Increased Plasma Levels of Growth Hormone, Insulin-Like Growth Factor (IGF)-I and IGF-Binding Protein 3 in Pregnant Rats with Exercise

Effects of maternal low-protein diet and spontaneous physical activity on the transcription of neurotrophic factors in the placenta and the brains of mothers and offspring rats

Maternal protein restriction and physical activity can affect the interaction mother-placenta-fetus. This study quantified the gene expression of brain-derived neurotrophic factor (BDNF), neurothrophin 4, tyrosine kinase receptor B (TrkB/NTRK2), insulin-like growth factor (IGF-1), and insulin-like growth factor receptor (IGF-1r) in the different areas of mother's brain (hypothalamus, hippocampus, and cortex), placenta, and fetus' brain of rats. Female Wistar rats (n = 20) were housed in cages containing a running wheel for 4 weeks before gestation. According to the distance spontaneously traveled daily, rats were classified as inactive or active. During gestation, on continued access to the running wheel, active and inactive groups were randomized to receive normoprotein diet (18% protein) or a low-protein (LP) diet (8% protein). At day 20 of gestation, gene expression of neurotrophic factors was analyzed by quantitative polymerase chain reaction in different brain areas and the placenta. Dams submitted to a LP diet during gestation showed upregulation of IGF-1r and BDNF messenger RNA in the hypothalamus, IGF-1r and NTRK2 in the hippocampus, and BDNF, NTRK2, IGF-1 and IGF-1r in the cortex. In the placenta, there was a downregulation of IGF-1. In the brain of pups from mothers on LP diet, IGF-1r and NTRK2 were downregulated. Voluntary physical activity attenuated the effects of LP diet on IGF-1r in the hypothalamus, IGF-1r and NTRK2 in the hippocampus, IGF-1 in the placenta, and NTRK2 in the fetus' brain. In conclusion, both maternal protein restriction and spontaneous physical activity influence the gene expression of BDNF, NTRK2, IGF-1, and IGF-1r, with spontaneous physical activity being able to normalize in part the defects caused by protein restriction during pregnancy.

Association of objectively measured physical fitness during pregnancy with maternal and neonatal outcomes. The GESTAFIT Project

Aim

To analyse i) the association of physical fitness during early second trimester and late pregnancy with maternal and neonatal outcomes; and ii) to investigate whether physical fitness is associated with the type of birth (vaginal or caesarean section).

Methods

Pregnant women from the GESTAFIT Project (n = 159) participated in this longitudinal study. Maternal physical fitness including upper- and lower-body strength, cardiorespiratory fitness (CRF) and flexibility were measured through objective physical fitness tests at the 16^th and 34^th gestational weeks. Maternal and neonatal outcomes were collected from obstetric medical records. Umbilical arterial and venous blood gas pH and partial pressure of carbon dioxide (PCO₂) and oxygen (PO₂), were assessed.

Results

At the 16^th week, greater upper-body muscle strength was associated with greater neonatal birth weight (r = 0.191, p<0.05). Maternal flexibility was associated with a more alkaline arterial pH (r = 0.220, p<0.05), higher arterial PO₂ (r = 0.237, p<0.05) and lower arterial PCO₂ (r = -0.331, p<0.01) in umbilical cord blood. Maternal CRF at the 16^th gestational week was related to higher arterial umbilical cord PO₂ (r = 0.267, p<0.05). The women who had caesarean sections had lower CRF (p<0.001) at the 16^th gestational week and worse clustered overall physical fitness, both at the 16^th (-0.227, p = 0.003, confidence interval (CI): -0.376, -0.078) and 34^th gestational week (-0.223; p = 0.018; CI: -0.432, -0.015) compared with the women who had vaginal births.

Conclusion

Increasing physical fitness during pregnancy may promote better neonatal outcomes and is associated with a decrease in the risk of caesarean section.

This trial was registered at ClinicalTrials.gov (NCT02582567) on October 20, 2015.

