1. The transmission from the flexor reflex afferents (FRA) to the spino-olivocerebellar paths ascending through the ventral funiculus (VF-SOCPs; Oscarsson and Sjölund, 1977) was compared with the transmission from the FRA to segmental reflex arcs in cats with the spinal cord transected in the third cervical segment sparing only the ventral funiculus on one side. The climbing fiber responses evoked in Purkinje cells by electrical stimulation of limb nerves were monitored by recording the mass activity at the cerebellar surface simultaneously from several termination zones, while the flexion reflex was recorded from a flexor nerve and the primary afferent depolarization (PAD) from a dorsal root filament. 2. Changes in the segmental reflex responses were produced by i.v. injections of l-Dopa and Clonidine. L-Dopa produced the expected depression of the flexion reflex and the FRA-induced PAD in the FRA, whereas Clonidine depressed only the flexion reflex but did not affect or even enhanced the FRA-induced PAD in the FRA. 3. The changes in transmission to one of the ascending paths, the a-VF-SOCP, parallelled that in the flexion reflex arc. The transmission to another path, the b2-VF-SOCP, parallelled that in the pathway responsible for the FRA-induced PAD in the FRA. 4. The remaining hindlimb paths, the c1- and c3-VF-SOCPs, monosynaptically activated from primary afferents, were little influenced by the changes induced in the segmental reflex arcs. 5. It is suggested that the a- and b2-VF-SOCPs carry information related to interneuronal activity in segmental centers, whereas the c1- and c3-VF-SOCPs forward information mainly related to peripheral events.

Afferent Pathways↗

PubMed1978

Projections to lateral vestibular nucleus from cerebellar climbing fiber zones.

1. The olivary projections to the lateral vestibular nucleus (LVN), direct and excitatory through climbing fiber collaterals and indirect and inhibitory through climbing fiber activated Purkinje cells, were investigated in cats with the spinal cord transected at C3 sparing only the contralateral ventral funiculus. In this preparation all spinocerebellar paths are interrupted except the ventral spino-olivocerebellar paths (VF-SOCPs). Three FV-SOCPs responding with different latencies and receptive fields on limb nerve stimulation project to different sagittal zones in the anterior lobe vermis: the a-zone medially and the b-zone laterally in the vermis and the c1-zone in the extreme lateral part of the vermis and the medial part of the pars intermedia. 2. The EPSPs evoked through climbing fiber collaterals and the following IPSPs evoked through climbing fiber activated Purkinje cells were recorded intracellularly from LVN neurons on limb nerve stimulation. Simultaneously the climbing fiber responses evoked in Purkinje cells located in the a-, b- and c1-zones were recorded as positive potentials from the cerebellar surface. 3. Three groups of LVN neurons were distinguished: X neurons (about 20%) which did not receive excitation or inhibition from the olivary paths, aCF neurons (about 5%) which received excitation and inhibition from the olivary path projecting to the a-zone, and bCF neurons (about 75%) which received excitation and inhibition from the olivary path projecting to the b-zone. No LVN neurons were related to the c1-zone. 4. The aCF and bCF neurons occurred intermingled throughout the LVN. The X neurons occurred predominantly in its ventral part. 5. The findings are discussed in relation to a hypothesis of cerebellar organization.

Animals↗

PubMed1978

Climbing fiber microzones in cerebellar vermis and their projection to different groups of cells in the lateral vestibular nucleus.

1. The projections from one of the paths (b-VF-SOCP) in the ventral spino-olivocerebellar system to the cortical b-zone located in the lateral part of the anterior lobe vermis and to the lateral vestibular nucleus (LVN) have been studied in cats with the spinal cord transected at C3 sparing only the contralateral ventral funiculus. The projection to the b-zone was studied by recording climbing fiber responses in single Purkinje cells on stimulation of limb nerves. The projections to the LVN, direct through climbing fiber collaterals and indirect through Purkinje cells, were studied by recordings EPSPs and IPSPs in LVN neurons. 2. The Purkinje cells in the b-zone were arbitrarily divided into five groups with different inputs and occupying different microzones each with a width of about 200 micron. On passing medially across the b-zone the microzones had the following input characteristics: 1. activation exclusively from hindlimb nerves, 2. short-latency activation from hindlimb and long-latency activation from forelimb nerves, 3. short-latency activation from hindlimb and forelimb nerves, 4. short-latency activation from forelimb and long-latency activation from hindlimb nerves, and 5. activation exclusively from forelimb nerves. 3. The five microzones projected to different groups of LVN neurons which occurred intermingled throughout the nucleus. The LVN neurons inhibited from a certain microzone were activated by the collaterals of the climbing fibers projecting to that microzone. 4. The organization of the spino-olivo-cerebello-vestibulo-spinal path is discussed. It is suggested that the microzone and collection of subcortical neurons represent the basic computational unit of the cerebellum.

Animals↗

PubMed1978

Simplified micro-method for the quantitative analysis of putrescine, spermidine and spermine in urine.

A simplified micro-method for the quantitative analysis of urinary polyamines is described. After acid hydrolysis of urine, the polyamines are converted to fluorescent 1-dimethylaminonaphthalene-5-sulfonyl (Dns; dansyl) derivatives and separated by means of thin-layer chromatography. Dns-NH2, which has been reported to interfere with the determination of putrescine, is well separated from di-Dns-putrescine. Putrescine, spermidine and spermine are quantitated by in situ scanning of their fluorescent spots on the chromatogram. The present method is both sensitive and reproducible. It eliminates a number of time-consuming steps and thus reduces preparative losses. Yet an adequate chromatographic resolution is obtained. Representative polyamine analyses of urine from normal volunteers and from cancer patients are reported. Elevated levels occur in the urines of pregnant women and of patients with various types of cancer.

Chromatography, Thin Layer↗

PubMed1978

Interference with S and G2 phase progression by polyamine synthesis inhibitors.

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Cell Cycle↗

PubMed1978

Accumulation of spermidine and spermine in Ehrlich ascites tumor cells during plateau phase growth. A function of an increased fraction of G2 phase cells and polyploid cells.

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Adenosylmethionine Decarboxylase↗

PubMed1978

Tumour cell death: the probable cause of increased polyamine levels in physiological fluids.

The occurrence of extracellular polyamines in Ehrlich ascites tumour-bearing mice was studied in relation to tumour growth. The concentration of putrescine and spermidine in cell-free ascites fluid and serum was found to increase significantly with increasing tumour mass. Data is presented which suggest that the observed accumulation of extracellular polyamines is a result of a continuous release from dead or dying tumour cells. This observation is consistent with the notion that extracellular polyamines accumulate during tumour growth and following radio- and chemotherapy as a result of tumour cell death, and emphasizes the potential clinical usefulness of the polyamine analysis for evaluating tumor cell kill.

Animals↗

PubMed1978