Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice
Mice are commonly used to study mandibular dynamics due to their similarity in chewing cycle patterns with humans. Adult mice treated unilaterally with botulinum toxin type A (BoNTA) in the masseter exhibit atrophy of this muscle characterized by an increase in the gene expression of atrophy-related...
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MDPI AG
2023-09-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/19/14740 |
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| author | Julián Balanta-Melo Andrea Eyquem-Reyes Noelia Blanco Walter Vásquez Kornelius Kupczik Viviana Toro-Ibacache Sonja Buvinic |
| author_facet | Julián Balanta-Melo Andrea Eyquem-Reyes Noelia Blanco Walter Vásquez Kornelius Kupczik Viviana Toro-Ibacache Sonja Buvinic |
| author_sort | Julián Balanta-Melo |
| collection | DOAJ |
| description | Mice are commonly used to study mandibular dynamics due to their similarity in chewing cycle patterns with humans. Adult mice treated unilaterally with botulinum toxin type A (BoNTA) in the masseter exhibit atrophy of this muscle characterized by an increase in the gene expression of atrophy-related molecular markers, and a reduction in both muscle fiber diameter and muscle mass at 14d. However, the impact of this muscle imbalance on the non-treated masticatory muscles remains unexplored. Here, we hypothesize that the unilateral masseter hypofunction leads to molecular and 3D morphometric signs of atrophy of the masseter and its agonist masticatory muscles in adult mice. Twenty-three 8-week-old male BALB/c mice received a single injection of BoNTA in the right masseter, whereas the left masseter received the same volume of saline solution (control side). Animals were euthanized at 2d, 7d, and 14d, and the masticatory muscles were analyzed for mRNA expression. Five heads were harvested at 14d, fixed, stained with a contrast-enhanced agent, and scanned using X-ray microtomography. The three-dimensional morphometric parameters (the volume and thickness) from muscles in situ were obtained. <i>Atrogin-1/MAFbx</i>, <i>MuRF-1,</i> and <i>Myogenin</i> mRNA gene expression were significantly increased at 2 and 7d for both the masseter and temporalis from the BoNTA side. For medial pterygoid, increased mRNA gene expression was found at 7d for <i>Atrogin-1/MAFbx</i> and at 2d–7d for <i>Myogenin</i>. Both the volume and thickness of the masseter, temporalis, and medial pterygoid muscles from the BoNTA side were significantly reduced at 14d. In contrast, the lateral pterygoid from the BoNTA side showed a significant increase in volume at 14d. Therefore, the unilateral hypofunction of the masseter leads to molecular and morphological signs of atrophy in both the BoNTA-injected muscle and its agonistic non-injected masticatory muscles. The generalized effect on the mouse masticatory apparatus when one of its components is intervened suggests the need for more clinical studies to determine the safety of BoNTA usage in clinical dentistry. |
| first_indexed | 2024-03-09T13:52:54Z |
| format | Article |
| id | doaj.art-4e98846f3d27466790f32bd1c5d7a93b |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T13:52:54Z |
| publishDate | 2023-09-01 |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-4e98846f3d27466790f32bd1c5d7a93b2023-11-30T20:46:42ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-09-0124191474010.3390/ijms241914740Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult MiceJulián Balanta-Melo0Andrea Eyquem-Reyes1Noelia Blanco2Walter Vásquez3Kornelius Kupczik4Viviana Toro-Ibacache5Sonja Buvinic6School of Dentistry, Faculty of Health, Universidad del Valle, Cali 760043, ColombiaInstitute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380544, ChileInstitute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380544, ChileInstitute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380544, ChileDepartment of Anthropology, Faculty of Social Sciences, Universidad de Chile, Santiago 7750000, ChileInstitute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380544, ChileInstitute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago 8380544, ChileMice are commonly used to study mandibular dynamics due to their similarity in chewing cycle patterns with humans. Adult mice treated unilaterally with botulinum toxin type A (BoNTA) in the masseter exhibit atrophy of this muscle characterized by an increase in the gene expression of atrophy-related molecular markers, and a reduction in both muscle fiber diameter and muscle mass at 14d. However, the impact of this muscle imbalance on the non-treated masticatory muscles remains unexplored. Here, we hypothesize that the unilateral masseter hypofunction leads to molecular and 3D morphometric signs of atrophy of the masseter and its agonist masticatory muscles in adult mice. Twenty-three 8-week-old male BALB/c mice received a single injection of BoNTA in the right masseter, whereas the left masseter received the same volume of saline solution (control side). Animals were euthanized at 2d, 7d, and 14d, and the masticatory muscles were analyzed for mRNA expression. Five heads were harvested at 14d, fixed, stained with a contrast-enhanced agent, and scanned using X-ray microtomography. The three-dimensional morphometric parameters (the volume and thickness) from muscles in situ were obtained. <i>Atrogin-1/MAFbx</i>, <i>MuRF-1,</i> and <i>Myogenin</i> mRNA gene expression were significantly increased at 2 and 7d for both the masseter and temporalis from the BoNTA side. For medial pterygoid, increased mRNA gene expression was found at 7d for <i>Atrogin-1/MAFbx</i> and at 2d–7d for <i>Myogenin</i>. Both the volume and thickness of the masseter, temporalis, and medial pterygoid muscles from the BoNTA side were significantly reduced at 14d. In contrast, the lateral pterygoid from the BoNTA side showed a significant increase in volume at 14d. Therefore, the unilateral hypofunction of the masseter leads to molecular and morphological signs of atrophy in both the BoNTA-injected muscle and its agonistic non-injected masticatory muscles. The generalized effect on the mouse masticatory apparatus when one of its components is intervened suggests the need for more clinical studies to determine the safety of BoNTA usage in clinical dentistry.https://www.mdpi.com/1422-0067/24/19/14740masticatory musclesX-ray microtomographymuscular atrophybotulinum toxinstype A |
| spellingShingle | Julián Balanta-Melo Andrea Eyquem-Reyes Noelia Blanco Walter Vásquez Kornelius Kupczik Viviana Toro-Ibacache Sonja Buvinic Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice International Journal of Molecular Sciences masticatory muscles X-ray microtomography muscular atrophy botulinum toxins type A |
| title | Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice |
| title_full | Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice |
| title_fullStr | Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice |
| title_full_unstemmed | Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice |
| title_short | Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice |
| title_sort | unilateral hypofunction of the masseter leads to molecular and 3d morphometric signs of atrophy in ipsilateral agonist masticatory muscles in adult mice |
| topic | masticatory muscles X-ray microtomography muscular atrophy botulinum toxins type A |
| url | https://www.mdpi.com/1422-0067/24/19/14740 |
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