Developmental Changes in the Calcium Dependency of γ‐Aminobutyric Acid Release from Isolated Growth Cones: Correlation with Growth Cone Morphology

Taylor, Joanne; Gordon‐Weeks, Phillip R.

doi:10.1111/j.1471-4159.1989.tb11780.x

Cited by 40 publications

(42 citation statements)

References 36 publications

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“…Isolated growth cones have also been found to accumulate 3H-GABA or 3H-noradrenaline (Gordon-Weeks et al, 1984; Lockerbie et al, 1985). The accumulation of 3H-GABA et al l 5-HT and Growth Cones by growth cones has also been confirmed by EM radioautography (Taylor and Gordon-Weeks, 1989). Enrichment of vesicular markers in the IGC fraction relative to their concentration in the LSS fraction was investigated in order to determine whether growth cones contain synaptic vesicles.…”

Section: Discussionmentioning

confidence: 93%

Synaptic properties of serotonergic growth cones in developing rat brain

1994

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In order to gain insight into the events that take place when serotonergic growth cones are remodeled into synapses, we tested the hypothesis that neurotransmitter-related properties of presynaptic terminals are already present in these growth cones before synaptogenesis begins. The ontogeny of markers for the specific reuptake of 5-HT and for 5-HT-storing synaptic vesicles was studied in isolated growth cone (IGC) fractions from developing rat brain. High- affinity 3H-imipramine binding (a marker for the plasma membrane 5-HT transporter) was significantly enriched in IGC fractions prepared before the beginning of cortical synaptogenesis [embryonic day 15 (E15) and E20]. Radioautography with 3H-imipramine or 3H-paroxetine (another marker for the transporter) confirmed that the 5-HT transporter is present in the cerebral cortex when it contains serotonergic growth cones, but not serotonergic synapses. Specific uptake of 3H-5-HT was found in IGC fractions as early as E15; this uptake was inhibited by fluoxetine. Electron microscopic radioautography demonstrated directly that growth cones were the structures in IGC fractions that took up 3H- 5-HT. The synaptic vesicle protein synaptophysin and a 45 kDa protein found specifically in serotonergic synaptic vesicles, serotonin-binding protein (SBP), were each enriched in IGC fractions from E15 to postnatal day 5; SBP immunoreactivity increased approximately 10-fold between E15 and E20. Endogenous 5-HT was detected in IGC fractions at E15 and increased in amount as development proceeded. The ratio of 5-HT to 5-hydroxyindole acetic acid suggested that 5-HT within growth cones is protected from catabolism by monoamine oxidase. Reserpine-induced depletion of 5-HT, a marker for the vesicular carrier of 5-HT, was apparent in IGC fractions at E20, but not at E15. These data suggest that properties that characterize the presynaptic components of mature serotonergic synapses develop in growth cones before synapses are formed. The early development of these properties may permit neurotransmission to be established rapidly during synaptogenesis or, alternatively, enable 5-HT to play a role in ontogeny.

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Section: Discussionmentioning

confidence: 93%

Synaptic properties of serotonergic growth cones in developing rat brain

1994

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“…Before P6, neuronal growth cones isolated from neonatal rat forebrain have been shown to extrude GABA in a calcium-independent manner. By P11, however, 50% of K+ -stimulated GABA release becomes calcium dependent (Taylor and Gordon-Weeks, 1989). The calciumindependent release appears to be mediated by a reversal of the GABA transporter (Taylor and Gordon-Weeks, 1991).…”

Section: Discussionmentioning

confidence: 98%

Embryonic and postnatal expression of four gamma-aminobutyric acid transporter mRNAs in the mouse brain and leptomeninges

1996

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The distribution of gamma-aminobutyric acid (GABA) transporter mRNAs (mGATs) was studied in mouse brain during embryonic and postnatal development using in situ hybridization with radiolabeled oligonucleotide probes. Mouse GATs 1 and 4 were present in the ventricular and subventricular zones of the lateral ventricle from gestational day 13. During postnatal development, mGAT1 mRNA was distributed diffusely throughout the brain and spinal cord, with the highest expression present in the olfactory bulbs, hippocampus, and cerebellar cortex. The mGAT4 message was densely distributed throughout the central nervous system during postnatal week 1; however, the hybridization signal in the cerebral cortex and hippocampus decreased during postnatal weeks 2 and 3, and in adults, mGAT4 labeling was restricted largely to the olfactory bulbs, midbrain, deep cerebellar nuclei, medulla, and spinal cord. Mouse GAT2 mRNA was expressed only in proliferating and migrating cerebellar granule cells, whereas mGAT3 mRNA was absent from the brain and spinal cord throughout development. Each of the four mGATs was present to some degree in the leptomeninges. The expression of mGATs 2 and 3 was almost entirely restricted to the pia-arachnoid, whereas mGATs 1 and 4 were present only in specific regions of the membrane. Although mGATs 1 and 4 may subserve the classical purpose of terminating inhibitory GABAergic transmission through neuronal and glial uptake mechanisms, GABA transporters in the pia-arachnoid may help to regulate the amount of GABA available to proliferating and migrating neurons at the sub-pial surface during perinatal development.

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“…GAT-mediated GABA accumulation (Hatten et al 1984) and release (Taylor and Gordon-Weeks 1989) was observed in the perinatal brain well before synapses are formed. GABA can be released by stimulation with high K + in a Ca 2+ -independent manner from isolated growth cones due to a reversal of the plasma membrane GABA transporters (Taylor et al 1990;Taylor and GordonWeeks 1991).…”

Section: Gaba Release From Growth Cones Via Plasma Membrane Gaba Tranmentioning

confidence: 97%

GABA signalling during development: new data and old questions

et al. 2001

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In addition to being the major inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) is thought to play a morphogenetic role in embryonic development. During the last decade, considerable progress has been made in elucidating the molecular mechanisms involved in GABA synthesis and biological action. The present review is an attempt to summarise recent results on the ontogeny of the different components of embryonic GABA signalling with an emphasis on the synthesis of GABA by different molecular forms of glutamic acid decarboxylase (GAD).

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Developmental Changes in the Calcium Dependency of γ‐Aminobutyric Acid Release from Isolated Growth Cones: Correlation with Growth Cone Morphology

Cited by 40 publications

References 36 publications

Synaptic properties of serotonergic growth cones in developing rat brain

Synaptic properties of serotonergic growth cones in developing rat brain

Embryonic and postnatal expression of four gamma-aminobutyric acid transporter mRNAs in the mouse brain and leptomeninges

GABA signalling during development: new data and old questions

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