Hanna Olausson

Determinants of vitamin D status in pregnant fair-skinned women in Sweden

Low maternal vitamin D status during pregnancy may have negative consequences for both mother and child. There are few studies of vitamin D status and its determinants in pregnant women living at northern latitudes. Thus, the present study investigates vitamin D status and its determinants during the third trimester of women living in Sweden (latitudes 57-58°N). A total of ninety-five fair-skinned pregnant women had blood taken between gestational weeks 35 and 37. The study included a 4 d food diary and questionnaires on dietary intake, supplement use, sun exposure, skin type, travels to southern latitudes and measure of BMI. Serum 25-hydroxyvitamin D (25(OH)D) was analysed using the chemiluminescence immunoassay. In the third trimester of pregnancy, mean serum concentration of 25(OH)D was 47.4 (sd 18.1) nmol/l (range 10-93 nmol/l). In total, 65% of women had serum 25(OH)D < 50 nmol/l and 17 % < 30 nmol/l. During the winter, 85% of the pregnant women had serum 25(OH)D < 50 nmol/l and 28 % < 30 nmol/l. The main determinants of vitamin D status were as follows: season; use of vitamin D supplements; travels to southern latitudes. Together, these explained 51% of the variation in 25(OH)D. In conclusion, during the winter, the majority of fair-skinned pregnant women had serum 25(OH)D < 50 nmol/l in their third trimester and more than every fourth woman < 30 nmol/l. Higher vitamin D intake may therefore be needed during the winter for fair-skinned pregnant women at northern latitudes to avoid vitamin D deficiency.

Body fat, insulin resistance, energy expenditure and serum concentrations of leptin, adiponectin and resistin before, during and after pregnancy in healthy Swedish women.

Healthy human pregnancy is associated with changes in food intake, body fatness, energy expenditure and insulin resistance. However, available knowledge is limited regarding the physiological basis of these changes. Published evidence suggests that so-called adipokines (i.e. leptin, adiponectin and resistin) have significant roles when such changes are established. We explored, throughout a complete pregnancy, relationships between total body fat (TBF), energy expenditure, insulin resistance (homeostasic model of insulin resistance, HOMA-IR) and serum concentrations of leptin, adiponectin and resistin. Such concentrations were assessed before pregnancy in gestational weeks 8, 14, 20, 32 and 35, and 2 weeks postpartum in twenty-three healthy women. TBF, BMR (n 23) and HOMA-IR (n 17) were assessed before pregnancy in gestational weeks 14 and 32 and 2 weeks postpartum. TBF (%) was correlated with HOMA-IR (r 0.68-0.79, P < 0.01) and with serum leptin (r 0.85-0.88, P < 0.001) before and during pregnancy. Serum leptin was correlated with HOMA-IR (r 0.53-0.70, P < 0.05) before and during pregnancy. Serum adiponectin was inversely correlated with HOMA-IR in gestational week 32 (r - 0.52, P < 0.05). When HOMA-IR was regressed on TBF (%), the slope of the regression line was 0.046 before pregnancy, which was significantly (P < 0.05) different from the corresponding value, 0.111, in gestational week 32. The results indicate that pregnancy has an enhancing effect on the relationship between body fatness and insulin resistance. This effect, possibly mediated by leptin, may represent a mechanism by which offspring size is regulated in response to the nutritional situation of the mother.

Longitudinal Study of the Maternal Insulin-Like Growth Factor System before, during and after Pregnancy in Relation to Fetal and Infant Weight

Background: The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete. Aims: To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight. Methods: Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression. Results: One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = –0.43 to –0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003). Conclusion: We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.

Maternal body composition in relation to infant birth weight and subcutaneous adipose tissue

Infant birth weight has increased recently, representing an obstetric and potentially a public health problem since high birth weight involves a risk of obesity later in life. Maternal nutritional status is important for fetal growth and therefore relationships between maternal body weight and composition v. birth weight and infant subcutaneous adipose tissue were investigated in twenty-three healthy women and their newborn infants using multiple and simple linear regression analysis. Furthermore, using previously published data for nineteen infants, it was demonstrated that an anthropometric method could provide useful estimates of the amount of subcutaneous adipose tissue. Birth weight was correlated with the maternal content of total body fat (TBF) both before pregnancy and in gestational week 32 and, together with gestational age at birth, TBF (%) before pregnancy explained 45% of the variation in birth weight. This figure was not increased when gestational gains in weight or TBF were added to the model. Furthermore, in infants, birth weight correlated with the amount of their subcutaneous adipose tissue. Together maternal TBF (%) and amount of subcutaneous adipose tissue in infants explained 61-63% of the variation in birth weight while the amount of infant subcutaneous adipose tissue alone explained only 55%. The maternal TBF content is likely to be important for the recent increase in birth weight. This factor probably causes a general augmentation in fetal growth rather than a specific stimulation of adipose tissue growth.

