Excess omega-3 fatty acid consumption by mothers during pregnancy and lactation caused shorter life span and abnormal ABRs in old adult offspring.

Consuming omega-3 fatty acids (omega-3 FA) during pregnancy and lactation is beneficial to fetal and infant development and might reduce the incidence and severity of preterm births by prolonging pregnancy. Consequently, supplementing maternal diets with large amounts of omega-3 FA is gaining acceptance. However, both over- and under-supplementation with omega-3 FA can harm offspring development. Adverse fetal and neonatal conditions in general can enhance age-related neural degeneration, shorten life span and cause other adult-onset disorders. We hypothesized that maternal over- and under-nutrition with omega-3 FA would shorten the offspring's life span and enhance neural degeneration in old adulthood. To test these hypotheses, female Wistar rats were randomly assigned to one of the three diet conditions starting from day 1 of pregnancy through the entire period of pregnancy and lactation. The three diets were Control omega-3 FA (omega-3/omega-6 ratio approximately 0.14), Excess omega-3 FA (omega-3/omega-6 ratio approximately 14.5) and Deficient omega-3 FA (omega-3/omega-6 ratio approximately 0% ratio). When possible, one male and female offspring from each litter were assessed for life span and sensory/neural degeneration (n=15 litters/group). The Excess offspring had shorter life spans compared to their Control and Deficient cohorts (mean+/-SEM=506+/-24, 601+/-14 and 585+/-21 days, p

Abnormal neurological responses in young adult offspring caused by excess omega-3 fatty acid (fish oil) consumption by the mother during pregnancy and lactation.

Consuming omega-3 fatty acids (omega-3 FA) during pregnancy and lactation benefits fetal and infant brain development and might reduce the severity of preterm births by prolonging pregnancy. However, diets that are relatively rich in omega-3 FA can adversely affect fetal and infant development and the auditory brainstem response (ABR), a measure of brain development and sensory function. We previously examined the offspring of female rats fed excessive, adequate or deficient amounts of omega-3 FA during pregnancy and lactation. The 24-day-old offspring in the Excess group, compared to the Control group, had postnatal growth retardation and poor hearing acuity and prolonged neural transmission times as evidenced by the ABR. The Deficient group was intermediate. The current study followed these offspring to see if these poor outcomes persisted into young adulthood. Based on prior findings, we hypothesized that the Excess and Deficient offspring would "catch-up" to the Control offspring by young adulthood. Female Wistar rats received one of the three diet conditions from day 1 of pregnancy through lactation. The three diets were the Control omega-3 FA condition (omega-3/omega-6 ratio approximately 0.14), the Excess omega-3 FA condition (omega-3/omega-6 ratio approximately 14.0) and Deficient omega-3 FA condition (omega-3/omega-6 ratio approximately 0% ratio). The Control diet contained 7% soybean oil; whereas the Deficient and Excess omega-3 FA diets contained 7% safflower oil and 7% fish oil, respectively. One male and female offspring per litter were ABR-tested as young adults using tone pip stimuli of 2, 4, 8 and 16 kHz. The postnatal growth retardation and prolonged neural transmission times in the Excess and Deficient pups had dissipated by young adulthood. In contrast, the Excess group had elevated ABR thresholds (hearing loss) at all tone pip frequencies in comparison to the Control and Deficient groups. The Deficient group had worse ABR thresholds than the Control group in response to the 8 kHz tone pips only. The Excess group also had ABR amplitude-intensity profiles suggestive of hyperacusis. These results are consistent with the Barker hypothesis concerning the fetal and neonatal origins of adult diseases. Thus, consuming diets that are excessively rich or deficient in omega-3 FA during pregnancy and lactation seems inadvisable because of risks for long-lasting adverse effects on brain development and sensory function.

Excess and deficient omega-3 fatty acid during pregnancy and lactation cause impaired neural transmission in rat pups.

Omega-3 fatty acids (omega-3 FA) consumption during pregnancy and lactation is beneficial to fetal and infant growth and may reduce the severity of preterm births. Thus, scientists and clinicians are recommending increasingly higher omega-3 FA doses for pregnant women and nursing babies for advancing the health of preterm, low birth weight, and normal babies. In contrast, some studies report that over-supplementation with omega-3 FA can have adverse effects on fetal and infant development by causing a form of nutritional toxicity. Our goal was to assess the effects of omega-3 FA excess and deficiency during pregnancy and lactation on the offspring's neural transmission as evidenced by their auditory brainstem responses (ABR). Female Wistar rats were given one of three diets from day 1 of pregnancy through lactation. The three diets were the Control omega-3 FA condition (omega-3/omega-6 ratio approximately 0.14), the Deficient omega-3 FA condition (omega-3/omega-6 ratio approximately 0%) and the Excess omega-3 FA condition (omega-3/omega-6 ratio approximately 14.0). The Control diet contained 7% soybean oil, whereas the Deficient diet contained 7% safflower oil and the Excess diet contained 7% fish oil. The offspring were ABR-tested on postnatal day 24. The rat pups in the Excess group had prolonged ABR latencies in comparison to the Control group, indicating slowed neural transmission times. The pups in the Excess group also showed postnatal growth restriction. The Deficient group showed adverse effects that were milder than those seen in the Excess group. Milk fatty acid profiles reflected the fatty acid profiles of the maternal diets. In conclusion, excess or deficient amounts of omega-3 FA during pregnancy and lactation adversely affected the offspring's neural transmission times and postnatal thriving. Consuming either large or inadequate amounts of omega-3 FA during pregnancy and lactation seems inadvisable because of the potential for adverse effects on infant development.

