bluuebunny/crossref_metadata_2025 huggingface dataset:
Post mortem changes in the content and specific radioactivity of several amino acids in four areas of the rat brain
Authors: Shank R. P. , Aprison M. H.
Published: January 2005

The contents of alanine, aspartate, GABA, glutamate, glutamine, glycine, serine, and lactic acid were measured in the cerebral hemispheres, midbrain, cerebellum, and pons‐medulla of rats killed by immersion into liquid nitrogen or by decapitation. The head of each decapitated rat was frozen as described. Only in the cases of lactic acid, alanine and GABA were marked post‐mortem changes observed within a few minutes after death. In rats killed 7 and 15 min after an intraperitoneal injection of (U−14C) glucose, there was a post‐mortem increae in the specific activity of GABA relative to glutamate. These post‐mortem changes in GABA support the idea that of the carbon units oxidized via the tricarboxylic acid cycle approximately 10% pass through the GABA bypath. These data are also consistent with the view that multiple pools of both glutamate and GABA exist in brain tissue.
Subcellular fractionation of cultured glial cells
Authors: Cotman C. , Herschman H. , Taylor D.
Published: January 2005

We have studied the subcellular fractionation of a clonal line of glial cells from rat brain. In comparison to rat brain, more of the total protein is collected in the crude nuclear fraction following differential centrifugation. When a crude mitochondrial fraction is prepared and resolved on a density gradient, we find that like brain the glial cell crude mitochondrial fraction is also heterogenous. On a sucrose density gradient, such as that used for the preparation of synaptosomes, the glial cell crude mitochondrial fraction resolves into two major fractions. One of these bands sediments to the same isopycnic density as synaptosomes. This fraction contains 20% of the protein, and 50% of the Na‐K ATPase and acid phosphatase of the crude mitochondrial fraction, but virtually no cytochrome oxidase or choline esterase. The fraction consists of numerous membrane structures resembling plasma membranes when examined by electron microscopy. Because the sedimentation properties of the glial membranes are very similar to synaptosomes, we conclude that synaptosomes prepared on sucrose gradients are probably contaminated by these membrane fragments. In contrast to the separation achieved on sucrose gradients, glial membranes separate from synaptosomes on Ficoll‐sucrose gradients.
Re‐Innervation of smooth muscle of the vas deferens transplanted into the anterior chamber of the eye
Authors: Malmfors T. , Furness J. B. , Campbell G. R. , Burnstock G.
Published: January 2005

Pieces of vas deferens were transplanted into the anterior chamber of the eye in guinea pigs. The transplants were observed in vivo and then removed and examined with cellular methods. Changes occurring in smooth muscle cells and in nerves were examined with the electron microscope and with the fluorescence histochemical method. Neuromuscular transmission in the transplant was examined with microelectrode and organ bath methods. Four main phases were distinguished in transplants between 2 days and 14 weeks (the oldest transplants examined): (1) initial degeneration of nerves and muscles; (2) vascularization followed by the onset of regeneration of muscle at 3 to 4 days; (3) re‐innervation by nerves from the iris and muscle‐bundle formation beginning at 1 to 2 weeks; (4) restitution of functional neuromuscular transmission beginning at about 4 weeks. The number of adrenergic nerves grandually increased, but even at 14 weeks, the overall density was less than in a normal adult preparation. Nevertheless, neuromuscular transmission was comparable to that in a normal vas deferens. The factors involved in the regeneration of single muscle fibers, the formation of muscle bundles and neuromuscular relationships, and the regulation of reinnervation density are discussed.
Central projection of sensory fibers from the cat knee joint
Authors: Clark Frank J.
Published: January 2005

The dorsal column projections of individual primary afferent fibers from the posterior articular nerve innervating the cat knee have been studied. The majority of fibers not projecting to cervical levels in the dorsal columns supply slowly adapting receptors. These fibers undergo a reduction in conduction velocity shortly after entering the dorsal columns and terminate in the upper lumbar to lower thoracic region of the spinal cord.
Spreading depression in tissue culture
Authors: Walker Franklin D. , Hild Walther J.
Published: January 2005

