Uptake and Metabolization of Serotonin by Granulosa Cells Form a Functional Barrier in the Mouse Ovary.

Serotonin (5-HT) plays an essential role in regulating female reproductive function in many animals. 5-HT accumulates in the mammalian ovary with the involvement of membrane serotonin transporter SERT and is functionally active in the oocytes of growing follicles, but shows almost no activity in follicular cells. In this study, we clarified the interplay between 5-HT membrane transport and its degradation by monoamine oxidase (MAO) in the mammalian ovary. Using pharmacologic agents and immunohistochemical staining of the cryosections of ovaries after serotonin administration in vitro, we demonstrated the activity of transport and degradation systems in ovarian follicles. The MAO inhibitor pargyline increased serotonin accumulation in the granulosa cells of growing follicles, indicating the activity of both serotonin uptake and degradation by MAO in these cells. The activity of MAO and the specificity of the membrane transport of serotonin was confirmed in primary granulosa cell culture treated with pargyline and fluoxetine. Moreover, the accumulation of serotonin is more effective in the denuded oocytes and occurs at lower concentrations than in the oocytes within the follicles. This confirms that the activity of SERT and MAO in the granulosa cells surrounding the oocytes impedes the accumulation of serotonin in the oocytes and forms a functional barrier to serotonin.

The Embryos Obtained from the Karyoplasts of Starfish Oocytes: Their Development and Sensitivity to Cytostatic Neurotransmitter Antagonists: (karyoplasts/oocytes/sensitivity to neurochemicals).

Karyoplasts obtained from full-grown oocytes of the starfish Aphelasterias japonica have practically no cytoplams and are incapable of maturation. Karyoplasts of oocytes of starfishes Marthasterias glacialis and Acanthaster planci have the cytoplasm (10%-15% of the total karyoplast volume) and are often capable of maturation, fertilization and one or several cleavage divisions. The embryoskaryoplasts completely lose supersensitivity and retain usual sensitivity to cytostatic antagonists of neurotransmitters. The assumption is made that the incapability or limited capability of this embryos for development might be due to a deficiency of certain components of the "prenervous" neurotransmitter systems.