Determinants of Vitamin D Status in Fair-Skinned Women of Childbearing Age at Northern Latitudes

Background and Objective Poor vitamin D status during pregnancy has been associated with unfavorable outcomes for mother and child. Thus, adequate vitamin D status in women of childbearing age may be important. The aim of this study is to investigate the determinants of 25-hydroxyvitamin D (25(OH)D) serum concentrations in women of childbearing age living in Sweden, at latitude 57–58° north. Method Eighty four non-pregnant, non-lactating, healthy, fair-skinned women aged between 25–40 years were included. All subjects provided blood samples, four day food records and answered questionnaires about sun exposure and lifestyle. Total serum 25(OH)D was analyzed using Roche Cobas® electrochemoluminiescent immunoassay. Results Mean 25(OH)D was 65.8±19.9 nmol/l and 23% of the subjects had concentrations <50 nmol/l. Only 1% had concentrations <25 nmol/l. Determinants of 25(OH)D concentrations were recent sunbed use, recent travel to southern latitude, season, estrogen contraceptive use and use of supplementary vitamin D (R2 = 0.27). Conclusion Every fifth woman had 25(OH)D concentrations <50 nmol/l. About 30% of the variation in vitamin D status was explained by sun exposure, use of vitamin D supplements and use of estrogen contraceptives. Cutaneous vitamin D synthesis seems to be a major contributor to vitamin D status, even at northern latitudes. Thus, recommendations on safe UV-B exposure could be beneficial for vitamin D status.

Neuropeptides as neuroprotective agents: Oxytocin a forefront developmental player in the mammalian brain

Oxytocin (OT) plays a major role in the establishment of social bonds. Social bonds are linked to the activation of cell signaling pathways that promote neurotrophic and synaptic maturation, plasticity and memory changes. Anti-social behavior is often associated with abnormalities of cell signaling pathways and/or defective function of brain neurotransmitters within behavioral CNS circuits due to unproper environmental and social factors, such as, diet, stress, chemical, air pollution, and noise, during gestational period or/and during early postnatal development. OT exerts an important regulatory functions in maternity and parental behaviors, lactation, attachment, bonding, trust, and sensorial functions such as: homeostatic cardiovascular control, satiety, touch, pain, analgesia and sexual behavior. Noteworthy, OT displays important neuroprotective properties against fetal programmed hypertension when administered during early postnatal life, added to its known anabolic properties shown in adult rats, e.g. body weight control, reduces blood pressure, and increases analgesia. This review focuses on the new evidences supporting OTs role as a major neuroprotective nonapeptide provided by its quality to reverse hypertension programmed in utero by undernutrition.

Oxytocin Treatment during Early Life Influences Reproductive Performance in ad libitum Fed and Food-Restricted Female Rats

Oxytocin treatment may permanently alter endocrine axes resulting in anti-stress and anabolic effects. However, the nutritional status influences the effects of oxytocin. The specific aims of this study were to investigate the effects of postnatal oxytocin treatment on reproductive performance in adult life, by studying maternal weight gain, adiposity, plasma levels of IGF-I as well as fetal and placental weights in the following groups of animals: (1) Ad libitum fed dams coming from ad libitum fed mothers. (2) Ad libitum fed dams coming from food-restricted mothers. (3) Food-restricted dams coming from ad libitum fed mothers. (4) Food-restricted dams coming from food-restricted mothers. Oxytocin treatment postnatally had long-term effects and increased adiposity in pregnant dams and stimulated placental and fetal growth relative to saline-treated dams. However, if the dams themselves had been exposed to food restriction during fetal life, the effect of postnatal oxytocin treatment changed. The oxytocin-treated mothers were still fatter but had smaller fetuses. In conclusion, postnatal oxytocin treatment influences reproductive performance in later life but is dependent on the mother’s previous and current nutritional experience.

