated in rats given phosphoramidon, indicating that NEP effectively degrades tachykininsin vivo. No significant potentiation was evident for any peptide in rats given captopril. Similarly, the plasma extravasation produced by capsaicin was potentiated in rats given phosphoramidon, but not in those given captopril. Pretreating rats with L-703,606 abolished the response to capsaicin. We conclude from these observations that NK-1 receptors mediate tachykinin-induced plasma extravasation in the rat trachea, and that NEP regulates this response with little or no contribution from ACE. 相似文献
11.
E. B. Manukhina M. G. Pshennikova A. V. Goryacheva I. P. Khomenko S. Yu. Mashina D. A. Pokidyshev I. Yu. Malyshev 《Bulletin of experimental biology and medicine》2008,146(4):391-395
NO synthesis disturbances play an important role in the development of neurodegenerative damage in Alzheimer disease. We previously
showed that adaptation to intermittent hypobaric hypoxia prevents cognitive disturbances in rats with experimental Alzheimer
disease [6]. Here we evaluated the role of NO in cognitive disorders and development of adaptive protection during experimental Alzheimer
disease. Adaptation to hypoxia in rats was performed in a hypobaric pressure chamber at a simulated altitude of 4000 m (4 h
per day for 14 days). Alzheimer disease was simulated by bilateral injections of a toxic fragment of β-amyloid (25–35) into
n. basalis magnocellularis. For evaluation of the role of NO in the development and prevention of memory disorders, the rats received intraperitoneally
either NO-synthase inhibitor Nω-nitro-L-arginin (L-NNA, 20 mg/kg, every other day for 14 days) or NO-donor dinitrosyl iron complex (200 μg/kg daily for 14
days). NO-synthase inhibitor potentiated the damaging effect of β-amyloid, abolished the protective effect of adaptation to
hypoxia, and produced memory disorders in rats similar to those observed during experimental Alzheimer disease. In contrast,
the increase in NO level in the body provided by injections of the NO-donor produced a protective effect against memory disorders
caused by β-amyloid similar to that induced by adaptation to hypoxia. We concluded that reduced NO production in the organism
plays an important role in the development of cognitive disorders produced by injections of β-amyloid, while prevention of
NO deficit by administration of NO-donors or nonpharmacological stimulation of NO synthesis can provide a protective effect
in experimental Alzheimer disease.
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 146, No. 10, pp. 371–375, October, 2008 相似文献
12.
We investigated the distribution of neutral endopeptidase (NEP; EC 3.4.24.11) activity, a possible regulatory enzyme for neuropeptide-induced leukocyte activations, in each cell type of human blood leukocytes. The NEP activity assessed by an NEP inhibitor phosphoramidon-sensitive Met5-enkephalin degrading activity was present in neutrophils and the common acute lymphoblastic leukemia antigen (CALLA)-positive leukemic cells (59 pmol/min/10(6) cells and 62 pmol/min/10(6) cells, respectively); however, the NEP activity was virtually absent in lymphocytes, monocytes, eosinophils, basophils, CALLA-negative leukemic cells, or a promyelocytic cell line HL-60. The enzymatic activity was characterized as NEP on the basis of the values of kinetic parameters (Km = 61 microM, Kcat = 1,692 min-1, and Kcat/Km = 28 min-1 microM-1) and the values of IC50 of two NEP inhibitors phosphoramidon and thiorphan (7.4 nM and 8.4 nM, respectively). The distribution of NEP detected immunocytochemically using anti-NEP monoclonal antibodies was also found to be parallel with the distribution of NEP activity among peripheral blood leukocytes. 相似文献
13.
A. V. Sergutina 《Bulletin of experimental biology and medicine》2009,147(1):45-47
Activity of histochemically determined glucose-6-phosphate dehydrogenase, a key enzyme of the pentose phosphate pathway, was
qualitatively determined in layer III and V neurons of the sensorimotor cortex and neurons of the caudate nucleus, nucleus
accumbens, and hippocampus (CA3) in mature male Wistar rats with high and low locomotor activity in an open field. A negative
correlation was revealed between locomotion of Wistar rats in the open field and activity of glucose-6-phosphate dehydrogenase
in the sensorimotor cortex, especially in efferent layer V neurons and neurons of the caudate nucleus and nucleus accumbens,
which attested to different capacity of the brain in Wistar rats with high and low open-field locomotion to regeneration of
phosphopyridine nucleotides (NADP+) and production of pentoses via the pentose phosphate shunt.