A method is described to record neuronal activity, steady potential, and the impedance of mammalian neural tissue maintained in culture without the perturbation of explants by the introduction of electrodes into the culture. A phenomenon similar, if not identical, to spreading depression is demonstrated and can be produced by a high concentration of potassium, by mechanical or electrical stimuli. The presence of neurons is not required for the characteristic dc shift and impedance changes recorded during this condition. The rate of neuronal activity in explants from various brain areas can be reduced by small additions of potassium which could be generated by neuroglia during spreading depression.
Neurite development in vitro. I. The effects of adenosine 3′5′‐cyclic monophosphate (cyclic AMP)
Authors: Roisen Fred J. , Murphy Richard A. , Braden Wanda G.
Published: January 2005

Elevated levels of 3′5′ adenosine monophosphate (cyclic AMP) stimulate a wide variety of cellular events including aggregation, differentiation, morphological expression, pigment migration, and secretion. The role of cyclic AMP in these events prompted our present study of embryonic chick dorsal root ganglia. Test substances were applied to cultures during the routine feeding procedure. Their development was quantitatively evaluated on the basis of explant size, length of glial‐like outgrowth, distribution of growth, neurite number, length, diameter, and degree of arborization. These parameters were all shown to be independent of each other. The high variability of in vitro neurite development necessitated the use of over 100 cultures per treatment group. Cultures treated with 5′ AMP exhibited no significant differences from controls. Those treated with cyclic AMP, dibutyryl cyclic AMP, or Nerve Growth Factor (NGF) exhibited statistically significant increases in area of outgrowth, the number of neurites per culture, and in diameters, lengths, and degree of neurite arborization. The growth promoting activity of dibutyryl cyclic AMP and NGF were greater than those of cyclic AMP. Electron microscopic study shows neurites formed under the influence of cyclic AMP or its dibutyryl derivative to resemble those grown in NGF. These studies suggest the possibility that cyclic AMP stimulates neurite growth by mediating the process of microtubule (MT) assembly. They further prompt us to speculate that one way NGF enhances neurite development is by stimulating MT assembly via a “Second Messenger System”.
Surface culture of fetal mammalian brain cells: Effect of subculture on morphology and choline acetyltransferase activity
Authors: Schrier Bruce K.
Published: January 2005

Cells from brains of fetal rats were grown in surfece cell culture for up to 46 days and were subjected to two subculturing cycles with mild trypsin treatment. The cells maintained their characteristic morphology into third passage, and some putative neurons developed the ability to abhere directly to plastic surfaces. The specific activity of choline acetyl‐transferase reached higher levels in third than in first passage cultures. An increase of at least 34‐fold was obtained in the total activity of enzyme, the major increments occurring during first and third passages. The data suggest that choline acetyltransferase‐producing cells may be capable of multiplication in culture.
Effects of lidocaine on axonal morphology, microtubules, and rapid transport in rabbit vagus In vitro
Authors: Byers Margaret R. , Fink B. Raymond , Kennedy Ross D. , Middaugh Mical E. , Hendrickson Anita E.
Published: January 2005

Treatment with lidocaine, at exposures which completely block impulse conduction and rapid axonal transport, resulted in a sequence of morphological effects on rabbit vagus never in vitro. Low exposures (0.3% for 90 min, 0.4% for 45 min, 0.6% for 25 min) caused a reorientation and proliferation of smooth endoplasmic reticulum (SER); the number of axonal microtubules either remained normal or was increased. Intermediate exposures (0.4% for 90 min, 0.6% for 45 min) Produced a similar effect on the SER, as well as causing a 50% reduction in microtubule number and some swelling of axons and Schwann cells. The highest exposure (0.6% for 75 min) caused over 90% reduction in microtubule number, a partial loss of neurofilaments, and severe swelling of axons, Schwann call, and mitochondria. Reversibility of these effects was tested in lidocaine‐treated nerves that had been washed with fresh culture medium. There was good recovery of nerve exposures. After intermediate exposures, there was only partial return of rapid transport, even though imposures, there was morphological, and no recovery occured throughout the excised vagus nerve in efferent and afferent axons as well as Schwann cells, and these events did not coincide with changes in the functional state of rapid axonal transport.
Incorporation of [35S] sulfate into chondroitin sulfates by organized cultures of murine peripheral, sympathetic and central nervous tissues
Authors: Uzman Betty G. , Murray Margaret R. , Saito Hidehiko
Published: January 2005

