Afferent-inherent regulation of myosin heavy chain isoforms in rat muscle spindles.
Afferent Pathways/physiology; Afferent/*physiology; Animals; Denervation; Female; Ganglia; Ganglionectomy; Isomerism; Muscle Spindles/*metabolism; Myosin Heavy Chains/*metabolism; Neurons; Rats; Spinal Cord/physiology; Spinal/physiology; Sprague-Dawley; Toes/innervation
Whether afferents exert their morphogenetic influence on spindles through release of trophic factors at intrafusal fiber junctions or via participation in proprioceptive pathways which modulate the motor activity to muscles was investigated by comparing myosin heavy chain (MHC) expression in intrafusal fibers after ablation of afferents (deafferentation, or DA) to the extensor digitorum longus (EDL) of adult rats or after ablation of the corresponding central processes of afferents to the spinal cord (central-process ablation, or CPA). DA and CPA elicited an exaggerated pedal plantarflexion, and hypertrophy of the EDL concomitant with atrophy of the soleus in the affected hindlimb. Frequencies and patterns of expression of seven MHCs expressed by intrafusal fibers in CPA muscles were indistinguishable from normal rats. However, frequencies and patterns of expression of several MHCs were abnormal following DA. Thus factors transported anterogradely from afferents to intrafusal fibers may regulate MHC expression in intrafusal fibers.
Walro J M; Wang J; Story G M
Muscle & nerve
1997
1997-12
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1002/(sici)1097-4598(199712)20:12%3C1549::aid-mus10%3E3.0.co;2-w" target="_blank" rel="noreferrer noopener">10.1002/(sici)1097-4598(199712)20:12%3C1549::aid-mus10%3E3.0.co;2-w</a>
The re-expression of two myosin heavy chains in regenerated rat muscle spindles.
Female; Animals; Immunohistochemistry; Rats; *Gene Expression Regulation; *Regeneration; Muscle Denervation; Myosins/*metabolism; Muscles/innervation/*metabolism; Neurons; Afferent/*physiology; Inbred F344
The vascular supply and tendons of the extensor digitorum longus (EDL) muscles of two adult rats were unilaterally severed and the muscles were allowed to regenerate for 40 days. Serial frozen sections of muscle grafts were cut and stained for enzymes that delineated fiber type, sensory endings and motor endings. MF30 and ALD58, two antibodies which react only to intrafusal fibers in normal rat muscle, were reacted against sections of nerve-intact muscle grafts. Data were compared to that from muscles of normal rats. Encapsulated fibers devoid of sensory innervation and some extrafusal fibers in muscle grafts had a weak to moderate reaction to MF30, but no reaction to ALD58. Regenerated, encapsulated fibers with sensory innervation bound both MF30 and ALD58. These data indicate that afferents which reinnervate regenerated spindles retain the capacity to induce expression of spindle-specific myosin isoforms in rats.
Fei C; Walro J M
Neuroscience letters
1989
1989-02
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/0304-3940(89)90142-0" target="_blank" rel="noreferrer noopener">10.1016/0304-3940(89)90142-0</a>