The herbal formula HT042 induces longitudinal bone growth in adolescent female rats

Abstract

The effect of HT042, a blend of three herbal extracts, on longitudinal bone growth was investigated in short- and long-term rat models. In the short-term model, we divided female Sprague-Dawley rats (3 weeks old) into six groups, according to treatment: vehicle, HT042 (100 mg/kg), Phlomis umbrosa (100 mg/kg), Astragalus membranaceus (100 mg/kg), and Eleutherococcus senticosus (100 mg/kg) were administered twice daily, and recombinant human growth hormone (rhGH) (1 IU) was subcutaneously injected once daily. Treatments were maintained for 4 days in each case. On day 3, tetracycline (20 mg/kg) was injected intraperitoneally (20 mg/kg) to form the fluorescent band on the growth plates. On days 2-4, 5-bromo-2'-deoxyuridine (BrdU) (50 mg/kg) was injected intraperitoneally to label proliferating cells. On day 5, the tibias were dissected and fixed in 30% sucrose. Dehydrated bone was sectioned at a thickness of 40 μm and observed. The bone growth in groups administered HT042 and rhGH was significantly increased to 433.50 ± 21.61 and 434.49 ± 15.21 μm/day, respectively, from 410.03 ± 17.4 μm/day (control). The height of the growth plates in the HT042 and rhGH groups was also significantly increased to 556.5 ± 21.1 and 544.2 ± 21.1 μm (P < .05), respectively, from 518.1 ± 4.1 μm (normal). The number of BrdU-positive cells in chondrocytes of the HT042 and rhGH groups was increased to 389 ± 36 and 627 ± 39 cells/mm² (P < .001), respectively, from 264 ± 17 cells/mm² (control). Insulin-like growth factor-1 and bone morphogenetic protein-2 in the HT042 group were highly expressed in the growth plate. In the long-term rat model, the body weight, nose-tail length, and nose-anus length were measured by microknemometry for 4 weeks. The body weight of the rhGH group was significantly increased. The nose-anus length of the HT042 and rhGH groups was significantly greater at 18.5 ± 0.3 and 18.7 ± 0.3 cm compared to 18.2 ± 0.2 cm (control).