Effects of fasting on corticosterone production by zona fasciculata-reticularis cells in ovariectomized rats.
BACKGROUND
To investigate the function and mechanism of fasting on the production of corticosterone in vitro by zona fasciculata-reticularis (ZFR) cells from ovariectomized (OVX) rats.


METHODS
Female rats were OVX for 4 days before decapitation. Rats were fed or fasted for 1 day before experiment. ZFR cells from fed and fasted rats were incubated with adrenocorticotropic hormone (ACTH), forskolin, 8-bromo-3',5'-cyclic adenosine monophosphate, SQ22536, nifedipine, chelerythrine chloride, trilostane or steroidogenic precursors at 37 degrees C for either 60 or 30 minutes. Corticosterone, pregnenolone concentrations in spent media, and the intracellular adenosine 3',5'-cyclic monophosphate (cAMP) concentration were determined by radioimmunoassay. The effects of fasting in response to ACTH on the protein expressions of steroidogenic acute regulatory protein (StAR) or cytochrome P450 side-chain cleavage enzyme (P450scc) in ZFR cells were determined by Western blot analysis.


RESULTS
The concentration of plasma corticosterone in fasted rats was significantly higher than that in fed rats (P<0.01). One-day fasting significantly increased the responsiveness of ZFR cells to ACTH, forskolin, and precursor-stimulated corticosterone productions and to forskolin-stimulated cAMP accumulation. The corticosterone production was reduced in fasted group when adenylyl cyclase was inhibited by SQ22536. The fasting-enhanced level of corticosterone production in ZFR cells was decreased by the administration of nifedipine but not altered by that of chelerythrine chloride. Fasting significantly increased trilostane-stimulated production of pregnenolone in ZFR cells. The activities of enzymes which converting cholesterol, pregnenolone, progesterone, and deoxycorticosterone to corticosterone and the expressions of StAR in ZFR cells were greater in fasted rats than in fed rats.


CONCLUSIONS
This study demonstrated that fasting increased the release of corticosterone and the accumulation of cAMP by rat ZFR cells. The action mediated through enhancing the responsiveness to ACTH stimulation, cAMP cascades and the activity of L-type calcium channels. The activities of steroidogenic enzymes including P450scc, 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase, and 11beta-hydroxylase were all enhanced by the fasting treatment.
Chang
Ling-Ling
LL
Department of Chemical Engineering, Chinese Culture University, Taipei, Taiwan, Republic of China.
Kau
Mei-Mei
MM
Wun
Wan-Song Alfred
WS
Ho
Low-Tone
LT
Wang
Paulus S
PS
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D002478:Cells, Cultured; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000096:biosynthesis; D005576:Colforsin / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood*; D017077:Culture Media, Conditioned / Q000737:chemistry; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D010052:Ovariectomy; D010617:Phenanthridines / Q000494:pharmacology; D010750:Phosphoproteins / Q000096:biosynthesis; D011284:Pregnenolone / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015383:Zona Fasciculata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015385:Zona Reticularis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000098682:Steroidogenic Acute Regulatory Protein
D000470:Alkaloids; D053119:Benzophenanthridines; D017077:Culture Media, Conditioned; D010617:Phenanthridines; D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D013196:Dihydrotestosterone; C017759:9-(tetrahydro-2-furyl)-adenine; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D011284:Pregnenolone; D000324:Adrenocorticotropic Hormone; C016299:chelerythrine; D002786:Cholesterol Side-Chain Cleavage Enzyme; D009543:Nifedipine; D000225:Adenine; C009954:trilostane; D003345:Corticosterone