<i>Humulus japonicus</i> Enhances Bone Growth and Microarchitecture in Rats: Potential Involvement of IGF-1 Signaling

This study investigated the effects of <i>Humulus japonicus</i> extract supplementation on bone growth and microstructural properties in male and female rats, with a particular focus on the JAK2/STAT5/IGF-1 signaling pathway. Three-week-old Sprague-Dawley rats were assigned to different groups receiving a normal diet (ND), growth hormone (GH), or varying doses of <i>H. japonicus</i> extract: low (L; 73 mg/kg body weight [bw]/day), medium (M; 146 mg/kg bw/day), and high (H; 292 mg/kg bw/day) for four weeks. The results demonstrated that the H group exhibited significant increases in femur and tibia lengths, trabecular and cortical bone mineral density, and growth plate thickness compared with the ND group. Furthermore, the H group demonstrated elevated serum and hepatic IGF-1 and IGFBP-3 levels, as well as enhanced phosphorylation of JAK2 and STAT5. The findings suggest that <i>H. japonicus</i> supplementation promotes longitudinal bone growth by stimulating growth plate activity and modulating the JAK2/STAT5-IGF-1 signaling pathway. This research indicates that <i>H. japonicus</i> extract could potentially be used as a natural therapeutic agent to support skeletal development and maintain bone health.