Objective To explore the effect of Guben Zenggu Formula（固本增骨方） combined with hyperbaric oxygen therapy on imbalances in bone metabolism of osteoporosis

as well as the possible mechanism underling the effect. Methods Fifty female Wistar rats were randomly divided into a blank group

a model group

a hyperbaric oxygen group

an herbal formula group

and a combination group

with 10 rats in each group. Ovariectomy method was used to establish the osteoporosis model in all groups except for blank group. After successful modeling

rats in the blank group

model group and hyperbaric oxygen group were all given 30 ml/kg normal saline by gavage; herbal suspension of Guben Zenggu Formula at a dose of 4.6 g/（kg·d） by gavage and hyperbaric oxygen were administered in herbal formula group and hyperbaric oxygen group

respectively; the combination group received both herbal suspension and hyperbaric oxygen. After 12 weeks of intervention

the bone metabolism markers were detected in serum including bone-specific alkaline phosphatase（BALP）

nuclear binding factor-α1（CBF-α1）

type I collagen carboxy-terminal peptide（CTX-Ⅰ）

type Ⅰ procollagen amino-terminal propertied（PⅠNP） and osteocalcin（OC）; micro CT imaging was used to detect femur bone density and bone trabecular microstructure; The protein and mRNA expression of osteoprotegerin（OPG） in rat hypothalamus and femoral tissue

and receptor activator of nuclear factor-kappa B ligand（RANKL） in rats hypothalamus and femur tissues. Results Compared to blank group

the model group had lower levels of bone density

BALP

CBF-α1

CTX-I

PINP

OC

relative bone volume fraction

trabecular bone number

thickness

and connection density

as well as higher trabecular bone separation

and structural model index; the OPG protein and mRNA expression significantly decreased while the RANKL protein and mRNA expression increased（P<0.05）. All the outcomes showed significant improvements in hyperbaric oxygen group

herbal formula group

and combination group compared to those in model group（P<0.05）; the herbal formula group and combination group showed better improvements compared to hyperbaric oxygen group

and the combination group showed the biggest changes（P<0.01）. Conclusion Guben Zenggu Formula combined with hyperbaric oxygen therapy can regulate the imbalances in bone metabolism

increase bone mass

and improve the trabecular bone microstructure

possibly through regulating the OPG/RANKL signaling pathway.