Are you C Johanson?

Claim your profile

Publications (4)15.21 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Human Reproduction 09/1989; 4(6):629-35. · 4.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Human corpora lutea (CL) of the menstrual cycle and early pregnancy were excised at operation, cut into pieces, and incubated or superfused in the presence of hCG or prostaglandin (PG) E2. After incubation, the tissue levels of cAMP and the medium concentrations of progesterone (P) were determined, while the concentration of P was analyzed after superfusion. PGE2 stimulated cAMP formation in CL from all phases of the menstrual cycle as well as from early pregnancy and caused an increase in P formation in CL from the early and midluteal phases of the menstrual cycle as well as from early pregnancy. A difference was found in the latency, the lag phase until maximal response, and the duration of response between the effects of PGE2 and hCG on both cAMP and P formation. Thus, the effect of PGE2 started more rapidly and was of shorter duration than that of hCG. The stimulatory effect of PGE2 on CL from early pregnancy was of the same magnitude as that of CL from the menstrual cycle. On the other hand, hCG had less stimulatory effect on cAMP and P formation in CL from early pregnancy compared to CL from the menstrual cycle. We conclude that PGE2 stimulates P and cAMP formation in isolated human CL from all phases of the menstrual cycle as well as in early pregnancy, indicating a luteotropic effect of this PG.
    Journal of Clinical Endocrinology &amp Metabolism 06/1988; 66(5):909-14. DOI:10.1210/jcem-66-5-909 · 6.31 Impact Factor
  • Annals of the New York Academy of Sciences 02/1988; 541:485-97. DOI:10.1111/j.1749-6632.1988.tb22285.x · 4.31 Impact Factor
  • K Nordenström, C Johanson
    [Show abstract] [Hide abstract]
    ABSTRACT: Steroid release was investigated in granulosa cells isolated from rat ovarian follicles at different maturation stages. Immature rats were treated with 10 IU of pregnant mare's serum gonadotrophin (PMSG) to induce follicular growth and maturation. Granulosa cells were isolated and subsequently incubated for 4 h in the absence or presence of follicle stimulating hormone (FSH), luteinizing hormone (LH) or forskolin. The concentrations of progesterone (P), 20 alpha-dihydroprogesterone (20 alpha DHP), testosterone (T) and oestradiol (E2) in the media were determined by radioimmunoassay. During maturation, basal release of T increased markedly at late dioestrus. At pro-oestrus, concomitant with a sharp rise in E2 and P release, T release returned to previously low levels. Addition of FSH or LH stimulated P release at late dioestrus and pro-oestrus but had no effect on E2 or T levels. Basal 20 alpha DHP levels remained low until a sharp rise at mid pro-oestrus. A stimulatory effect of gonadotrophins on 20 alpha DHP was first seen at this stage. The adenylate cyclase stimulator forskolin resembled FSH in all its effects. In summary, the present study demonstrates that maturing, but not preovulatory, granulosa cells have an increased capacity to release T during a relatively short period. It is suggested that this T peak could be of great importance for the further progress of follicular maturation.
    Acta endocrinologica 05/1985; 108(4):550-6. DOI:10.1530/acta.0.1080550