bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of a functional adrenergic input to intraocular cerebellar grafts: Ingrowth of inhibitory sympathetic fibers
Authors: Hoffer Barry , Olson Lars , Seiger Åke , Bloom Floyd 
Published: January 2005

AbstractThe intraocular transplantation technique was used to study the ingrowth of peripheral sympathetic adrenergic nerves from the iris into transplants of fetal rat cerebellum, and the possible function of these nerves. The transplants, grown in oculo for one‐half to eight months, were analyzed by fluorescence histochemistry and electrophysiological techniques. Peripheral sympathetic adrenergic fibers from the iris were able to grow into the cerebellar transplants and arborize in a pattern similar to that in situ, appearing in all three cortical layers and the noncortical areas of the transplants. The density of visible nerves without pretreatment and after preincubation in 10−6 or 10−5 M α‐methylnorepinephrine was comparable to mature rat cerebellum.The spontaneous discharge of the Purkinje cells in oculo was inhibited by microiontophoresis of norepinephrine (NE) and amphetamine in sympathetically innervated, as well as sympathectomized transplants denervated by ganglionectomy. The NE response was blocked by the adrenergic β‐receptor blocker MJ‐1999. GABA also inhibited the Purkinje cell activity while glutamate accelerated the discharge. Parenteral amphetamine inhibited Purkinje cell activity in sympathetically innervated transplants, but was ineffective in denervated transplants.The Purkinje cell spontaneous activity was inhibited by electrical stimulation of the NE fiber input through the cervical sympathetic trunk. This inhibition could be antagonized by parenteral reserpine or the β‐adrenergic antagonist propranolol.The responses of the Purkinje cells within the transplants to drugs and transmitters mimic those of the adult rat in situ. In view of the fluorescence histochemical evidence for an ingrowth of peripheral sympathetic adrenergic fibers into the cerebellar transplants, and the results of stimulating the sympathetic trunk, it is suggested that peripheral adrenergic fibers may be able to establish functional connections with the Purkinje cells similar to the cerebellar adrenergic synapses normally formed in situ by fibers from the locus coeruleus.
Uptake of GABA by neuronal and nonneuronal cells in dispersed cell cultures of postnatal rat cerebellum
Authors: Lasher Robert S. 
Published: January 2005

AbstractA study was made of the time course and kinetics of [3H]GABA uptake by dispersed cell cultures of postnatal rat cerebellum with and without neuronal cells. The properties of GABA neurons were calculated from the biochemical difference between the two types of cultures. It was found that for any given concentration of [3H]GABA, or any time up to 20 min, GABA neurons in cultures 21 days in vitro had an average velocity of uptake several orders of magnitude greater than that of nonneuronal cells. In addition, the apparent Km values for GABA neurons for high and low affinity uptake were 0.33 × 10−6 M and 41.8 × 10−4 M, respectively. For nonneuronal cells, the apparent Km for high affinity uptake was 0.29 × 10−6 M. The apparent Vmax values for GABA neurons for high and low affinity uptake were 28.7 × 10−6 mol/g DNA/min and 151.5 mmol/g DNA/min, respectively. For nonneuronal cells, the apparent Vmax for high affinity uptake was 0.06 × 10−6 mol/g DNA/min. No low affinity uptake system for nonneuronal cells could be detected after correcting the data for binding and diffusion. By substituting the apparent kinetic constants in the Michaelis‐Menten equation, it was determined that for GABA concentrations of 5 × 10−9 M to 1 mM or higher over 99% of the GABA should be accumulated by GABA neurons, given equal access of all cells to the label. In addition, high affinity uptake of [3H]GABA by GABA neurons was completely blocked by treatment with 0.2 mM ouabain, whereas that by nonneuronal cells was only slightly decreased. Most (75–85%) of the [3H]GABA (4.4 × 10−6 M) uptake by both GABA neurons and nonneuronal cells was sodium and temperature dependent.
Norepinephrine: Adenosinetriphosphate ratios in purified adrenergic vesicles
Authors: Yen S.‐S. , Klein R. L. , Chen‐Yen, S.‐H. , Thureson‐Klein Å. 
Published: January 2005

