bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alteration of neuronal activity in response to cyclic nucleotide agents in Aplysia
Authors: Drake Peter F. , Treistman Steven N. 
Published: January 2005

AbstractResponsiveness of Aplysia neurons to agents that affect cyclic nucleotide levels was not limited to neurons exhibiting a spontaneous bursting activity pattern. Analyses of the I‐V relationship elicited by triangular current ramps within cells exposed to different agents presumably causing elevated cyclic nucleotide levels showed qualitatively similar alterations. These included an increased slope conductance at more negative potentials, possibly related to anomalous rectification, and the induction of a hysteresis in response to a triangular ramp. The paired metacerebral giant cells showed induction of synchronous bursting when exposed to phosphodiesterase inhibitors, and we examined this phenomenon more closely. classical methods to inactivate a presynaptic source did not eliminate the induction of synchronous bursting. Intracellular injection of a phosphodiesterase inhibitor into a metacerebral giant cell caused changes in the current‐voltage relationship similar to those described above for other cells. Subsequent perfusion with the inhibitor caused an enhancement of these effects and the induction of bursting. The alternation of the current‐voltage plot in the metacerebral cells and abdominal ganglion cells is qualitatively similar to that induced in the similarly treated bursting neuron R15, suggesting a similar mechanism of action in both burster and nonburster neurons. The implications of these results for cyclic nucleotide mediation of neuronal events are discussed.
Calcium independence of slow currents underlying spike frequency adaptation
Authors: Donald Partridge L. 
Published: January 2005

AbstractThis study assessed the role of calcium in the activation of the slow potassium current responsible for spike frequency adaptation in molluscan neurons. Inward calcium currents were eliminated by using Co2+, Cd2+, or OCa2+ EGTA in the bathing solution. In each case adaptation was found to persist, as did the slow current believed to be responsible for adaptation. Injection of EGTA into neurons was also found not to block adaptation. This potassium current provides an example of a slow voltage‐dependent potassium process which is independent of calcium influx.
A peptide action in a lobster neuromuscular preparation
Authors: Schwarz Thomas L. , Harris‐Warrick Ronald M. , Glusman Silvio , Kravitz Edward A. 
Published: January 2005

AbstractThe neuropeptide proctolin causes a sustained contraction of the opener muscle of the dactyl of the lobster walking leg. This substance acts directly on the muscle at concentrations as low as 10−10M. The contraction is dependent on extracellular calcium. Neither a significant depolarization nor a detectable change in the input resistance accompanies the response. No presynaptic action of proctolin is indicated; excitatory and inhibitory junctional potential sizes and the frequency of spontaneous miniature excitatory junctional potentials are unaffected.
Dipteran flight motor pattern: Invariabilities and changes during postlarval development
Authors: Kutsch W. , Hug W. 
Published: January 2005

AbstractFor Calliphora the wingbeat frequency and the underlying motoneuronal activity were recorded during adult life. Wingbeat frequency increases during the ten days following last molt. The activity of motoneurons serving four selected flight muscles (nonfibrillar and fibrillar ones) also increases with age. The motoneuronal activity of young and old flies was analyzed statistically (serial and cross‐correlograms, latency and phase histograms). In addition, several wing manipulations were carried out to evaluate the significance of sensory feedback on pattern generation during maturation. These ontogenetic studies suggest a centrally generated motor pattern that (1) is essentially complete with the molt to adulthood, (2) shows a progressive increase in intrinsic activity, and (3) is modulated by sensory feedback from the wing region by the same amount irrespective of age. Similarities in the postlarval development of the flight pattern of neurogenic and myogenic flyers are discussed.
Age‐dependent anatomical changes in an identified neuron in the cns of Aplysia californica
Authors: Papka R. , Peretz B. , Tudor J. , Becker J. 
Published: January 2005

