摘要:

AbstractSynaptosomes from the rat medulla and spinal cord have been examined in an attempt to formulate morphological criteria for distinguishing between those found in two subfractions of P1(nuclear fraction). The mean diameter of those in the lighter of the subfractions (P1C) is 0.6 μm, with a preponderance in the range 0.4–0.6 μm and a minor peak at 0.7–0.8 μm. Subjunctional bodies are associated with 60.2% of the junctional regions in this subfraction. By contrast, those in the heavy subfraction (P1D) have a larger overall diameter (0.7 μm), a greater percentage of them have visible junctional regions (68.1% opposed to 51.6%), but of the junctional regions a lower percentage have associated subjunctional bodies (36.2%).The subjunctional bodies consist of a central core with five spokes radiating from it. The tips of the spokes are connected by fine strands which connect individual bodies to neighboring ones, as well as to the postsynaptic thickening. The persistence of subjunctional bodies in synaptosomes highlights the strergth of the attachment between them and the postsynaptic thickening, and suggests that these bodies may be integral components of the “postsynaptic thickening complex.” They may also help in the formulation of criteria by which different populations of these synaptosomes may be separated from

ISSN:0022-3034    

DOI:10.1002/neu.480070102

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

年代:1976

数据来源: WILEY

摘要:

AbstractNorepinephrine (NE):adenosinetriphosphate (ATP) ratios were studied in a highly purified fraction of large dense core vesicles isolated from the bovine splenic nerve. Vesicles prepared from nerves chilled ∼10 and 30 min post mortem were compared. The NE:ATP molar ratio decreased from 6.3 to 4.8,p<0.005; NE decreased from 61 to 42 nmol, while ATP decreased only from 9.6 to 8.8 nmol/mg protein. Animals weighing 180‐360 kg were compared with heavier ones weighing 400‐700 kg. NE increased from 42 to 68 nmol and ATP increased from 5.9 to 13.2 nmol/mg protein, while the NE:ATP molar ratio decreased from 7.2 to 5.2,p<0.005. Changes during vesicle maturation were studied by comparing vesicles identically prepared from equal weights of a proximal nerve segment close to the coeliac ganglion and a distal, intrasplenic segment. NE increased from 45 to 70 nmol while ATP remained unchanged at 10.0 nmol/mg protein and the NE:ATP molar ratio increased from 4.5 to 7.0,p<0.005. It was interpreted that vesicle ATP content, like dopamine β‐hydroxylase, was established early in the cell body and remained unchanged during axoplasmic transport. ATP was in a complex which was relatively stable to post mortem hydrolysis at least between 10 and 30 min prior to chilling the nerves. The addition of newly synthesized NE into a readily releasable pool during axoplasmic transport occurs without ATP and can account for the increased ratio above 4:1 in the distal segment

ISSN:0022-3034    

DOI:10.1002/neu.480070103

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

年代:1976

数据来源: WILEY

摘要:

AbstractForty‐six analogs ofL‐glutamate were tested for activity on muscle fibers in the walking limbs of lobsters. Effects on the membrane potential, input resistance, and amplitude of neurally evoked EPSPs and IPSPs were studied as well as effects on appliedL‐glutamate. Seventeen of the compounds studied depolarized the muscle fibers in a manner indicative of an agonistic action on receptors in the neuromuscular excitatory membrane. Six analogs selectively reduced the amplitude of evoked EPSPs, and at least three of these (kainic acid,D‐glutamate, andD‐aspartate) antagonized the excitatory action of appliedL‐glutamate. Kainic acid was the most potent of the blockers of neuromuscular excitation, but even it was relatively weak since a concentration of 1 mMwas required for an apparent effect. Generally those analogs in the l‐configuration which possessed activity, had agonistic actions, whereas those in the d‐configuration were usually antagonistic.These observations provide pharmacological evidence for the concept thatL‐glutamate is the transmitter agent which mediates neuromuscular excitation in the walking limbs of lobsters. In addition, our results are consistent with recent studies which indicate that l‐aspartate may also function in this neuromuscular

