ISSN:
1432-0878
Keywords:
Granulosa cells
;
Ionomycin
;
Lasalocid (X537A)
;
Steroidogenesis
;
White Leghorn hen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Granulosa cells, isolated by collagenase digestion from the mature ovarian follicle of laying hens, were incubated in the presence of two ionophores, lasalocid (X537A) and ionomycin, to determine their effects on basal and stimulated steroidogenesis, as well as their effects on various cell parameters including DNA, RNA, and protein synthesis. Both ionophores caused a dose-dependent inhibition of agonist-promoted progesterone production and, in the presence of calcium, a small but significant increase in basal output of progesterone. Whereas the conversion of pregnenolone to progesterone was unaffected by the ionophores, the activity of cholesterol side-chain cleavage enzyme was inhibited in a dose-related manner. Both ionophores decreased cellular levels of ATP and inhibited the incorporation of radioactively-labeled precursors into DNA, RNA, and proteins. Morphologically, ionophoretreated cells showed swelling of the rough endoplasmic reticulum. Similar morphological changes were also observed in cells treated with oligomycin, a known metabolic inhibitor. These results suggest that the ionophores lasalocid and ionomycin impair release of energy and thereby exert the principal cause of the inhibited steroidegenic response by granulosa cells to a variety of agonists.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00216483
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