Organized cultures of mouse dorsal root ganglia (PNS), cerebellum (CNS), and sympathetic chain ganglia (ANS) were exposed to feeding media containing radioactive Na235SO4 for 10 day periods beginning either at the onset of myelination or during myelin maintenance. During this period, the used medium was collected at each of three feedings and frozen. Some cultures were frozen and together with the collected medium were analyzed for mucopolysaccharides (MPS). Sister cultures were fixed in ruthenium red‐glutaraldehyde and processed for [35S] radioautography by light microscopy, and cellular localization of MPS by electron microscopy. [35S] MPS were isolated from both cultures and medium (by alkali treatment, proteolytic digestion, TCA treatment, and dialysis, followed by precipitation with cetylpyridinium chloride and ethanol). Isolated MPS were analysed by paper chromatography after digestion with chondroitinase‐ABC and testicular hyarulonidase. Fifty‐five to seventy‐five percent of the total sulfated MPS formed in all types of cultures were chondroitin sulfates (Ch‐S) A, B, and C,

ChS‐A, ChS‐B, and ChS‐C are used throughout to indicate chondroitin ‐4‐ sulfate, dermatan sulfate, and chondroitin ‐6‐ sulfate, respectively

chondroitin sulfate A accounting for 50 to 60% of the total MPS. PNS and ANS exceeded CNS cultures in total sulfated MPS formed by 10:1.

Qualitatively, CNS cultures produced a higher proportion of ChS‐C and a lower proportion of ChS‐B compared to PNS and ANS. Rutheniumred positive material covered all types of cell surfaces, collagen fibers, and the surfaces of enveloped axons; the layers of compact myelin and its underlying axon‐Schwann cell interface showed no such staining, though it appeared regularly in the external mesaxon.
Axoplasmic transport of RNA
Authors: Bondy Stephen C. , Madsen Carol Jean
Published: January 2005

The transport of RNA from the ganglion cell bodies within the retina to the contralateral optic tectum has been studied in the chick following intraocular injection of radioactive uridine. By tracing the appearance of labeled RNA at the proximal end of the optic nerve as it leaves the eyeball and comparing this to the time of arrival of RNA within the optic tectum, the migratory velocity of axonal RNA has been calculated to be around 12 mm per day. The continuation of RNA migration to the optic tectum in the presence of intracerebrally injected actinomycin‐D but not in the presence of the intraocularly injected drug, suggests a retinal site of synthesis of the excess RNA found in the tectum innervated by the injected eye. A study of the rate of disppearance of radioactivity of the transported RNA in the optic lobes, suggested that this RNA turns over more rapidly than the bulk of tectal RNA. The destination of migrating RNA within the optic tectum has been autoradiographically examined. Most radioactive RNA is found in the outer tectal layers in which are found the afferent fibers of the optic tract and most of their synaptic terminations. Label is not confined to these areas however but is also present in the deeper layers of the optic tectum which are not known to contain any primary synapses of the axons from retinal ganglion cells.
Interconversion of glycine and serine in a synaptosome fraction isolated from the spinal cord, medulla oblongata, telencephalon, and cerebellum of the rat
Authors: McBride W. J. , Daly E. , Aprison M. H.
Published: January 2005