AbstractNeurons of Aplysia californica are naturally pigmented and the pigment accumulates with age. In the present study the pigment was examined in the same neuron from Aplysia of three postmetamorphic ages: young, sexually mature, and old. The large central neuron, R2, was examined by light and electron microscopy to determine if the pigment possessed properties similar to lipofuscin pigment seen in aging mammalian neurons. We used the same microscopic techniques that demonstrate the presence of lipofuscin in mammalian neurons. Light microscopic studies demonstrated a regional correlation between autofluorescence, staining with Sudan Black, and the naturally occurring pigment in old R2s. Electron microscopic studies revealed the presence of large vacuolated and lamellated membrane‐bound bodies in the peripheral cytoplasm of old R2s, similar to those found in mammalian neurons. The bodies were located in the same region in which autofluorescence and Sudan Black staining were observed. Although the naturally occurring pigment accumulates with age, it acquires characteristics of lipofuscin pigment in the neurons of older sexually mature animals. The presence of these pigment characteristics can be used as an index of aging in Aplysia neurons as they are in mammalian neurons.
Age‐dependent behavioral changes and physiological changes in identified neurons in Aplysia californica
Authors: Rattan Kuldip S. , Peretz Bertram 
Published: January 2005

AbstractThe gill withdrawal reflex (GWR) to direct gill stimulation was studied in sexually mature Aplysia and in those older by at least two months. The GWR threshold in old Aplysia was five‐ to sevenfold higher than that in mature animals. In the habituation paradigm, the GWR amplitude decremented rapidly to zero in old animals whereas in mature animals it persisted for at least ten trials. The GWR could not be dishabituated in old animals. The GWR is an age‐dependent behavior in that parieto‐visceral ganglion suppression of the GWR appears to increase with age. Also the electrophysiological properties of two neurons in the parieto‐visceral ganglion were compared in the two age groups: L7 a neuron which dishabituates the GWR in mature and not in old animals; and R2 which manifests cytological changes with age. In old animals L7′s input resistance was lower, the time constant was increased, and the size of the psp evoked by gill stimulation was smaller than those of mature L7s. Similar membrane changes with age were measured in R2. Soma size of L7 was approximately the same in the two age groups as was that of R2. The physiological parameters of neurons of known function continue to change during postmetamorphic life of Aplysia.
Effect of fatty acids on the membrane fluidity of cultured chick dorsal root ganglion measured by fluorescence photobleaching recovery
Authors: Takenaka Toshifumi , Horie Hidenori , Kawasaki Yukishige 
Published: January 2005

AbstractThe effect of fatty acids on the membrane fluidity in tissue cultured chick embryo dorsal root ganglion was studied by fluorescence recovery method. Lateral motion of the lipid was measured by observing the fluorescent probe, 5‐(octadecylthiocarbamoylamino) fluorescence, F18. The effective lateral diffusion coefficient of the membrane was around 0.30 × 10−8 cm2/sec in control cells, 0.42 × 10−8 cm2/sec in 2‐decenoic acid treated cells, and 0.35 × 10−8 cm2/sec in valeric acid treated cells. From these results it is concluded that effective mobilities of the membrane complex increased about 40% by the external application of 2‐decenoic acid, while valeric acid increased it only 12%. From the physiological results that 2‐decenoic acid inhibits the Na‐channel, it is suggested that this increase in the membrane fluidity might affect the Na‐channel.
Subcellular localization of neutral red staining in Limulus ventral photoreceptors
Authors: Chamberlain Steven C. , Battelle Barbara‐A. , Calman Bruce G. 
Published: January 2005

AbstractLimulus ventral photoreceptors are vitally stained by neutral red. In other systems such staining has been correlated with the presence of monoamines or neuropeptides. The stained cellular components in ventral photoreceptors are clusters of small ovoids which have been identified as residual bodies. These structures are unlikely candidates for monoamine or neuropeptide synthesis or storage sites, but may be part of the cyclic synthesis and degradation of photosensitive membrane. While vital staining with neutral red is a particularly useful method for identifying certain classes of neurons in vivo, in the case of ventral photoreceptors, the association of the vital staining property with the presence of a particular class of neurotransmitter candidates has proven difficult. Neutral red is useful, however, for visualizing the segmentation of ventral photoreceptors in vivo.
Localization of calcium in nerve fibers
Authors: Chan S. Y. , Ochs S. , Jersild R. A. 
Published: January 2005

