Distribution and colocalisation of glutamate decarboxylase isoforms in the rat spinal cord

Mackie, Margaret; Hughes, David I.; Maxwell, David; Tillakaratne, Niranjala J.K.; Todd, Andrew J.

doi:10.1016/s0306-4522(03)00174-x

Cited by 131 publications

(128 citation statements)

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“…We previously identified clusters of axon terminals that were intensely stained with GAD65 Ab in lamina IX of the rat spinal cord and suggested that these might be the P boutons (6). The results of the present study confirm this suggestion by showing that GAD65-intense boutons are associated with (and often surround) primary afferent terminals and that they form axoaxonic synapses.…”

Section: Resultssupporting

confidence: 88%

“…As described in ref. 6, many boutons with strong GAD65 immunoreactivity were present in lamina IX of the rat spinal cord, and these frequently formed clusters. Much lower levels of GAD65 were seen in many other boutons throughout the ventral horn; however, these could easily be distinguished from the strongly immunoreactive boutons, which for convenience are referred to as GAD65-intense.…”

Section: Resultsmentioning

confidence: 94%

“…More recently, two forms of the enzyme have been identified, and based on their molecular weights these forms have been named GAD65 and GAD67 (4). Both forms are present in the ventral horn of the rat spinal cord but have a very different distribution (5,6). The majority of GABAergic boutons throughout the ventral horn show strong GAD67 immunoreactivity and a low level of GAD65.…”

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confidence: 99%

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P boutons in lamina IX of the rodent spinal cord express high levels of glutamic acid decarboxylase-65 and originate from cells in deep medial dorsal horn

Hughes

Mackie

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

112

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Presynaptic inhibition of primary muscle spindle (group Ia) afferent terminals in motor nuclei of the spinal cord plays an important role in regulating motor output and is produced by a population of GABAergic axon terminals known as P boutons. Despite extensive investigation, the cells that mediate this control have not yet been identified. In this work, we use immunocytochemistry with confocal microscopy and EM to demonstrate that P boutons can be distinguished from other GABAergic terminals in the ventral horn of rat and mouse spinal cord by their high level of the glutamic acid decarboxylase (GAD) 65 isoform of GAD. By carrying out retrograde labeling from lamina IX in mice that express green fluorescent protein under the control of the GAD65 promoter, we provide evidence that the cells of origin of the P boutons are located in the medial part of laminae V and VI. Our results suggest that P boutons represent the major output of these cells within the ventral horn and are consistent with the view that presynaptic inhibition of proprioceptive afferents is mediated by specific populations of interneurons. They also provide a means of identifying P boutons that will be important in studies of the organization of presynaptic control of Ia afferents.GABA ͉ Ia afferent ͉ presynaptic inhibition T he inhibitory transmitter GABA is used by many neurons in the spinal cord and generates both postsynaptic inhibition at axo-dendritic and axo-somatic synapses and presynaptic inhibition at axo-axonic synapses (1). GABA is synthesized by the enzyme glutamic acid decarboxylase (GAD), and Abs against GAD have been used to identify GABAergic axonal boutons in the spinal cord (2, 3). More recently, two forms of the enzyme have been identified, and based on their molecular weights these forms have been named GAD65 and GAD67 (4). Both forms are present in the ventral horn of the rat spinal cord but have a very different distribution (5, 6). The majority of GABAergic boutons throughout the ventral horn show strong GAD67 immunoreactivity and a low level of GAD65. However, there are clusters of boutons in lamina IX that contain very high levels of GAD65. We have suggested (6) that these clusters may correspond to the P boutons that form axo-axonic synapses with terminals of group Ia afferents (7-10). In this work, we have used a variety of approaches to confirm this hypothesis and to identify the cells of origin of these boutons. MethodsAll experiments were approved by the Ethical Review Process Applications Panel of the University of Glasgow or the Animal Care and Protection Committee at the University of Debrecen and were performed in accordance with the U.K. Animals (Scientific Procedures) Act 1986 and the European Communities Council Directives. Immunocytochemical reactions were performed on free-floating 60-m transverse Vibratome sections that had been treated with 50% ethanol for 30 min to enhance Ab penetration. Abs were diluted in PBS with 0.3% Triton X-100 (except on sections used for EM).Primary Afferent Labeling. Transgang...

