The effectiveness of intermittent rat parathyroid hormone (1-34) treatment on low bone mass due to oestrogen or androgen depletion in skeletally mature rats

Abstract

Rat parathyroid hormone (PTH) 1-34 (4 microg/kg/day) was applied for 2.5 months to 9 month-old rats immediately after ovariectomy or orchidectomy or to 15 month-old rats with low bone mass which had been castrated 6 months before in order to know the effects on serum biochemistry parameters, lumbar and femoral bone mineral density, histology, cancellous and cortical bone histomorphometry, mineralisation content profile in cortical bone by backscattered-electron microscopy, and femoral torsion biomechanical testing. In ovariectomised rats, preventive PTH treatment avoided cancellous bone loss in tibial metaphysis and partially in lumbar vertebra, while in cortical bone, PTH increased endosteal resorption and periosteal formation. In intervention study, PTH did not restore cancellous bone but a strong endosteal and periosteal new bone formation was detected. In orchidectomised rats, PTH, in preventive study, avoided cancellous bone loss in metaphysis and lumbar vertebra, and a mild new bone formation in cortical bone was found. In intervention study, PTH maintained baseline cancellous bone mass, but in cortical bone a strong endosteal and periosteal new bone formation was detected. The PTH-induced new bone formation was confirmed by histology and by mineral content profiles. After castration, biomechanical properties were affected in females but not in male rats and PTH reverted this effect.

Teriparatide as a Chondroregenerative Therapy for Injury-Induced Osteoarthritis

“…In two of these studies, 40 μg/kg/day was demonstrated to effectively accelerate fracture healing in the mouse, with enhancement of chondrogenesis and expansion of the cartilaginous callus [65, 66]. It should be noted that 40μg/kg/day is significantly higher than accepted and optimal ranges in other species including rat (4–20μg/kg/day) [69, 70], rabbit (10 μg/kg/day) [71], macaque (5 μg/kg/day) [72], and human (0.25 μg/kg/day) [73]. We anticipate that there is a similar species-associated shift in the range of effective concentrations supporting chondro-protective and chondro-regenerative effects.…”

Modifications in Bone Matrix of Estrogen-Deficient Rats Treated with Intermittent PTH

“…Indeed, Iida-Klein et al [ 32 ] showed that long bones responded to iPTH already between 1-2 weeks, whereas the increase in vertebral bone was only detected after 7 weeks in mice treated with a dose of 40 μ g/kg/day. Other studies also reported that the hormone has skeletal site-specific action, promoting the cortical increase through a mechanism that involves increased in both bone formation and resorption in the cortical bone [ 33 – 36 ].…”