Synergistic effect of glucocorticoids and IGF-1 on myogenic differentiation through the Akt/GSK-3ß pathway in C2C12 myoblasts.

Purpose: Glucocorticoids are the only therapeutics that can delay the progression of Duchenne musculardystrophy (DMD), the most prevalent type of inherited neuromuscular disorder in males. However, beyond theiranti-inflammatory effects, glucocorticoids have other underlying mechanisms that remain unclear. Moreover, muscleand circulating levels of insulin growth factor-1 (IGF-1) often decrease in response to glucocorticoids. Therefore, wehypothesized that glucocorticoids, either alone or in combination with IGF-1, can improve myogenic differentiation.Materials and methods: Established C2C12 myoblasts were employed as an in vitro model of myogenic differentiation,and myogenic differentiation markers, as assessed by Western blot (myogenin, MyoD, and MyHC protein expression),cellular morphology analysis (fusion index) and RT-PCR (MCK mRNA expression), were measured.Results: Myogenic differentiation markers were increased by glucocorticoid treatment. Furthermore, this effect was furtherenhanced by IGF-1, and these results suggest that glucocorticoids, either alone or together with IGF-1, can promotemyogenic differentiation. Akt and GSK-3ß play important roles in myogenic differentiation. Interestingly, the levels ofboth phosphorylated Ser473-Akt and phosphorylated Ser9-GSK-3ß were increased by glucocorticoid and IGF-1 cotreatment.Pharmacological manipulation with LY294002 and LiCl was employed to inhibit Akt and GSK-3ß, respectively.We found that cellular differentiability was inhibited by LY294002 and enhanced by LiCl, indicating that theAkt/GSK-3ß signaling pathway is activated by glucocorticoid and IGF-1 treatment to promote myogenic differentiation.Conclusions: Glucocorticoids together with IGF-1 promote myogenic differentiation through the Akt/GSK-3ßpathway. Thus, these results further our knowledge of myogenic differentiation and may offer a potential alternativestrategy for DMD treatment based on glucocorticoid and IGF-1.

Long-term treatment of blepharospasm with botulinum toxin A: a service-based study over a 16-year follow-up in southern China.

OBJECTIVE: To elucidate the effect of long-term treatment with botulinum toxin A (BTX-A) for blepharospasm. Prevalence data and clinical features in southern China and influencing factors for selecting BTX-A treatment were explored. METHODS: We collected data retrospectively from 338 consecutive patients diagnosed with blepharospasm over 16 years to assess prevalence data and clinical features. Thereafter, all patients were classified into BTX-A (n = 135) or non-BTX-A (n = 203) treatment groups according to the patients' requests in order to explore the factors influencing whether BTX-A treatment was chosen. Furthermore, dynamic follow-up data were analyzed to evaluate the long-term efficacy in the BTX-A group. RESULTS: The prevalence was 23.3 per million, with an onset age of 50.3 ± 12.3 years and a female:male ratio of 2.4:1; the most common symptom was excessive blinking (91.2%). The symptom severity and psychological assessment scores were significantly decreased by treatment with BTX-A (p < 0.01), and there was no significant difference in response duration with the prolongation of BTX-A injections. Adverse events occurred 52 times (5.0%) among 1038 injections. The symptom severity and psychological assessment scores and the occurrence of eye-opening difficulty were higher, and medical expenses and the symptom tolerability rate were lower in the BTX-A group than in the non-BTX-A group (p < 0.05). CONCLUSION: The onset age was earlier than that in Western countries. However, starting BTX-A treatment early is justified, even though a higher dosage was needed to maintain reliable long-term efficacy. Additionally, symptom severity and medical expenses are the primary factors affecting whether patients select BTX-A treatment.