Cold-induced elevation of forearm vascular resistance is inversely related to birth weight

Perinatal low-protein diet alters brainstem antioxidant metabolism in adult offspring

BACKGROUND AND OBJECTIVES

Studies in humans and animal models have established a close relationship between early environment insult and subsequent risk of development of non-communicable diseases, including the cardiovascular. Whereas experimental evidences highlight the early undernutrition and the late cardiovascular disease relation, the central mechanisms linking the two remain unknown. Owing to the oxidative balance influence in several pathologies, the aim of the present study was to evaluate the effects of maternal undernutrition (i.e. a low-protein (LP) diet) on oxidative balance in the brainstem.

METHODS AND RESULTS

Male rats from mothers fed with an LP diet (8% casein) throughout the perinatal period (i.e. gestation and lactation) showed 10× higher lipid peroxidation levels than animals treated with normoprotein (17% casein) at 100 days of age. In addition, we observed the following reductions in enzymatic activities: superoxide dismutase, 16%; catalase, 30%; glutathione peroxidase, 34%; glutathione-S-transferase, 51%; glutathione reductase, 23%; glucose-6-phosphate dehydrogenase, 31%; and in non-enzymatic glutathione system, 46%.

DISCUSSION

This study is the first to focus on the role of maternal LP nutrition in oxidative balance in a central nervous system structure responsible for cardiovascular control in adult rats. Our data observed changes in oxidative balance in the offspring, therefore, bring a new concept related to early undernutrition and can help in the development of a new clinical strategy to combat the effects of nutritional insult. Wherein the central oxidative imbalance is a feasible mechanism underlying the hypertension risk in adulthood triggered by maternal LP diet.

Maternal malnutrition and placental insufficiency induce global downregulation of gene expression in fetal kidneys

Malnutrition during pregnancy causes intrauterine growth restriction and long-term changes in the offspring's physiology and metabolism. To explore molecular mechanisms by which the intrauterine environment conveys programming in fetal kidneys, an organ known to undergo substantial changes in many animal models of late gestational undernutrition, we used a microswine model of maternal protein restriction (MPR) in which sows were exposed to isocaloric low protein (LP) diet during late gestation/early lactation to encompass the bulk of nephrogenesis. To define general v. model-specific effects, we also used a sheep model of placental insufficiency. In kidneys from near-term fetal and neonatal microswine LP offspring, per cell levels of total RNA, poly(A)+ mRNA and transcripts of several randomly chosen housekeeping genes were significantly reduced compared to controls. Microarray analysis revealed only a few MPR-resistant genes that escape such downregulation. The ratio of histone modifications H3K4m3/H3K9m3 (active/silenced) was reduced at promoters of downregulated but not MPR-resistant genes suggesting that transcriptional suppression is the point of control. In juvenile offspring, on a normal diet from weaning, cellular RNA levels and histone mark patterns were recovered to near control levels, indicating that global repression of transcription is dependent on ongoing MPR. Importantly, cellular RNA content was also reduced in ovine fetal kidneys during placental insufficiency. These studies show that global repression of transcription may be a universal consequence of a poor intrauterine environment that contributes to fetal restriction.

The Relationship of Low Birth Weight to Blood Pressure, Cortisol Levels, and Reactivity in African American Adolescents: A Pilot Study

Epidemiological studies show a relationship between low birth weight (LBW) and adult cardiovascular disease. Blood pressure and cortisol hyper-responsiveness during physiologic stress may function as biological markers for hypertension. The purpose of this study was to explore the relationship of blood pressure and cortisol levels with induced physiologic stress to LBW. Forty-eight adolescents, 14 to 16 years old, were tested for blood pressure and cortisol levels at rest and in response to a physiological stressor. A history of LBW was obtained. Multivariate repeated measures analysis and chi-square analyses were used to determine the changes in blood pressure and cortisol.Forty-eight African American adolescents, mean age 14.98 years (SD = 0.33), completed the study. Thirteen adolescents (27%) reported LBW. Although not statistically significant, systolic and diastolic pressures were 6 mmHg and 2 mmHg, respectively, higher in the LBW group when compared with the normal birth weight (NBW) group (p = 0.33 and p = 0.21, and 6 (46%) had elevated blood pressures (p = 0.005)). Blood pressure changes, cardiovascular reactivity, elevated blood, or all of these were significantly higher in LBW African American adolescents (p = 0.006). Cardiovascular reactivity was not significant (p = 0.208)). The mean average cortisol levels were (18.8 nmol/dL (SD = 11.0) but comparable (p = 0.72)). The number of LBW adolescents with cortisol reactivity was significantly higher that in the NBW group (p = 0.041). This study adds support to the association of LBW to biological markers of hypertension in childhood.

The association of low birth weight and physiological risk factors of hypertension in African American adolescents

Low birth weight (LBW) has been associated with increased blood pressure and the development of cardiovascular disease including hypertension. Elevated blood pressure, cortisol, and hyperresponsiveness during physiologic stress may function as hypertension biological markers. We examined the association of blood pressure and cortisol levels during induced physiologic stress with LBW in an African American adolescent population (n = 106).

METHODS AND RESULTS

Birth weight was obtained from parents. Blood pressure and cortisol levels were measured at rest and in response to an induced physiological stressor. Compared with normal birth weight group (n = 73), the LBW group (n = 33) demonstrated elevated (+4 mm Hg) diastolic pressure (P = .002) and cortisol hyperresponsiveness (P = .05). Seventy-nine percent of LBW adolescents had elevated blood pressure and/or cardiovascular reactivity (P = .04), and 39% had elevated blood pressures.

CONCLUSIONS

Low birth weight African American adolescents demonstrated physiological risk factors for hypertension, and these findings add support to the association between LBW and the development of hypertension.

Abnormal circulatory stress responses of preterm graduates

Preterm birth and chronic lung disease may increase the risk of hypertension and cardiovascular disease in infancy and adolescence. Here we looked for evidence of early circulatory dysfunction associated with these perinatal complications. We compared infants born at term (n = 12) with those born preterm with an uncomplicated neonatal course (n = 12) or diagnosed with bronchopulmonary dysplasia (BPD) (n = 10). We measured blood pressure (BP) (Finometer), and heart rate (HR) responses to 4 min of breathing 4% CO2 during quiet sleep. Hypercapnia accelerated HR and increased BP of term infants. Preterm infants either (i) had an exaggerated pressor but little or no HR response to CO2 (healthy or mild-moderate BPD) or (ii) had a diminished pressor response and accompanying decrease in HR (severe BPD). Short-term reflex cardiovascular control was consequently altered by premature birth, with potentially more serious aberrations associated with severe BPD. Most anomalies had not resolved by the time infants born preterm reached term age; some may be early signs of emerging long-term cardiovascular dysfunction.