Changes of masseter muscle activity following injection of botulinum toxin type A in adult rats

Structured Objectives To investigate changes in masseter muscle function following intramuscular injection of different dose‐dependent botulinum toxin type A (BTXA). Setting and Sample Population Department of Orthodontics at Taipei Medical University. Fifty‐two, 70‐day‐old male Wistar rats were ran...

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Bibliographic Details
Published in:Orthodontics & craniofacial research 2015-11, Vol.18 (4), p.202-211
Main Authors: Tsai, C. Y., Lei, Y. Y., Yang, L. Y., Chiu, W. C.
Format: Article
Language:English
Subjects:
Analog-Digital Conversion
Animals
botulinum toxin type A
Botulinum Toxins, Type A - administration & dosage
Dentistry
Dose-Response Relationship, Drug
Electromyography - drug effects
EMG
Male
masseter muscle
Masseter Muscle - anatomy & histology
Masseter Muscle - drug effects
Mastication - physiology
Neuromuscular Agents - administration & dosage
Organ Size - drug effects
Random Allocation
Rats
Rats, Wistar
Time Factors
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Summary:Structured Objectives To investigate changes in masseter muscle function following intramuscular injection of different dose‐dependent botulinum toxin type A (BTXA). Setting and Sample Population Department of Orthodontics at Taipei Medical University. Fifty‐two, 70‐day‐old male Wistar rats were randomly divided into four groups. Group I received 7.5 U of BTXA (0.3 ml), Group II received 5.0 U, and Group III received 2.5 U in the right masseter muscle, respectively. Group IV is the control and received no BTXA injection. Materials and Methods A wire electrode device was implanted to record muscle activity. One week after implantation, the rats were fed every 2 h and EMG signals were recorded during the first hour. All signals were recorded for 12 weeks. Thereafter, EMG data were analyzed for statistical calculation and weights of masseter muscles were measured. Results Masseter muscle activity decreased 99% during the first week after BTXA injection and gradually recovered from the 3rd week on in Groups I‐III. By the 12th week, muscle activity recovered to 41% in Groups I and II and 56.26% in Group III. No significant changes of muscle activity were observed in Group IV. Conclusion BTXA induced a reduction in masseter muscle activity and an increased toxin dose resulted in greater depression of muscle activity.
ISSN:1601-6335
1601-6343
DOI:10.1111/ocr.12095