HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Anderson, B. C. Articles by McLoon, L. K. Search for Related Content PubMed PubMed Citation Articles by Anderson, B. C. Articles by McLoon, L. K.

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

¹From the Departments of Ophthalmology, ²Pediatrics, and ⁴Neuroscience, University of Minnesota, Minneapolis, Minnesota; and the ³Department of Human Nutrition, Foods and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.

PURPOSE. Previous work has demonstrated the effectiveness of insulin-like growth factor (IGF)-II in increasing force generation in extraocular muscle (EOM). Studies in the literature have suggested that IGF-I would be even more effective than IGF-II. This study was performed to assess the effects on muscle mass and force generation of IGF-I injection in adult rabbit superior rectus muscle.

METHODS. Adult rabbits received a single injection of IGF-I at one of several doses into one superior rectus muscle. One week after treatment, the rabbits were euthanatized, and the superior rectus muscle from each orbit was removed. Force generation was measured using an in vitro apparatus, and injected muscles were compared with the contralateral control. A second group of animals were injected similarly, and the muscles were examined at 1 week for changes in cross-sectional area of individual myofibers.

RESULTS. EOMs demonstrate significant numbers of cells expressing the IGF receptor. After the EOMs were injected with IGF-I, there were significant increases both in muscle force generation and cross-sectional area at all doses tested in this study. Doses of 10 and 25 µg IGF-I were most effective.

CONCLUSIONS. Direct muscular injection of IGF-I effectively increases EOM force generation without the potential biomechanical hazards of surgery such as permanently altered muscle length or insertional position on the globe.

This article has been cited by other articles:

				R. S. Antunes-Foschini, D. Miyashita, H. E. A. Bicas, and L. K. McLoon Activated Satellite Cells in Medial Rectus Muscles of Patients with Strabismus Invest. Ophthalmol. Vis. Sci., January 1, 2008; 49(1): 215 - 220. [Abstract] [Full Text] [PDF]

				B. C. Anderson, S. P. Christiansen, and L. K. McLoon Myogenic Growth Factors Can Decrease Extraocular Muscle Force Generation: A Potential Biological Approach to the Treatment of Strabismus Invest. Ophthalmol. Vis. Sci., January 1, 2008; 49(1): 221 - 229. [Abstract] [Full Text] [PDF]

				E. E. Spangenburg, D. Le Roith, C. W. Ward, and S. C. Bodine A functional insulin-like growth factor receptor is not necessary for load-induced skeletal muscle hypertrophy J. Physiol., January 1, 2008; 586(1): 283 - 291. [Abstract] [Full Text] [PDF]