The Effect of Resection on Satellite Cell Activity in Rabbit Extraocular Muscle

Abstract

Both active and passive stretch of the rectus muscles produced by strabismus surgery dramatically upregulated the processes of satellite cell activation, integration of new myonuclei into existing myofibers, and concomitant upregulation of immature myosin heavy chain isoforms. Understanding the effects of strabismus surgery on muscle cell biological reactions and myofiber remodeling may suggest new approaches for improving surgical outcomes.

Effects of Recession versus Tenotomy Surgery without Recession in Adult Rabbit Extraocular Muscle

“…12 We found that this muscleshortening procedure resulted in a significant increase in satellite cell activation and their rapid fusion into existing myofibers. This result was present in both the actively stretched, resected muscle and in its passively stretched, antagonist muscle.…”

“…Immunostaining used standard methods. 12 Briefly, the sections were blocked with 10% normal horse serum; incubated for 1 hour in primary antibody at room temperature, followed by sequential incubation in reagents from the ABC kit (VectaElite; Vector Laboratories), labeled with peroxidase; and developed with diaminobenzidine with heavy metals. In addition, sections were stained with hematoxylin and eosin and used for myofiber cross-sectional area measurements.…”

Increased Extraocular Muscle Strength with Direct Injection of Insulin-like Growth Factor-I

“…25 Expression patterns of these isoforms are highly adaptable and appear to change with most perturbations of the muscle. [27][28][29] Injection of IGF-I resulted in decreased expression of neonatal MyHC, and this was most pronounced at the highest dose of IGF-I tested. Developmental MyHC expression increased in the global layer, but only in the midbelly region of the treated muscles.…”

Changes in muscle fiber size and in the composition of myosin heavy chain isoforms of rabbit extraocular rectus muscle following recession surgery

“…Another study examined the effect of resection in rabbit EOMs and found a dramatic increase in the number of myofi bers positive for neonatal MyHC in the resected muscle and in the passively stretched antagonist muscle. 25 Immature MyHC isoforms were upregulated in both actively and passively stretched rectus muscles. 25 There are no reports on the correlation between the changes in the muscle fi ber size after recession surgery and the MyHC isoform composition of EOMs.…”