TY - JOUR
T1 - Histomorphometric Changes of the Masseter Muscle of Rats After a Single Injection of Botulinum Toxin Type A
AU - Ramos, Douglas Massoni
AU - de Brito Silva, Raira
AU - De la Torre Canales, Giancarlo
AU - Resende, Luciana
AU - Esquisatto, Marcelo Augusto Marretto
AU - Moreira, Nádia Cristina Fávaro
AU - Ernberg, Malin
AU - Rizzatti-Barbosa, Célia Marisa
N1 - Publisher Copyright:
© Springer Science+Business Media, LLC, part of Springer Nature and International Society of Aesthetic Plastic Surgery 2023.
PY - 2024/3
Y1 - 2024/3
N2 - Background: It has been reported that botulinum toxin type A (BoNT-A) produces structural changes in masticatory muscles. However, not all histomorphometric parameters affected by BoNT-A parameters have been assessed. This study investigated the histomorphometric changes in the masseter muscle of rats after a single injection of BoNT-A. Methods: Forty-four adult animals were randomly divided into control group (n = 22) and BoNT-A group (n = 22). Controls received a single dose of 0.14 mL/kg of saline in masseter muscles, and the BoNT-A group received a 7 U/Kg of BoNT-A. The groups received the same volume of injected substances. Animals were sacrificed on 7th (n = 5), 14th (n = 5), 21st (n = 5), 28th (n = 4) and 90th (n = 3) days post-treatment. Histological masseter tissue slides were obtained from hematoxylin–eosin treatment and analyzed in optical microscopy regarding muscle cross-sectional area, amount of connective tissue and quantity and diameter of myocytes. For statistical analysis, generalized linear models were used to compare the data (ANOVA). In all test, the significance level of 5% was set. Results: BoNT-A values of cross-sectional area of the masseter muscle were significantly lower than controls (p < 0.01) throughout the study. Regarding myocytes quantity, BoNT-A subgroups presented higher values than controls (p < 0.0001) since the 14th day until the end of the study; however, the diameter of myocytes was smaller in all BoNT-A subgroups (p < 0.0001) in all assessment points. The amount of connective tissue was higher in BoNT-A subgroups (p < 0.0001) throughout the study. Conclusion: A single injection of BoNT-A altered the structure of masseter muscle of rats, regarding its histomorphometric parameters. No Level Assigned: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.
AB - Background: It has been reported that botulinum toxin type A (BoNT-A) produces structural changes in masticatory muscles. However, not all histomorphometric parameters affected by BoNT-A parameters have been assessed. This study investigated the histomorphometric changes in the masseter muscle of rats after a single injection of BoNT-A. Methods: Forty-four adult animals were randomly divided into control group (n = 22) and BoNT-A group (n = 22). Controls received a single dose of 0.14 mL/kg of saline in masseter muscles, and the BoNT-A group received a 7 U/Kg of BoNT-A. The groups received the same volume of injected substances. Animals were sacrificed on 7th (n = 5), 14th (n = 5), 21st (n = 5), 28th (n = 4) and 90th (n = 3) days post-treatment. Histological masseter tissue slides were obtained from hematoxylin–eosin treatment and analyzed in optical microscopy regarding muscle cross-sectional area, amount of connective tissue and quantity and diameter of myocytes. For statistical analysis, generalized linear models were used to compare the data (ANOVA). In all test, the significance level of 5% was set. Results: BoNT-A values of cross-sectional area of the masseter muscle were significantly lower than controls (p < 0.01) throughout the study. Regarding myocytes quantity, BoNT-A subgroups presented higher values than controls (p < 0.0001) since the 14th day until the end of the study; however, the diameter of myocytes was smaller in all BoNT-A subgroups (p < 0.0001) in all assessment points. The amount of connective tissue was higher in BoNT-A subgroups (p < 0.0001) throughout the study. Conclusion: A single injection of BoNT-A altered the structure of masseter muscle of rats, regarding its histomorphometric parameters. No Level Assigned: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.
KW - Adverse effects
KW - Botulinum toxin
KW - Connective tissue
KW - Masticatory muscle
KW - Myocytes
UR - http://www.scopus.com/inward/record.url?scp=85168603555&partnerID=8YFLogxK
U2 - 10.1007/s00266-023-03572-z
DO - 10.1007/s00266-023-03572-z
M3 - Article
AN - SCOPUS:85168603555
SN - 0364-216X
VL - 48
SP - 1037
EP - 1044
JO - Aesthetic Plastic Surgery
JF - Aesthetic Plastic Surgery
IS - 5
ER -