Maternal exercise in rats upregulates the placental insulin-like growth factor system with diet- and sex-specific responses: minimal effects in mothers born growth restricted

KEY POINTS

The placental insulin-like growth factor (IGF) system is critical for normal fetoplacental growth, which is dysregulated following several pregnancy perturbations including uteroplacental insufficiency and maternal obesity. We report that the IGF system was altered in placentae of mothers born growth restricted compared to normal birth weight mothers, with maternal diet- and fetal sex-specific responses. Additionally, we report increased body weight and plasma IGF1 concentrations in fetuses from chow-fed normal birth weight mothers that exercised prior to and continued during pregnancy compared to sedentary mothers. Exercise initiated during pregnancy, on the other hand, resulted in placental morphological alterations and increased IGF1 and IGF1R protein expression, which may in part be modulated by reduced Let 7f-1 miRNA abundance. Growth restriction of mothers before birth and exercise differentially regulate the placental IGF system with diet- and sex-specific responses, probably as a means to improve fetoplacental growth and development, and hence neonatal survival. This increased neonatal survival may prevent adult disease onset.

ABSTRACT

The insulin-like growth factor (IGF) system regulates fetoplacental growth and plays a role in disease programming. Dysregulation of the IGF system is implicated in several pregnancy perturbations associated with altered fetal growth, including intrauterine growth restriction and maternal obesity. Limited human studies have demonstrated that maternal exercise enhances fetoplacental growth and decreases cord IGF ligands, which may restore the placental IGF system in complicated pregnancies. This study investigated the impact maternal exercise has on the placental IGF system in placentae from mothers born growth restricted and if these outcomes are dependent on maternal diet or fetal sex. Uteroplacental insufficiency (Restricted) or sham (Control) surgery was induced on embryonic day (E) 18 in Wistar-Kyoto rats. F1 offspring were fed a chow or high-fat diet from weaning, and at 16 weeks were randomly allocated an exercise protocol: Sedentary, Exercised prior to and during pregnancy (Exercise), or Exercised during pregnancy only (PregEx). Females were mated (20 weeks) with placentae associated with F2 fetuses collected at E20. The placental IGF system mRNA abundance and placental morphology was altered in mothers born growth restricted. Exercise increased fetal weight and Control plasma IGF1 concentrations, and decreased female placental weight. PregEx did not influence fetoplacental growth but increased placental IGF1 and IGF1R (potentially modulated by reduced Let 7f-1 miRNA) and decreased placental IGF2 protein. Importantly, these placental IGF system changes occurred with sex-specific responses. These data highlight that exercise differently influences fetoplacental growth and the placental IGF system depending on maternal exercise initiation, which may prevent the transgenerational transmission of deficits and dysfunction.

DNA damage in Wistar Kyoto rats exercised during pregnancy

Purpose:

To evaluate DNA damage levels in pregnant rats undergoing a treadmill exercise program.

Methods:

Wistar Kyoto rats were allocated into two groups (n= 5 animals/group): non-exercise and exercise. The pregnant rats were underwent an exercise protocol on a treadmill throughout pregnancy. Exercise intensity was set at 50% of maximal capacity during maximal exercise testing performed before mating. Body weight, blood pressure and glucose levels, and triglyceride concentration were measured during pregnancy. At day 10 post-natal, the animals were euthanized and maternal blood samples were collected for DNA damage.

Results:

Blood pressure and glucose levels and biochemical measurements showed no significant differences. Increased DNA damage levels were found in exercise group compared to those of non-exercise group (p<0.05).

Conclusion:

The exercise intensity protocol used in the study might have been exhaustive leading to maternal increased DNA damage levels, demonstrating the relevance of an adequate protocol of physical exercise.

The Clinical Values of Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor Binding Protein-3 Levels in Blood and Thyroid Nodules

AIM

Insulin-like growth factor-1 (IGF-1) is a potent mitogen for many cells. IGF-1 plays a role in the pathogenesis of various tumors with its mutagenic and antiapoptotic properties. The aim of this study was to determine both the serum and intranodular levels of IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) in patients with nodular thyroid diseases.

MATERIALS AND METHODS

In this study, 80 subjects who performed fine-needle aspiration biopsy (FNAB) were required in order to investigate the effects of serum and intranodular IGF-1 and IGFBP-3 in the pathogenesis of nodules. After performing FNAB, IGF-1 and IGFBP-3 levels were determined in blood and aspiration samples.

RESULTS

The serum levels of IGF-1 (232.8 ± 12.9 ng/ml) and IGFBP-3 (4.8 μg/ml) were found significantly higher than that of the intranodular IGF-1 (39.1 ng/ml) and intranodular IGFBP-3 levels (0.173 μg/ml) (p < 0.01). Intranodular levels of IGF-1 and IGFBP-3 were higher in subjects with multinodular thyroid gland than those of subjects with solitary nodules (p = 0.043). A positive correlation between the nodule size and the serum IGFBP-3 levels was detected (p = 0.042, r = 0.23).

