Immunocytochemical evidence for an axonal localization of GABA in the optic nerves of rabbits, rats, and cats

Rogers, Penny; Pow, David V.

doi:10.1017/s0952523800006787

Cited by 22 publications

(16 citation statements)

References 32 publications

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“…High concentrations of neurotransmitter such as GABA and glycine are also present in a sub-population of mature WM axons in several species (Carlton et al, 1996;Davanger et al, 1991;Rogers and Pow, 1995;Todd and Sullivan, 1990;van den Pol and Gorcs, 1988;Wilson et al, 1996). Block of GABA uptake mimics the effects of GABA upon axon conduction in the neonatal rat optic nerve (Sakatani et al, 1991), while block of catecholamine uptake mimics the effect of nor-adrenaline (Nikolaeva et al, 2009); observations consistent with tonic operation of functional neurotransmitter uptake in the tissue.…”

Section: Gaba and Glycinementioning

confidence: 63%

Neurotransmitter signaling in white matter

Butt

Fern

Matute

2014

Glia

113

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White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca 21 signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function. GLIA 2014;62:1762-1779 Key words: glia, axon, astrocyte, oligodendrocyte, glutamate, ATP Introduction W hite matter (WM) is defined as a tract of myelinated axons-WM appears opaque or dense due to the fatty myelin in anatomical sections and in brain scans. Notwithstanding this, myelination is not restricted to WM and is also critical to rapid communication and integration in grey matter (GM) areas, such as in axons in the cortical GM and hippocampus. Hence, many aspects of neurotransmitter signaling to be covered in this review have resonance in GM and higher cognitive function. Indeed, in the human brain WM is a prominent feature of the cerebral cortex, the seat of higher intelligence. Myelination of GM is also evident in rodents, but discrete WM tracts are not pronounced in the cerebral cortex. As a general concept, WM are simply concentrations of myelinated axons bundled together into tracts that interconnect areas of GM. The molecular physiology of myelinated axons will be very similar in WM and GM, and they will be subject to the same neurotransmitter signaling phenomena that is the subject of this review. The main cells associated with myelinated axons are the myelinating oligodendro...

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Section: Gaba and Glycinementioning

confidence: 63%

Neurotransmitter signaling in white matter

Butt

Fern

Matute

2014

Glia

113

View full text Add to dashboard Cite

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“…However, in our hands, this antibody produces much higher proportion of GABA-labelled MGP neurones, and we found robust staining of neurones in control tissue, such as the thalamic reticular nucleus. Furthermore, one of us (Rogers and Pow, 1995) has also demonstrated that in the visual system, the sensitivity of this antibody has allowed detection of GABA at sites where it was not previously known to be present.…”

Section: Discussionmentioning

confidence: 99%

“…The antibodies have been used and published (Pow and Crook, 1993;Pow et al, , 1995Pow and Robinson, 1994;Rogers and Pow, 1995;Pow and Rogers, 1996;Pow and Barnett, 1999;Arckens et al, 2000;Kha et al, 2000), and a comparison of the sensitivity of the antibodies has been discussed. Nonspecific labelling of neurones by glutamate antisera seems unlikely because the level of nonspecific staining was determined by omitting either the primary or secondary antibody.…”

Section: Discussionmentioning

confidence: 99%

Projections from the substantia nigra pars reticulata to the motor thalamus of the rat: Single axon reconstructions and immunohistochemical study

Kha

Finkelstein

Tomas

et al. 2001

J of Comparative Neurology

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This is a study in the rat of the distribution of specific neurotransmitters in neurones projecting from the substantia nigra reticulata (SNR) to the ventrolateral (VL) and ventromedial (VM) thalamic nuclei. Individual axons projecting from the SNR to these thalamic nuclei have also been reconstructed following small injection of the anterograde tracer dextran biotin into the the SNR. Analysis of reconstructions revealed two populations of SNR neurones projecting onto the VL and VM thalamic nuclei. One group projects directly onto the VM and VL, and the other projects to the VM/VL and to the parafascicular nucleus. In another set of experiments Fluoro-Gold was injected into the VL/VM to label SNR projection neurones retrogradely, and immunohistochemistry was performed to determine the distribution of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), gamma-aminobutyric acid (GABA), and glutamate in Fluoro-Gold-labelled SNR projection neurones. Most SNR-VL/VM thalamic projection neurones were immunoreactive to acetylcholine or glutamate, whereas only 25% of the projection neurones were found to be immunoreactive to GABA.

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“…Moreover, the growth cones of cultured postnatal rat forebrain GABAergic neurons release GABA despite the absence of immunoreactivity for the vesicular component proteins P65 and synaptophysin (Taylor et al, 1990). In the developing visual system, high levels of GABA immunoreactivity are found in the neonatal rat optic nerve astrocytes and axons prior to the development of any vesicular release machinery (Sakatani et al, 1992;Rogers and Pow, 1995). Together, these data indicate that GABA is released from developing neurons before the onset of synaptic vesicles.…”

Section: Discussionmentioning

confidence: 73%

GABA and development of the Xenopus optic projection

Ferguson

McFarlane

2002

J. Neurobiol.

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In the developing visual system of Xenopus laevis retinal ganglion cell (RGC) axons extend through the brain towards their major target in the midbrain, the optic tectum. Enroute, the axons are guided along their pathway by cues in the environment. In vitro, neurotransmitters have been shown to act chemotropically to influence the trajectory of extending axons and regulate the outgrowth of developing neurites, suggesting that they may act to guide or modulate the growth of axons in vivo. Previous work by Roberts and colleagues (1987) showed that populations of cells within the developing Xenopus diencephalon and mid-brain express the neurotransmitter gamma amino butyric acid (GABA). Here we show that Xenopus RGC axons in the midoptic tract grow alongside the GABAergic cells and cross their GABA immunopositive nerve processes. Moreover, RGC axons and growth cones express GABA-A and GABA-B receptors, and GABA and the GABA-B receptor agonist baclofen both stimulate RGC neurite outgrowth in culture. Finally, the GABA-B receptor antagonist CGP54626 applied to the developing optic projection in vivo causes a dose-dependent shortening of the optic projection. These data indicate that GABA may act in vivo to stimulate the outgrowth of Xenopus RGC axons along the optic tract.

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Immunocytochemical evidence for an axonal localization of GABA in the optic nerves of rabbits, rats, and cats

Cited by 22 publications

References 32 publications

Neurotransmitter signaling in white matter

Neurotransmitter signaling in white matter

Projections from the substantia nigra pars reticulata to the motor thalamus of the rat: Single axon reconstructions and immunohistochemical study

GABA and development of the Xenopus optic projection

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