摘要:

AbstractNewly synthesized poly (A)‐associated mRNA was analysed in the hippocampal CA3pyramidal nerve cells in rats subjected to training to reverse handedness.The nerve cells of trained animals showed a smaller percentage of poly (A)‐associated mRNA than did the active controls. However, a specific fraction of this poly (A) hippocampal RANA with a SEvalue of around 25 was reproducibly stimulated. This qualitative nerve cell mRNA change is discussed in relation to similar changes in the protein pattern as a function of train

ISSN:0360-4012    

DOI:10.1002/jnr.490020402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractFrog skin touch receptors are discrete structures which appear as dome‐shaped translucent elevations of the epidermis. These domes are particularly responsive to direct touch. Tactile stimulation adjacent skin never caused impulse activity, except when the skin distortion disturbed the domes. On stimulation at threshold intensity, the response of all units studied always consisted of a single impulse whether the stimulus energy was electrical or mechanical. While most tactile units discharged one impulse upon application of mechanical stimulation, a few also discharged one impulse upon stimulus release (on‐off response). No after discharge was seen at stimulus strengths of three or four times threshold or after repetitive stimulation at 1,000 pps. The range of distribution of active domes/receptive field was 1–14. Generally the most sensitive domes appeared to be in or near center field.Twice as many of the tactile units responded more readily to cold than to warmth. The impulse frequency of units responding to thermal stimulation ranged from 3–11/Sec. The conduction velocity of tactile units measured was within a range of 9–25m/sec, with a mean of 12 m/sec. The results suggest the following: (1) the existence of discrete structures which respond to tactile stimuli; a phylogenetic relationship might be postulated; (2) cold/touch receptors which appear to be present in greater quantity in the frog's skin than are warm/touch receptors, (3) touch units which should be considered primarily as mechanoreceptros with a possible secondary function as thermo

ISSN:0360-4012    

DOI:10.1002/jnr.490020403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractThe investigations reported here demonstrate high affinity transport systems localized in glial cells which appear to be specific for amino acid neurotransmitter candidates. Data on uptake of γ‐aminobutyric acid (GABA), glutamate, glycine, and taurine, show transport systems with KT's in the range of 10−5M. In addition, the distribution of the glial transport system for glycine is shown to parallel the presumed distribution of glycine as an inhibitory neurotransmitter. Results of these studies also suggest that transport studies on brain homogenates or synaptosomal preparations do not serve to localize these functions to synaptic elements as is widely believed. This report shows that glia can form vesicles during homogenization which band with synaptosomes in density gradients, and retain transport activity. Glia also may contribute to the release of neurotransmitters via control of the extracellular to cause release of Ca++by

ISSN:0360-4012    

DOI:10.1002/jnr.490020404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractThis experiment was directed toward determining the relative effectiveness of discrete and diffuse pain stimuli in influencing perception and behavior. Shocks to the footpads were use to activate the discrete pain pathways. In the first phase of this experiment, cats were trained to escape from foot shock in a shuttle box. Current applied to the feet was varied in ascending and descending sequences for each animal according to the psychophysical method of limits and each animal was trained until stable thresholds for escape responding were achieved. In the second phase of the experiment, the effect on behavior of simultaneous activation of both the discrete and diffuse pain systems was assessed. The principal finding in this experiment was that escape responding that was well established when foot shock was presented alone was routinely abolished on trials when tooth shock and foot shock were presented together. These results were interpreted as indicating that the diffuse pain system was prepotent in influencing behavior when both the discrete and diffuse pain systems were activated simultaneously.

ISSN:0360-4012    

DOI:10.1002/jnr.490020405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractWeanling male Sprague‐Dawley rats received bilateral electrolytic lesions in the dorsomedial hypothalamic area by means of a direct cathodal current. Sham‐operated rats served as controls. Ponderal and linear growth, obesity index, food intake, and several indices of intermediary metabolims of adipose tissue and muscle were measured. Cathodal lesions, as did anodal lesions reported on previously, resulted in retardation of body weight, length, and food intake, while the obesity index remained in the normal range. Similarly, the metabolic data in adipose tissue and muscle are comparable to those from experiments in which dorsomedial lesions were placed by anodal current: incorporation of glucose into CO2, lipid, and glycogen of muscle tissue (diaphragm) were similar in DMN‐lesioned rats and controls. The difference between anodal and cathodal lesions in this hypothalamic syndrome is a delay in the onset of hypophagia until about 30 days after the hypothalamic operation. The data support the concept that lesions in the hypothalamus, in general, exert their effect by destruction of neuronal assemblies, i.e., nerve cells and/or fiber tracts passing through the lesioned