AbstractUsing the desheathed nerve preparation, a pyroantimonate precipitation method was used to examine the distribution of electron‐dense particles seen in various organelles of the nerve fibers following exposure of nerve to various levels of Ca2+ in vitro. The presence of Ca2+ in the electron‐dense particles was indicated by their extraction with EGTA and by the use of energy‐dispersive X‐ray microanalysis.In normal Ringer or in a Ca2+‐free medium, electron‐dense particles were seen associated with the outer membrane of the mitochondria, with the smooth endoplasmic reticulum (SER), along the axolemma and yet others scattered throughout the axoplasm.When nerves were incubated in media containing higher than normal concentrations of 20–60 mM Ca2+, an increase in the number of such electron‐dense particles was seen in the axoplasm and within the mitochondrial matrix. Nerves loaded with a high concentration of 60mM Ca2+ could be depleted of these particles after transfer to a Ca2+‐free or low Ca2+ Ringer medium.The sequenstration of Ca2+ in axonal organelles is discussed with respect to Ca2+‐regulatory mechanisms in the axon needed to maintain a low level of Ca2+ which is optimal for the support of axoplasmic transport.
Fast axonal transport in central nervous system and peripheral nervous system axons following axotomy
Authors: Redshaw J. D. , Bisby M. A. 
Published: January 2005

AbstractAfter axotomy, changes in the composition of fast axonally transported proteins (FTP) within the peripheral nervous system (PNS) axons have been reported. The most significant and reproducible changes involved polypeptides found within the molecular weight range of 31.0 to 14.5 kilodaltons (Bisby, 1980). We wished to determine whether similar changes following axotomy occur in axons of the central nervous system (CNS). Intracranial axotomy of the left optic tract was performed stereotaxically in rats. Six days post axotomy 50 μCi 35[S]‐methionine was injected into the vitreous body of both eyes. FTP were isolated within the optic nerves 2 h after isotope injection. The nerve segments were processed for SDS‐PAGE, fluorography, and compared to similarly prepared fluorographs of normal and eight day postaxotomy sciatic nerve segments. The labelling of 5 major polypeptide bands (S1, MW ≃ 28,000; S2a, MW ≃ 25,000; S2b, MW ≃ 23,000; T1, MW ≃ 20,200; and T2, MW ≃ 17,000) was studied by laser densitometry. Band S2b showed a highly significant (p < 0.001) increase in concentration, while bands S1 and T1 demonstrated highly significant decreases in concentration following axotomy of the sciatic nerve. In contrast, after axotomy of the retinal ganglion cell axons the only significant change was a decrease (p < 0.05) in T1. We suggest that failure of CNS axons to respond similarly to PNS axons following axotomy may be related to the failure of CNS axons to regenerate.
Neuromuscular modulation in Limulus by both octopamine and proctolin
Authors: Rane Stanley G. , Gerlach Peter H. , Wyse Gordon A. 
Published: January 2005

AbstractBoth octopamine and proctolin potentiate nerve‐evoked skeletal muscle contractions in the horseshoe crab, Limulus. The threshold concentration for octopamine was 10−9 to 10−8M, while for proctolin it was 3 × 10−9M. Norepinephrine and dopamine produced effects similar to octopamine but at higher thresholds; tyramine and serotonin were ineffective. Octopamine caused significant increases in amplitudes of excitatory postsynaptic potentials (epsps) of muscle fibers, but had little effect on muscle fiber input resistance or membrane potential. Also, octopamine did not affect depolarization of muscle fibers and subsequent contraction due to the direct action of exogenously applied glutamate. These results suggest that octopamine potentiates nerve‐evoked contractions primarily by facilitating release of neuromuscular transmitter. At concentrations above 10−7M, however, octopamine sometimes caused muscle spikes in response to motoneuron stimulation, a finding that suggests that octopamine may also have some postsynaptic action. Proctolin potentiated the muscle contractions evoked by glutamate but had little effect on glutamate‐evoked muscle fiber depolarization, muscle fiber input resistance, or membrane potential. Thus, proctolin appears to act directly on skeletal muscle to enhance contractility. The proctolin‐induced potentiations of contraction were sometimes accompanied by modest increases in epsp amplitude, so that unlike lobster skeletal and Limulus cardiac neuromuscular preparations, proctolin may have a secondary direct synaptic effect. Both octopamine and proctolin have been found in Limulus cardiac ganglion. This potential access to the hemolymph and the relatively low threshold concentrations needed for physiological action suggest that octopamine and proctolin could function as hormonal modulators of neuromuscular function in Limulus.
Depression of fast axonal transport produced by tullidora
Authors: Muñoz‐Martínez E. J. , Massieu D. , Ochs S. 
Published: January 2005

