The beneficial effect of fiber supplementation in high- or low-fat diets on fetal development and antioxidant defense capacity in the rat.

BACKGROUND: There is mounting evidence that an imbalance in oxidant/antioxidant activities plays a pivotal role in fetal development. AIM OF THE STUDY: To determine the effects of maternal intake of fat and fiber on fetal intrauterine development and antioxidant defense systems of rats. METHODS: Virgin female Sprague-Dawley rats were randomly assigned to 4 groups according to diet: the low-fat, low-fiber group (LL); the low-fat, high-fiber group (LH); the high-fat, low-fiber group (HL); and the high-fat, high-fiber group (HH). The diets were fed 4 weeks prior to breeding through day 17.5 of pregnancy. Dietary intakes of fiber (wheat bran and oat) and fat were quantitatively varied, while intakes of energy and essential nutrients were kept constant among the diets. RESULTS: Rats fed a fiber-rich diet had significantly improved fetal numbers, as well as enhanced activity of superoxide dismutase (SOD) and capacity of scavenging free radicals (p < 0.05). Meanwhile, the placental malondialdehyde and protein carbonyl levels were affected by the diet fat and fiber levels (p < 0.05). Compared with the LL group, the mRNA abundance of hypoxia-inducible factor 1α (HIF-1α) and thioredoxin-2 (Trx2) in the maternal liver and glutathione peroxidase 1 (GPx1) in the placenta and fetus were significantly downregulated in the HL group (p < 0.05). Furthermore, rats fed a fiber-rich diet had significantly upregulated mRNA expressions of Cu,Zn-SOD, Mn-SOD, and HIF-1α in the maternal liver (p < 0.05); Cu,Zn-SOD and Mn-SOD in the placenta (p < 0.05); and Cu,Zn-SOD in the fetus (p < 0.05). CONCLUSION: When energy intakes are equivalent, consumption of fiber in high- or low-fat diets benefits fetal development and growth, through improvements in maternal, placental, and fetal antioxidant defense capacities.

Beneficial effects of dietary fibre supplementation of a high-fat diet on fetal development in rats.

The objective of the present study was to investigate the effects of the addition of fibre and the antioxidant N-acetylcysteine (NAC) to fat-rich diets on fetal intrauterine development in rats. A total of eighty virgin female Sprague-Dawley rats were fed a control diet, a high-fat diet (HF), a high-fat and high-fibre diet (HFF) or a high-fat NAC diet until day 19·5 of gestation. Maternal HFF consumption resulted in a significantly higher mean fetal number and placental weight than in the other groups (P < 0·05). The HFF diet significantly abrogated HF-induced decreases in maternal serum and placental superoxide anion and hydroxyl radical scavenging capacities (P < 0·05); partially abrogated HF-induced increases in maternal serum and placental malondialdehyde (MDA) and protein carbonyl concentrations (maternal serum MDA and placental protein carbonyl, P < 0·05); resulted in significantly higher fetal liver total superoxide dismutase (SOD), Cu- and Zn-containing SOD and Mn-containing SOD (Mn-SOD) activities than in the HF group (P < 0·05). Furthermore, mRNA expressions of hypoxia-inducible factor 1-α, thioredoxin 2 and Mn-SOD in fetal liver and Mn-SOD in fetal heart and placental GLUT3 in the HFF group were higher than those in the other groups (P < 0·05). The inclusion of dietary fibre in the HF diet was more effective than NAC supplementation in maintaining maternal serum and placental superoxide anion and hydroxyl radical scavenging capacities close to those of the control. These results suggest that maternal fibre intake during pregnancy is beneficial for fetal intrauterine development possibly through the improvement of maternal, placental and fetal antioxidant capacities and placental nutrient transfer capacity.

Active immunization with GnRH-tandem-dimer peptide in young male rats reduces serum reproductive hormone concentrations, testicular development and spermatogenesis.

GnRH sterilization vaccines have been developed for various practical and clinical reasons. However, conjugation of GnRH peptide to carrier protein has many drawbacks, hampering the further commercialization of GnRH vaccines. In this study, a new nonconjugated GnRH vaccine, D-Lys6-GnRH-tandem-dimer peptide (TDK), emulsified in Specol adjuvant was investigated for its immunocastration efficacy in young male rats. Prepubertal male rats were randomly allocated into three groups (n = 12): control (no treatment), surgically castrated or immunized against 100 µg TDK in Specol adjuvant at 6 weeks of age (with a booster 8 weeks later). Blood samples (for antibody titers and hormone concentrations) were collected at 2-week intervals until rats were killed (18 weeks of age). Compared to intact controls, active immunization against TDK reduced (P < 0.05) serum concentrations of testosterone, inhibin B, LH and FSH, prevented the onset of spermatogenesis at puberty. Furthermore, mRNA expressions of GnRH receptor, LH-ß and FSH-ß in the pituitary, LH receptor, FSH receptor, inhibin α, ßA and ßB subunit in the testes were decreased in immunocastrated rats compared to intact controls (P < 0.05). These results demonstrate for the first time that GnRH-tandem-dimer peptide emulsified in Specol is a promising veterinary sterilization medicine.

Active immunization against GnRH reduces the synthesis of GnRH in male rats.

We sought to determine the effects of active anti-GnRH immunization on GnRH synthesis in the hypothalamus. Adult male rats (n = 36) were randomly and equally allocated into three groups: Control (no treatment), surgically castrated, or immunized against 50 µg D-Lys6-GnRH-tandem-dimer peptide conjugated to ovalbumin in Specol adjuvant at 12 week of age (with a booster 8 week later). Blood samples (for antibody titers and hormone concentrations) were collected at 2-week intervals until rats were killed (20 week). Compared with intact controls, immunocastration reduced (P < 0.05) serum concentrations of testosterone, LH, and FSH, and GnRH content in the median eminence, reduced the weight of the hypohysis (P < 0.01), and induced testicular atrophy (suppression of spermatogenesis). Furthermore, mRNA expression of GnRH in the hypothalamus, GnRH receptor, LH-ß and FSH-ß in the pituitary, LH receptor and FSH receptor in the testes, and genes in sex steroid feedback loops (androgen receptor [AR], kisspeptin encoded gene (Kiss-1), and kisspeptin receptor (GPR54) in the hypothalamus were decreased in immunocastrated rats compared with intact controls (P < 0.05). Similarly, surgical castration reduced GnRH in the median eminence as well as mRNA expression of GnRH, AR, Kiss-1, and GPR54 in the hypothalamus (P < 0.05). We concluded that anti-GnRH immunization in adult rats reduced synthesis of hypothalamic GnRH by decreasing androgen-AR-Kisspeptin-GPR54 signaling pathways, and caused dysfunction of the pituitary-testicular axis, thereby suppressing spermatogenesis, resulting in testicular atrophy.