Effects of intra-amniotic meconium exposure on the fetal rat: development of a pathogenic model.

OBJECTIVE: To develop an in vivo animal model for the study of the effects of intrauterine meconium exposure on the fetus. METHODS: Timed pregnant Long-Evans rats were purchased on gestational day (GD) 12 and allowed to acclimate for at least 48 h prior to surgery. Laparotomy was performed and both uterine horns were exteriorized through the abdominal incision. A 26-gauge needle was used to inject either 0.1-cm(3) sterile normal saline or a 20% meconium suspension into each individual gestational sac. The uterus was returned to the abdomen and the incision was closed. On GD 21 (term = 21 days) a cesarean section was completed and the number and viability of fetuses in each horn were recorded. RESULTS: A total of 14 animals were involved in this pilot study. One rat underwent sham surgery with only intra-amniotic saline injection and 13/15 fetuses survived to term. Two animals that underwent surgery on day 18 expired < 24 h postinjection. Eleven maternal animals were injected on GD 20 and underwent cesarean delivery at term; survival rates for saline-injected animals were 71.2% compared to 66.2% for meconium-exposed fetuses. CONCLUSION: We have established an in vivo animal model that allows for the examination of the effects of prolonged intrauterine meconium exposure on the fetus.

Magnesium prevents seizure-induced reduction in excitatory amino acid receptor (kainate and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) binding in pregnant rat brain.

OBJECTIVE: Our purpose was to evaluate the effect of seizures on kainate and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor binding in maternal rat brain and whether maternal peripheral administration of magnesium sulfate can decrease this effect. STUDY DESIGN: Rats were implanted with a bipolar electrode into the hippocampus. One week of recovery was allowed before breeding. Pregnant rats were randomly assigned to 1 of 4 groups, as follows: group 1, sodium chloride and no seizures (n = 5); group 2, magnesium sulfate and no seizures (n = 4); group 3, sodium chloride and seizures (n = 8); and group 4, magnesium sulfate and seizures (n = 9). Doses of sodium chloride or magnesium sulfate were administered every 20 minutes for 4 hours to all rats on gestational days 9, 11, 13, 15, 17, and 19, followed by seizure induction (groups 3 and 4). On gestational day 20, rats were perfused, brains were dissected, and cryostat sections were taken, labeled in vitro, and placed on Hyperfilm for 4 weeks. The ligands used included kainate receptor agonist and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor agonist and antagonist. Optical density measurements of binding in 15 brain regions on each section were evaluated by 1- and 2-way analysis of variance. RESULTS: Seizure activity was associated with decreased alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor binding of its agonist in pregnant rat brains (seizure effect, 25.9 +/- 3.2 and 92.6 +/- 3.4 fmol/mg tissue in hindbrain and forebrain, respectively; no seizure effect, 44.5 +/- 4.7 and 110. 7 +/- 5.0 fmol/mg tissue in hindbrain and forebrain, respectively; P <.01). Magnesium administration was associated with increased binding of tritiated alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (magnesium effect, 44.9 +/- 4.2 and 110.4 +/- 4.5 fmol/mg tissue in hindbrain and forebrain, respectively; sodium chloride effect, 25.5 +/- 3.7 and 92.9 +/- 4.0 fmol/mg tissue in hindbrain and forebrain, respectively; P <.01). The same trend was seen with the kainate receptor in the hippocampus and hypothalamus, with a significant interaction effect between seizure and magnesium (P <.05). CONCLUSIONS: The mechanism for maternal rat brain injury resulting from seizure activity may be, at least in part, associated with alteration in the function of excitatory amino acid receptors. Administration of magnesium sulfate can counteract this effect and may reduce resultant maternal brain damage.

Magnesium sulfate protection of fetal rat brain from severe maternal hypoxia.

