## 4 Discussion
should have been extended in order to achieve a reduction in muscle mass. MuRF-1 and atrogin-1 have been demonstrated to induce muscle protein degradation, which can lead to the development of muscle degradation. In addition, DEX has been shown to activate the UPS, thereby promoting the expression of MuRF-1 and atrogin-1 [45]. Myogenic regulatory factors, including myogenin and MyoD, are involved in muscle cell proliferation and differentiation. These factors promote the synthesis of muscle cellsby differentiating myoblasts into myotubes [46]. Myogenin and Myo induce skeletal muscle development by forming myofibrils. In addition, DEX reduces the expression of myogenic regulatory factors, including myogenin and MyoD, which are involved in myogenic differentiation [47; 48; 49]. The mRNA expression of MyoD and myogenin in the tibialis anterior (TA) was found to be significantly increased in the DMH group. It was hypothesised that the elevation in MyoD and myogenin levels led to a notable increase in TA weight. The present study revealed no significant differences in MuRF-1 or atrogin-1 mRNA expression between the groups. However, myogenin and MyoD mRNA expression levels were significantly elevated in rats fed the DMH-supplemented diet in comparison to those in the DEX group. Furthermore, the DEX + DMH group exhibited a notable increase in grip strength and TA weight compared with the other groups. Despite an increase in mRNA expression of MyoD and myogenin in the DMH group, there was no corresponding increase in the weight of GAS. Despite an increase in the weight of the TA, its proportion of total body weight remained relatively insignificant. Consequently, we speculate that there was no significant difference in weight recovery between the DEX and DEX + DMH groups. The present study was limited in that it was not possible to determine the direct mechanism by which DMH induced increased mRNA expression of myogenin and MyoD by western blot. Furthermore, it should be noted that the histological sections of muscle tissue were not identified through tissue staining, which represents a limitation of the study. The increase in myogenin and MyoD levels following DMH consumption is due to the activation of protein kinase B, also known as Akt [50]. Akt is a serine-threonine kinase that promotes myogenesis by regulating protein synthesis. Akt activation promotes muscle differentiation by increasing the expression of myogenin and MyoD [51; 52]. A recent study on mealworms reported that rats fed mealworm-derived protein supplements exhibited activated Akt and ameliorated skeletal muscle atrophy [53]. Another study reported that orally administered mealworm extracts activated Akt, increased myogenin expression, and improved grip strength [54]. Edible insects have recently emerged as potential alternative sources of animal protein owing to their nutritional profiles and environmental benefits. They are not only a rich source of protein and essential amino acids but also offer a cost-effective and sustainable alternative to conventional animal farming, which has been linked to high greenhouse gas emissions [55; 56]. In particular, mealworms are a rich source of minerals, including calcium and magnesium, and are highly nutritious owing to their high protein content and abundance of essential amino acids, which can contribute to the development of muscle tissue [57]. Moreover, it has been demonstrated that mealworms possess the capacity to facilitate the growth of muscle cells and to avert the development of musculoskeletal ailments in older adults [58]. The present study demonstrated that DMH protected C2C12 cells from DEX-induced damage and that DMH-fed rats exhibited increased grip strength and TA weight. MyoD is associated with an increase in myoblasts, while myogenin is a factor associated with the differentiation of myoblasts into myotubes. It can therefore be postulated that DMH may induce muscle protein synthesis by promoting the differentiation of myoblasts into myotubes.