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 147, No. 1, pp. 47–49, January, 2009 相似文献
14.
Experimental data were obtained on the nature of rabbit sensorimotor cortex neuron reactions to stimulation of the food motivation
center of the lateral hypothalamus in conditions in which food was or was not presented to the animals combined with microiontophoretic
application of tetragastrin and bradykinin. These neuropeptides were able to alter the relationship between motivation and
reinforcement.
This work was supported by the Neurophysiology Program of the Russian-Indian Agreement on Scientific Cooperation.
P. K. Anokhin Science Research Institute of Normal Physiology, Russian Academy of Medical Sciences. Science Research Center
of Medical Narcology, Ministry of Health of the Russian Federation, Moscow. Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti,
Vol. 45, No. 4, pp. 757–764, July–August, 1995. 相似文献
15.
Graf AV Maklakova AS Krushinskaya YV Sokolova NA 《Bulletin of experimental biology and medicine》2006,142(1):32-34
Physical development, spontaneous behavior, and training capacity were evaluated in adult progeny of albino rats exposed to
acute hypobaric hypoxia on days 9–10 of gestation, corresponding to the early organogenesis period. Prenatal hypoxia caused
delayed behavioral disorders, which were more pronounced in females born from mothers with low resistance to hypoxia. Therapeutic
intranasal administration of Pro-Gly-Pro peptide in a dose of 1 mg/kg to rat pups on days 13–15 of life completely prevented
the negative consequences of acute prenatal hypoxia in adult females and leveled virtually all negative consequences, except
delayed physical development, in males.
__________
Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 7, pp. 38–41, July, 2006 相似文献
16.
N. V. Pasikova Yu. S. Mednikova I. V. Averina 《Neuroscience and behavioral physiology》2011,41(7):696-702
Studies using living slices of guinea pig sensorimotor cortex showed that changes in temperature from 24°C to 37°C produced
stepwise increases in neuron spike frequency at two temperature zones: 27–29°C and 34–36°C. Changes in spontaneous activity
were accompanied by decreases in spike amplitude at t < 27°C and t > 34°C. After cooling to 24°C, spike amplitude generally recovered completely when the temperature was increased to 32–34°C.
The decrease in spike amplitude at t > 35°C could not be restored by decreasing the temperature. It is suggested that these effects are associated with the K+ permeability of neuron membranes. 相似文献
17.
K. N. Dudkin V. K. Kruchinin I. V. Chueva 《Neuroscience and behavioral physiology》1996,26(6):545-551
The effects of modification of NMDA-ergic structures by microdialysis perfusion in the prefrontal cortex (field 8) with NMDA
glutamate (2 mM) on visual recognition and short-term memory (STM) were studied in rhesus macaques, using methods based on
the deferred differentiation of stimuli of different colors. Impulse activity of neurons in the prefrontal and visual cortex
was measured during these experiments, both before and after administration of NMDA. NMDA increased (2-fold) the duration
of short-term retention of information and significantly reduced the latent period of the motor response at all delay periods,
and also produced significant changes in neuron activity in the prefrontal cortex: depending on the stage of behavior, activity
decreased in 60–75% of neurons and increased in 8–26%. NMDA produced significant increases in the cross-correlation coefficients
between the responses of neurons in the visual and prefrontal cortex. The results showed that glutaminergic structures in
the prefrontal cortex are involved in processes of visual recognition and STM in monkeys. The effect of NMDA, which synchronized
cortical neuronal processes, improved the short-term understanding of visual information.
Laboratory for the Regulation of Brain Neuron Function (Director M. O. Samoilov), I. P. Pavlov Institute of Physiology, Russian
Academy of Sciences, St. Petersburg. Translated from Fiziologicheskii Zhurnal im. I. M. Sechenova, Vol. 81, No. 1, pp. 32–39,
January, 1995. 相似文献
18.