CONCLUSION

This study demonstrated the possible role of both IGF-1 and IGFBP-3 in the growth and the formation of multinodularity of thyroid nodules.

Physiological mechanisms of vascular response induced by shear stress and effect of exercise in systemic and placental circulation

Physiological vascular function regulation is essential for cardiovascular health and depends on adequate control of molecular mechanisms triggered by endothelial cells in response to mechanical and chemical stimuli induced by blood flow. Endothelial dysfunction is one of the main risk factors of cardiovascular pathology, where the imbalance between the synthesis of vasodilator and vasoconstrictor molecules is common in the development of vascular disorders in systemic and placental circulation. In the placenta, an organ without autonomic innervations, the local control of vascular tone is critical for maintenance of fetal growth and mechanisms that underlie shear stress response induced by blood flow are essential during pregnancy. In this field, shear stress induced by moderate exercise is one of the most important mechanisms to improve vascular function through nitric oxide synthesis and stimulation of mechanical response of endothelial cells triggered by ion channels, caveolae, endothelial NO synthase, and vascular endothelial growth factor, among others. The demand for oxygen and nutrients by tissues and organs, especially in placentation and pregnancy, determines blood flow parameters, and physiological adaptations of vascular beds for covering metabolic requirements. In this regard, moderate exercise versus sedentarism shows potential benefits for improving vascular function associated with the enhancement of molecular mechanisms induced by shear stress. In this review, we collect evidence about molecular bases of physiological response to shear stress in order to highlight the relevance of moderate exercise-training for vascular health in adult and fetal life.

Programmed changes in the adult rat offspring caused by maternal protein restriction during gestation and lactation are attenuated by maternal moderate–low physical training

The effects of maternal moderate–low physical training on postnatal development, glucose homeostasis and leptin concentration in adult offspring subjected to a low-protein diet during the perinatal period were investigated. Male Wistar rats (aged 150 d old) were divided into four groups according to maternal group: untrained (NTp, n 8); trained (Tp, n 8); untrained with a low-protein diet (NT+LPp, n 8); trained with a low-protein diet (T+LPp, n 8). The trained mothers were subjected to a protocol of moderate physical training over a period of 4 weeks (treadmill, 5 d/week, 60 min/d, at 65 % VO2max) before mating. At pregnancy, the intensity and duration of exercise was progressively reduced (50–20 min/d, at 65–30 % VO2max). The low-protein diet groups received an 8 % casein diet, and their peers received a 17 % casein diet during gestation and lactation. The pups' birth weight and somatic growth were recorded weekly up to the 150th day. Fasting blood glucose, cholesterol, serum leptin concentration, glucose and insulin tolerance tests were evaluated. The Tp animals showed no changes in somatic and biochemical parameters, while the NT+LPp group showed a greater abdominal circumference, hyperglycaemia, hypercholesterolaemia, glucose intolerance and lower plasma leptin. In the T+LPp animals, all of those alterations were reversed except for plasma leptin concentration. In conclusion, the effects of a perinatal low-protein diet on growth and development, glucose homeostasis and serum leptin concentration in the offspring were attenuated in pups from trained mothers.

Insulin-like growth factor-I gene and insulin-like growth factor binding protein-3 polymorphism in patients with thyroid dysfunction

BACKGROUND AND AIMS

Thyroid hormones have important roles in normal growth and skeletal muscle development. IGF-I is one of the most important growth factors and is needed for the proliferation and development of thyroid cells. It stimulates fibroblasts, follicular and endothelia cells in thyroid gland. It has been shown that thyroid hormones play an important role in the regulation of IGF-I and IGFBP-3. In this study we proposed that IGF-I (CA)(19) and IGFBP-3-202 A/C gene polymorphism may affect thyroid functions. For this purpose, frequency of IGF-I (CA)(19) and IGFBP-3-202 A/C gene polymorphism in hypo- and hyperthyroid patients and possible role of these polymorphism in thyroid functions were investigated.

