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Published on: April 3, 2016
Effects of Short-Term Treatment of Rabbit Extraocular Muscle With Ciliary Neurotrophic Factor
Jolene C Rudell1, Linda K McLoon2,3
1Department of Ophthalmology, University of California San Diego, La Jolla, California, United States.
Purpose:
Little is known about the effect of ciliary neurotrophic factor (CNTF) on extraocular muscles, but microarray studies suggested CNTF might play a role in the development and/or maintenance of strabismus. The effect of short-term treatment of adult rabbit extraocular muscle with injected CNTF was examined for its ability to alter muscle characteristics.
Methods:
Eight adult New Zealand white rabbits received an injection into one superior rectus muscle of 2 µg/100 µL CNTF on 3 consecutive days. One week after the first injection, the rabbits were euthanized, and the treated and contralateral superior rectus muscles were assessed for force generation capacity and contraction characteristics using an in vitro stimulation protocol and compared to naïve control superior rectus muscles. All muscles were analyzed to determine mean cross-sectional areas and expression of slow twitch myosin heavy chain isoform.
Results:
Short-term treatment of rabbit superior rectus muscles with CNTF resulted in a significant decrease in muscle force generation, but only at the higher stimulation frequencies. Significantly decreased myofiber cross-sectional areas of the treated muscles correlated with the decreased generated force. In addition, there were significant changes to contractile properties of the treated muscles, as well as a decrease in the number of myofibers expressing slow twitch myosin heavy chain.
Conclusions:
We show that short-term treatment of a single rabbit superior rectus muscle results in decreased myofiber size, decreased force, and altered contractile characteristics. Further studies are needed to determine if it can play a role in improving alignment in animal models of strabismus.
Insights
Ciliary neurotrophic factor (CNTF) injection decreased rabbit extraocular muscle force and myofiber size. Further research is needed to explore CNTF’s role in strabismus treatment.
Area of Science:
- Ophthalmology
- Muscle Physiology
- Neuroscience
Background:
- Ciliary neurotrophic factor (CNTF) involvement in extraocular muscles is poorly understood.
- Microarray data suggests a potential role for CNTF in strabismus development and maintenance.
Purpose of the Study:
- To investigate the effects of short-term CNTF treatment on adult rabbit extraocular muscle characteristics.
- To assess CNTF's impact on muscle force generation and contractile properties.
Main Methods:
- Adult rabbits received daily CNTF injections into the superior rectus muscle over three days.
- Treated and control muscles were analyzed for force generation, contraction characteristics, myofiber cross-sectional area, and slow-twitch myosin expression.
Main Results:
- CNTF treatment significantly reduced muscle force at higher stimulation frequencies.
- Decreased myofiber cross-sectional areas correlated with reduced force generation.
- Contractile properties were altered, and slow-twitch myosin expression decreased in treated muscles.
Conclusions:
- Short-term CNTF application diminishes myofiber size, force, and contractile function in rabbit superior rectus muscles.
- Further investigation is required to determine CNTF's therapeutic potential in strabismus animal models.
