Maxillofac Plast Reconstr Surg.  2015 Dec;37(12):46. 10.1186/s40902-015-0049-6.

Early effect of Botox-A injection into the masseter muscle of rats: functional and histological evaluation

Affiliations
  • 1Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea.
  • 2Department of Oral Medicine and Diagnosis, College of Dentistry, Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung, South Korea.
  • 3Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, South Korea. epker@chol.com
  • 4Sericultural and Apicultural Materials Division, National Academy of Agricultural Science, Suwon, South Korea.

Abstract

BACKGROUND
The purpose of this study was to evaluate the change of food intake after different dosages of botulinum toxin A (BTX) injection in the animal model. Additionally, the dimensional and histological change at 14 days after BTX injection was also evaluated.
METHODS
The comparative study was performed using the BTX injection model in rats (n = 5 for each group). Group 1 was the saline-injected group. Group 2 was the 5-unit BTX-injection group to each masseter muscle. Group 3 was the 10-unit BTX-injection group to each masseter muscle. Food intake rates and body weight were checked daily before and after BTX injection until 10 days. All animals were sacrificed at 14 days after BTX injection, and the specimens underwent hematoxylin and eosin stain and immunohistochemical staining for myosin type II (MYH2).
RESULTS
The recovery of food intake in groups 2 and 3 decreased significantly compared with group 1 from day 2 to day 7 and day 9 after injection (p < 0.05). The BTX-treated masseter muscles were significantly smaller than those in group 1 (p = 0.015). The immunohistochemical findings demonstrated that the expression of MYH2 was significantly higher in group 3 compared to groups 1 and 2 (p < 0.001).
CONCLUSIONS
BTX injection to the masseter muscle in rats demonstrated short food-intake-rate reduction with recovery until 10 days after injection. The thickness of the masseter muscle and MYH2 expression were significantly changed according to the injected dose of BTX.

Keyword

Keywords; Botulinum toxin A; Masseter muscle; Myosin type II; Food intake

MeSH Terms

Animals
Body Weight
Botulinum Toxins
Eating
Eosine Yellowish-(YS)
Hematoxylin
Masseter Muscle*
Models, Animal
Myosin Type II
Rats*
Botulinum Toxins
Eosine Yellowish-(YS)
Hematoxylin
Myosin Type II
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