The metabolism of glycine was studied in vitro using preparations of synaptosomes (P2) isolated from the spinal cord, medulla oblongata, telencephalon, and cerebellum of the rat. The content of aspartate, glutamate, glutamine, serine, threonine, glycine, and alanine was determined in the crude synaptosomal fraction (P2) from the four regions of the CNS. In general, the content of the amino acids in the subcellular fraction from the medulla oblongata and spinal cord resembled one another whereas the same was true for the telencephalon and cerebellum. Significantly greater amounts of glutamate, aspartate, glutamine, and serine were found in the synaptosomal fraction of the telencephalon and cerebellum than in similar P2 fractions from the medulla oblongata and spinal cord. On the other hand, glycine had a higher content in the latter two preparations than in the P2 fractions from the telencephalon and cerebellum. [U‐14C]‐serine and [U‐14C]‐glycine were readily taken up by the crude synaptosomal fractions. The rate of conversion of serine to glycine appeared to be 18.5, 3.9, 2.9, and 2.7 times greater than the conversion of glycine to serine in the incubated synaptosomal fractions from the cerebellum, spinal cord, medulla oblongata, and telencephalon, respectively. The conversion of serine carbons into glycine appeared to be 2.5, 1.9 and 1.6 times greater in the synaptosomal fraction from the cerebellum, spinal cord, and medulla oblongata than in similar preparations from the telencephalon. The data are discussed in terms of the possible synthesis pathway for the pool of glycine used as a transmitter.
The cholinergic excitatory and inhibitory postsynaptic responses of Aplysia ganglion cells during and after lithium‐ringer perfusion
Authors: Ono Hirohisa , Sato Makoto , Maruhashi Juro
Published: January 2005

The excitatory and inhibitory postsynaptic responses of Aplysia ganglion cells were elicited by either stimulating cholinergic afferent fibers or by topically applying acetylcholine (ACh) to the cell under study. The responses were evaluated as an increase in membrane conductance and compared before, during, and after perfusion with Li+‐Ringer. Excitatory postsynaptic responses were significantly depressed during 30–60 min of Li+‐Ringer perfusion. Upon return to normal Ringer, they increased sharply beyond the control, showing post‐Li+ augmentation.

Inhibitory postsynaptic responses were augmented during 30–60 min of Li+‐Ringer perfusion when the cells were examined before treatment with anticholinesterase. After treatment with neostigmine, however, they were found to be also depressed in Li+‐Ringer. This finding suggested a suppressing effect of Li+‐Ringer on the acetylcholinesterase (AChE) activity.

The reversal potential of ACh‐induced depolarizing response was altered from the normal value of –25 mV to –5 mV during 1–2 hr of Li+‐Ringer perfusion and gradually returned to normal value in 2–3 hr after return to normal Ringer. The reversal potential of ACh‐induced hyperpolarizing response remained practically unchanged (–62 mV) during 1–2 hr of Li+‐Ringer perfusion.

Post‐Li+ augmentation of ACh‐induced depolarizing responses was explained by an increase in driving force for Na+ movement resulting from a depletion of intracellular Na+. The systematic shift of the dose‐response curves during Li+‐Ringer perfusion suggested that the affinities of both excitatory and inhibitory receptors to ACh are depressed and the effect is greater on the excitatory receptors.
Some chemical and electrophysiological effects of glutamate in cerebral cortex
Authors: Kaczmarek L. K. , Adey W. R.
Published: January 2005

The efflux of 45Ca2+ and 3H‐GABA from cat cerebral cortex has been measured in vivo by a superfusion technique. Under control conditions, the efflux of both these isotopes is sensitive to increments in the calcium concentration of the superfusion medium but insensitive to the addition of 25 mM GABA. After 40 min of contact with medium containing 25 mM glutamate, however, neither 45Ca2+ nor 3H‐GABA efflux is affected by added Ca2+ but 3H‐GABA efflux becomes considerably enhanced by 25 mM GABA. The mean membrane potentials at this time were found to be less than controls. Depolarization generally continued past this time, recovery beginning 150 min after superfusion with glutamate. Peaks in 45Ca2+ efflux were also correlated with seizure activity which was sometimes elicited by topical glutamate. It is suggested that the transport systems for Ca2+ and GABA may be sensitive to states of neural activity, such as spreading depression.
Physiological and pharmacological properties of Purkinje cells in rat cerebellum degranulated by postnatal X‐irradiation
Authors: Woodward D. J. , Hoffer B. J. , Altman J.
Published: January 2005

