Pharmacological effects of propylthiouracil on corticosterone secretion in male rats.
BACKGROUND
We investigated the direct effects of propylthiouracil (PTU) on corticosterone secretion both in vivo and in vitro.


METHODS
Male rats were divided into 4 groups and then injected subcutaneously with saline, PTU, PTU plus thyroxine (T4), or T4 once daily for 2 weeks. After 2 weeks, rats were decapitated or received adrenocorticotropic hormone (ACTH), intravenously. Zona fasciculata-reticularis (ZFR) cells from normal, saline-, PTU-, PTU plus T4-, or T4-treated rats were incubated with ACTH, forskolin, 8-Br-cAMP, deoxycorticosterone (DOC) +/- PTU (1, 2, or 5 mg/mL) at 37 degrees C for 2 hours. Corticosterone concentrations in plasma and cell media, and 3':5'-cyclic adenosine monophosphate (cAMP) production in ZFR cells were determined by radioimmunoassay. The effects of PTU on the activities of steroidogenic enzymes in ZFR cells were measured by the amounts of intermediate steroidal products separated by thin-layer chromatography.


RESULTS
The basal and ACTH-stimulated levels of plasma corticosterone in PTU-treated rats were lower as compared to saline-treated animals. Both basal and ACTH-stimulated corticosterone secretion were inhibited by PTU > 2 mg/mL in rat ZFR cells. The cAMP production induced by forskolin was lower in PTU, PTU plus T4, or T4-treated rats than in saline-treated animals. Chronic administration of PTU or PTU plus T4 inhibited the 3 beta-hydroxysteroid dehydrogenase, 21 beta-hydroxylase, and 11 beta-hydroxylase activities. Administration of PTU (1, 2, and 5 mg/mL) suppressed the basal, ACTH, 8-Br-cAMP, forskolin, and DOC-stimulated corticosterone secretion in rat ZFR cells. Likewise, PTU > 2 mg/mL inhibited the ACTH and 8-Br-cAMP-stimulated levels of intracellular cAMP in rat ZFR cells.


CONCLUSIONS
These results suggest that PTU counteracts both basal and ACTH-induced adrenal steroidogenesis through their attenuation of the activity of 11 beta-hydroxylase and cAMP production in rat ZFR cells.
Lo
M J
MJ
Department of Physiology, National Yang-Ming University, Taiwan, Republic of China.
Wang
S W
SW
Kau
M M
MM
Chen
J J
JJ
Chen
Y H
YH
Fang
V S
VS
Ho
L T
LT
Wang
P S
PS
D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D013956:Antithyroid Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood / Q000378:metabolism*; D000242:Cyclic AMP / Q000096:biosynthesis; D008297:Male; D006899:Mixed Function Oxygenases / Q000187:drug effects / Q000378:metabolism; D011441:Propylthiouracil / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D011988:Receptors, Thyroid Hormone / Q000097:blood; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
D013956:Antithyroid Agents; D011988:Receptors, Thyroid Hormone; D005576:Colforsin; D011441:Propylthiouracil; D000324:Adrenocorticotropic Hormone; D013972:Thyrotropin; D000242:Cyclic AMP; D006899:Mixed Function Oxygenases; D013974:Thyroxine; D003345:Corticosterone