Effects of hypophysectomy and growth hormone treatment on renal hydroxylation of 25-hydroxycholecalciferol in rats

in Journal of Endocrinology
Authors:
N. Wongsurawat
Search for other papers by N. Wongsurawat in
Current site
Google Scholar
PubMed
Close
,
H. J. Armbrecht
Search for other papers by H. J. Armbrecht in
Current site
Google Scholar
PubMed
Close
,
T. V. Zenser
Search for other papers by T. V. Zenser in
Current site
Google Scholar
PubMed
Close
,
L. R. Forte
Search for other papers by L. R. Forte in
Current site
Google Scholar
PubMed
Close
, and
B. B. Davis
Search for other papers by B. B. Davis in
Current site
Google Scholar
PubMed
Close
Restricted access
Rent on DeepDyve

Sign up for journal news

ABSTRACT

Growth hormone stimulates intestinal calcium absorption. This action has been linked to vitamin D metabolism. We have investigated the effects of hypophysectomy and GH treatment on renal metabolism of 25-hydroxycholecalciferol (25-OH-D3). Renal hydroxylation of 25-OH-D3 was measured in vitro using the renal slice technique. Experiments were performed in young F344 rats fed a vitamin D-replete, low calcium diet for 4 weeks. In hypophysectomized rats, renal conversion of 25-OH-D3 to 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was markedly reduced compared with sham-operated rats. Renal conversion of 25-OH-D3 to 24,25-(OH)2D3 was markedly increased in hypophysectomized rats compared with sham-operated rats. Treatment of hypophysectomized rats with rat GH (rGH) for 10 days resulted in a significant increase in renal conversion of 25-OH-D3 to 1,25-(OH)2D3 and a significant decrease in conversion to 24,25-(OH)2D3. Rat GH treatment caused no significant changes in serum levels of immunoreactive parathyroid hormone. Serum calcium concentrations were similar in all groups, and serum phosphorus was low in hypophysectomized rats. Treatment of hypophysectomized rats with ovine GH for 6 days caused changes which were much less pronounced than those induced by rGH. Renal conversion of 25-OH-D3 to 1,25-(OH)2D3 and 24,25-(OH)2D3 correlated well with growth rate (weight gain). These results suggest that GH, either directly or indirectly, modulates renal metabolism of 25-OH-D3.

J. Endocr. (1984) 101, 333–338

 

  • Collapse
  • Expand