Usefulness of Detecting Brain-Derived Neurotrophic Factor in Intervertebral Disc Degeneration of the Lumbosacral Spine

Abstract

BACKGROUND In determining the etiology of pain of discogenic origin, attention is paid to the role of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF). Considering the potential role of BDNF in the etiology of pain during intervertebral disc degeneration (IVDD), this study aimed to assess changes in the number of BDNF-positive nerve fibers and levels of BDNF in IVDD of the lumbosacral spine in comparison to intervertebral discs (IVDs) of the control group (cadavers). MATERIAL AND METHODS The study group comprised 113 patients with IVDD of the lumbosacral spine. The control group consisted of 81 people (cadavers). We performed hematoxylin-eosin staining to assess IVD structures (degeneration), immunohistochemistry to determine the number of BDNF-positive nerve fibers, and an enzyme-linked immunosorbent assay and western blot to quantify BDNF levels in IVDs. RESULTS Levels of BDNF in the study group were significantly higher than in the control group (17.91±19.58 pg/mg; P<0.05). Furthermore, BDNF levels were significantly higher in the annulus fibrosus compared to the nucleus pulposus of the intervertebral disc (5.50±6.40 pg/mg; P<0.05). Neither the number of BDNF-positive nerves (P=0.359) nor BDNF concentration (P=0.706) were significantly correlated with the degree of perceived pain. The number of BDNF-positive fibers per 1 mm2 was not found to differ significantly according to the radiological degree of degeneration of the lumbosacral spine based on the Pfirrmann scale (P=0.735). CONCLUSIONS The level of BDNF expression may be indicative of IVD degeneration, although it does not predict the degree of this degeneration.

Figure 1

The number of patients declaring pain intensity in the range of 2–10 (according to the VAS) and whose radiological advancement of degenerative changes in the IVD was in the range of 2–5 (according to the Pfirrmann scale).

Figure 2

Results of H&E staining of intervertebral disc in control group and experimental group (×50) [own picture]. (A) Healthy intervertebral disc; (B) degeneration intervertebral disc.

Figure 3

Expression of pro-BDNF in IVD obtained from the study and control groups, and annulus fibrosus, and nucleus pulposus from the control group obtained via the western blot technique. P – stage of radiological advancement of changes according to the Pfirrmann scale.