AbstractThe fast axoplasmic transport of labeled proteins was studied in cats showing hindlimb paralysis 4–7 weeks after a single oral dose of tullidora (Karwinskia humboldtiana) toxins. The isotope (3H‐leucine) was injected into the spinal ganglion and the contralateral spinal cord of the seventh lumbar segment in order to study transport in sensory and motor fibers.The axoplasmic transport in motor fibers of the sciatic nerve was clearly altered in tullidora‐treated cats. The majority of these animals showed a gradual decline of radioactivity from the cord to the periphery instead of the clear‐cut wave front always seen in normal cats. An apparent wave was seen in three treated cats but the wave peak was behind the normal position and the slope of the wave front was reduced. While the rate of transport indicated by the farthest extent of the foot of the slope was not in all cases significantly changed, the results all indicated a hindered transport by the reduced slope front in the distal segments of the motor axons. In contrast, the axoplasmic transport appeared normal in the sensory fibers of all but one tullidora‐treated cat.Light and electron microscopy of medial gastrocnemius and sural (cutaneous) nerves revealed axonal constrictions and axolemal irregularities associated with organelle retention after tullidora treatment. Also, some mitochondria appeared swollen. These changes were more frequent and intense in the motor nerve fibers than in the cutaneous nerve fibers.
Sprouting and functional regeneration of an identified serotonergic neuron following axotomy
Authors: Murphy A. Don , Barker David L. , Loring Jeanne F. , Kater S. B. 
Published: January 2005

AbstractAn identified serotonergic neuron (C1) in the cerebral ganglion of Helisoma trivolvis sprouts following axotomy and rapidly (seven to eight days) regenerates to recover its regulation of feeding motor output from neurons of the buccal ganglia. The morphologies of normal and regenerated neurons C1 were compared. Intracellular injection of the fluorescent dye, Lucifer Yellow, into neuron C1 was compared with serotonin immunofluorescent staining of the cerebral and buccal ganglia. The two techniques revealed different and complimentary representations of the morphology of neuron C1. Lucifer Yellow provided optimal staining of the soma, major axon branches, and dendritic arborization. Immunocytochemical staining revealed terminal axon branches on distant targets and showed an extensive plexus of fine fibers in the sheaths of ganglia and nerve trunks. In addition to C1, serotonin‐like immunoreactivity was localized in approximately 30 other neurons in each of the paired cerebral ganglia. Only cerebral neurons C1 had axons projecting to the buccal ganglia. No neuronal somata in the buccal ganglia displayed serotonin‐like immunoreactivity.Observations of regenerating neurons C1 demonstrated: (1) Actively growing neurites, both in situ and in cell culture, displayed serotonin‐like immunoreactivity; (2) severed distal axons of C1 retained serotonin‐like immunoreactivity for up to 28 days; (3) axotomized neurons C1 regenerated to restore functional control over the feeding motor program.
Modulation of a respiratory motor program by peptide‐secreting neurons in Aplysia
Authors: Schaefer Mark , Brownell Philip H. 
Published: January 2005

AbstractRespiratory pumping of the gill and siphon of Aplysia californica is a fixed‐action pattern coordinated by a defined set of interneurons and motor neurons. In semi‐intact preparations of the gill and siphon innervated by the abdominal ganglion, respiratory pumping is facilitated for a prolonged period following activation of the peptidergic bag cell neurons. The induced changes in contractile behavior of the gill and siphon correlate with cell specific actions of the bag cells on motor neurons regulating these organs. Our results suggest that peptidergic neurons can alter the expression of a fixed pattern of behavior by modulating the excitability of motor neurons controlling the behavior.
Steroid interactions with structure and function of avian song control regions
Authors: DeVoogd Timothy J. 
Published: January 2005