Elimination of most granule, basket, and stellate interneurons in the rat cerebellum was achieved by repeated doses of low level x‐irradiation applied during the first two weeks of postnatal life. Purkinje neurons in these rats, studied when adults, exhibited sustained spiking activity in Halothane anesthetized preparations. Mean firing rates were 35‐‐40/sec, no different from normal. Spontaneous bursts presumed to be generated by climbing fiber synaptic activity differed from normal by often consisting of full sized spikes rather than characteristic inactivation responses. Intracellularly observed correlates of bursts consisted of epsp's of several discretely different amplitudes appearing independently in time. Stimulation of white matter revealed evidence for, (a) graded synaptic excitation of Purkinje cells indicating more than one converging excitatory synapse, and (b) inhibitory actions on Purkinje cells either through a few remaining inhibitory interneurons or through Purkinje cell recurrent collaterals. Iontophoretic drug application studies showed normal chemosensitivity of the Purkinje cell membrane, i.e., excitation by glutamate and inhibition by gamma‐amino butyric acid, serotonin, norepinephrine, and 3′5′ cyclic AMP.

These studies indicate considerable autonomy of Purkinje cell ontogenesis in the absence of normal interneuronal input. A unique synaptic relation only rarely found in normal cerebellum is the innervation of single Purkinje cells by more than one climbing fiber.
Electrolyte‐ and fluid‐spaces of rat brain in situ after infusion with dinitrophenol
Authors: Baethmann A. , Sohler K.
Published: January 2005

Chemical distribution measurements of radioactive sodium‐thiosulfate (35S) and of the brain water indicate that infusion of 2.4‐dinitrophenol into a carotid artery of rats caused a water uptake and fluid shifts from the extra‐ into the intracellular compartments in the central nervous system.

The extracellular marker compound was administered to the brain via ventriculo‐cisternal perfusion and intravenous injection yielding almost equal concentrations in plasma‐ water and perfusate. In order to prevent an active efflux of the label from the tissue, high concentrations were utilized in the perfusate to saturate potential outward transport mechanisms. The indicator space (based on total brain water) was 16% in controls and 12% in experimental animals when marker equilibrium had been attained, which is equivalent in reduction of the extracellular space of about 1/4. Intracellular water and Na+ rose after DNP, while K+ remained all but unchanged.

The fluid shift into the intracellular compartment was found to relate closely with a cellular uptake of Na+. The Na+ concentration both in plasma and in the perfusion fluid leaving the ventricular system was consistently reduced in experimental animals. The K+ concentration was significantly elevated in the plasma of experimental animals but virtually unchanged in the cisternal effluate.
Biosynthesis of catecholamines in organotypic cultures of the peripheral autonomic nervous system: Modifications by biopterin and other agents
Authors: Cöté L. J. , Benitez H. H. , Murray M. R.
Published: January 2005

Organotypic cultures of chick‐embryo sympathetic ganglion chains maintained in vitro for 3–4 weeks rapidly synthesized catecholamines, as demonstrated by the conversion of L‐[U‐14C]tyrosine to catechol derivatives and by histofluorescence assay. The biosynthesis of catechols from radioactive L‐tyrosine leveled off at 6 hr of incubation and dropped slightly at 10 hr. The addition of DL‐α‐methyl‐p‐tyrosine to the culture medium did not affect protein synthesis, but produced a complete block in the synthesis of catecholamines from L‐tyrosine, with consequent loss of fluorescence in the bodies and proximal processes of adrenergic neurons in 2 hr, and essentially complete loss in 6 hr. Our observations suggest that a major portion of the catecholamines were synthesized in the perikarya and transported via neuronal processes to their terminals. The addition of monoamine oxidase inhibitors to the incubation medium produced a moderate to pronounced increase in fluorescence; reserpine caused a rapid and profound loss of catecholamines. When added to the culture medium, crude biopterin produced an increase in the synthesis of catechol derivatives from radioactive L‐tyrosine and a marked increase in fluorescence, beginning in the neuronal perikarya. This effect was completely blocked by DL‐α‐methyl‐p‐tyrosine. The mechanism of biopterin's action in the synthesis of catecholamines in cultures of sympathetic ganglia is not completely elucidated from these studies, but may be related to the role it plays as cofactor for tyrosine hydroxylase.
Cooperative interaction of glutamate and aspartate with receptors in the neuromuscular excitatory membrane in walking limbs of the lobster
Authors: Shank R. P. , Freeman A. R.
Published: January 2005

