RESUMEN
OBJECTIVE: Repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible, ie, bruxism, is traditionally linked to pain and unpleasantness in the active muscles. The aim of this study was to investigate the effects of standardized craniofacial muscle contractions on self-reported symptoms. METHODS: Sixteen healthy volunteers performed six 5-minute bouts of 20% maximal voluntary contraction task of the jaw-closing (Jaw), the orbicularis-oris (O-oris), and the orbicularis-oculi (O-oculi) muscles. Participants rated their perceived pain, unpleasantness, fatigue, and mental stress levels before, during, and after the contraction tasks on 0-10 Numeric Rating Scales (NRS). Each muscle contraction task (= 1 session) was separated by at least 1 week and the order of the sessions was randomized in each subject. RESULTS: All muscle contraction tasks evoked significant increases in NRS scores of pain (mean ± SD: Jaw; 3.8 ± 2.7, O-oris; 1.9 ± 2.2, O-oculi; 1.4 ± 1.3, P < .014), unpleasantness (Jaw; 4.1 ± 2.5, O-oris; 2.1 ± 1.9, O-oculi; 2.9 ± 1.8, P < .001), fatigue (Jaw; 5.8 ± 2.0, O-oris; 3.2 ± 2.3, O-oculi; 3.6 ± 1.9, P < .001), and mental stress (Jaw; 4.1 ± 2.1, O-oris; 2.2 ± 2.7, O-oculi; 2.9 ± 2.2, P < .001). The Jaw contractions were associated with higher NRS scores compared with the O-oris and the O-oculi contractions (P < .005) without differences between the O-oris and the O-oculi (P > .063). All symptoms disappeared within 1 day (P > .469). CONCLUSIONS: The results showed that submaximal static contractions of different craniofacial muscle groups could evoke transient, mild to moderate levels of muscle pain and fatigue and increased stress scores. The fatigue resistance may differ between different muscle groups. Further studies are warranted to better understand the contribution of specific craniofacial muscle groups for the characteristic presentation of musculoskeletal pain conditions in the head.
Asunto(s)
Bruxismo/fisiopatología , Músculos Faciales/fisiopatología , Dolor Facial/fisiopatología , Fatiga/fisiopatología , Contracción Muscular/fisiología , Estrés Psicológico/fisiopatología , Adulto , Bruxismo/complicaciones , Estudios Cruzados , Dolor Facial/etiología , Fatiga/etiología , Femenino , Humanos , Masculino , Estrés Psicológico/etiología , Adulto JovenRESUMEN
A recent study showed that the frequency of an antiretroviral factor TRIM5 gene-derived isoform, TRIMCyp, in cynomolgus macaques (Macaca fascicularis) varies widely according to the particular habitat examined. However, whether the findings actually reflect the prevalence of TRIMCyp in wild cynomolgus macaques is still uncertain because the previous data were obtained with captive monkeys in breeding and rearing facilities. Here, we characterized the TRIM5 gene in cynomolgus macaques captured in the wild, and found that the frequency of the TRIMCyp allele was comparable to those in captive monkeys. This suggests that the previous results with captive monkeys do indeed reflect the natural allele frequency and that breeding and rearing facilities may not affect the frequency of TRIM5 alleles. Interestingly, the prevalence of a minor haplotype of TRIMCyp in wild macaques from the Philippines was significantly lower than in captive ones, suggesting that it is advantageous for wild monkeys to possess the major haplotype of TRIMCyp. Overall, our results add to our understanding of the geographic and genetic prevalence of cynomolgus macaque TRIMCyp.