Refractoriness to follicle-stimulating hormone in rat ovarian granulosa cells--a concentration- and time-dependent phenomenon.
Granulosa cells from pre-ovulatory ovarian follicles of rats were exposed, in vitro, to one or two pulses of follicle-stimulating hormone (FSH) in a superfusion apparatus. The superfusate was analysed for cyclic adenosine-3',5' monophosphate (cAMP) and steroids. In experiments with two consecutive FSH pulses, the response to the second pulse (100 ng/ml) was inversely related to the concentration of the first FSH pulse (2.5-100 ng/ml). Within certain limits, a lower total amount of cAMP and progesterone was accordingly released in response to the two FSH pulses when the concentration of the first pulse was increased. This refractoriness declined within a few hours as shown in experiments with extended pulse intervals. Two short and separate FSH pulses also evoked a higher combined response than did a single long FSH pulse lasting the whole time period. In these cases the cells thus responded with a lower total cAMP and progesterone release when exposed to a higher amount of FSH. Clinical trials on i.m. versus pulsatile i.v. FSH administration to anovulatory women have shown a similar relationship between FSH dose and effect, though other parameters were measured than those in the present study.
Johanson
C
C
Department of Physiology, University of Göteborg, Sweden.
Nordenström
K
K
Hamberger
L
L
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D011374:Progesterone / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D011374:Progesterone; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP