ISSN:0022-3034    

DOI:10.1002/neu.480010102

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

年代:1969

数据来源: WILEY

摘要:

AbstractDibucaine hydrochloride, pentobarbital sodium, tropinep‐tolyl acetate hydrochloride (tertiary form), and tropinep‐tolyl acetate methiodide (quaternary form) reversibly blocked both peak transient and steadystate components of conductance changes from either side of the squid nerve membrane. With external and internal applications of dibucaine and with internal application of the tertiary topine, the steady‐state current declined somewhat, leaving a “hump.” The time to the early peak transient current was unaffected by either external or internal application of dibucaine, but prolonged by either external or internal application of pentobarbital. The curve relating the peak transient conductance to the membrane potential was shifted along the potential axis in the direction of depolarization by external or internal application of pentobarbital. It is suggested that the mechanism of blockage of the peak transient conductance by these anesthetic agents is different from that by tetrodotoxin or by uncharged lipid‐solubl

ISSN:0022-3034    

DOI:10.1002/neu.480010103

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe ganglia and connectives of the ventral nerve cord of a leech (Mooreobdella fervida) were subjected to fixation by freeze substitution. This method is believed to preserve the water distribution in the tissue more faithfully than conventional fixation, but has the disadvantage that only the superficial 10 to 15 μU of these structures can be examined. Electron micrographs of this material showed the following differences from nervous tissue fixed by immersion in an osmium tetroxide solution. The lamellae of the packet glia cells were narrower and the extracellular spaces between them were wider than in conventionally fixed material. The cytoplasm of the lamellae was finely granular and lacked the vacuoles which characterize this tissue when fixed by immersion. In the neuropil the nervous elements tended to be separated by glial material which sometimes consisted of a single sheet, but often of several lamellae with rather more extracellular space than in conventionally fixed material. In the connectives thin axons were present in bundles containing little or no glia but surrounded by glial lamellae. The fibers had a rounded appearance and these axon fields showed an appreciable extracellular space. The large axons showed irregular but generally more rounded profiles than in conventionally fixed material. They were usually individually enveloped by glial lamellae with rather ample space between them. In the neuropil and the connective fixed by immersion in OsO4solutions the extracellular space consisted of the narrow 100 to 150 Å spaces between the tissue elements typical for OsO4fixed materia

ISSN:0022-3034    

DOI:10.1002/neu.480010104

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe binding capacity of isolated acetylcholinesterase‐rich nerve‐ending membranes of the cat cerebral cortex for dimethyl‐14C‐d‐tubocurarine (1.5 × 10−6M) was studied with anin vitrotechnique. After treatment of the membranes with organic solvents, most of the radioactivity was found in the extract and bound either to the lipids or proteolipids, but not to the gangliosides.Comparing the binding capacity per milligram of proteolipid protein of theM11.0 nerve‐ending fraction with that of myelin, there was a tenfold increase in specific activity in the former. This layer cromatography of a lipid extract, previously passed through Sephadex G 25 fine, showed that the radioactivity remained at the point of origin together with the proteolipids. The use of a special technique with Sephadex LH20demonstrated that the bound dimethyl‐14C‐d‐tubocurarine was eluted together with a protein peak which had no cholesterol and negligible amounts of phospholipids.Experiments using precipitation with ether of the proteolipid protein and passage through the Sephadex LH20column gave similar results and confirmed that the receptor properties ford‐tubocurarine may be in a special type of proteolipid present in the nerve‐ending membrane, probably at the junctional complex. These results are discussed in relation to previous attempts, reported in the literature, to isolat

ISSN:0022-3034    

DOI:10.1002/neu.480010105

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

年代:1969

数据来源: WILEY

摘要:

AbstractMetal microelectrodes were chronically implanted in the optic nerve and circumesophageal commissure of the crayfish. The activity from single units was recorded in freely moving animals, and responsiveness to visual stimuli was found correlated with motor activity of the animal. The lowest firing rate corresponded to states of quietness and the highest to fighting reactions. The two types of visual units studied showed a different degree of modulation. Thesustaining fibers, which signal the intensity of illumination, were facilitated at all levels of motor excitation. Themovement fibers, which are phasic units, reacted to great enhancements of motor activity by an increased number of spikes in each response to movement, and by a lowering in the rate of “habituation.” This facilitatory influence is neural in origin, presumably conveyed by the “activity”fibers, which run efferently in the optic nerve, carrying information about movement of the various bod

ISSN:0022-3034    

DOI:10.1002/neu.480010106

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

年代:1969

数据来源: WILEY

摘要:

