Intermittent PTH treatment can delay the transformation of mature osteoblasts into lining cells on the periosteal surfaces.

Mature osteoblasts have three fates: as osteocytes, quiescent lining cells, or osteoblasts that undergo apoptosis. However, whether intermittent parathyroid hormone (PTH) can modulate the fate of mature osteoblasts in vivo is uncertain. We performed a lineage-tracing study using an inducible gene system. Dmp1-CreERt2 mice were crossed with Rosa26R reporter mice to obtain targeted mature osteoblasts and their descendants, lining cells or osteocytes, which were detected using X-gal staining. Rosa26R:Dmp1-CreERt2(+) mice were injected with 0.25 mg 4-OH-tamoxifen (4-OHTam) on postnatal days 5, 7, 9, 16, and 23. In a previous study, at 22 days after the last 4-OHTam, most LacZ+ cells on the periosteal surface were inactive lining cells. On day 25 (D25), the mice were challenged with an injection of human PTH (1-34, 80 µg/kg) or vehicle daily for 10 (D36) or 20 days (D46). We evaluated the number and thickness of LacZ+ osteoblast descendants in the calvaria and tibia. In the vehicle group, the number and thickness of LacZ+ osteoblast descendants at both D36 and D46 significantly decreased compared to D25, which was attenuated in the PTH group. In line with these results, PTH inhibited the decrease in the number of LacZ+/osteocalcin-positive cells compared to vehicle at both D36 and D46. As well, the serum levels of sclerostin decreased, as did the protein expression of sclerostin in the cortical bone. These results suggest that intermittent PTH treatment can increase the number of periosteal osteoblasts by preventing mature osteoblasts from transforming into lining cells in vivo.

ANABOLIC EFFECTS OF TU-CHUNG EXTRACT / 体力科学

We evaluated the effect of Tu-Chung (<I>Eucommia ulmoides</I> OLIV.) extract on anabolic action in castrated exercise and non-exercise rats in which the effects of male sex hormone from the testis were excluded. Castration was performed on 32 male Wistar rats aged 4 weeks. The rats were then divided into 4 groups: a non-exercise group treated with Tu-Chung extract (non Ex. Tu-chung G, n = 8), on exercise group treated with the extract (Ex. Tu-Chung G, n = 8), a non-exercise control group not treated with the extract (non Ex. Cont. G, n8), = and an untreated exercise control group (Ex. Cont. G, n=8) .<BR>The Tu-Chung extract was administered orally at a dose of 1g/kg body weight once daily for 4 weeks. Distilled water was given by a similar method to the control groups. As the exercise load, the rats exercised on an animal treadmill at a starting speed of 20 m/min with an increase of 10 m/min every week for 30 min without rest daily for 4 weeks.<BR>The following results were obtained:<BR>1. The relative weight of the adrenal gland (gland weight/100 g body weight ) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and in the Ex. Tu-Chung G than in the Ex. Cont. G or the non Ex. Cont. G (p<0.001 each) .<BR>2. The relative weight of the kidneys (kidney weight/100 g body weight) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and was slightly higher in the Ex. Tu-Chung G than in the Ex. Cont. G.<BR>3. The relative weight of the musculus levator ani (muscle weight/100g body weight) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.001) .<BR>4. The 17-KS level in a 24h urine sample after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G or the Ex. Tu-Chung G (p<0.001 each) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.001) .<BR>5. The total urinary nitrogen level after 4 weeks was significantly lower in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) or the exercise group treated with the extract (p<0.05) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.05) .<BR>These results suggest that administration of Tu-Chung extract significantly increases the relative weight of the adrenal gland, enhances androgen secretion from the reticular layer of the adrenal cortex, and promotes protein anabolic action in castrated rats. In addition, this extract appears to increase the adaptation ability of the adrenal cortex to the stress caused by exercise.

Anabolic effects of Tu-Chung extract. Studies using castrated rat / 体力科学

We evaluated the effect of Tu-Chung (<I>Eucommia ulmoides</I> OLIV.) extract on anabolic action in castrated exercise and non-exercise rats in which the effects of male sex hormone from the testis were excluded. Castration was performed on 32 male Wistar rats aged 4 weeks. The rats were then divided into 4 groups: a non-exercise group treated with Tu-Chung extract (non Ex. Tu-chung G, n = 8), on exercise group treated with the extract (Ex. Tu-Chung G, n = 8), a non-exercise control group not treated with the extract (non Ex. Cont. G, n8), = and an untreated exercise control group (Ex. Cont. G, n=8) .<BR>The Tu-Chung extract was administered orally at a dose of 1g/kg body weight once daily for 4 weeks. Distilled water was given by a similar method to the control groups. As the exercise load, the rats exercised on an animal treadmill at a starting speed of 20 m/min with an increase of 10 m/min every week for 30 min without rest daily for 4 weeks.<BR>The following results were obtained:<BR>1. The relative weight of the adrenal gland (gland weight/100 g body weight ) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and in the Ex. Tu-Chung G than in the Ex. Cont. G or the non Ex. Cont. G (p<0.001 each) .<BR>2. The relative weight of the kidneys (kidney weight/100 g body weight) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and was slightly higher in the Ex. Tu-Chung G than in the Ex. Cont. G.<BR>3. The relative weight of the musculus levator ani (muscle weight/100g body weight) after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.001) .<BR>4. The 17-KS level in a 24h urine sample after 4 weeks was significantly higher in the non Ex. Tu-Chung G than in the non Ex. Cont. G or the Ex. Tu-Chung G (p<0.001 each) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.001) .<BR>5. The total urinary nitrogen level after 4 weeks was significantly lower in the non Ex. Tu-Chung G than in the non Ex. Cont. G (p<0.001) or the exercise group treated with the extract (p<0.05) and also in the Ex. Tu-Chung G than in the Ex. Cont. G (p<0.05) .<BR>These results suggest that administration of Tu-Chung extract significantly increases the relative weight of the adrenal gland, enhances androgen secretion from the reticular layer of the adrenal cortex, and promotes protein anabolic action in castrated rats. In addition, this extract appears to increase the adaptation ability of the adrenal cortex to the stress caused by exercise.