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 vesicles.
Electrophysiological study of corticocaudate projections in cats
Authors: Blake D. J. , Zarzecki P. , Somjen G. G. 
Published: January 2005

AbstractThe potential waves evoked in the caudate nucleus (CN) of cats by stimulation of the cerebral neocortex were stereotactically recorded. The head and the body of the caudate nucleus were systematically explored. Stimulation of the ipsilateral sigmoid gyrus and the orbitofrontal cortex evoked waves with the largest amplitude in the CN. Smaller potentials were evoked from the ipsilateral ectosylvian and suprasylvian gyri and from the sigmoid gyrus on the contralateral side. Antidromic conduction from the caudate nucleus to the cortex demonstrated the directness of the corticocaudate pathway. By stimulating the white matter and by making lesions, the corticocaudate pathway was shown to pass, in part, through the subcallosal fasciculus and, in part, through the internal capsule. Corticocaudate connections were shown to be separate from the fibers of the corticospinal tract. A staggered and extensively overlapping topographic progression of the corticocaudate projections was demonstrable along the antero‐posterior axis, but was less evident in the medio‐lateral direction. It was concluded that the intranuclear distribution of functional synaptic connections must be more profusely branched than was suspected from anatomical data.
Biochemical studies of taste sensation. III. Preparation of a suspension of bovine taste bud cells and their labeling with a fluorescent probe
Authors: Brand Joseph G. , Cagan Robert H. 
Published: January 2005

AbstractA method to prepare suspensions of taste bud cells is described. Bovine circumvallate papillae, which contain most of the taste buds in this animal, are incubated in collagenase‐containing medium and the epidermal sidewall tissue is then dissected from the inner gelatinous dermis. The sidewall tissue, which contains the taste buds, is gently homogenized by manual operation of an all‐glass homogenizer with a loose‐fitting pestle. The suspended material is separated on a discontinuous Ficoll gradient (2%, 8%, 10%, 12% w/w). The material banding at the 8–2% interface is greatly enriched in spindle‐shaped cells that are morphologically similar to taste bud cells as they appear in situ. These cells are not seen when the procedure is done with tissues devoid of taste buds, namely the upper surface of the circumvallate papilla or epithelium from the intermolar eminence.Fluorescence analysis indicates that the hydrophobic probe, 8‐anilino‐1‐naphthalenesulfonate (ANS), binds to relatively nonpolar sites in the suspension. It is postulated that the probe is adsorbing onto the surface membrane of the cell.These preparations may be useful in studying specificity and transduction in taste sensation.
Fast axonal transport in motor nerve regeneration
Authors: Griffin John W. , Drachman Daniel B. , Price Donald L. 
Published: January 2005

AbstractThis report describes the fast axonal transport of [3H]‐leucine‐labeled proteins in regenerating rat sciatic motor nerves. A normal rate of fast transport (383 ± 33 mm/day) was present in the regenerating sprouts, as well as in the central stumps. The rapidly transported proteins passed the level of axotomy without impediment, and accumulated in the endings of the regenerating sprouts, as shown by electron microscope autoradiography. In addition, transported proteins accumulated in terminal neuromas. The relative amount of protein‐incorporated radioactivity in the crest of fast transport in the regenerating nerves was increased compared to control nerves. These results are interpreted to suggest that the mechanism of fast transport is the same in regenerating sprouts as in normal axons; during regeneration fast transport appears to add newly synthesized materials to the growing tip.
Evidence for a multiple innervation of purkinje cells by climbing fibers in the immature rat cerebellum
Authors: Crepel Francis , Mariani Jean , Delhaye‐Bouchaud Nicole 
Published: January 2005

