1. Pharmacological manipulation of nitric oxide levels in mouse follicle cultures demonstrates key role of extrafollicular control of ovulation.
- Author
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Mitchell LM, Kennedy CR, and Hartshorne GM
- Subjects
- Animals, Enzyme Inhibitors pharmacology, Female, Interleukin-1 pharmacology, Isothiuronium pharmacology, Lipopolysaccharides pharmacology, Mice, Mice, Inbred Strains, NG-Nitroarginine Methyl Ester pharmacology, Nitric Oxide agonists, Nitric Oxide antagonists & inhibitors, Nitric Oxide Donors pharmacology, Nitric Oxide Synthase antagonists & inhibitors, Nitric Oxide Synthase metabolism, Nitric Oxide Synthase Type II, Nitric Oxide Synthase Type III, Nitroarginine pharmacology, Nitroso Compounds pharmacology, Organ Culture Techniques, Ovarian Follicle cytology, S-Nitroso-N-Acetylpenicillamine pharmacology, omega-N-Methylarginine pharmacology, Isothiuronium analogs & derivatives, Nitric Oxide metabolism, Ovarian Follicle drug effects, Ovarian Follicle metabolism, Ovulation drug effects, Ovulation physiology
- Abstract
Background: Nitric oxide (NO) is involved in ovulation, but it is uncertain whether the mechanisms responsible are systemic or local. In vivo and in perfused ovaries, inhibition of nitric oxide synthase (NOS) reduces ovulation. This study used a well-characterized system of isolated follicle culture to assess which isoforms of NOS might be involved at the follicular level., Methods: NOS inhibitors, stimulators and NO donors were used to manipulate the environment of mouse cultured follicles, selectively targeting different isoforms of NOS. Follicle survival and ovulation in vitro were monitored using established markers., Results: Inhibition of endothelial NOS did not affect survival or ovulation of cultured follicles. Inhibition of inducible nitric oxide synthase (iNOS) had mild effects in this system, generally inhibitory of ovulation. NO donors had variable inhibitory effects, including toxic effects. Stimulators of iNOS appeared to show mixed, mostly inhibitory, effects that possibly involved different mechanisms., Conclusions: The results suggest that relatively minor effects on survival and ovulation in vitro are achieved by modulating the NO pathway, and the marked effects of NOS inhibitors in vivo do not occur in vitro. It is therefore probable that the effects of NOS inhibitors in vivo are mediated via effects outside the follicle., (Copyright 2004 European Society of Human Reproduction and Embryology)
- Published
- 2004
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