ISSN:0022-3034    

DOI:10.1002/neu.480070104

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe effects of anisomycin (ANM) on newborn chicks have been studied with respect to brain protein synthesis, growth, EEG, toxicity, and several passive avoidance learning tasks. It was found that intracerebral ANM (80 nmol) gave a maximum inhibition of brain protein synthesis of 30%, while a combination of subcutaneous (10 μmol; 53 mg/kg) plus intracerebral (80 nmol; 21 μg) ANM, inhibited by 91% in the first 2 hr and by 75% in the subsequent 2 hr period. Cycloheximide (CXM) also in combined injections at the same doses as ANM, inhibited by 97% in the 4 hr that followed injection. However, all the CXM‐injected chicks were dead by 18 hr, while the lethality of ANM did not differ from that of saline. ANM also did not affect EEG measured at 1, 3, 5, or 24 hr following the subcutaneous plus intracerebral injections, nor did ANM affect body or brain growth curves or brain protein accretion.In the learning experiments, animals were initially trained to peck at water‐coated metal spheres (type A learning) or at water‐imbibed birdseed (types B and C learning) in less than 1 sec, and were exposed to the same lures treated with the aversant methylanthranilate (MeA) one day later on one occasion (types A and B learning) or exposed twice (type C learning) and tested for learning retention one day later. Learning criterion was set as failure to peck at the lure during the first 20 sec of presentation. If ANM was injected 1 hr prior to MeA exposure, large and highly significant memory deficits were found during the retention test, as compared with saline injected controls. No effect of ANM was seen, however, if it was injected one day after learning, indicating that it did not interfere with retrieval mechanisms. ANM also decreased the external manifestations of fear or displeasure that chicks express during retention testing. Such manifestations have a high correlation with pecking suppression (r= 0.88,P

ISSN:0022-3034    

DOI:10.1002/neu.480070105

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

年代:1976

数据来源: WILEY

摘要:

AbstractCombined differential and density gradient centrifugation was used for the isolation of a capillary‐rich fraction from the cerebral cortex and a brush border containing fraction from the bovine choroid plexus.The activities of γ‐glutamyl transpeptidase and several other marker enzymes were monitored during the fractionation procedure. Electron microscopic examination showed a membrane‐rich fraction in the choroid plexus high in γ‐glutamyl transpeptidase and 5'‐nucleotidase activities. From the brain cortex, a capillary‐rich fraction was obtained which was high in γ‐glutamyl transpeptidase and alkaline phosphatase activities. A histochemical examination showed γ‐glutamyl transpeptidase activity localized in

ISSN:0022-3034    

DOI:10.1002/neu.480070106

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

年代:1976

数据来源: WILEY

摘要:

AbstractFive‐hydroxy tryptamine (5‐HT) causes a hyperpolarization and increased conductance of the leech body wall muscle cell membrane. If 5‐HT is applied in the absence of the Cl−ion, the response appears as a depolarization, whereas if 5‐HT is applied in the absence of the K+ion, the response is a hyperpolarization. In both cases, the conductance of the muscle cell membrane is increased. Stimulation of the peripheral nerve to the body wall muscle produces a complex junctional potential in muscle cells. Exposing the muscle tod‐tubocurarine (d‐TC) eliminates the excitatory component (EJP) of the complex potential. The inhibitory potential (IJP) that remains has an equilibrium potential at approximately 65 m V. Furthermore, this IJP appears as a depolarization when the nerve is stimulated in the presence ofd‐TC and low CL−, whereas this is not the case if the nerve is stimulated in the presence ofd‐TC and low K+. The drugs BOL‐148 and cyproheptadine block the IJP's in the body wall muscle. These data are interpreted as indicating that 5'HT acts on leech body wall muscle cells by increasing the conductance to the Cl−ion and that the IJP's caused by nerve stimulation are probably the result of 5‐HT release at nerve terminals.As a final point, it has been shown that the inhibition by 5‐HT of the spontaneous EJP's that occur on the leech body wall muscle results from an inhibition of central neurons and not from any direct effect on the muscle cel

ISSN:0022-3034    

DOI:10.1002/neu.480070107

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

年代:1976

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480070108

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

年代:1976

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480070109

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

年代:1976

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480070110

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

年代:1976

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480070101

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

年代:1976

数据来源: WILEY