Effect of reduction of cholinergic input on the concentration of specific proteins in different cortical regions of the rat brain

The effect of lesioning the nucleus of the tractus diagonalis on the concentration of specific proteins in the hippocampus and the occipital cortex was assessed. Rats received either a sham or an electrolytic lesion and were killed 9 or 35 days later. Tissue samples were removed by microdissection and proteins were separated by two-dimensional gel electrophoresis. Gels were stained with silver, and then analyzed by quantitative computerized scanning densitometry. Of the 143 proteins analyzed, only four were found to be altered in concentration in both brain areas as a result of the lesion. Protein 82 (molecular weight 39,000, pI 6.5) was reduced 71% in the hippocampus and 50% in the occipital cortex 9 days after the lesion, while protein 109 (molecular weight 32,000, pI 6.4) was elevated 140% in the hippocampus and 130% in the occipital cortex at the same time point. Protein 6 (molecular weight 58,000, pI 5.7) was unchanged 9 days after the lesion but was elevated in concentration in both the hippocampus and the occipital cortex 35 days after lesioning. Protein 74 (molecular weight 39,000, pI 5.8) was elevated in concentration both 9 and 35 days after lesioning in the occipital cortex, but only at day 35 in the hippocampus. These results demonstrate that the concentration of these four proteins may be regulated by the cholinergic input to the hippocampus and the occipital cortex. The possibility exists that one or more of these proteins may be related to either the muscarinic or nicotinic cholinergic receptor in rat brain.     

The rat claustrum: Afferent and efferent connections with visual cortex

We have examined the afferent and efferent projections between the claustrum and visual cortex in the Long-Evans rat using anterograde and retrograde axonal transport techniques. Injections of either wheat germ agglutinin/horseradish peroxidase (WGA/HRP) or Fast Blue were made into each of the main visual regions (17, 18a or 18b) as well as directly into the claustrum. The cortical injections were placed in either the upper, middle or deep layers so as to assist in determining the laminar organization of these connections. Of the 3 visual areas, only area 18b appears to have extensive and reciprocal connections with the claustrum. After a WGA/HRP injection of this area, dense labeled terminals and numerous labeled cells were found intermixed throughout the full extent of the claustrum. The density of this labeled activity was found to vary directly with the amount of the infragranular layers involved by the injections. Injections in the other visual areas did produce labeled cells in the claustrum, but their number was always small or even negligible. There was never any evidence of anterograde labeled terminals in the claustrum from any injection of areas 17 or 18a. Tracer injections directly in the claustrum confirmed and extended these findings by showing that the labeled terminals and/or labeled cells were localized predominantly in layer VI of area 18b of visual cortex. On the basis of these injections, two major conclusions are reached. First, the pattern of connections between the claustrum and visual cortex in the rat differs fundamentally with that found in other species.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential rearing effects on rat visual cortex synapses. I. Synaptic and neuronal density and synapses per neuron

The bulk of the evidence indicating that different experiences can lead to differences in synapse numbers involves inference from measures of postsynaptic surface (spines and dendrites) in Golgi impregnated tissue. The capriciousness of Golgi impregnation and the absence of direct evidence regarding changes in afferents mandate confirmation of synapse changes by electron microscopy. We calculated the ratio of synapses per neuron in layers I-IV of occipital cortex of rats reared in complex (EC), social (SC), or isolated (IC) environments. Synaptic density estimates were derived from electron micrographs of osmium-uranyl-lead stained tissue and neuronal density estimates were derived from toluidine blue stained semithin sections using stereological methods which correct for group differences in the sizes of synapses and neuronal nuclei. The ratio of these densities, synapses per neuron, was highest in complex environment rats, intermediate in socially reared rats and lowest in isolates, in accordance with predictions from prior Golgi studies. The bulk of the differences were attributable to neuronal density, which was highest in IC rats and lowest in ECs. Synaptic density did not differ statistically across groups. These results indicate, at least within this area and paradigm, that differences in dendritic measures in Golgi impregnated tissue reflect differences in the number of synapses per neuron.     

Disinhibition as a basic process in the expression of striatal functions. II. The striato-nigral influence on thalamocortical cells of the ventromedial thalamic nucleus

Besides the nigro-collicular pathway, the nigro-thalamic projection to the ventromedial thalamic nucleus represents another efferent system of the basal ganglia through which striatum can influence motor centers. Since the striato-nigrothalamic circuit is composed of two successive GABAergic inhibitory links and the SNR is tonically active, we tested that by inhibiting nigrothalamic cells, the striatum may exert a facilitatory influence on VM-thalamocortical cells. We show that a transitory block of SNR (substantia nigra pars reticulata) firing (induced by either intranigral application of GABA or by stimulating the inhibitory striato-nigral pathway), causes a perfectly time-locked increase of activity in a large number of VM cells projecting to motor cortex. Moreover, the striatally evoked excitation of VM-thalamocortical cells requires the functional integrity of the GABAergic striato-nigral link. We conclude that the double inhibitory striato-nigrothalamic pathway acts on VM-thalamocortical cells through a disinhibitory mechanism. The functional implication of such a mechanism is discussed.     

