Activation of mitogen-activated protein kinase pathways is critically involved in naturally occurring programmed cell death of motoneurons during development, but the upstream mediators remain undetermined. We found that mice deficient in ZPK, also called DLK (ZPK/DLK), an upstream kinase in these pathways, have twice as many spinal motoneurons as do their wild-type littermates. Nuclear HB9/MNX...

Some spinal and brain stem motoneurons are electrically coupled in the early postnatal period. To test whether respiratory motoneurons in the brain stem are electrically coupled, we performed single and dual whole cell patch recordings from presumptive motoneurons in the nucleus ambiguus in a rhythmically active brain stem slice from newborn mice. Two of eight (25%) biocytin-injected neurons sh...

Background and Objective: Evaluation of degenerative changes of motoneurons and their related synapses can be useful in understanding the mechanisms of neurodegenerative diseases and their potential treatment. The present electron microscopic and immunohistochemical study investigates the axotomy-induced...

Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-c...

To identify candidate genes that may be involved in motoneuron degeneration, we combined laser capture microdissection with microarray technology. Gene expression in motoneurons was analyzed during the progression of the disease in transgenic SOD1(G93A) mice that develop motoneuron loss. Three major observations were made: first, there was only a small number of genes that were differentially e...

The expression pattern of the fibroblast growth factor receptor Fgf-R1, R2 and R3 genes was studied in the chicken spinal cord using in situ hybridization (ISH). Unlike Fgf-R1 which is widely expressed in motoneurons, Fgf-R3 is expressed in a subset of motoneurons in the medial subdivision of the median motor column (MMCm) that also express Islet-1 and Lim-3. The motoneuron identity of the labe...

BACKGROUND Much of our understanding of how neural networks develop is based on studies of sensory systems, revealing often highly stereotyped patterns of connections, particularly as these diverge from the presynaptic terminals of sensory neurons. We know considerably less about the wiring strategies of motor networks, where connections converge onto the dendrites of motoneurons. Here, we inve...

The electrical properties of cat medial gastrocnemius (MG) spinal motoneurons were studied 14-21 d following injection of type A botulinum toxin (BTX) into the MG muscle. Treated MG muscles were atrophic, displayed pronounced fibrillation activity, and were markedly but not completely paralyzed. MG motoneuron electrical properties from animals with the highest MG muscle-twitch forces (greater t...