Neurotrophin-3 And Trkc In Muscle Are Non-essential For The Development Of Mouse Muscle Spindles
afferents; expression; growth factors; mice; muscle spindles; neonatal rats; neurons; Neurosciences & Neurology; neurotrophin-3; proprioception; transgenic mice; TrkC
NEUROTROPHIN-3 (NT3) or TrkC null mutant mice were examined for the presence of muscle spindles. Muscles of mastication, but not limbs, contained spindles in newborn and adolescent mutants. The intramuscular distribution and morphological properties of spindles in mutant masticatory muscles were indistinguishable from those of wild-type spindles. Intrafusal fibers of NT3- or trkC-deficient spindles expressed the slow-tonic isoform of myosin heavy chains, characteristic of wild-type spindles. Sensory nerve endings were observed in spindles of mutants by electron microscopy. Thus, NT3 or trkC, which is expressed in wild-type spindles, may serve functions other than those related to spindle assembly. Presumably, proprioceptive neurons innervating jaw muscles are dependent on factors other than NT3 for survival and maintenance. (C) 1998 Rapid Science Ltd.
Kucera J; Fan G P; Walro J; Copray S; Tessarollo L; Jaenisch R
Neuroreport
1998
1998-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1097/00001756-199803300-00026" target="_blank" rel="noreferrer noopener">10.1097/00001756-199803300-00026</a>
Formation Of Supernumerary Muscle Spindles At The Expense Of Golgi Tendon Organs In Er81-deficient Mice
Anatomy & Morphology; Developmental Biology; ETS transcription factors; expression; Golgi tendon organs; group; ia afferents; innervation; motor neurons; muscle spindles; mutant mice; myosin heavy-chain; neonatal rats; nerve growth-factor; neurotrophin-3; primary sensory neurons; proprioceptive afferents; transcription factors
ER81, a member of the ETS family of transcription factors, is essential for the formation of connections between sensory and motor neurons in the spinal cord. Mice lacking Er81 genes exhibit reduced monosynaptic sensory-motoneuron connectivity in response to muscle nerve stimulation. Proximal muscle nerve stimulation elicits fewer monosynaptic potentials than stimulation of distal nerves in hind-limbs, a deficit that is paralleled by a paucity of muscle spindles in proximal muscles (Arber et al., 2000). We examined whether a presence of spindles innervated by afferents in distal muscles correlated with the increased preservation of monosynaptic sensory-motor potentials in distal muscle nerves. Not only were spindles and Ia afferents present, but also they were supernumerary in distal muscles such as the soleus, medial gastrocnemius, and extensor hallucis longus. Concomitantly, a deficiency of Golgi tendon organs (GTOs) and Ib afferents was observed in distal muscles, as if supernumerary spindles formed at the expense of tendon organs in the absence of Er81. Thus, ER81 may be involved in mechanisms that regulate acquisition of the Ia and Ib phenotypes by subsets of proprioceptive muscle afferents. Segmental differences in muscle spindle and GTO dependence on ER81 suggest that more than one ETS transcription factor may participate in the regulation of limb proprioceptive system assembly in the mouse. (C) 2002 Wiley-Liss, Inc.
Kucera J; Cooney W; Que A; Szeder V; Stancz-Szeder H; Walro J
Developmental Dynamics
2002
2002-03
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/dvdy.10066" target="_blank" rel="noreferrer noopener">10.1002/dvdy.10066</a>
Formation Of A Full Complement Of Cranial Proprioceptors Requires Multiple Neurotrophins
Anatomy & Morphology; brain-derived neurotrophic factor; central-nervous-system; Developmental Biology; expression; in-vivo; masseter muscle; mesencephalic trigeminal neurons; messenger-rna; mice; muscle spindles; muscle spindles; mutant; neurotrophin-3; neurotrophin-4; nt-3 activation; proprioceptive sensory neurons; sensory neurons; Trk receptors; Trk receptors
Fan G P; Copray S; Huang E J; Jones K; Yan Q; Walro J; Jaenisch R; Kucera J
Developmental Dynamics
2000
2000-06
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/(sici)1097-0177(200006)218:2%3C359::aid-dvdy9%3E3.0.co;2-l" target="_blank" rel="noreferrer noopener">10.1002/(sici)1097-0177(200006)218:2%3C359::aid-dvdy9%3E3.0.co;2-l</a>
Development of fusimotor innervation correlates with group Ia afferents but is independent of neurotrophin-3
deficits; Developmental Biology; expression; fusimotor innervation; growth factor; messenger-rna; mice; motor-neurons; muscle spindle; nervous-system; Neurosciences & Neurology; neurotrophin-3; proprioception; rat; transgenic mice
Fusimotor neurons, group Ia afferents and muscle spindles are absent in mutant mice lacking the gene for neurotrophin-3 (NT3). To partition the effect of Ia afferent or spindle absence from that of NT3 deprivation on fusimotor neuron development, we examined the fusimotor system in a mutant mouse (NesPIXpNT3) that lacks Ia afferents and spindles, but has normal or elevated tissue levels of NT3 during embryogenesis. Fusimotor fibers were absent in lumbar ventral spinal roots, and limb muscles were devoid of Ia afferents and spindles in adult NesPIXpNT3 mice. In contrast, no deficiency in motoneuron numbers was observed in the trigeminal nucleus which contains cell bodies of motor axons innervating muscles of mastication. Spindles and Ia afferents were also present in the masticatory muscles. Thus, the development and/or survival of fusimotor neurons correlates with the presence of Ia afferents and/or spindles, and not with the amount of NT3 in the spinal cord or muscle. (C) 1998 Elsevier Science B.V. All rights reserved.
Ringstedt T; Copray S; Walro J; Kucera J
Developmental Brain Research
1998
1998-12
Journal Article
<a href="http://doi.org/10.1016/s0165-3806(98)00146-1" target="_blank" rel="noreferrer noopener">10.1016/s0165-3806(98)00146-1</a>