. 2021 Feb 17;22(6):1281–1304. doi: 10.1093/pm/pnab070

Table 2.

List of markers used to identify neural elements in the human intervertebral disc

Abbreviation	Full Name(s)	Function	Location
AChE [17, 35]	Acetylcholinesterase	Enzyme that catalyzes the breakdown of acetylcholine	Variety of motor and sensory neurons; cholinergic and non-cholinergic neurons^a
CGRP [32–34, 43]	Calcitonin gene-related peptide	Peptide that acts as a vasodilator, is involved in nociception, and may contribute to nerve regeneration^b^,^c	Somatic motor and sensory neurons^b; autonomic neurons^c
GAP43 [36, 40, 45]	Growth-associated protein 43	Cytoplasmic protein in axons and presynaptic terminals that aids with neurite growth, regeneration, and plasticity	Neurons in the central and peripheral nervous systems^d Also found in glial cells of central and peripheral nervous systems^e
GFAP [38]	Glial fibrillary acidic protein	Type III intermediate filament involved in astrocyte-neuron interactions	Expressed primarily in astrocytes^f; also found in ependymal and Leydig cells^g^,^h
IB4 [43]	Isolectin B4 (isolated from Griffonia simplicifolia)	Carbohydrate-binding protein involved in biological recognitionⁱ	Subpopulation of primary afferent neurons in dorsal root gangliaⁱ
NF200 [38, 41, 44, 49, 50] NF68 [45]	Neurofilament 200; neurofilament heavy polypeptide Neurofilament 68; neurofilament light polypeptide	Type IV intermediate filament that helps form neuronal cytoskeleton Type IV intermediate filament that is shown to be indicative of axonal damage in neurological disorders^j	Neurons in central and peripheral nervous systems^k
NGF [45]	Nerve growth factor	Neuropeptide involved in the growth, proliferation, and maintenance of neurons	Present in most neurons^l; required for survival in sensory and sympathetic neurons^m
NPY/CPON [32–34, 37]	Neuropeptide-Y; c-flanking peptide of neuropeptide-Y	Neurotransmitter that acts through G-coupled protein receptors Regulates multiple functions such as neuroendocrine release, blood pressure, food intake, anxiety, bone formation, obesity, and painⁿ	Primarily in GABAergic interneurons in central nervous systemⁿ; sympathetic neurons^o
p75 [40]	p75 neurotrophin receptor; low-affinity nerve growth factor receptor	One of two receptor types for neurotrophins^p, which are growth factors that stimulate neuronal survival and differentiation, and include NGF, BDNF, NT-3, NT-4	Variety of neurons in the central and peripheral nervous system^p
PGP9.5 [32–34, 36–40, 42, 43, 48, 49, 51]	Protein gene product 9.5; ubiquitin carboxy-terminal hydrolase L1	Cytoplasmic protein that hydrolyzes ubiquitin to generate ubiquitin monomers^q	Neurons in central and peripheral nervous systems; neuroendocrine cells^q
PRPH [38]	Peripherin	Type III intermediate filament expressed primarily in neurons within the peripheral nervous system^r	Somatic sensory neurons^r; spinal motor neurons^r; autonomic neurons^r
PTN [44]	Pleiotrophin; heparin-binding brain mitogen	Protein that promotes neurite outgrowth and acts as a mitogen^s	Shown to exist in the central and peripheral nervous systems during development^s
S100 [46, 47, 50, 52]	S100 protein	Protein that aids with intracellular and extracellular functions such as protein phosphorylation and the inflammatory response^t	Cells derived from the neural crest (Schwann cells, chondrocytes, macrophages, adipocytes, etc.)
SNS/PN3 and NaN/SNS2 [39]	Tetrodotoxin-resistant, voltage-gated sodium channels	Involved in the initiation and propagation of action potentials^u	Somatic sensory neurons^v
SP [17, 32–37, 41, 45, 51–53]	Substance P	Neuropeptide released in response to biological stressors^w Vasodilator, initiates expression of cytokines, and is highly involved in pain perception and transmission to the central nervous system^w	Somatic afferent neurons^w; immune cells^x (microglia, T-cells, eosinophils, dendritic cells)
SYN [37]	Synaptophysin; major synaptic vesicle protein p38	Synaptic vesicle glycoprotein involved in synaptic transmission	Present in most neurons and neuroendocrine cells^y
TrkA [40]	Tropomyosin receptor kinase A; high-affinity nerve growth factor receptor	Second of two receptor types (first was p75) for neurotrophins that mediates neuronal survival and differentiation	Variety of neurons in the central and peripheral nervous system^p
VIP [32, 33, 41]	Vasoactive intestinal peptide	Neurotransmitter and neuroendocrine factor that: Regulates circadian rhythms, relaxes smooth muscle, and increases neuronal survival (central nervous system)^z Increases secretion and relaxes smooth muscle (digestive system)^z	Variety of neurons in the central nervous system^z; autonomic neurons^z (especially in enteric nervous system)

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ⁱ

Bennett et al. 1998. J. Neurosci. 18(8):3059–72. doi: 10.1523/JNEUROSCI.18-08-03059.1998.

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ⁿ

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