AbstractMetal microelectrodes were implanted in the optic nerve of the crayfish,Procambarus clarki, and the activity of thesustaining fibers(units which react tonically to changes in illumination) was continuously recorded over periods up to 8 weeks. In animals kept in darkness, the response to periodic test light pulses was found to vary in a circadian manner. The duration of the cycles varied between 22 24 hr, with a phase of high responsiveness during the subjective night, which abruptly changed to one of low responsiveness at subjective dawn. The phase, amplitude, and shape of the cycles were modifiable by light pulses. The spontaneous activity of these units in darkness showed a similar fluctuation, and so did the electroretinogram amplitude, the spontaneous motor activity of the animal, as indicated by records from mechanoreceptive and activity fibers (units which are activated, directly or indirectly by body movements), and the motor responsiveness to light. The time course of these cycles suggests that they are driven by a common “clock,” through humoral mechani

ISSN:0022-3034    

DOI:10.1002/neu.480010107

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

年代:1969

数据来源: WILEY

摘要:

AbstractSympathetic nerves of the pineal gland contain both serotonin and norepinephrine. Inhibition of norepinephrine synthesis with a tyrosine hydroxylase inhibitor, α‐methyl‐p‐tyrosine (αMPT), causes an elevation of pineal serotonin. The administration of dopamine or norepinephrine blocks the elevation of pineal serotonin by αMPT. When sympathetic nerves to the pineal are interrupted αMPT no longer causes a rise in pineal serotonin. Tryptophan causes a marked increase in pineal serotonin; αMPT enhances and norepinephrine blocks

ISSN:0022-3034    

DOI:10.1002/neu.480010108

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

年代:1969

数据来源: WILEY

摘要:

AbstractCarbohydrate‐containing macromolecules of brain were substantially labeled after intracerebral injection of C14‐glucosamine. The “half‐life” of the labeled macromolecules, as measured in these experiments, was about one week. Acetoxycycloheximide inhibited incorporation of C14‐glucosamine into these substances. This appears to be secondary to inhibition of synthesis of polypeptide chains which act as “acceptors” for carbohydrate residues. Acetoxycycloheximide inhibited incorporation of C14‐glucosamine (and its derivatives) into the soluble carbohydrate‐containing macromolecules of nerve endings far less than that of the other subcellular fractions of brain. This suggests that the polypeptide “acceptors” of carbohydrate residues at nerve endings are not synthesized locally but are transported to the nerve endings. Final incorporation of carbohydrates into carbohydrate‐containing macromolecules occurs at nerve endings. The “turnover” of these substances in nerve endings was found to be relatively rapid. Evidence suggesting reversible incorporation and removal of some carbohydrate residues of carbohydrate‐containing macromolecules of brain was found and the possible regulatory rol

ISSN:0022-3034    

DOI:10.1002/neu.480010109

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

年代:1969

数据来源: WILEY

摘要:

AbstractStudies were undertaken to explore the effects of two amnesic agents upon appetitive and aversive learning in the same apparatus.Ss given electroconvulsive shock (ECS) within 80 sec or 15 min of punishing shock, andSs administered ECS or ether 20 sec after the end of a 60‐sec water reinforcement period evidenced significant deficits on retention tests. The footshock‐ECSSs showed significantly shorter latencies and greater activity thanSs given footshock alone. Conversely,Ss given water reinforcement and ECS had longer latencies and less activity thanSs given only water reinforcement. The results support the contention that postrial ECS and either disrupt perseverative neural processes representing appetitive as well as aversive learning and suggest the possibility that memory consolidation takes place at different rates for the two types of ta

ISSN:0022-3034    

DOI:10.1002/neu.480010110

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

年代:1969

数据来源: WILEY

摘要:

AbstractProlonged treatment of castrated‐male rats with testosterone causes the development of taste buds in abnormal locations in the vallate papilla (i.e., upper surface of the papilla). Since taste buds are morphologically dependent on a trophic factor delivered to them via intact gustatory nerves, investigations of the possible role of testosterone as a trophic agent were undertaken. The effects of testosterone propionate on taste buds were studied in normal male and female, castrated‐male, and male rats in which the taste buds were totally denervated. There was no apparent change in the number, distribution, or appearance of the taste buds normally found in the trench walls of testosterone treated normal or castrated rats. However, in the normal‐male and castrated‐male rats, 1–3 taste buds were found on the top surface of the papilla 6 weeks after treatment. No new buds were seen at 1 or 2 weeks, nor were any seen in hormonally treated females, or in control animals injected with sesame oil alone. Furthermore, testosterone did not maintain old or initiate new taste bud formation in the denervated papilla. Thus, testosterone in the form, doses, and times employed, could not subserve the trophic function of intact gustatory nerves. The results however indicate that new taste bud formation is the result of a nerve–hormone interaction, and not a change induced by castration and subsequent testosterone treatment. Further studies of the nerve–hormone interaction involved in taste bud formation s

ISSN:0022-3034    

DOI:10.1002/neu.480010111

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

年代:1969

数据来源: WILEY