摘要:

AbstractEffects of biogenic amines on a centrally generated motor pattern inManduca sextawere examined by pressure injecting nanomole to micromole amounts of octopamine, dopamine or serotonin into thoracic ganglia. Motor output was recorded extracellularly from a pair of antagonistic flight muscles and their motor neurons. The monoamines were found to alter production of a motor pattern that produces rhythmic wing flapping (10 Hz) and exhibits phase relationships similar to those in the flight pattern of intact moths.In mesothoracic ganglia with sensory nerves intact, octopamine (4 × 10−9mol) injected into lateral regions evoked regular firing of a single motor neuron, whereas a higher dose (4 × 10−8mol) often elicited the flight motor pattern. In the absence of sensory input, these doses of octopamine had little effect. Low doses (10−10mol) greatly enhanced motor responses to electrical stimulation of a wing sensory nerve.Dopamine (2 × 10−10mol) injected into the medial region of the mesothoracic ganglion elicited the flight motor pattern in the presence or absence of sensory input. Rhythmic output induced by dopamine (5 × 10−10mol) was suppressed by injecting serotonin (5 × 10−10mol) into the same region.These findings demonstrate that dopamine, octopamine, and serotonin have different effects on motor output inManducaand suggest that these amines are involved in initiating, maintaining and terminating flight behavior, respectively. Octopamine may elicit flight production by enhancing the efficacy of sensory transmission thereby increasing excitability or arousal. Dopamine may act on interneurons involved in generating the flig

ISSN:0022-3034    

DOI:10.1002/neu.480170102

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

年代:1986

数据来源: WILEY

摘要:

AbstractRecent studies have shown that soluble calcium activated proteases (calpains) in brain degrade proteins associated with the cytoskeleton and vary markedly in activity across regions and as a function of development. It was suggested that the observed differences in calpain activity reflect differences in the turnover rate of structural elements. The present study extends this analysis by measuring the properties and activity of calpain in representatives of the five classes of vertebrates with particular emphasis on the mammals.No evidence for proteolysis was found in soluble fractions of fish brains at neutral pH in the presence or absence of added calcium. A substantial calcium‐independentproteolytic activity was found in amphibian brains—the effects of a variety of protease inhibitors indicated that it is also a neurtral thiol (cysteine) protease. Reptilian brains exhibited both calcium‐independent and calcium‐dependent proteolytic activity. Virtually all proteolytic activity in birds (5 species) and mammals (9 species) measured at neutral pH was calcium‐dependent. The endogenous substrates for the calcium activated proteases were very similar in several species of birds and mammals as were the effects of a variety of protease inhibitors. However, the activity of the enzyme, expressed per mg of soluble protein, was highly and negatively correlated with brain size in the mammals. The allometric expression for this relationship was similar to that found for the density of neurons in cerebral cortex as a function of absolute brain size. These results indicate that soluble proteolytic enzymes in brain are differentially expressed among classes of vertebrates and suggest that the turnover of cytoskeletal elements in birds and mammals differs in important ways from that found in fish and amphibians. The results obtained for mammals raise the possibility of a relationship between brain size and the rate at which structural elements are broken down and replaced in this vertebr

ISSN:0022-3034    

DOI:10.1002/neu.480170103

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

年代:1986

数据来源: WILEY

摘要:

AbstractNeurons of the motor nerve net ofCyanea capillatawere examined using video‐enhanced DIC optics. A variety of organelles were visible within the axons and many were mobile. To quantify the movement organelles were divided into three classes (large, medium, and small) and the rates, direction, and types of movement displayed by the different particle types examined. The overall behavior and rates of movement of transported particles were camparable with those in axons from other species. The largest particles, mainly mitochondria were the slowest moving but were the only particles to reverse their direction of movement or to undergo interactions with other particles. The fastest movement was by the small particles, but both they and medium sized particles were transported continuously. In addition, the linear elements in these axons underwent considerable lateral movemen

ISSN:0022-3034    

DOI:10.1002/neu.480170104

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

年代:1986

数据来源: WILEY

摘要:

AbstractMammalian neocortical tissues were incubated in [14C] adenine‐containing fluids and their newly‐synthesized adenine derivatives examined after periods of superfusion. Increased [K+] released adenine derivatives from the tissues, a release diminished by homocysteine. Homocysteine acted also to diminish the tissue content of adenosine plus its metabolites hypoxanthine and inosine, while increasing that ofS‐adenosylhomocysteine. Hypoxia also increased the tissue content and the output of adenosine plus its metabolites, and again homocysteine augmented theS‐adenosylhomocysteine. Glutamic acid also increased tissue content and output of adenosine and derivatives, an action diminished by homocysteine and associated with augmentedS‐adenosylhomocysteine. Colchicine or dipyridamole did not prevent augmentation ofS‐adenosylhomocysteine by the reagents described; the sequence from adenosine phosphates toS‐adenosylhomocysteine is concluded to be intracellular and not to involve extracellular formation of precursor adenosine. Adenosine displayed properties consistent with its being involved in two distinct categories of homeostasis, and also with its exerting an inhibitory tone in normal cer

ISSN:0022-3034    

DOI:10.1002/neu.480170105

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

年代:1986

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480170106

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

年代:1986

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480170107

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

年代:1986

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480170108

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

年代:1986

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480170101

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

年代:1986

数据来源: WILEY