Effects of nitric oxide and cGMP on inhibin A and inhibin subunit mRNA levels from cultured rat granulosa cells.
OBJECTIVE
To determine the effects of nitric oxide (NO) and cGMP on inhibin A and inhibin subunit mRNA levels from cultured rat granulosa cells.


METHODS
Basic research study.


METHODS
University research laboratory.


METHODS
Primary cell culture of granulosa cells obtained from estrogen-treated, immature Sprague-Dawley female rats.


METHODS
Functionally immature rat granulosa cells were incubated for 48 hours with media alone; FSH; forskolin; the NO generator DETA/NO; an inhibitor of soluble guanylyl cyclase (ODQ); and/or a cell-permeable cGMP analog.


METHODS
Media concentrations of inhibin A were measured by solid-phase immunosorbent assay. Inhibin alpha and betaA subunit mRNA levels were determined by Northern and slot blot analyses.


RESULTS
Whereas FSH caused a 20-fold increase in inhibin A levels compared with untreated granulosa cells, the NO generator DETA/NO significantly inhibited FSH-stimulated inhibin A concentrations. Similarly, cotreatment with FSH plus dibutyryl cGMP significantly attenuated inhibin A concentrations, compared with those in cells treated with FSH alone. Incubation with forskolin (FSK) stimulated inhibin A levels sevenfold, whereas cotreatment with FSK plus DETA/NO or FSK plus dibutyryl cGMP effectively decreased inhibin A concentrations. The effects of NO on inhibin A levels were not prevented by cotreatment with an inhibitor of soluble guanylyl cyclase. In addition, there was no influence of DETA/NO or dibutyryl cGMP on inhibin subunit mRNA levels.


CONCLUSIONS
These findings indicate that NO and cGMP can attenuate inhibin A concentrations through actions at one or more post-FSH receptor sites. These influences may reflect inhibition of inhibin A secretion, rather than gene expression and protein synthesis. In addition, NO decreases inhibin A concentrations through both cGMP-dependent and -independent pathways. These results suggest local roles for NO and cGMP in the regulation of granulosa cell function.
Chen
You-Hsin Jean
YH
Department of Biological Sciences, California State University, Los Angeles, Los Angeles, California, USA.
Tafoya
Michael
M
Ngo
Anna
A
LaPolt
Philip S
PS
D000818:Animals; D015152:Blotting, Northern; D005576:Colforsin / Q000494:pharmacology; D006152:Cyclic GMP / Q000037:antagonists & inhibitors / Q000378:metabolism; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D007265:Inhibins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D010069:Oxadiazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D010069:Oxadiazoles; D011810:Quinoxalines; D012333:RNA, Messenger; C422362:inhibin A; D005576:Colforsin; D009569:Nitric Oxide; D003995:Dibutyryl Cyclic GMP; D004958:Estradiol; D007265:Inhibins; D005640:Follicle Stimulating Hormone; D006152:Cyclic GMP