| Objective: Amyotrophic lateral sclerosis (ALS) is a common progressive neurodegenerative disease in central nervous system. It is characterized by selective degeneration of motor neurons in brain and spinal cord, which clinical features are delayed onset, chronic progression, weakness and atrophy of limbs'muscles, the occurrence of pathologic reflex. ALS is a lethal disease, with most patients died of respiratory failure 3-5 years later. From its stigmata of episode and heredity, ALS can be divided into familial amyotrophic lateral sclerosis (FALS) and sporadic amyotrophic lateral sclerosis (SALS). FALS is less than 10% of the total ALS patients, while SALS is more than 90%. FALS is mainly caused by the mutation of copper/zinc superoxide dismutase (Cu/Zn SOD) gene, whose site is at 21q22.1～22.2. This suggests that FALS should be a kind of genetic disease. The etiology of SALS, which accounts for the majority of all ALS cases, remains to be resolved, and several pathogenic mechanisms may be involved: 1) excitotoxicity, 2)oxidative stress, 3) autoimmunity, 4) mitochondria dysfunction, 5) over phosphorylation of neurofilament , 6) deficiency of neurotrophic factors, et al. Insulin-like growth factor-1(IGF-1) is a pleiotrophic protein that acts on many tissue and orgens. It has been used for the treatment of several diseases, including growth deficiency,osteoporosis, catabolic disorders and diabetes. Recent evidence supports the significance of IGF-1 in the maintenance of the integrity and homostasis of the nervous system. Clinical trials have revealed that IGF-1 possesses potential clinical applications, particularly in neurodegenerative disorders. Both in vivo and in vitro studies have shown that IGF-1 promotes motor neuron survival and strongly enhances motor nerve regeneration. IGF-1 is currently in clinical trials for treatment of ALS. However, little is known concerning the concentration of IGF-1 in the cerebrospinal fluid (CSF) and serum in patients with ALS. The aim was to evaluate IGF-1 concentration of CSF and serum in patients with ALS.Methods:1 Patients The patients were examined in the Department of Neurology, the Scond Hospital of Hebei Medical University, Shijiazhuang. Informed consent was obtained from each individual and the study protocal was approved by the ethics committees of the hospital. The ALS patients had clinically or laboratory-supported definite or probable ALS according to the E1 Escorial criteria. The dignosis of ALS requires the presence of (1) signs of lower motor neuron (LMN) degeneration by clinical, electrophysiological or neuropathologic examination, (2) signs of upper motor neuron (UMN) degeneration by clinical examination, and (3) progressive spread of signs within a region or two other regions, together with the absence of (1) electrophysiological evidence of other disease processes that might explain the signs of LMN and/or UMN degeneration, and (2) neuroimaging evidence of other disease processes that might explain the observed clinical and electrophysiological signs. Definite ALS is defined on clinical grounds alone by the presence of UMN as well as LMN signs in the bulbar region and at least two of the other spinal regions or the presence of UMN and LMN signs in three spinal regions. Probable ALS is defined on clinical grounds alone by UMN and LMN signs in at least two regions. Disease controls included 20 patients who underwent lumbar puncture beacause of suspicion of infectious disease but turn out to have tension headache , migraine, depression or epilepsy. Healthy controls included 18 persons who underwent vein puncture because of health examination and turn out to had no disease.2 collection of serum and CSF sampleThe serum samples were obtained by vein puncture, centrifuged, frozen in small aliquots and stored at–80℃. No haemolysis was seen in the samples. The CSF samples were obtained by lumbar puncture, immediatelly centrifuged, frozen in small aliquots and stored at–80℃. No contamination of erythrocytes was seen in the sample.3 Determination of IGF-1The IGF-1 was determined by enzyme linked immunosorbent assay (ELISA) with commercially available kit according to the instructions of the manufacturer. IGF-1 ELISA is a enzymatically amplified"two step"sandwich-type immuno- assay. In the assay, Standards, Controls and unknown serum or CSF samples are incubated with IGF-1 antibody in microtitration wells. After incubation and washing, the wells are treated with another anti-IGF-1 detection antibody labeled with the enzyme horseradish peroxidase (HRP). After a second incubation and washing step, the wells are incubated with the substrate tetramethylbenzidine (TMB). An acidic stopping solution is then added and the degree of enzymatic turnover of the substrate is determined by dual wavelength absorbance measurement at 450 and 620 nm. The absorbance measured is directly proportional to the concentration of Free IGF-1 present.4 Statistical analysisResults are presented as means±SEM. The effects of ALS on IGF-1 were analyzed by Student's t-test. Pearson's correlation coefficient was used to examine the relationship between CSF and serum IGF-1(α=0.05).Results:1 The concentration of IGF-1 in the serum of patients with ALS was 158.06±71.02ng/mL, healthy control group's was 143.90±37.09ng/mL. Levels of serum concentrations of IGF-1 did not significantly differ between the ALS group and the healthy controls(P = 0.4601).2 The concentration of IGF-1 in the CSF of patients with ALS was 26.62±2.60ng/mL, disease control group's was 27.24±1. 92ng/mL. Levels of CSF concentrations of IGF-1 did not significantly differ between the ALS group and the disease controls(P = 0.4018).3 There was no correlation between CSF level of IGF-1 and serum level's in patients with ALS(r=-0.2089,P=0.4055).Conclusions:We conclude concentrations of serum IGF-1 or CSF IGF-1 are not changed in patients with ALS. Serum level of IGF-1 does not correlated with CSF IGF-1 concentration and do not reflect changes of the protein in the brain. CSF IGF-1 might come from central nerve system. |
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