Daily subcutaneous injection of graded
doses of 0, 4, 8, or 16Ðg / 100g hPTH 1-34
of 19-week-old male spontaneously hypertensive
rat (SHR) of five rats in each group for
14 days were done. The 21-week-old SHR
exhibited a significant lower metaphyseal
trabecular bone volume osteopenia
accompanied by poor trabecular architecture
than in Wistar-Kyoto (WKY) rats were
observed in the study. The preservation of
trabecular bone volume in the PTH-treated
rats was associated with an increase in
number of osteoblasts, bone surface extent of
osteoblasts, double labelled bone surface,
mineral apposition rate and trabecular
thickness. Trabecular number remained
comparable to control. Measurements of
resorption such as percent eroded surface and
numbers of osteoclasts also remained
comparable to control values. These dual
effects increase the bone formation rate and in
the absence of significant resorption, result in
a net increase in bone mass. The above
findings of histomorphometric data support
the hypothesis that the PTH increase bone
mass by specific effects on osteoblast
activation and function.
