摘要:

Unipolar brush cells (UBCs) are excitatory neurons in the mammalian cerebellum and cochlear nuclei (CN), including the CN of primates, as shown only recently. UBCs are readily identified by their expression of the calcium-binding protein calretinin (CR), except for those of the primate CN that hardly immunostain for CR. The present findings corroborate the existence of UBCs in the CN of a primate,Callithrix. Furthermore, evidence is presented for UBCs in the cerebellum and a small subpopulation of UBCs in the CN ofCallithrixto express the calcium-binding protein calbindin (CB). This may be unique forCallithrixas CB-expressing UBCs have not been recognized in any other mammal. Presence of CB but not CR in UBCs of theCallithrixCN may indicate a certain interchangeability between these two calcium-binding proteins.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The pattern of distribution and co-localization of nitric oxide synthase (NOS) and quinacrine fluorescence (indicative of vesicular adenosine 5'-triphosphate, ATP), and co-localization of NADPH-diaphorase (NADPH-d) activity and NOS-immunoreactivity in the myenteric plexus of pre-term human fetal (6–17 weeks of gestation) stomach and small intestine was examined using immunohistochemical and histochemical techniques. In all stages of gestation investigated, NOS-immunoreactive and NADPH-d-reactive myenteric neurons and nerve fibres were seen in the fetal intestine and stomach. However, in fetuses of 6–10 weeks of gestation, only 15% of the NADPH-d-positive myenteric neurons were NOS-immunoreactive, whereas a 100% co-localization was found in samples of 12–17 weeks of gestation. Quinacrine fluorescent myenteric neurons and nerve fibres were found only in the fetal intestine of 12–17 weeks of gestation, of which 25% of the NADPH-d-positive myenteric neurons in these samples were quinacrine fluorescent. These findings demonstrate the presence and co-localization of markers for nitric oxide (NO)- and ATP-utilizing myenteric neurons and nerve fibres in the early stages of gestation, suggesting possible co-transmitter and/or trophic roles of ATP and NO in the process of development and maturity of human myenteric neurons. In addition, the fact that only a small percentage of NADPH-d-reactive myenteric neurons express NOS immunoreactivity at 6–10 weeks of gestation confirms that NADPH-d-reactivity does not always represent NOS activity.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The neuronal apoptosis inhibitory protein (NAIP) is known to have anti-apoptotic functions, and its gene is often mutated in severe cases of spinal muscular atrophy (SMA), a disease characterized by motor neuron degeneration. In this study, we examined the distribution of the endogenous NAIP protein in normal human spinal cord and brain tissue by using a polyclonal antibody against NAIP. Immunohistochemical staining demonstrated that NAIP is strongly expressed in anterior horn and motor cortex neurons of normal brains, and it is not altered in the remaining motor neurons of patients with amyotrophic lateral sclerosis (ALS). NAIP is also located in human fetal neurons and in adult choroid plexus cells. These results suggest that the antiapoptotic molecule NAIP may be important in motor neurons, but it specifically does not appear to be altered in ALS.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Abnormal iron deposition occurs in the brains of patients with multiple sclerosis (MS) and may cause MRI T2 shortening (‘black T2'; BT2). The frequency, distribution and clinical significance of BT2 in MS is unknown. Analysis of brain MRI scans of 114 MS patients showed BT2 in thalamus (n= 65; 57%), putamen (n= 48; 42%), caudate (n= 27; 24%) and Rolandic cortex (n= 9; 8%). BT2 was significantly related to longer disease duration and advancing neurological disability. Wheelchair-bound patients had worse BT2 in thalamus (p< 0.05), putamen (p< 0.001) and Rolandic cortex (p< 0.05). Patients with secondary progressive disease (n= 34) had worse BT2 in thalamus, putamen and caudate (allp< 0.05) than those with relapsing-remitting disease (n= 80). BT2 is proposed as a clinically relevant finding relating to neuronal degeneration in MS.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The mode of discharge of auditory cortex cells was studied during iontophoretic application of noradrenaline (NA). Only seven of 190 cells showed changes in interspike interval distribution during NA application. A similar conclusion was drawn when the analysis focused on 68 cells classified as burs+ing (n= 15), regular spiking (n= 49) or thin spike (n= 4) cells. Only two bursting cells showed changes in their ISI distribution. The effects on the mode of discharge were independent of the effect on the spike rate and were not a function of cortical depth. These results suggest that the changes in firing mode previously describedin vitrooccur for a limited percentage of cells and/or for cell types not very often recordedin vivo.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Distribution of the cAMP-specific phosphodiesterase PDE4A was examined in the accessory olfactory system by immunohistochemistry. Adjacent sections through the vomeronasal organ (VNO) and accessory olfactory bulb (AOB) were alternately immunostained with antibodies against PDE4A or the G-protein α subunit Goα, which labels basal VNO neurons, in order to determine whether PDE4A occurs preferentially in one of two segregated VNO pathways. We found that PDE4A strongly labeled apical VNO neurons and rostral AOB glomeruli. There was virtually no overlap in Goαand PDE4A staining, and there were no regions of the VNO neuroepithelium or AOB glomeruli not labeled by either antibody. These results identify a potential member of the pheromone transduction cascade in apical neurons, and provide further evidence that the VNO consists of functionally distinct pathways.