| Abstrakt: |
LH pulse frequency and amplitude vary significantly during the menstrual cycle; however, it is not clear what significance the secretory pattern has for the ovary. We have developed an in-vitro perifusion system in which luteinized human granulosa cells (GC) can be exposed to various patterns of gonadotrophin stimulation. GC were recovered following follicle aspiration for in-vitro fertilization, grown on Cytodex-3 for 6 days, and then perifused with medium containing LH (or hCG), delivered with differing pulse frequencies and amplitudes. When pulses of LH were applied to the cells, progesterone secretion rose initially and then fell to the baseline as the LH concentration declined. Pulsatile administration of LH, over a period of 10 h, stimulated progesterone secretion more efficiently than did continuous LH. Finally, delivery to the cells of pulses of hCG, a ligand known to bind to the LH receptor but with binding characteristics distinct from those of LH, failed to elicit pulses of progesterone. |
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