When applied to lobster muscle fibers, L‐glutamate, L‐aspartate, and combinations of the two amino acids can induce membrane depolarization. Under normal conditions, a quantitative analysis of the depolarization response or change in membrane conductance was precluded by nonlinearities in the voltage—current relationship of the membrane. By including γ‐aminobutyrate (GABA) in the bathing medium, the voltage—current relationship was made linear in the depolarizing direction over a range of 15–20 mV from the resting potential. However, a meaningful examination of the increase in membrane conductance caused by glutamate and aspartate was still not possible. Therefore, the depolarization responses caused by the excitatory amino acids were taken as a quantitative reflection of receptor activation in the excitatory postsynaptic membrane. In the presence of GABA, aspartate by itself, at concentrations up to 10 mM, had little excitatory activity, whereas glutamate effected an appreciable membrane depolarization at concentrations of 0.1 to 0.2 mM. Aspartate, at concentrations which exhibited no activity alone, markedly enhanced the excitatory action of glutamate. Aspartate shifted the glutamate dose‐response curve to the left, but did not appear to affect the maximum depolarization response elicited by glutamate. These observations are consistent with the concept that aspartate increases the affinity between glutamate and the glutamate binding sites. Limiting slopes of log‐dose versus log‐response curves for the excitatory action of glutamate suggest that the interaction of glutamate with excitatory receptors is a cooperative process. The possibility exists that individual receptors contain multiple and distinct glutamate and aspartate binding sites. These results support the view that neuromuscular excitation in the lobster is mediated by glutamate and asparate functioning synergistically.
Axonal transport of RNA during regeneration of the optic nerves of goldfish
Authors: Ingoglia Nicholas A. , Weis Peddrick , Mycek John
Published: January 2005

The distribution of radioactive RNA and RNA precursors in the goldfish optic tecta following intraocular injection of 3H‐uridine has been studied during various stages of optic nerve regeneration. 3H‐uridine was injected into the posterior chamber of the right eye 17, 30, or 60 days after both optic nerves were crushed. Fish were sacrificed at time intervals ranging from 0.5 to 21 days after injection. One day prior to sacrificing, 14C‐proline was also injected into the right eye as a marker of fast axonal protein transport. Seventeen to 23 days after crushing, the approximate time of nerve reconnection, the amount of radioactive RNA appearing in the left optic tectum was increased by more than ten times control values. Approximately 30 days after crushing the nerve, when the reconnected nerve is maturing, RNA values were still elevated, but significantly decreased from the earlier stage. By 60 days after crushing the optic nerve, the amounts of RNA in the left tectum was close to normal. Evidence suggesting that, at least, some of the radioactive RNA in the tectum originated from RNA transported along optic axons rather than from RNA synthesized locally in the tectum was provided by autoradiographic experiments. Autoradiograms of paraffin sections taken from the goldfish optic tecta after the intraocular injection of 3H‐uridine showed a distribution of grains in a linear pattern, suggesting a distribution over the incoming fibers during the reconnection stage of regeneration. Electron microscopic autoradiography of glutaraldehyde fixed epoxy sections confirmed that a significant number of grains (shown to be 3H‐RNA) were, in fact, over regenerating optic axons. Intracranial injection of 3H‐uridine, during the same stage of regeneration, on the other hand, resulted in a distribution of grains, specifically over cell perikarya. These experiments suggest that during the reconnection phase of nerve regeneration, large amounts of RNA may be carried within regenerating optic axons as they enter the optic tectum.
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

The 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

A 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

Norepinephrine (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

The 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

A 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

This 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

Climbing 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

The 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

Ca 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

The 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

The 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

The 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

The 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.