AbstractClimbing fiber (CF)–‐Purkinje cell (PC) relationships were studied electrophysiologically on the cerebellum of 8 to 15 day old rats. Some animals were rendered agranular by x‐irradiation from birth; some others were treated with 3‐acetyl pyridine 3 days before study to selectively destroy the CF. Unitary extracellular recordings in 8–9 day old normal rats revealed that more than 50μ of the PC units each exhibited either two types of all‐or‐none climbing fiber responses (CFR) or stepwise graded CFRs. The other PC units only presented one type of all‐or‐none CFR. These activities were entirely mediated via CF since they persisted at the same age in x‐irradiated rats, but were absent in animals treated with 3‐acetyl pyridine. Interaction experiments were performed between juxtafastigial and Inferior Olive stimulations on 49 PC units in 8–9 day old normal rats. Collisions between impulses set up in CFs were disclosed in 21 out of the 24 PCs which exhibited only one type of CFR. In the three others and in each of the 25 PCs that displayed two types of all‐or‐none CFRs, or CFRs graded by steps, no collision was detected. Moreover intracellular recordings of epsp's mediated via CFs in PCs of 8–9 day old normal rats revealed that they frequently fluctuated in stepwise fashion. These results demonstrate that in the immature rat more than 50μ of PCs are each innervated by at least two distinct CFs; later on, the disappearance of the supernumerary synapses between CF and PC leads, as early as day 15, to the one‐to‐one relationship between CF and PC.
Lipochondria and the light response ofAplysiagiant neurons
Authors: Baur Paul S. , Brown A. M. , Rogers T. D. , Brower Margaret E. 
Published: January 2005

AbstractThe ultrastructure, absorbance, and elemental content of lipochondria present in the cytoplasm ofAplysiagiant neurons have been investigated before and after 30–1,200 sec doses of white light at intensities which produce saturated light responses. The effects of exposure to the calcium ionophore A‐23187 and to EGTA were also examined. The lipochondria of nonilluminated neurons are membrane‐bound, and contain lipids, protein, Na, K, Mg, Ca, Si, Cl, Br, P, and a pigment which is probably β‐carotene. The cytoplasm appeared to have little pigment. When neurons were illuminated for 20 min, 60–70% of the lipochondria showed marked ultrastructural alterations, the most notable being the appearance of membranous material. Earlier changes which occur after 30 sec of illumination include the appearance of paracrystalline arrays and mottling. Less than 10% of lipochondria in nonilluminated neurons have a similar appearance. These effects were greatly enhanced in illuminated neurons exposed to the calcium ionophore or EGTA. In nonilluminated neurons, the ionophore also produced ultrastructural changes. In frozen specimens, the calcium content of the most electron dense lipochondria of illuminated neurons was reduced. Other elements which were counted were also reduced. The lipochondria are the main intracellular site of photopigment. They may also act as an intracellular source for calcium which, as the accompanying paper indicated, may mediate phototransduction inAplysianeurons.
Internal calcium concentration and potassium permeability in Paramecium
Authors: Satow Youko 
Published: January 2005

AbstractCa or EGTA was ionophoretically injected into Paramecium tetraurelia to change [Ca]1. Ca decreased the resting membrane resistance and hyperpolarized the membrane. EGTA had the opposite effect. EGTA following TEA, which suppress GK, had little effect on resistance or resting potential. The I—V relation at steady state was studied before and after EGTA injection while the cell bathed in either K‐ or TEA‐solution. The response to inward test pulses after EGTA injection was similar to that after TEA injection. These results show that [Ca]i controls a steady‐state K permeability in Paramecium tetraurelia.A prolonged Ca‐spike was recorded after EGTA injection. The plateau potentials in various Ca concentrations in a TEA‐solution show the Nernst slope (29 mV for tenfold change in [Ca]0). This result suggests that the prolonged depolarization in this condition is due to a Ca current, after suppression of K‐permeability and when [Ca]i is low. The difficulty of obtaining quantitative data an the internal Ca, and the difference between the effects of EGTA injection and TEA injection are discussed.
Neurobiology of Polyorchis. I. Function of effector systems
Authors: Spencer A. N. 
Published: January 2005