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Activity-related shifts in intracellular pH (pHi) can exert potent neuromodulatory actions. Different states of neuronal activity of thalamocortical neurons were found to differentially modulate pHi. Tonic activity evoked by injection of depolarizing current led to a reversible rise in [H+]iwhich was nearly abolished in the presence of TTX. Block of voltage-gated calcium channels with 1 mM Ni2+reduced the [H+]itransients related to tonic activity. Rhythmic activation of burst discharges caused changes of [H+]iwhich were decreased by TTX, whereas 1 mM Ni2+almost abolished the [H+]itransients. The present results show that different forms of neuronal activity can lead to intracellular acidification caused by different mechanisms, i.e. Na+and Ca2+influx through sodium and Ca2+channels, respectively, and the subsequent activation of a Ca2+/H+pump. The resulting acidosis is suggested to reduce further Ca2+influx and prevent excessive neuronal excitation.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

We have reported the presence of continuous gamma (30–150 Hz) activity in the human medial temporal lobe (MTL). Since the MTL is involved in learning and memory, we speculated that MTL gamma activity is related to such higher brain functions. It is thus of interest to learn how this activity changes during different states of consciousness. In this study, we recorded electrocorticographic (ECoG) activity directly from the surface of the MTL after various doses of sevoflurane anesthesia. Five epileptic patients underwent electrode placement operations in which electrodes were attached to the surfaces of the MTL and the basal temporal lobe (BTL). Immediately following the operation ECoG was recorded from each patient under four concentrations of sevoflurane anesthesia (1.5, 2.0, 2.5 and 3.0%). Fast Fourier Transform (FFT) analysis was performed on the MTL ECoGs. Under the lowest sevoflurane concentration, MTL gamma activity was observed in all patients. However, gamma activity was progressively suppressed by increased concentrations of sevoflurane, in a dose-dependent manner. Sevoflurane has been known to reduce neuronal excitability in the rat hippocampusin vitro, probably by changing GABAergic inhibition. The reduction of MTL gamma in the present study may be the result of such a mechanism. Although memory function was not tested in this study, the amount of MTL gamma activity may be related to residual memory function during anesthesia.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Humans share with animals a primitive neural system for processing emotions such as fear and anger. Unlike other animals, humans have the unique ability to control and modulate instinctive emotional reactions through intellectual processes such as reasoning, rationalizing, and labeling our experiences. This study used functional MRI to identify the neural networks underlying this ability. Subjects either matched the affect of one of two faces to that of a simultaneously presented target face (a perceptual task) or identified the affect of a target face by choosing one of two simultaneously presented linguistic labels (an intellectual task). Matching angry or frightened expressions was associated with increased regional cerebral blood flow (rCBF) in the left and right amygdala, the brain's primary fear centers. Labeling these same expressions was associated with a diminished rCBF response in the amygdalae. This decrease correlated with a simultaneous increase in rCBF in the right prefrontal cortex, a neocortical region implicated in regulating emotional responses. These results provide evidence for a network in which higher regions attenuate emotional responses at the most fundamental levels in the brain and suggest a neural basis for modulating emotional experience through interpretation and labeling.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Chronic pain remains a major health problem afflicting an estimated 70% of patients with advanced cancer and inflammatory disorders, and up to 94% of patients with spinal cord injuries. Although progress has been made in the pharmacotherapy of chronic pain management, such as usage of adjuvant drugs and more effective methods of drug delivery, the mainstay of clinical pain management still depends on opiates. NMDA receptor activation, at the level of the spinal cord has been shown to play an important role in the facilitation of nociception (pain) in several animal models. Unfortunately, potent NMDA receptor antagonists, such as MK-801 and APV, have toxic properties and low safety margins that preclude their clinical use. We present evidence which indicates that the use of antisense oligonucleotides targeted to the NMDA-R1 receptor subunit (AS-NMDA-R1), but not sense, abolishes NMDA and formalin induced behaviors. Moreover, we demonstrate that spinal administration of AS-NMDA-R1 results in the abolition of staining for immunoreactive NMDA-R1 in the spinal cord. These data provide novel evidence supporting the feasibility of the use of gene therapy approaches in the management of neuropathic pain.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID