Nerve growth factor of cultured medium extracted from human degenerative nucleus pulposus promotes sensory nerve growth and induces substance p in vitro.
METHODS
We investigated the mechanism of discogenic low back pain using an in vitro model.


OBJECTIVE
To evaluate the axonal growth and induction of a painful neuropeptide, substance P (SP), using rat dorsal root ganglion (DRG) neurons and degenerated human disc cells in vitro.


BACKGROUND
Degeneration of the lumbar intervertebral disc is a cause of low back pain. The pathologic mechanism is thought to be sensory nerve ingrowth into the inner layers of the degenerated intervertebral disc; however, the precise patho-mechanism has not been clarified.


METHODS
The nucleus pulposus (NP) and annulus fibrosus (AF) of human intervertebral discs were harvested from patients with discogenic low back pain. Extracted medium from human degenerative intervertebral discs was cultured with neurons of rat DRGs. We evaluated the promotion of axonal growth and SP induction of DRG neurons in extracted medium from the NP and AF using immunocytochemistry.


RESULTS
The average length of growing axons in the NP and AF was significantly longer than that in the control (P < 0.005). That in the NP was significantly longer than that in the AF. The average length of growing axons in the NP was significantly shortened after anti-nerve growth factor (NGF)beta treatment (P < 0.005); however, that in the AF was not (P > 0.05). The percentage of SP-immunoreactive cells with growing axons was significantly higher only in the NP group compared with the control and AF groups (P < 0.005), and anti-NGFbeta treatment decreased the expression of SP in the NP group (P < 0.05).


CONCLUSIONS
Extracted medium from the NP and AF promoted axonal growth. Furthermore, NGF from the NP promoted axonal growth and induced SP. These in vitro results may suggest that NGF from the NP promotes the growth of sensory nerve fibers innervating the degenerated intervertebral disc and may induce SP related with pain transmission.
Yamauchi
Kazuyo
K
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. kazuyo@sb3.so-net.ne.jp
Inoue
Gen
G
Koshi
Takana
T
Yamashita
Masaomi
M
Ito
Toshinori
T
Suzuki
Munetaka
M
Eguchi
Yawara
Y
Orita
Sumihisa
S
Takaso
Masashi
M
Nakagawa
Koichi
K
Aoki
Yasuchika
Y
Ochiai
Nobuyasu
N
Kishida
Shunji
S
Endo
Mitsuharu
M
Yamashita
Toshihide
T
Takahashi
Kazuhisa
K
Ohtori
Seiji
S
D000328:Adult; D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D001369:Axons / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry* / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005727:Ganglia, Spinal / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000737:chemistry*; D017116:Low Back Pain / Q000209:etiology; D008875:Middle Aged; D020932:Nerve Growth Factor / Q000276:immunology / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology*; D013122:Spinal Diseases / Q000150:complications / Q000378:metabolism*; D013373:Substance P / Q000096:biosynthesis*
D000906:Antibodies; D003470:Culture Media; D011994:Recombinant Proteins; D013373:Substance P; D020932:Nerve Growth Factor