TY  - JOUR
A1  - Simon, Christian M.
A1  - Rauskolb, Stefanie
A1  - Gunnersen, Jennifer M.
A1  - Holtmann, Bettina
A1  - Drepper, Carsten
A1  - Dombert, Benjamin
A1  - Braga, Massimiliano
A1  - Wiese, Stefan
A1  - Jablonka, Sibylle
A1  - Pühringer, Dirk
A1  - Zielasek, Jürgen
A1  - Hoeflich, Andreas
A1  - Silani, Vincenzo
A1  - Wolf, Eckhard
A1  - Kneitz, Susanne
A1  - Sommer, Claudia
A1  - Toyka, Klaus V.
A1  - Sendtner, Michael
T1  - Dysregulated IGFBP5 expression causes axon degeneration and motoneuron loss in diabetic neuropathy
JF  - Acta Neuropathologica
N2  - Diabetic neuropathy (DNP), afflicting sensory and motor nerve fibers, is a major complication in diabetes.The underlying cellular mechanisms of axon degeneration are poorly understood. IGFBP5, an inhibitory binding protein for insulin-like growth factor 1 (IGF1) is highly up-regulated in nerve biopsies of patients with DNP. We investigated the pathogenic relevance of this finding in transgenic mice overexpressing IGFBP5 in motor axons and sensory nerve fibers. These mice develop motor axonopathy and sensory deficits similar to those seen in DNP. Motor axon degeneration was also observed in mice in which the IGF1 receptor(IGF1R) was conditionally depleted in motoneurons, indicating that reduced activity of IGF1 on IGF1R in motoneurons is responsible for the observed effect. These data provide evidence that elevated expression of IGFBP5 in diabetic nerves reduces the availability of IGF1 for IGF1R on motor axons, thus leading to progressive neurodegeneration. Inhibition of IGFBP5 could thus offer novel treatment strategies for DNP.
KW  - Motor nerve biopsy
KW  - Diabetic polyneuropathy
KW  - Neuropathy
KW  - Neurotrophic factors
KW  - Axonal degeneration
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-154569
VL  - 130
SP  - 373
EP  - 387
ER  - 
TY  - JOUR
A1  - Zeller, Daniel
A1  - Dang, Su-Yin
A1  - Weise, David
A1  - Rieckmann, Peter
A1  - Toyka, Klaus V.
A1  - Classen, Joseph
T1  - Excitability decreasing central motor plasticity is retained in multiple sclerosis patients
N2  - Background: Compensation of brain injury in multiple sclerosis (MS) may in part work through mechanisms involving neuronal plasticity on local and interregional scales. Mechanisms limiting excessive neuronal activity may have special significance for retention and (re-)acquisition of lost motor skills in brain injury. However, previous neurophysiological studies of plasticity in MS have investigated only excitability enhancing plasticity and results from neuroimaging are ambiguous. Thus, the aim of this study was to probe long-term depression-like central motor plasticity utilizing continuous theta-burst stimulation (cTBS), a non-invasive brain stimulation protocol. Because cTBS also may trigger behavioral effects through local interference with neuronal circuits, this approach also permitted investigating the functional role of the primary motor cortex (M1) in force control in patients with MS. Methods: We used cTBS and force recordings to examine long-term depression-like central motor plasticity and behavioral consequences of a M1 lesion in 14 patients with stable mild-to-moderate MS (median EDSS 1.5, range 0 to 3.5) and 14 age-matched healthy controls. cTBS consisted of bursts (50 Hz) of three subthreshold biphasic magnetic stimuli repeated at 5 Hz for 40 s over the hand area of the left M1. Corticospinal excitability was probed via motor-evoked potentials (MEP) in the abductor pollicis brevis muscle over M1 before and after cTBS. Force production performance was assessed in an isometric right thumb abduction task by recording the number of hits into a predefined force window. Results: cTBS reduced MEP amplitudes in the contralateral abductor pollicis brevis muscle to a comparable extent in control subjects (69 ± 22% of baseline amplitude, p < 0.001) and in MS patients (69 ± 18%, p < 0.001). In contrast, postcTBS force production performance was only impaired in controls (2.2 ± 2.8, p = 0.011), but not in MS patients (2.0 ± 4.4, p = 0.108). The decline in force production performance following cTBS correlated with corticomuscular latencies (CML) in MS patients, but did not correlate with MEP amplitude reduction in patients or controls. Conclusions: Long-term depression-like plasticity remains largely intact in mild-to-moderate MS. Increasing brain injury may render the neuronal networks less responsive toward lesion-induction by cTBS.
KW  - Medizin
KW  - Multiple sclerosis
KW  - LTD
KW  - Motor plasticity
KW  - TMS
KW  - Motor cortex
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-76333
ER  -