RESUMEN
Cheonggukjang (CKJ), a fermented soybean product, has been reported to have beneficial effects on various chronic diseases, including cardiovascular disease, cancer and immune diseases. To investigate whether CKJ induces growth sensitivity in mammals, alterations of key parameters related to their growth were analyzed. SpragueDawley (SD) rats were treated with a high concentration of CKJ (HCKJ) or a low concentration of CKJ (LCKJ) for 10 days, and compared with vehicle-treated rats. The CKJ contained a high concentration of total flavonoids, phenolic compounds, daidzein and genistein, compared with the non-fermented soybean product. Body weight was higher in the HCKJtreated group compared with that in the vehicle and LCKJtreated groups, whereas the weights of three organs (the brain, liver and kidney) were higher in the LCKJtreated group compared with the remaining two groups. However, no significant differences in femur length and weight were detected between the CKJ and vehicletreated groups. The thickness of the epiphyseal growth plate in proximal femoral epiphysis was broadest in the HCKJtreated group compared with the vehicle- and LCKJtreated groups. Furthermore, the level of growth hormone (GH) was highest in the serum of the LCKJtreated group, although that of the HCKJtreated group was lower compared with that in the LCKJ group. Moreover, the expression levels of the GH receptor increased in the liver tissue, but not in the muscle tissue, of the LCKJ and HCKJtreated groups. In the downstream signaling pathway of the GH receptor, the phosphorylation levels of Akt and Erk were differentially regulated between the liver and muscle. These results suggest that CKJ extract may enhance the sensitivity of the femur, liver and muscle epiphyseal growth plate in SD rats, through the upregulation of GH secretion.