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Interference with biological rhythm: a novel approach to metabolic disorders in women
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
1992 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Women seem to be largely protected against certain ‘welfare disorders’ such as cardiovacular disease and osteoporosis, during their fertile years.The metabolic changes observed during women’s non-menstrual states, i.e. during pregnancy, after the menopause and during use of oral contraceptives, indicate the importance of sex steroids and an undisturbed biological rhythm. Treatment with monophasic, combined oral contraceptives constitutes a model for the non-cyclic state.Growth hormone (GH) is a pituitary hormone that has major metabolic effects. The pattern of GH exposure to the target organ is of vital importance for the effects and changes in rhythm could possibly induce metabolic changes.Growth hormome, cholecystokinin (CCK), osteocalcin and angiotensinogen were used as markers for metabolic effects and the concentrations in serum were recorded in women during non-menstrual states. The clinical material comprised a total of 60 women: 18 healthy non-pregnant, 25 pregnant, one lactating woman and 16 postmenopausal women. Using a portable pump and a non-thrombogenic venous catheter, blood samples could be collected at 30-min intervals during 24-h periods. Furthermore, the effects of estrogen and GH in the regulation of angiotensinogen were investigated in an experimental model in the rat.Oral contraceptives were found to alter the secretion of GH towards a pattern of lower and more frequent peaks, though the total amount secreted during 24 h was unchanged. Oral contraceptives seem to induce a suppression of the 24-h concentrations of CCK, which may be important with respect to weight gain in some women. Osteocalcin in serum display a significant circadian variation. This emphasizes the need for careful timing of single point measurements and the value of continuous blood sampling. Oral contraceptives may reduce osteocalcin serum concentrations. The long-term effects on bone are unknown. During late pregnancy osteocalcin levels are extremely low, which could indicate osteoblast inhibition and reduced bone turnover. The mode of GH administration is important for the plasma concentration of angiotensinogen in the non-pregnant rat. Estrogen effects on this protein may be mediated via a modification of GH secretion. Oral contraceptives not only increase angiotensinogen concentrations in serum but also markedly enhance their variability. Further studies are needed to elucidate the relation between the individual pattern of angiotensinogen and hypertension.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 1992. , 42 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 345
Keyword [en]
Growth hormone, GH, cholecystokinin, CCK, osteocalcin, angiotensinogen, diurnal variation, oral contraception, pregnancy, menopause
National Category
Obstetrics, Gynecology and Reproductive Medicine Family Medicine
URN: urn:nbn:se:umu:diva-101301ISBN: 91-7174-658-7OAI: diva2:798898
Public defence
1992-05-27, Sal 135, By 9A, Regionsjukhuset i Umeå, Umeå universitet, Umeå, 09:00

S. 1-42: sammanfattning, s. 43-88: 6 uppsatser

Available from: 2015-04-17 Created: 2015-03-26 Last updated: 2015-04-17Bibliographically approved

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