AbstractThe electrical correlates of activity in the effector systems responsible for swimming, crumpling and postural changes have been recorded in the anthomedusan Polyorchis penicillatus.Motor spikes (pre‐swim pulses), that initiate swimming contractions, appear without delay at distant sites on the inner nerve‐ring in unstimulated preparations. Levels of Mg++ anaesthesia which block the neuromuscular junctions between PSP giant neurons and swimming muscle do not affect PSP activity.Swimming muscle potentials can be recorded from subumbrella and velar muscle sheets using extra‐ and intracellular electrodes. These action potentials have a distinct plateau and are propagated in a myoid fashion. Resting potentials average −70 mV with spikes overshooting zero by some 62 mV. The effects of repetitive stimulation are described.Extracellular recordings indicate that neuronal pathways may play a major role in mediating crumpling, unlike many other species where epithelial pathways are more important. Endodermal spikes recorded intracellularly from the radial and ring canals have amplitudes of some 92 mV arising from resting potentials that average −55 mV. Repetitive stimulation causes a decrease in amplitude and increase in duration of epithelial action potentials.Tentacle length is controlled by a pacemaker system located in both nerve rings. The frequency of spikes (PTPs) generated by this system determines the length and tonus of tentacles. The neuromuscular junctions between the motor neurons and tentacle muscle are Mg++ sensitive and show facilitating properties.
Feeding motor program inLimax. I. Neuromuscular correlates and control by chemosensory input
Authors: Gelperin Alan , Chang Joseph Jin , Reingold Stephen C. 
Published: January 2005

AbstractThe feeding motor program (FMP) of the terrestrial slugLimax maximuswas examinedin vivoandin vitro.The feeding pattern of intact animals shows an initial increase in bite frequency followed by a plateau phase. Recordings obtained from semi‐intact preparations of the lips, brain, and buccal mass established the correlation of activity in buccal ganglion nerve roots with the protraction‐retraction bite cycle. A preparation of the lips, cerebral ganglia, and buccal ganglia was developed, such that, repetitive chemostimulation of the lips yields reproducible bouts of FMP. Sources of proprioceptive feedback from buccal muscles were demonstrated. The feasibility of computer scoring of the FMP is documented. These results demonstrate that aspects ofin vivofeeding behavior are retained and identifiable in highly dissected,in vitropreparations.
Effects of amino acids on calcium uptake by glial and neuroblastoma cells
Authors: Borg Jacques , Mark Jean , Mandel Paul 
Published: January 2005

AbstractThe uptake of [45Ca] has been studied in clonal glial and neuronal cells. It was somewhat more efficient in the neuroblastoma clone M1 compared to glial clones. In all cases [45Ca] uptake was shown to depend on the phosphate concentration in the incubation medium. It was decreased by the ionophore A 23187 at 200 μM concentration in both neuronal and glial clones. The influence of amino acids some of which are putative neurotransmitters was investigated; the interactions between [45Ca] uptake and these amino acids were related to their concentration and the type of cells used (neuronal or glial). L‐aspartate and taurine for example had two opposite effects on [45Ca] uptake by the glial clone NN at two different concentrations; they could therefore play a role in the control of calcium level in the synaptic cleft.
Inhibition of spinal interneuronal activity by repeated cutaneous stimulation: A possible substrate of flexor reflex habituation
Authors: MacDonald J. F. , Pearson J. A. 
Published: January 2005

AbstractThe responses of interneurones, situated in the lumbar region of the rat spinal cord, to repeated cutaneous stimulation, were studied. The main purpose of this investigation was to attempt to determine the extent to which habituation of the flexor reflex might be explained on the basis of a progressive development of inhibition. Spontaneously active interneurones, which were inhibited by cutaneous stimuli, were investigated in detail. In rats whose spinal cords were intact, the period of inhibition was shown to increase with successive stimuli. This increase in inhibition was directly related to the intensity and frequency of stimulation, occurred more rapidly during a second series of stimuli and was antagonized by strychnine. In spinal animals, an increase in the duration of the period of inhibition to repeated stimulation could not be demonstrated. In this preparation, a gradual decrease in inhibition occurred. It is tentatively concluded that inhibition of spinal interneurones, the development of which depends upon descending influences from supraspinal centres, may be partially responsible for habituation.
Biochemical studies of taste sensation. VII. Enhancement of taste stimulus binding to a catfish taste receptor preparation by prior exposure to the stimulus
Authors: Cagan Robert H. 
Published: January 2005