J. P. Mortola Daniele Merazzi Lina Naso 《Pflügers Archiv : European journal of physiology》1999,437(2):255-260
Brown adipose tissue (BAT) non-shivering thermogenesis is stimulated by cold temperature and depressed by hypoxia. We investigated
the extent to which changes in metabolic rate during cold and hypoxia, singly or combined, were accompanied by changes in
BAT perfusion. One-month-old rabbits were instrumented for measurements of regional blood flow by the coloured microsphere
technique. One group of rabbits was tested in warm (24 °C, n=17), and the other in cold (13 °C, n=9) conditions, first in normoxia (inspired oxygen concentration FIO2 about 21%, arterial oxygen saturation S
aO2 approximately 88%) followed by hypoxia (FIO2 approximately 10%, S
aO2 approximately 54%). In warm conditions, oxygen consumption (V·O2, measured by an open-flow method) averaged 22 ml·kg–1·min–1 (STPD), and BAT blood flow 98 ml·100g–1·min–1. In hypoxia, V·O2 dropped on average to 87%, whereas BAT flow dropped to 43% of the normoxic values. In the cold during normoxia, V·O2 averaged 31 ml·kg–1·min–1
(STPD), and BAT blood flow was 155 ml·100g–1·min–1. In cold and hypoxia V·O2 dropped to 19 ml·kg–1·min–1 (STPD) (i.e. 60% of the normoxic value), whereas BAT blood flow was not altered significantly (148 ml·100g–1·min–1). Hence, BAT blood flow decreased in hypoxia in absence of cold stimuli, whereas it remained high when hypoxia occurred during
cold, despite the major drop in V·O2. We conclude that cold is more important than hypoxia in determining BAT perfusion, and that changes in BAT blood flow are
not a mechanism for the hypoxic control of V·O2.
Received: 24 June 1998 / Received after revision: 21 September 1998 / Accepted: 29 September 1998 相似文献
19.
T. A. Savina T. G. Shchipakina O. V. Godukhin 《Neuroscience and behavioral physiology》2010,40(9):981-985
Ca2+-calmodulin-dependent protein kinase II (CaMKII) and protein phosphatase 2B (calcineurin) play critical roles in the formation
of nerve cell responses to incoming Ca2+ signals. The studies report here addressed how single seizures might affect the functioning of these enzymes. Sounds (80
dB, 12–15 kHz) induced single convulsions in male Krushinskii–Molodkina rats, which have an inherited predisposition to audiogenic
seizures. Biochemical investigations were performed two days after seizures. Immunoblotting studies with specific monoclonal
antibodies demonstrated increases in the level of the neurospecific α subunit of CaMKII in the sensorimotor cortex and hippocampus
of the rats of the experimental group, as compared with controls. The hippocampus of rats which had had seizures also showed
increases in the catalytic subunit of calcineurin. CaMKII activity in the hippocampus and cortex of postseizure rats increased,
though that of the Ca2+-calmodulin-independent functional form of the enzyme did not change. It is suggested that the long-term changes seen here
may represent an adaptive mechanism induced by convulsive activity and directed to increasing the threshold of neuron excitability
in the brain. 相似文献
20.
Characterization of a streptococcal endopeptidase with homology to human endothelin-converting enzyme 总被引:4,自引:0,他引:4 下载免费PDF全文
A gene encoding an endopeptidase from Streptococcus parasanguis FW213 has been cloned and shown to have high sequence homology to genes encoding mammalian metalloendopeptidases. The gene, designated S. parasanguis pepO, was cloned into the pET28a expression vector, resulting in a fusion of vector sequences encoding a hexahistidine tag at the carboxyl terminus. The recombinant PepO (rPepO) was expressed in Escherichia coli and purified using an Ni(2+) affinity column. Polyclonal antiserum to rPepO was raised in rabbits and used to localize FW213 PepO to the cytosol. Southern hybridization and immunoblot analysis revealed that other oral streptococci contain regions of DNA with homology to pepO and produce a protein with antigenic properties similar to that of FW213 PepO. Enzymatic activity assays indicated that only S. parasanguis species possess the ability to cleave metenkephalin, the natural substrate of the human neutral endopeptidase (NEP). Inhibition assays revealed that S. parasanguis PepO is a member of the M13 category of metalloendopeptidases, which includes NEP and endothelin-converting enzyme 1 (ECE-1), an enzyme involved in the maintenance of vascular tone. Thiorphan and phosphoramidon, two specific inhibitors of this category of endopeptidases, were used to determine that S. parasanguis PepO is more similar to ECE-1 than to NEP. 相似文献