ISSN:0360-4012    

DOI:10.1002/jnr.490020406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractThe acute mortality caused by two irreversible inhibitors of cholinesterases [disiopropylfuorophosphate (DFP) and diethoxyphosphorylthiocholine, 217 MI‐phospholine iodide] has been investigated on chick embryos at different stages of development.The results demonstrate that the above compounds do not show any acute lethal action when administered before the 9th day of incubation; on the other hand, the administration is regularly followed by death after the 9th day of incubation. The doses are comparable to those causing death in hatched chicks.It has also been observed that no appreciable difference exists in DFP uptake from the yolk before and after the 9th day of incubation and that drug‐induced cholinesterase inhibition is of the same order of magnitude at any developmental stage; the compound pyridine‐2‐aldoxime methanesulfonate (2‐PAM) was a good antidote against DFP acute lethality.It seems likely that between the 8th and the 9th day of incubation the target system of organophosphorus inhibitors, that is, the cholinesterase enzymatic system, reaches a new point of m

ISSN:0360-4012    

DOI:10.1002/jnr.490020407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractIn order to investigate the effect of nutrient deprivation on brain development, mouse cerebellum cultures were grown in nutrient media with reduced serum concentration. After 9–18 days in vitro, experimental cultures grown in media with low serum concentration exhibited a delayed and retarded myelination. Electron microscopic examination of experimental cultures revealed profiles of deficient myelination, but showed normal neuronal and synaptic structures. The amount of myelin basic protein measured by radioimmunoassay was markedly reduced in experimental cultures. Activity of cholinesterase in these experimental cultures was also decrease

ISSN:0360-4012    

DOI:10.1002/jnr.490020408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractStimulation of the hippocampus or amygdala of adrenalectomized cats occurred for 10 sec followed by a 50 sec period of no stimulation, beginning 30 min prior to and ending 30 min after administration of 100 μCi of3H‐hydrocortisone into a lateral ventricle. Sixty min after administration of labeled hormone, the hypothalamus was excised and homogenized. Cytosol and nuclear extract fractions were obtained and analyzed for radioactivity and protein content. Separation of bound from free hydrocortisone was achieved by charcoal adsorption assay.Results reveal that stimulation of the hippocampus resulted in a greater concentration of3H‐hydrocortisone taken up into hypothalamic cells. Also, a greater percentage of total hormone found in the nuclear extract was assayed as bound3H‐hydrocortisone, and the concentration of bound radioactivity in the nuclear extract was increased over control values. Amygdalar stimulation, in general, yielded results similar to those obtained from control cats. However, although a lesser percentage of total hormone in the hypothalamic cytosol was assayed as bound hormone, there was a greater concentration of nuclear bound hormone than in controls, but less than that determined in the hippocampal stimulation group.These results add to the evidence that hippocampus and amygdala have a modulating influence upon the hypothalamo‐hypophyseal axis. They also suggest that one manner in which these limbic structures may influence hypothalamic function is to modulate the uptake and binding of hydrocortisone in hypothalam

ISSN:0360-4012    

DOI:10.1002/jnr.490020409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of hypothyroidism on cerebral and cerebellar synaptosome development has been studied. Neonatal hypothyroidism was induced following addition of 0.3% propylthiouracil to the diet of nursing mothers. Maturation profiles of total synaptosome fraction and specific activities of lactate dehydrogenase, Na+K ATPase, cytochromecoxidase, and protein were obtained from days 6 to 32 on synaptosomes isolated from Ficoll‐sucrose gradients. The greatest changes were found in the total activities of enzymes isolated from the cerebellum. Hypothyroidism induced a retardation of LDH and cytochrome c oxidase in cerebellar synaptosomes, but no change in corresponding specific activities. Maximum rates of14C‐leucine incorporation into cerebellar synaptosome protein was found at 16–20 days, after which a rapid decline occurred to adult levels at 32 days. In neonatal hypothyroidism, synthesis was significantly reduced at 8 and 14 days, but reached control levels or above at 21–32 days. In the cerebrum, maximum rates of14C‐leucine incorporation into synaptosome protein were identified at 8–12 days in normal with a rapid drop to adult levels at approximately 20 days. In neonatal hypothyroidism, peak activities were identified at 14 days and increased activities over control were noted at 14, 20 and 30 days.These observations demonstrate the sensitivity of the developing cerebellar synaptic apparatus to neonatal hypothyroidism, with a protraction in the peak levels of synaptosome protein synthesis in cerebrum and

ISSN:0360-4012    

DOI:10.1002/jnr.490020410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490020401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1976

数据来源: WILEY