AbstractFollowing the pioneering work of Nottebohm, the brain regions involved in song production in songbirds have become a focus of extensive research in several laboratories. As both singing behavior and the neuroanatomy of song control regions are strongly affected by sex steroids in many songbird species, this system has become regarded as an ideal model system in which one can potentially determine how steroids affect neuronal anatomy, how altered anatomy leads to altered physiology, and how the altered physiology causes changes in singing. In the initial part of this review, I shall focus on canaries and zebra finches as most of our knowledge of the song system has been obtained from these two species. I shall describe singing behavior, the constituents of the song system, what is known of how these nuclei contribute to song, and how each is affected by steroid fluctuations. I shall then speculate on new ways of posing questions on hormone—anatomy interaction in this system (which I will illustrate with preliminary data from my own lab). This review will be brief as several reviews of aspects of the song system have recently been published (Arnold, 1982; Nottebohm, 1984; Arnold and Gorski, 1984; DeVoogd, 1984; Konishi, 1985).
Effects of octopamine on miniature excitatory junction potentials from developing and adult moth muscle
Authors: Klaassen Leland W. , Kammer Ann E. , Fitch Greg K. 
Published: January 2005

AbstractIntracelluar recordings of excitatory junction potentials (EJPs) and miniature EJPs (MEJPs) were made from the dorsal longitudinal muscle of Manduca sexta to determine the sites of action of octopamine. MEJPs increased in amplitude and frequency as the moth developed during the 3 days before eclosion. DL‐Octopamine (5 × 10−6M) increased the amplitude of excitatory junction potentials in both immature moths (one day before eclosion) and adults. Octopamine (10−5M) also increased the amplitude and frequency of MEJPs from immature animals (one and two days before eclosion) but had the opposite effect on adults and pharate adults ready to eclose. Treatment with octopamine (10−5M) resulted in a decrease in input resistance and a hyperpolarization in both immature and adult muscle fibers.The results suggest that octopamine acts both presynaptically and postsynaptically but that the increase in the amplitude of the evoked response is due primarily to influences on presynaptic processes.
Serotonin immunoreactivity of neurons in the gastropod Aplysia californica
Authors: Longley Roger D. , Longley Alison J. 
Published: January 2005

AbstractSerotonergic neurons and axons were mapped in the central ganglia of Aplysia californica using antiserotonin antibody on intact ganglia and on serial sections. Immunoreactive axons and processes were present in all ganglia and nerves, and distinct somata were detected in all ganglia except the buccal and pleural ganglia. The cells stained included known serotonergic neurons: the giant cerebral neurons and the RB cells of the abdominal ganglion. The area of the abdominal ganglion where interneurons are located which produced facilitation during the gill withdrawal reflex was carefully examined for antiserotonin immunoreactive neurons. None were found, but two bilaterally symmetric pairs of immunoreactive axons were identified which descend from the contralateral cerebral or pedal ganglion to the abdominal ganglion. Because of the continuous proximity of this pair of axons, they could be recognized and traced into the abdominal ganglion neuropil in each preparation. If serotonin is a facilitating transmitter in the abdominal ganglion, these and other antiserotonin immunoreactive axons in the pleuroabdominal connectives may be implicated in this facilitation.
Silencing normal input permits regenerating foreign afferents to innervate an identified crayfish sensory interneuron
Authors: Krasne Franklin B. 
Published: January 2005

AbstractInterneuron A, an identified first‐order sensory interneuron that is innervated by mechanoreceptors on one side of the crayfish tailfan, normally resists extra innervation by regenerating contralateral mechanoreceptor axons. However, if its normal innervation is silenced by covering mechanosensory hairs with a surgical glue, it accepts contralateral innervation. This finding on an arthropod provides evidence for the generality and antiquity of the principle, critical in development of the vertebrate nervous system, that activity of one set of afferents can control whether other afferents form synapses on a target.