Multiple system atrophy is associated with changes in peripheral insulin‐like growth factor system

Abstract

Insulin-like growth factors (IGF-I and IGF-II) have been shown to have several neurotrophic actions and IGF system may be impaired in neurodegenerative disorders. The aim of this study was to investigate the IGF system in patients with MSA and to evaluate correlations between this endocrine system and clinical features of the disease. Serum levels of IGF-I, IGF-II, insulin, IGF-binding protein 1 (BP1), and IGF-binding protein 3 (BP3) were measured in 25 patients with probable MSA and 25 age, sex and BMI-matched healthy controls. Clinical status of each patient was evaluated with the Unified Multiple System Atrophy Rating Scale (UMSARS) Part II and the Hoehn and Yahr rating scale. IGF-I levels were significantly higher in MSA (164.1 + 66.2 μg/L) than in healthy controls (111.7 + 60.3 μg/L; p = 0.001). Insulin levels were significantly higher in MSA patients (21.9 ± 14.4 μU/mL) than in healthy controls (13.3 ± 5.1 μU/mL, p = 0.048). No significant difference was found in serum IGF-II, IGF-BP1, and IGF- BP3 levels between patients with MSA and healthy controls. There was a trend toward significantly higher IGF-II levels in MSA patients with UMSARS score <26 (1026.3 ± 442.6 μg/L) than MSA patients with UMSARS score >26 (796.1 ± 234 μg/L, p = 0.055). The results of this study demonstrated that IGF system is altered in MSA. The degenerative process in MSA could lead to a compensatory increase in IGF-I and insulin in an attempt to provide additional support to degenerating neurons.