Asbjørn Aakvaag
University of Oslo
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Featured researches published by Asbjørn Aakvaag.
Archive | 1984
Kenneth W. McKerns; Asbjørn Aakvaag; Vidar Hansson
In living, freshly isolated rat seminiferous tubules, cyclic changes in FSH binding, cAMP secretion (basal and FSH stimulated) and the activities of cAMP and cGMP phosphodiesterases could be detected which were related to specific ~~dge~ of spermatogenes1s. FSH binding (per em stage) increased gradually between stages VII and IX and then, after remaining relatively constant, was elevated further in stages XIV-I. Thereafter, binding fell to a nadir stage VIIa-b. FSH stimulated cAMP secretion was at its lowest in stage VIIa-b and maximal between stages XIV-V. The greatest specific activities of the cAMP and cGMP phosphodiesterases were detected in stages VII-VIII which are associated with spermiation in the rat. A degree of dissociation was found to exist in the cAMP and cGMP hydrolysing capacities at certain stages (IX-XII), suggesting the existence of different isoforms of the enzyme which may be differentially controlled. Exposure of the various stages to FSH or dibutyryl cAMP for 4 hr in vitro did not alter the profiles of phosphodiesterase activity. The phosphodiesterase profiles were inversely related to the quantity of cAMP produced by the tubular segments after stimulation with FSH, both in the presence and absence of the
Cell and Tissue Research | 1970
Arne Attramadal; Asbjørn Aakvaag
SummaryThe anterior hypophysis and hypothalamus of male and female rats given 3H-oestradiol were examined with regard to 1) the kinetics of the uptake of the radioactive material, 2) the chemical nature of the labelled material, and 3) the influence of non-labelled oestradiol-17β, oestradiol-17α and testosterone on the uptake of 3H-oestradiol. The anterior hypophysis was found to concentrate and retain oestradiol in basically the same manner in male and female rats. The pattern of the uptake was similar to that of the uterus and vagina, with a concentration peak 2 hours after the injection. Non-target tissues such as cerebral cortex, liver and blood attained their maximum uptake already 15 minutes after the injection. Thereafter the concentration gradually decreased. The ratio between the concentration of labelled material in the anterior hypophysis and brain cortex gradually increased until a peak was reached at 8 hours in both sexes. In the female, the concentration of labelled material in the anterior hypophysis was then 106.3 times greater than in the brain cortex, while in the male the ratio was 63.2.In the hypothalamus the uptake followed a pattern similar to that of the brain cortex. However, in the former the concentration of labelled material was consistently greater than in the latter. At maximum uptake, registered 4 hours after the injection, the concentration was about two times greater in the hypothalamus than in the cerebral cortex.The neurohypophysis contained, on an average, 1/6 of the amount of radioactive material registered in the anterior lobe one hour after the injection, but it was about two times greater than in the brain cortex.Isolation and identification of the radioactive material in the anterior hypophysis and hypothalamus showed that in both sexes nearly all of it was chemically unchanged oestradiol. Graded doses of non-labelled oestradiol-17β were found to decrease the uptake of 3H-oestradiol in the anterior hypophysis and hypothalamus almost linearly, while the concentration of labelled material in the brain was unaltered. Oestradiol-17α and testosterone were without significant effect on both the pituitary and hypothalamic accumulation of 3H-oestradiol. Therefore, a limited number of binding sites, with a high degree of specificity for oestradiol, appear to exist in both tissues. The results were essentially the same in male and female rats.
Archive | 1984
Peter A. Torjesen; Asbjørn Aakvaag
The corpus luteum (CL) is necessary for the maintenance of early pregnancy in all mammals, and for some species, luteal function is required throughout pregnancy. By interfering with the function of the CL, possible means of controlling fertility may be obtained.
Endocrinology | 1976
Oddvar Naess; Egil Haug; Arne Attramadal; Asbjørn Aakvaag; Vidar Hansson; Frank S. French
Endocrinology | 1975
Oddvar Naess; Arne Attramadal; Asbjørn Aakvaag
Endocrinology | 1969
Kjell J. Tveter; Asbjørn Aakvaag
Scandinavian Journal of Haematology | 2009
G. Asbjørnsen; Kaare Molne; Olbjørn Klepp; Asbjørn Aakvaag
International Journal of Andrology | 1982
Sophie D. Fosså; Olbjørn Klepp; Kaare Molne; Asbjørn Aakvaag
BJUI | 1980
Sophie D. Fosså; Olbjørn Klepp; Asbjørn Aakvaag
International Journal of Andrology | 1980
Sophie D. Fosså; Olbjørn Klepp; Asbjørn Aakvaag; Kaare Molne