Motoneurons from E14 rat embryos have been retrogradely labeled with the carbocyanine derivative dil and purified 12-fold by centrifugation on a density gradient made of Nycodenz, as assessed by the increase in CAT activity per cell and in the percentage of dil-labeled cells. A 20- to 36-fold purification was achieved by the microdissection of the labeled lumbar motor columns followed by densit...

The activity of most motoneurons controlling one-joint muscles during locomotion are locked to either extensor or flexor phase of locomotion. In contrast, bifunctional motoneurons, controlling two-joint muscles such as posterior biceps femoris and semitendinosus (PBSt) or rectus femoris (RF), express a variety of activity patterns including firing bursts during both locomotor phases, which may ...

Motoneurons are an essential component of all metazoan nervous systems, but it is unknown whether there is an evolutionarily conserved mechanism for generating motoneurons during neurogenesis. In the vertebrate CNS, HB9/MNR2 transcription factors are specifically expressed in all somatic motoneurons and are necessary to distinguish motoneurons from interneurons, in part by repressing interneuro...

The neural organization of the pathways from the superior colliculus (SC) to trochlear motoneurons was analyzed in anesthetized cats using intracellular recording and transneuronal labeling techniques. Stimulation of the ipsilateral or contralateral SC evoked excitation and inhibition in trochlear motoneurons with latencies of 1.1-2.3 and 1.1-3.8 ms, respectively, suggesting that the earliest c...

Ciliary neurotrophic factor (CNTF) is an abundant cytosolic molecule in myelinating Schwann cells of adult rodents. In newborn animals in which CNTF is not yet expressed, exogenous CNTF that is locally administered very effectively protects motoneurons from degeneration by axotomy. To evaluate whether endogenous CNTF, released after nerve injury from the cytosol of Schwann cells, supports moton...

Expression of transforming growth factor (TGF ), a member of the epidermal growth factor (EGF) family, is a general response of adult murine motoneurons to genetic and experimental lesions, TGF appearing as an inducer of astrogliosis in these situations. Here we address the possibility that TGF expression is not specific to pathological situations but may participate to the embryonic developmen...

Plasticity underlying adaptive, long-term changes in breathing behavior is hypothesized to be attributable to the modulation of respiratory motoneurons by intracellular second-messenger cascades. In quiescent preparations, protein kinases, including cAMP-dependent protein kinase A (PKA), potentiate glutamatergic inputs. However, the dynamic role of protein kinases or phosphatases in functionall...

Low levels of the survival motor neuron protein (SMN) cause the disease spinal muscular atrophy. A primary characteristic of this disease is motoneuron dysfunction and paralysis. Understanding why motoneurons are affected by low levels of SMN will lend insight into this disease and to motoneuron biology in general. Motoneurons in zebrafish smn mutants develop abnormally; however, it is unclear ...

Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental enc...

ALS (amyotrophic lateral sclerosis) is an adult-onset and deadly neurodegenerative disease characterized by a progressive and selective loss of motoneurons. Transgenic mice overexpressing a mutated human gene (G93A) coding for the enzyme SOD1 (Cu/Zn superoxide dismutase) develop a motoneuron disease resembling ALS in humans. In this generally accepted ALS model, we tested the electrophysiologic...