We examined the massive early cell death that occurs in the ventral horn of the cervical spinal cord of the chick embryo between embryonic days 4 and 5 (E4 and E5). Studies with immunohistochemical, in situ hybridization, and retrograde-tracing methods revealed that many dying cells express Islet proteins and Lim-3 mRNA (motoneuron markers) and send their axons to the somatic region of the embr...

As many studies have focused on the mechanisms of motoneuron specification, little is known about the factors that control the subsequent development of postmitotic motoneurons. Previously, we showed that the transcription factor Nkx6.1 is required for the early specification of somatic motoneuron progenitors in the spinal cord. Our present analysis of hindbrain motoneuron development in Nkx6.1...

Purified motoneurons from chick, cultured on polycationic substrata treated with myotube-conditioned (MCM), respond by rapidly extending neurites. When MCM, partially purified by salt precipitation and ion-exchange chromatography, was fractionated on Sepharose CL-4B, the peak of neurite outgrowth-promoting activity (NOPA) corresponded to a peak of laminin (LA) immunoreactivity. Fractions from t...

Stroke survivors often exhibit abnormal motoneuron excitability, manifested clinically as spasticity with exaggerated stretch reflexes in resting muscles. We examined whether this abnormal excitability is a result of increased activation of intrinsic voltage-dependent persistent inward currents (PICs) or whether it is a result of enhanced synaptic inputs to the motoneuron. This distinction was ...

ALS (amyotrophic lateral sclerosis), a fatal motoneuron (motor neuron) disease, occurs in clinically indistinguishable sporadic (sALS) or familial (fALS) forms. Most fALS-related mutant proteins identified so far are prone to misfolding, and must be degraded in order to protect motoneurons from their toxicity. This process, mediated by molecular chaperones, requires proteasome or autophagic sys...

In vivo stimulation of a relatively "silent" phasic crayfish motoneuron changes the ultrastructure of its synaptic terminals to a more tonic phenotype. The closer muscle of the crayfish claw is supplied by only 2 excitatory motoneurons, one of which is phasic and the other tonic. The ultrastructures of conditioned phasic, unconditioned phasic, and tonic motor terminals were compared. The termin...

The dopamine system plays an integral role in motor physiology. Dopamine controls movement by modulation of higher-order motor centers (e.g., basal ganglia) but may also regulate movement by directly controlling motoneuron function. Even though dopamine cells synapse onto motoneurons, which themselves express dopamine receptors, it is unknown whether dopamine modulates skeletal muscle activity....

We used computer simulations to study the dendritic spatial distribution of low voltage-activated L-type calcium (Ca(V)1.3 type) channels, which mediate hysteretic persistent inward current (PIC) in spinal motoneurons. This study was prompted by the growing experimental evidence of the functional interactions between synaptic inputs and active conductances over the motoneuron dendritic tree. A ...

background and objective: deprenyl is a drug for the treatment of parkinson’s disease, where the dopaminergic neurons are the target of this drug. several reports also documented that deprenyl has an effect on the sensory and motor neurons. there are some reports about the mode of action of deprenyl on motoneurons as a neuroprotective agent, while others believe that deprenyl acts as a neurores...