AbstractThe technical assistance of Ardithanne Boyle, Linda Graham and Pamela Burke is appreciated. I thank Dr. H. Ronald Kaback and Dr. Leonard D. Kohn for their suggestions of experiments relevant to transport questions. This research was supported in part by NIH research grant No. NS‐08775 from NINCDS.The taste receptor membrane fraction (Fraction P2) was prepared from a homogenate of the taste tissue of the channel catfish Ictalurus punctatus. This included the rostral, dorsal, and dorsolateral surfaces of the catfish in addition to those of the barbels. The yield of Fraction P2 is 4–7 mg protein from an individual fish, with a purification averaging 8‐ to 15‐fold over that of the crude whole homogenate and essentially quantitative recovery of binding activity in Fraction P2.Treatment of Fraction P2 in vitro with a high concentration of the taste stimulus molecule L‐alanine led to a several‐fold enhancement of binding activity. Enhancement of the binding of 3H L‐alanine was observed after treatment with unlabeled 10mM L‐alanine and removal of the L‐alanine by washing. Enhancement occurred whether the preparation was stored frozen (−65°C) for an extended period in the presence of the L‐alanine, or merely exposed to it in the cold without freezing. D‐Alanine enhanced the binding activity of 3H L‐alanine to about 60% of the level induced by L‐alanine. Nonspecific binding of 3H L‐alanine was unaffected by the treatment. Scatchard analyses of saturation curves for binding of 3H L‐alanine to freshly prepared Fraction P2 and to L‐alanine‐treated Fraction P2 revealed no change in the KD value, but a several‐fold increase occurred in the amount bound.Binding activity is operationally defined. Because the enhancement observed here is reminiscent of an increase in transport due to a countertransport effect, further studies were carried out to examine whether the phenomenon reflects transport or true binding. The measured binding was not increased in the presence of Na+, indicating that it is not due to an Na+‐ coupled transport of L‐alanine. When Fraction P2 was preloaded with L‐alanine (10−6 – 10 −2M) prior to assay, no stimulation of binding was observed; instead, binding decreased. This result is consistent with a true binding phenomenon but not with a carrier‐mediated transport process to expiain the enhancement phenomenon. Binding assays carried out over a range of osmolarities revealed decreased binding at high osmotic strengths, suggesting that a significant portion of the ligand might be contained in vesicles.It is postulated that “hidden” or “buried” receptor sites exist in the Fraction P2 as isolated, and that these are exposed upon perturbation of the membrane structure by ahigh ligand concenration.
Ultrastructure of Aplysia neurons having different degrees of light sensitivity
Authors: Krauhs J. M. , Andresen M. C. , Baur P. S. , Brown A. M. 
Published: January 2005

AbstractThe relationship between ultrastructure and photosensitivity of pigmented neurons of the abdominal ganglion of Aplysia californica was investigated using electron microscopy and electrophysiological methods. Four identified neurons of similar light microscopic appearance were examined; two are photoresponsive and two are not. Illumination hyperpolarizes both responsive neurons. One of them, R2, requires roughly 100 times greater light intensities than does the other, the ventral photoresponsive neuron (VPN), for similar responses. Two neurons lying adjacent to VPN and similar in appearance to VPN do not have measurable electrophysiological responses to even the highest light intensities. All four neurons contained lipochondria, pigmented organelles associated with the light response. Therefore the presence of these organelles is not the only requirement for light sensitivity in these neurons. Illumination appeared to increase the number of membranous lipochondria in both R2 and the ventral neurons, but only in R2 was this increase significant. Factors such as the concentration of lipochondria near the plasma membrane may affect quantitative aspects of the light response, but in the insensitive cells the lipochondria are apparently uncoupled from other factors required for the light response.