Potential role of nitric oxide in endothelin-1 provoked inhibition of progesterone secretion by isolated ovarian granulosa cells.
OBJECTIVE
Nitric oxide (NO) is involved in different cell functions including ovarian steroid production. Endothelin-1 (ET-1) was found to regulate the steroidogenesis in ovarian granulosa cells (GC). The present study was designed to receive more information about the mechanism of action of NO in the process of ET-1 induced progesterone (P) inhibition, using nicotine amide dinucleotide phosphate-diaphorase (NADPH-d) histochemistry as a cofactor of oxidoreductase enzymes (e. g. nitric oxide).


METHODS
Granulosa cells were isolated from ovaries of: 1. young women with natural cycle or after in vitro fertilization (IVF), 2. premenopausal women. The obtained cells were cultured with endothelin-1 and the concentration of progesterone in conditioned media was determined by RIA. For the estimation of NADPH-d the histochemical reaction was used.


RESULTS
The suppressive effect of ET-1 on P production in granulosa cells was more pronounced in young women with natural cycles, slightly weaker after IVF and the most ineffective in premenopausal patients. The number of NADPH-d positive GCs was higher in young non-hormonally stimulated women, slightly lower after IVF and small in premenopausal ones.


CONCLUSIONS
The results indicate the possible role of NADPH-d or NOS in the mechanism of ET-1 provoked P suppression.
Denkova
R
R
Institute of Experimental Morphology and Anthropology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria. rdenkova@hotmail.com
Bourneva
V
V
Yaneva
E
E
Baleva
K
K
Nikolov
B
B
Ivanov
I
I
Simeonov
K
K
Timeva
T
T
D000328:Adult; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro; D006107:Granulosa Cells / Q000201:enzymology / Q000502:physiology*; D006651:Histocytochemistry; D006801:Humans; D009252:NADPH Dehydrogenase / Q000032:analysis; D009569:Nitric Oxide / Q000502:physiology*; D017697:Premenopause; D011374:Progesterone / Q000378:metabolism*
D017077:Culture Media, Conditioned; D019332:Endothelin-1; D009569:Nitric Oxide; D011374:Progesterone; D009252:NADPH Dehydrogenase