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Michael A. Muniak Zachary M. Mayko David K. Ryugo Christine V. Portfors 《Journal of visualized experiments : JoVE》2012,(64)
It is well known that anesthesia alters neural response properties in various regions of the brain.13. In the auditory system, fundamental response properties of brainstem neurons including threshold, frequency specificity, and inhibitory sidebands are altered in significant ways under anesthesia1-2. These observations prompted physiologists to seek ways to record from single neurons without the contaminating effects of anesthesia. One result was a decerebrate preparation, where the brainstem was completely transected at the level of the midbrain4. The drawbacks of this preparation are a formidable surgery, the elimination of descending projections from the forebrain, and an inability to use sensory stimulation to examine structures above the midbrain. A different strategy has been to implant electrode arrays chronically to record from single neurons and multiunit clusters while the animal is awake and/or behaving5,6. These techniques however are not compatible with injecting tracer dyes after first electrophysiologically characterizing a brain structure. To avoid altering neural response properties with anesthetics while recording electrophysiological response properties from single neurons, we have adapted a head restraint technique long used in bats7-9 to mouse10-12. Using this method, we are able to conduct electrophysiological recordings over several days in the unanesthetized mouse. At the end of the recording sessions, we can then inject a dye to reconstruct electrode positions and recording sites or inject a tracer so that pathways to and from the recording loci can be determined. This method allows for well isolated single neuron recordings over multiple days without the use anesthetics. 相似文献
74.
We studied the effects of stress induced by different influences (immobilization and compulsory swimming) on the activity of angiotensin-converting enzyme (ACE, an enzyme of the proteolytic conversion of angiotensin II) in structures of the hypothalamo-hypophyseal-adrenocortical system (HHAS) of unilaterally adrenalectomized (hemiadrenalectomized, HAE) rats. The pattern of stress-induced changes in the activity of ACE depended on the type of stress; rigid daily immobilization of rats for 1 h resulted in more significant shifts. Post-immobilization stress changes in the activity of ACE in the HHAS structures of HAE rats (with a lower basal activity of the endogenous angiotensin system in their hypothalamus) differed from the stress-induced reaction of the enzyme in intact rats. In HAE rats, we also observed inhibition of the activity of a glucocorticoid link of the stress system, as compared with that in intact animals. An inhibitor of ACE, captopril, and a stable analog of leucine-enkephalin, dalargin, when injected before stressing, were capable of decreasing the stress-induced ACE reaction in the hypothalamus and adenohypophysis and of limiting manifestations of the reaction of the adrenals to immobilization. This is interpreted as a proof of the involvement of the components of the angiotensin and enkephalin systems in the formation of the HHAS system to stressing of HAE rats. 相似文献
75.
76.
Abhishek Chatterjee Celia Caballero-Franco Dannika Bakker Stephanie Totten Armando Jardim 《The Journal of biological chemistry》2015,290(42):25579-25594
Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. Pathogenesis associated with enterohemorrhagic E. coli involves direct delivery of virulence factors from the bacteria into epithelial cell cytosol via a syringe-like organelle known as the type III secretion system. The type III secretion system protein EspD is a critical factor required for formation of a translocation pore on the host cell membrane. Here, we show that recombinant EspD spontaneously integrates into large unilamellar vesicle (LUV) lipid bilayers; however, pore formation required incorporation of anionic phospholipids such as phosphatidylserine and an acidic pH. Leakage assays performed with fluorescent dextrans confirmed that EspD formed a structure with an inner diameter of ∼2.5 nm. Protease mapping indicated that the two transmembrane helical hairpin of EspD penetrated the lipid layer positioning the N- and C-terminal domains on the extralumenal surface of LUVs. Finally, a combination of glutaraldehyde cross-linking and rate zonal centrifugation suggested that EspD in LUV membranes forms an ∼280–320-kDa oligomeric structure consisting of ∼6–7 subunits. 相似文献
77.
The early intracellular signaling pathway for the insulin/insulin-like growth factor receptor family in the mammalian central nervous system 总被引:8,自引:0,他引:8
Franco Folli Silvana Ghidella Luca Bonfanti C. Ronald Kahn Adalberto Merighi 《Molecular neurobiology》1996,13(2):155-183
Several studies support the idea that the polypeptides belonging to the family of insulin and insulin-like growth factors
(IGFs) play an important role in brain development and continue to be produced in discrete areas of the adult brain. In numerous
neuronal populations within the olfactory bulb, the cerebral and cerebellar cortex, the hippocampus, some diencephalic and
brainstem nuclei, the spinal cord and the retina, specific insulin and IGF receptors, as well as crucial components of the
intracellular receptor signaling pathway have been demonstrated. Thus, mature neurons are endowed with the cellular machinery
to respond to insulin and IGF stimulation. Studies in vitro and in vivo, using normal and transgenic animals, have led to
the hypothesis that, in the adult brain, IGF-I not only acts as a trophic factor, but also as a neuromodulator of some higher
brain functions, such as long-term potentiation and depression. Furthermore, a trophic effect on certain neuronal populations
becomes clearly evident in the ischemic brain or neurodegenerative disorders. Thus, the analysis of the early intracellular
signaling pathway for the insulin/IGF receptor family in the brain is providing us with new intriguing findings on the way
the mammalian brain is sculpted and operates. 相似文献
78.
Douglas L. Weeks David E. Sherwood Stephen A. Wallace 《Journal of electromyography and kinesiology》1991,1(4):250-262
Research examining the electromyographic (EMG) burst structure of rapid discrete limb movements has led to discordant findings concerning agonist burst duration. Some research has shown that duration varies as a function of movement speed while other research has shown burst constancy. Unfortunately, much of this research may be confounded by not carefully controlling movement termination accuracy and movement time (MT). Due to these potential problems, the present study was conducted to determine the effects of strict spatiotemporal constraints on EMG characteristics of a rapid elbow flexion-extension response under two movement extent conditions across five different MTs. Results revealed that a decreased MT was accompanied by a decreased agonist (biceps) burst duration and increased agonist burst amplitude. The burst duration and amplitude both increased as the movement extent increased with MT held constant. None of three current theoretical perspectives of rapid movement control (the impulse-timing model, the speed-control system hypothesis, or the speed-sensitive strategy) could fully account for these results. Instead, a control strategy was exhibited in which moving faster was accomplished by relative scaling of burst area via concomitant expansion of burst amplitude and compression of burst duration. 相似文献
79.
80.
Phorbol 12-myristate 13-acetate (PMA) treatment elicited an increased 32P incorporation into phospholipids namely phosphatadyl-inositol (PI); phosphatidyl-inositol-4-phosphate (PIP); phosphatidyl-inositol-4,5-bis-phosphate (PIP2); phosphatidyl-acid (PA); phosphatidyl-choline (PC) and phosphatidyl-ethanolamine (PE) particularly at the 20–30th min after treatment. The ratio of members of the phosphoinositol system, especially PIP and PI, related to the total phospholipid content was increased. PMA (2 × 10?7 M ) was the most effective of the three concentrations tested. The results call attention to the presence of a working phosphoinositol system in Protozoa. 相似文献