Long-Term Modulation By Postnatal Oxytocin of the α2-Adrenoceptor Agonist Binding Sites in Central Autonomic Regions and the Role of Prenatal Stress

The aim of this work was to evaluate whether oxytocin administered in male rats subcutaneously early in life in the absence or presence of food restriction during pregnancy has life‐long effects on the α2‐agonist binding sites in the nucleus of the solitarii tract (NTS), in the hypothalamus and the amygdala, as evaluated by quantitative receptor autoradiography. Maternal food restriction alone increased the affinity of the α2‐agonist [3H]UK14.304 binding sites exclusively in the NTS. In offspring from ad libitum fed dams, oxytocin treatment significantly increased the density of α2‐agonist binding sites in the NTS and in the hypothalamus. The Kd value of the α2‐agonist binding sites in the hypothalamus of these rats, but not in the other regions studied, was also significantly increased. In offspring from food‐restricted dams, oxytocin treatment produced a significant increase of the Bmax values in the hypothalamus and the amygdala and the Kd value of the α2‐agonist binding sites in the NTS of these rats also was selectively and significantly increased. These results suggest that a postnatal, oxytocin‐induced increase of regional α2‐adrenoceptor function can be seen in adulthood by a persistent, regionally selective increase in the density of central α2‐adrenoceptor agonist binding sites, in the absence of an affinity change in the NTS. Such a regional increase of α2‐adrenoceptor signalling in adulthood may contribute to the anti‐stress action of postnatal oxytocin. By contrast, after prenatal stress, the potential increase in α2‐adrenoceptor signalling takes place via selective increases of density with no changes of affinity of the α2‐agonist binding sites in the hypothalamus and the amygdala.

Maternal serum concentrations of insulin-like growth factor (IGF)-I and IGF binding protein-1 before and during pregnancy in relation to maternal body weight and composition and infant birth weight

Maternal nutritional status, e.g. body weight and composition, is associated with fetal growth. It has been suggested that the insulin-like growth factor (IGF) system may be a mediator of this relationship. In twenty-three healthy Swedish women, we studied (1) the relationships before and during pregnancy between maternal serum concentrations of IGF-I and IGF binding protein-1 (IGFBP-1) and maternal body weight and composition; (2) interactions between serum concentrations of IGF-I (before and in early pregnancy) and maternal nutritional status in relation to infant birth weight. We found that serum IGF-I during pregnancy was positively correlated with maternal body weight (r 0.47-0.56) and fat-free body weight (r 0.61-0.65), whereas serum IGFBP-1 was negatively correlated with maternal body weight (r - 0.44 to - 0.69) and body fat (r - 0.64 to - 0.76) before and during pregnancy. Women with a lower body fat content (%) before pregnancy had greater increases in serum IGFBP-1 during pregnancy than women with a higher prepregnant body fat content (%). In addition, significant fractions of the variation in corrected infant birth weight were explained by variables related to the maternal nutritional status when these were combined with serum concentrations of IGF-I in gestational week 14 (adjusted r2 0.25-0.44, P = 0.001-0.021), but not when they were combined with such concentrations before pregnancy (adjusted r2 0.11-0.12, P = 0.105-0.121). These results suggest mechanisms by which the IGF system may be a mediator between maternal nutritional status and fetal growth.

Maternal beef and postweaning herring diets increase bone mineral density and strength in mouse offspring

The maternal diet during gestation and lactation affects the long-term health of the offspring. We sought to determine whether maternal and postweaning crossover isocaloric diets based on fish or meat affect the geometry, mineral density, and biomechanical properties of bone in mouse offspring in adulthood. During gestation and lactation, C57BL/6 dams were fed a herring- or beef-based diet. After weaning, half of the pups in each group were fed the same diet as their dams, and half were fed the other diet. Areal bone mineral density (aBMD) and bone mineral content (BMC) of the whole body and lumbar spine were measured in the offspring by dual X-ray absorptiometry at 9 and 21 weeks of age. At 22–26 weeks, tibia bone geometry (length, cortical volumetric (v) BMD, BMC, area and thickness) was analyzed by peripheral quantitative computed tomography, and the biomechanical properties of the tibia were analyzed by the three-point bending test. Plasma insulin-like growth factor-1 was analyzed at 12 weeks. In comparison to the maternal herring diet, the maternal beef diet increased aBMD and BMC in the whole body and lumbar spine of adult offspring, as well as cortical vBMD, BMC, bone area, and thickness at the mid-diaphyseal region of the tibia and the biomechanical properties of tibia strength. In contrast, a postweaning beef diet decreased aBMD in the lumbar spine and BMC in the whole body and lumbar spine compared with a postweaning herring diet, which instead increased plasma insulin-like growth factor-1 levels. The change from a maternal beef diet before weaning to a herring diet after weaning decreased body weight and increased the cortical area, vBMD, BMC, thickness, and strength of the tibia. These significant crossover effects indicate that a preweaning maternal beef diet and a postweaning herring diet are optimal for increasing BMC and bone strength in offspring in adulthood.