METHODS

This study was performed on 37 volunteer hyperthyroid and 76 hypothyroid patients as well as with 50 healthy subjects as controls. DNA isolation was applied in peripheral blood samples obtained from patients and controls. Required areas were amplified with PCR by using proper primers belonging to these gene areas from the isolated DNA samples. The products were evaluated with visualization by UV gel documentation system.

RESULTS

Frequency of IGF-I (CA)(19) gene polymorphism among hypothyroidism patients, hyperthyroidism patients and controls were statistically significant (chi(2) = 11.55, df = 4, p = 0.021). Genotypic variations between hyper- and hypothyroid patients were significant (chi(2) = 11.39, df = 2, p = 0.003), whereas there was no difference in IGF-I (CA)(19) gene polymorphism between the patients and controls. Differences in the IGFBP-3-202 A/C gene polymorphism between controls and hypo- as well as hyperthyroid patients were not significant. But IGFBP-3-202 A/C gene polymorphism genotype frequencies showed a significant difference between hypo- and hyperthyroid patients (chi(2) = 6.24, df = 2, p = 0.044).

CONCLUSIONS

These findings suggests that IGF-I (CA)(19) and IGFBP-3-202 A/C gene polymorphisms may be a risk factor for hypothyroidism.

The effects of aerobic exercise training on the age-related lipid peroxidation, Schwann cell apoptosis and ultrastructural changes in the sciatic nerve of rats

The potential role of exercise in preventing the age-related spontaneous peripheral neuropathy has not been studied. We examined the effects of long-term aerobic exercise training on lipid peroxidation, Schwann cell (SC) apoptosis and ultrastructural changes in the sciatic nerve of rats during aging. Three groups of 12-week old Wistar rats ran on a treadmill for 6, 9 and 12 months (exercise trained (ET) group, n=10 each) according to an exercise training program targeted at a speed of 22 m/min (at 7 degrees incline), 60 min/day, 6 days/week. Three corresponding groups of untrained rats were used as the controls (sedentary (SED) group). At the end of each period, sciatic nerve biopsies were performed, and processed for biochemical, immunohistochemical and ultrastructural analyses. The results showed that aging was associated with an increased level of nerve malondialdehyde (MDA, marker of lipid peroxidation) and a higher number of SC apoptosis in SED group. The SED group showed irregular nerve fibers with thin myelin sheaths and areas of myelin-axon detachment. However, the ET group had significantly diminished nerve lipid peroxidation and SC apoptosis. In the ET group, nerve fibers had a thick myelin sheath with frequent folding. These findings suggest that aerobic exercise training protects peripheral nerves by attenuating oxidative reactions, and preserving SCs and myelin sheath from pathologic changes, which occur during normal aging.

Serotonergic and noradrenergic lesions suppress the enhancing effect of maternal exercise during pregnancy on learning and memory in rat pups

The beneficial effects of exercise on learning and memory are well documented but the effects of prenatal exposure to maternal exercise on offspring are not clear yet. Using a two-trial-per-day Morris water maze for five consecutive days, succeeded by a probe trial 2 days later we showed that maternal voluntary exercise (wheel running) by pregnant rats increased the acquisition phase of the pups' learning. Maternal forced swimming by pregnant rats increased both acquisition and retention phases of the pups' learning. Also we found that the rat pups whose mother was submitted to forced-swimming during pregnancy had significantly higher brain, liver, heart and kidney weights compared with their sedentary counterparts. On the other hand we estimated the cell number of different regions of the hippocampus in the rat pups. We found that both exercise models during pregnancy increased the cell number in cornus ammonis subregion 1 (CA1) and dentate gyrus of the hippocampus in rat pups. To determine the role that noradrenergic and serotonergic neurotransmission and N-methyl-D-aspartate (NMDA) receptors hold in mediation of the maternal exercise in offspring, we used N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), p-chloroamphetamine (PCA) and MK-801 to eliminate or block the above systems, respectively. Blocking the NMDA receptors, significantly abolished learning and memory in rat pups from all three experimental groups. Elimination of noradrenergic or serotonergic input did not significantly attenuate the learning and memory in rat pups whose mothers were sedentary, while it significantly reversed the positive effects of maternal exercise during pregnancy on rat pups' learning and memory. The presented results suggest that noradrenergic and serotonergic systems in offspring brain seem to have a crucial specific role in mediating the effects of maternal physical activity during pregnancy on rat pups' cognitive function in both models of voluntary and forced exercise.