Two groups of corticofugal neurons identified with the pontine stimulation in the cat parietal association cortex: an intracellular HRP study

A classification of the parietal corticofugal neurons was performed in cats under Nembutal anesthesia. Eighty-eight neurons were identified with antidromic activation by the pontine stimulation. Thirteen neurons were furthermore identified with intracellular HRP staining. In these neurons, we found the close correlation between morphological features and conduction velocities. The faster conducting group of the neurons had relatively large somata, sparsely spinous apical dendrites, tap root basal dendrites and wide apical dendritic fields. The slower group had small somata and numerous dendritic spines.     

Effect of opiates on the release of cholecystokinin from in vitro hypothalamus and frontal cortex of Zucker lean (Fa/−) and obese (fa/fa) rats

Opiates, morphine and [d-Ala²-d-Leu⁵]-enkephalin (DADLE), inhibited the K⁺-stimulated release of cholecystokinin (CCK) from the hypothalamus of both Zucker obese (fa/fa) and lean (Fa/−) rats, in vitro. Morphine and DADLE did not inhibit the K⁺-stimulated release of CCK from frontal cortex from either strain. The opiates did not affect basal efflux of CCK and their effects were all blocked by equimolar concentrations of naloxone. These studies indicate a regional specificity for the effect of opiates on CCK release, and may provide evidence for a cellular mechanism by which endogenous opiates modulate feeding behavior.     

Functional Organization of Area V2 in the Alert Macaque

We studied the relation between anatomical structure and functional properties of cells in area V2 of the macaque. Visual function was assessed in the alert animal during fixation of gaze. Recording sites were reconstructed with respect to cortical lamination and the cytochrome oxidase pattern. We measured orientation and direction selectivity, end-stopping, sensitivity to binocular disparity and ocular dominance, and determined more complex functions like sensitivity to anomalous contours and lines defined by coherent motion. Orientation selectivity was found in all parts of area V2, with high frequencies in the pale and thick stripes of the cytochrome oxidase pattern, and with lower frequency in the thin stripes. Representations of anomalous contours were found in the pale and thick stripes with similar frequencies, but generally not in the thin stripes, which have been thought to process colour. Lines defined by coherent motion were most frequently represented in the thick stripes; they were less frequent in the pale stripes, and (as with anomalous contours) were not found in the thin stripes. Sensitivity to binocular disparity was found in all types of stripes, but more frequently in the thick stripes, where the exclusively binocular neurons were also concentrated. By contrast, no segregation was found for direction selectivity and end-stopping. All neuronal properties were distributed evenly across cortical laminae. We conclude that mechanisms for figure–ground segregation involve the pale and the thick stripes of the cytochrome oxidase pattern, perhaps with greater emphasis on 'shape from motion'and 'stereoscopic depth'in the thick stripes, while more elementary neuronal properties are distributed almost evenly across the stripe pattern.     

Distribution of a Brain-specific Proteoglycan, Neurocan, and the Corresponding mRNA During the Formation of Barrels in the Rat Somatosensory Cortex

Neurocan is a developmentally regulated chondroitin sulphate proteoglycan in the rat brain. In the present study, spatiotemporal patterns of expression of neurocan and the corresponding mRNA were examined in the developing cortical barrel field of the rat brain by using a monoclonal antibody that was highly specific to neurocan and a riboprobe for a portion of the mRNA. Immunohistochemical analysis revealed that neurocan was distributed throughout the cerebral cortex during early postnatal development but was excluded from the centres of cortical barrels at the time of entry and arborization of thalamocortical axons. At this developmental stage, expression of neurocan mRNA was shown by in situ hybridization to be down-regulated in the barrel centres. When a row of whisker follicles was laser-cauterized on postnatal day 1, the pattern of expression of neurocan was disturbed in the row of barrels that corresponded to the lesioned whisker follicles in the contralateral somatosensory cortex. From these observations, it appears that neuronal stimuli through early thalamocortical fibres from the sensory periphery cause reduced expression of neurocan mRNA in neurocan-producing cells in the presumptive barrel centres. Our findings also suggest that the pattern of distribution of neurocan in early postnatal barrel fields may be due mainly to the down-regulation of expression of neurocan mRNA.     

黄芪刺五加治疗卵巢恶性肿瘤的免疫学研究

黄芪刺五加具有免疫增强作用。该文44例卵巢恶性肿瘤患者在化疗间歇期服黄芪刺五加,并测定其免疫功能。结果发现,用药后诱生α干扰素(IFN-α)和自然杀伤细胞(NK)活性水平逐渐增高。提示黄芪刺五加具有明显促进产生内源性IFN的作用,可对抗癌细胞和化疗药物的免疫抑制作用。