Nerve growth factor and expression of its receptors in patients with diabetic neuropathy.
OBJECTIVE
Low serum nerve growth factor (NGF) levels have been reported in patients with diabetic peripheral neuropathy (DPN), but the role of NGF in the development of neuropathy is unclear. Thus, we investigated the associations of serum NGF level and NGF receptor activity with the presence and severity of DPN.


METHODS
One hundred and thirty-six patients with Type 2 diabetes were included in this cross-sectional study. Serum NGF levels were measured by ELISA. Expressions of NGF receptors (TrkA and p75(NTR)) were measured by immunohistochemical staining. The presence and severity of DPN were assessed by neuropathy disability score (NDS) and by corneal nerve fibre length (cNFL) and nerve branch density (cNBD) using in vivo confocal microscopy.


RESULTS
Patients with DPN had higher serum NGF levels (56-451 pg/ml) than patients without DPN (4-54 pg/ml). However, in DPN patients, serum NGF was negatively associated with neuropathy severity (mild 222 +/- 64 pg/ml; moderate 114 +/- 17 pg/ml; severe 89 +/- 20 pg/ml). This negative association was consistent in all severity indices (NDS, P < 0.001; cNFL, P < 0.001; cNBD P = 0.010) even after adjustment for age, sex, diabetes duration, insulin use, fasting glucose and glycated haemoglobin. Although NGF receptor activities had significantly (P < 0.05) negative associations with the presence and severity of neuropathy, these associations were not significant when adjusted for other factors.


CONCLUSIONS
Serum NGF level was positively associated with the presence of DPN but negatively associated with neuropathy severity in DPN patients. The change in serum NGF might be a consequence of, rather than a contributor to, the early development of DPN.
Kim
H C
HC
Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea.
Cho
Y J
YJ
Ahn
C W
CW
Park
K S
KS
Kim
J C
JC
Nam
J S
JS
Im
Y S
YS
Lee
J E
JE
Lee
S C
SC
Lee
H K
HK
D000368:Aged; D003315:Cornea / Q000294:innervation; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000378:metabolism* / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology; D020932:Nerve Growth Factor / Q000097:blood*; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*; D012720:Severity of Illness Index
D017475:Receptors, Nerve Growth Factor; D020932:Nerve Growth Factor