Expression of the c-fos gene induced by parathyroid hormone in the bones of SAMP6 mice, a murine model for senile osteoporosis.
SAMP6 mice are a murine model for senile osteoporosis, characterized by low peak bone mass seen at 4 or 5 months of age. Parathyroid hormone (PTH)-induced c-fos expression was examined in the bones, bone-marrow cells and kidney tissues of 2-month-old male SAMP6 mice. SAMP2 mice, which have a higher peak bone mass, were used as controls. The expression of c-fos in the bone peaked at 30 min after 60 microg/kg of human PTH(1-34) administration. After peaking, the expression fell quickly in SAMP2 mice. This decrease in expression was delayed in SAMP6 mice and the expression was higher at 1 h than in SAMP2 mice. The phenomenon observed in the bone appears to be tissue specific as it was not seen in the bone-marrow cells or kidney tissue. Immunohistochemical studies showed that c-Fos protein was localized to the nuclei of some of the osteocytes and a few of the osteoblasts in the cortical bone, and that osteocytes expressing c-Fos protein increased after PTH treatment. These results suggest that osteocytes might contribute to the maintenance of higher levels of c-fos expression in the bones of SAMP6 mice and may be related to cortical osteopenia in these mice by modulating bone remodeling and/or modeling.
Takeda
N
N
Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Japan.
Tsuboyama
T
T
Kasai
R
R
Takahashi
K
K
Shimizu
M
M
Nakamura
T
T
Higuchi
K
K
Hosokawa
M
M
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D004195:Disease Models, Animal; D005269:Femur / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000378:metabolism; D008297:Male; D051379:Mice; D010024:Osteoporosis / Q000235:genetics* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics*; D051381:Rats; D013977:Tibia / Q000378:metabolism / Q000473:pathology
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D016760:Proto-Oncogene Proteins c-fos