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 94%

mentioning

confidence: 99%

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P boutons in lamina IX of the rodent spinal cord express high levels of glutamic acid decarboxylase-65 and originate from cells in deep medial dorsal horn

Hughes

Mackie

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

112

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“…GAD67 synthesizes GABA and is a marker for GABAergic inhibitory interneurons (Mackie et al, 2003). Using GAD67 mRNA in situ hybridization, we found that, 4 weeks after SNI, the number of GABAergic interneurons in the ipsilateral dorsal horn decreases by 24.2 Ϯ 2.7% in laminas I-II and 25.0 Ϯ 2.5% in lamina III, compared with the contralateral side ( p Ͻ 0.001).…”

Section: Blocking Apoptosis Prevents the Loss Of Spinal Inhibitionmentioning

confidence: 91%

Blocking Caspase Activity Prevents Transsynaptic Neuronal Apoptosis and the Loss of Inhibition in Lamina II of the Dorsal Horn after Peripheral Nerve Injury

et al. 2005

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We show that transsynaptic apoptosis is induced in the superficial dorsal horn (laminas I-III) of the spinal cord by three distinct partial peripheral nerve lesions: spared nerve injury, chronic constriction, and spinal nerve ligation. Ongoing activity in primary afferents of the injured nerve and glutamatergic transmission cause a caspase-dependent degeneration of dorsal horn neurons that is slow in onset and persists for several weeks. Four weeks after spared nerve injury, the cumulative loss of dorsal horn neurons, determined by stereological analysis, is Ͼ20%.

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“…However, the inhibitory neurotransmitters glycine and serotonin, which co-exist in some spinal cord GABAergic neurons, may have accounted for the inhibition and anti-allodynic effects recorded. 27 Additionally, evidence suggests that following nerve injury, activation of microglia results in a BDNF-mediated shift in the chloride gradient of projection neurons in lamina I and deep in the dorsal horn, which leads to GABAergic inputs becoming somewhat paradoxically excitatory and pro-nociceptive. 28,29 The results from Mackie, De Koninck and Price's studies do not corroborate the functional integrative mechanism postulated by Braz et al's study.…”

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confidence: 99%

Stem cell therapies for neuropathic pain

Seewoodhary

Harvey

2014

Br J Diabetes

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Neuropathic pain is a large-scale epidemiological problem affecting 13-26% of the diabetic population. The complex aetiology and pathophysiology coupled with the lack of a diagnostic test for the underlying cause renders the assessment of neuropathic pain subjective and the treatment difficult, especially as current licensed treatments are limited in their application towards the attainment of palliation.Cell therapies offer a novel curative therapeutic dimension for neuropathic pain. This is based on replacing damaged neuronal tissue, protecting against progressive nerve damage, and releasing soluble factors that act in a paracrine or endocrine manner, which facilitate repair and reversal of the pathology that underlies the genesis and propagation of damage within the somatosensory system. Cell therapies with potential utility for the treatment of neuropathic pain include embryonic stem cells, adult stem cells and induced pluripotent stem cells.

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Distribution and colocalisation of glutamate decarboxylase isoforms in the rat spinal cord

Cited by 131 publications

References 33 publications

P boutons in lamina IX of the rodent spinal cord express high levels of glutamic acid decarboxylase-65 and originate from cells in deep medial dorsal horn

P boutons in lamina IX of the rodent spinal cord express high levels of glutamic acid decarboxylase-65 and originate from cells in deep medial dorsal horn

Blocking Caspase Activity Prevents Transsynaptic Neuronal Apoptosis and the Loss of Inhibition in Lamina II of the Dorsal Horn after Peripheral Nerve Injury

Stem cell therapies for neuropathic pain

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