Fathers that are born small program alterations in the next-generation preimplantation rat embryos.

BACKGROUND: Low birth weight is associated with increased risk of adult cardiovascular and metabolic disease development, with recent studies highlighting transmission to subsequent generations via both maternal and paternal lines. However, the timing of parent-specific programming of disease risk to the next generation remains to be characterized. OBJECTIVE: The aim of this study was to examine how paternal low birth weight affects the cellular and molecular physiology of the next-generation [second-generation (F2)] blastocysts, before uterine implantation. METHODS: Uteroplacental insufficiency was surgically induced in Wistar Kyoto pregnant rats in late gestation, giving rise to first-generation restricted (born small) and sham-operated control (normal birth weight) male offspring, respectively. First-generation restricted and control male rats were naturally mated with normal females. RESULTS: Resultant F2 blastocysts derived from restricted males displayed reduced expression of growth regulatory genes of the mammalian target of rapamycin pathway compared with F2 control blastocysts (9-74%; P < 0.05). No differences were found in F2 restricted blastocyst structural characteristics, cell number, or carbohydrate utilization at the time of blastocyst retrieval or after 24 h of in vitro culture. However, histidine, methionine, pyruvate, serine, and tryosine consumption and aspartate and leucine production were greater in F2 restricted outgrowth than in controls (P < 0.05). CONCLUSIONS: The findings from this study clearly indicate that male rat offspring born small, arising from uteroplacental insufficiency, have physiologic alterations that manifest as modifications in gene expression levels and nutrient metabolism of F2 blastocysts, even in the absence of overt cellular growth differences. These data demonstrate that growth restriction and associated disease risk have the capacity to be transmitted to the next generation of offspring via the male germ line and is manifest as early as the blastocyst stage of development.

Low female birth weight and advanced maternal age programme alterations in next-generation blastocyst development.

Low birth weight is associated with an increased risk for adult disease development with recent studies highlighting transmission to subsequent generations. However, the mechanisms and timing of programming of disease transmission to the next generation remain unknown. The aim of this study was to examine the effects of low birth weight and advanced maternal age on second-generation preimplantation blastocysts. Uteroplacental insufficiency or sham surgery was performed in late-gestation WKY pregnant rats, giving rise to first-generation (F1) restricted (born small) and control offspring respectively. F1 control and restricted females, at 4 or 12 months of age, were naturally mated with normal males. Second-generation (F2) blastocysts from restricted females displayed reduced expression of genes related to growth compared with F2 control (P<0.05). Following 24 h culture, F2 restricted blastocysts had accelerated development, with increased total cell number, a result of increased trophectoderm cells compared with control (P<0.05). There were alterations in carbohydrate and serine utilisation in F2 restricted blastocysts and F2 restricted outgrowths from 4-month-old females respectively (P<0.05). F2 blastocysts from aged restricted females were developmentally delayed at retrieval, with reduced total cell number attributable to reduced trophectoderm number with changes in carbohydrate utilisation (P<0.05). Advanced maternal age resulted in alterations in a number of amino acids in media obtained from F2 blastocyst outgrowths (P<0.05). These findings demonstrate that growth restriction and advanced maternal age can alter F2 preimplantation embryo physiology and the subsequent offspring growth.

Transgenerational left ventricular hypertrophy and hypertension in offspring after uteroplacental insufficiency in male rats.

Epidemiological studies have shown an association between low birthweight and adult disease development with transmission to subsequent generations. The aim of the present study was to examine the effect of intrauterine growth restriction in rats, induced by uteroplacental insufficiency, on cardiac structure, number, size, nuclearity, and adult blood pressure in first (F1) and second (F2) generation male offspring. Uteroplacental insufficiency or sham surgery was induced in F0 Wistar-Kyoto pregnant rats in late gestation giving rise to F1 restricted and control offspring, respectively. F1 control and restricted females were mated with normal males, resulting in F2 control and restricted offspring, respectively. F1 restricted male offspring were significantly lighter at birth (P < 0.05), but there were no differences in birthweight of F2 offspring. Left ventricular weights and volumes were significantly increased (P < 0.05) in F1 and F2 restricted offspring at day 35. Left ventricular cardiomyocyte number was not different in F1 and F2 restricted offspring. At 6 months-of-age, F1 and F2 restricted offspring had elevated blood pressure (8-15 mmHg, P < 0.05). Our findings demonstrate the emergence of left ventricular hypertrophy and hypertension, with no change in cardiomyocyte number, in F1 restricted male offspring, and this was transmitted to the F2 offspring. The findings support transgenerational programming effects.

Maternal adaptations and inheritance in the transgenerational programming of adult disease.

Adverse exposures in utero have long been linked with an increased susceptibility to adult cardio-renal and metabolic diseases. Clear gender differences exist, whereby growth-restricted females, although exhibiting some phenotypic modifications, are often protected from overt disease outcomes. One of the greatest physiological challenges facing the female gender, however, is that of pregnancy; yet little research has focused on the outcomes associated with this, as a potential 'second-hit' for those who were small at birth. We review the limited evidence suggesting that pregnancy may unmask cardio-renal and metabolic disease states and the consequences for long-term maternal health in females who were born small. Additionally, a growing area of research in this programming field is in the transgenerational transmission of low birth weight and disease susceptibility. Pathways for transmission might include an abnormal adaptation to pregnancy by the growth-restricted mother and/or inheritance via the parental germline. Strategies to optimise the pregnancy environment and/or prevent the consequences of inheritance of programmed deficits and dysfunction are of critical importance for future generations.