Effects of exogenous growth hormone on bone mineralization and remodeling and on plasma calcitriol in intact pigs.
Growing pigs were given subcutaneous (SC) injections of 40 micrograms porcine GH/kg body weight (BW) or its vehicle twice daily for 2 months. Animals were pair-fed with a diet containing 1.1% Ca, 0.6% P, and 1000 IU vitamin D3/kg. At slaughter, several bone characteristics including histomorphometric data (using double tetracycline labeling) were measured on tibia and metacarpals. GH accelerated growth, with greater (p < 0.01) tibial and metacarpal weights, greater tibial length (p < 0.01) and diameters (outside and inside, p < 0.01), and greater tibial ash weight (p < 0.02) in GH-treated pigs than in controls. The similar values of apparent bone density (weight/volume) and ash/bone volume or ash/dry matter in the two groups suggest adequate coupling between bone growth and mineralization in GH-treated pigs. Histomorphometric data for the distal metacarpal metaphysis indicated greater trabecular bone volume (p < 0.01), osteoblastic surface (p < 0.01), and mineral apposition rate (p < 0.05) in GH-treated pigs. The osteoclast surface, lacuna depth, and osteoid-related parameters in GH-treated and control pigs were similar. The plasma PTH of the two groups of pigs were similar throughout the experiment. These data and the elevated plasma alkaline phosphatase activity (p < 0.05) in GH-treated pigs suggest that GH specifically affects bone formation. GH had no effect on the plasma 25-OH vitamin D3 but 1,25(OH)2 vitamin D3 (calcitriol) was higher (p < 0.01) in treated pigs throughout the experiment. This suggests that calcitriol may help adapt bone mineralization to accelerated bone formation during growth hormone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Denis
I
I
LNSA-INRA, Jouy-en-Josas, France.
Zerath
E
E
Pointillart
A
A
D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000187:drug effects*; D016723:Bone Remodeling / Q000187:drug effects*; D002112:Calcifediol / Q000097:blood; D002117:Calcitriol / Q000097:blood*; D002118:Calcium / Q000097:blood; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008663:Metacarpus / Q000187:drug effects; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013552:Swine; D013977:Tibia / Q000187:drug effects
D010281:Parathyroid Hormone; D010710:Phosphates; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium