AJP - Endocrinology and Metabolism, Vol 262, Issue 6 E884-E890, Copyright © 1992 by American Physiological Society
Physiological effects of 1,25-dihydroxyvitamin D3 in TM4 Sertoli cell line
V. L. Akerstrom and M. R. Walters
Department of Physiology, Tulane Medical School, New Orleans, Louisiana 70112.
1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] receptors have been previously
described in Sertoli cells. This study was performed to assess biological
activity of the receptor in the mouse Sertoli cell line TM4. A 2-h
preincubation with 0.01-25 nM 1,25(OH)2D3 resulted in a dose-dependent
rapid uptake of 45Ca2+ within 5 min of addition of the isotope to the cells
(27 +/- 8%, n = 4 experiments; P less than 0.05). This response was
specific for 1,25(OH)2D3, in that it was not induced by 25-hydroxyvitamin
D3, estradiol, cortisol, R 5020 (promegestone), or testosterone. However, a
combination of testosterone and 1,25(OH)2D3 inhibited uptake by 23 +/- 8%
(n = 3 experiments, P less than 0.01). That the mechanism responsible for
1,25(OH)2D3-stimulated uptake may involve 1,25(OH)2D3 receptor interaction
is supported by the observation that cycloheximide inhibited the response.
Conversely, there was no detectable change in uptake by 1,25(OH)2D3-treated
cells after 24-h incubation with 0.1-5 nM 1,25(OH)2D3. Increased levels of
DNA and protein content also resulted from a 2-h incubation with the
steroid and were sustained up to 24 h without a concomitant increase in
cell number or a detectable change in cell morphology. The presence of
specific 1,25(OH)2D3 receptor-like binding sites was demonstrated by
sucrose gradient analysis and hydroxylapatite assay. These data demonstrate
that 1,25(OH)2D3 may play an important role in testicular function through
regulation of receptor-mediated events.