OBJECTIVE: To determine whether severe maternal hypoxia affects fetal rat physical characteristics and causes neuronal damage, and whether magnesium sulfate can decrease these effects. METHODS: At 17 days gestation, rats were randomly assigned to one of four groups that received saline injections and room air (n = 6), magnesium sulfate and room air (n = 5), saline and hypoxia (n = 5) or magnesium sulfate and hypoxia (n =5). Maternal magnesium sulfate or saline injections were given for 4 hours. In groups 3 and 4 this was followed by a hypoxia chamber protocol that included a gas mixture of 9% oxygen and 3% carbon dioxide for 2 hours. After 72 hours of recovery, fetuses were delivered abdominally, perfused transcardially, and brains removed intact. Fetal body and brain weight and size were measured. Brains were embedded in paraffin, sectioned, and stained. A neuropathologist masked to the protocol performed histologic grading of brain regions. RESULTS: Exposure to the hypoxia chamber resulted in decreased maternal oxygen tension and pH (from 82.8 +/- 20.0 to 49.2 +/- 14.4 mmHg, and from 7.37 +/- 0.05 to 7.20 +/- 0.04, respectively; P <.005). Magnesium sulfate administration resulted in higher magnesium levels in blood (from 1. 52 +/- 0.2 to 3.77 +/- 0.7 mg/dL; P <.001). The hypoxia protocol resulted in a significant decrease in fetal body and brain size, but not weight. Hypoxia also caused an increase in the proportion of fetal rats that had brain injury, including shrinkage of cells and karyorrhexis in the hippocampus and thalamus (from 0% to 38.1% and 38.9%, respectively; P <.05). Magnesium sulfate reduced these effects on fetal brain histopathology and size. CONCLUSION: Severe maternal rat hypoxia resulted in significant fetal neuronal damage and decreased fetal body and brain size. Maternal magnesium sulfate administration reduced the effect of hypoxia on fetal brain histopathology and size without affecting body size.

Fetal rat brain damage caused by maternal seizure activity: prevention by magnesium sulfate.

OBJECTIVE: Our purpose was to determine whether maternal rat seizure activity was associated with fetal histopathologic brain changes and whether magnesium sulfate reduced these changes. STUDY DESIGN: Electrodes were stereotaxically implanted into the hippocampus of nonpregnant rats 1 week before breeding. Pregnant rats were randomly assigned to 1 of 4 groups: (1) sodium chloride solution and no seizure (n = 2), (2) magnesium sulfate and no seizure (n = 2), (3) sodium chloride solution and seizure (n = 5), and (4) magnesium sulfate and seizure (n = 5). On gestational days 9, 11, 13, 15, 17, and 19, subcutaneous doses of sodium chloride solution or magnesium sulfate were administered to all rats every 20 minutes for 4 hours (loading-maintenance-loading), followed by seizure induction. On gestational day 20, the rats were perfused with formalin and fetuses were delivered via cesarean. Fetuses were perfused with formalin, brains were obtained and embedded in paraffin, and the forebrain and hindbrain were sectioned in the coronal plane and stained with hematoxylin and eosin. A neuropathologist masked to the protocol performed histopathologic grading of each section, including extent and nature of cellular damage. Eleven brain regions were examined in each section. Scores were expressed as mean +/- SD. Kruskal-Wallis analysis of variance was used, and P <.05 was considered significant. RESULTS: We evaluated 26 fetal brains in group 1, 9 in group 2, 72 in group 3, and 45 in group 4. Fetuses in the sodium chloride solution-and-seizure group (group 3) presented significantly higher grades of neuronal damage in the hippocampus (group 1, 0.50 +/- 0. 88; group 2, 0.22 +/- 0.66; group 3, 1.01 +/- 1.17; and group 4, 0. 48 +/- 0.72) and in the tegmentum region (group 1, 1.0 +/- 1.0; group 2, 0.8 +/- 1.0; group 3, 1.7 +/- 0.7; and group 4, 1.5 +/- 0. 8) (P <.05, group 3 compared with others). Isolated and patchy neuronal injury with shrinkage of cells, nuclear pyknosis, and karyorrhexis were the main histologic findings. CONCLUSIONS: Maternal rat seizure activity was associated with histologic brain injury in the fetus. Maternal administration of magnesium sulfate before seizure prevented or significantly decreased this effect.

Fetal rat brain injury: effect of transient maternal hypoxemia.

OBJECTIVE: To determine whether transient acute maternal hypoxemia during the end of pregnancy may cause neuronal damage in fetal rat brains. STUDY DESIGN: Nine pregnant rats (4 study and 5 controls) at 16-17 gestational days were studied. The study rats were placed in a chamber and breathed a gas mixture of 11.8% oxygen, 4.95% CO2, and nitrogen for either 1 or 2 h, while the control animals breathed room air. Tail venous blood was collected and gases were evaluated at the beginning and conclusion of the exposure periods. After 72 h of recovery, at 19-20 days' gestation, the fetal cardiovascular systems were perfused with saline and formalin. The brains were embedded in paraffin, sectioned in coronal plane, and stained with hematoxylin and eosin Histologic assessment of sections was performed by a neuropathologist blinded to the protocol. Statistical analysis of the data was performed using analysis of variance and the chi-square test. RESULTS: Exposure to the gas mixture resulted in decreased maternal pO2 from 39.9 +/- 7.6 mm Hg in the control group to 28.8 +/- 2.0 mm Hg in the 2-hour hypoxia group (p < 0.05). No significant changes in maternal pH or pCO2 status have been noted. A total of 34 fetal rat brains served as controls and 26 brains as the hypoxia study group There was a significant increase in isolated neuronal damage, including necrosis and shrinkage of cells, with karyorrhexis (fragmentation and breakage of the nucleus) in the hippocampus, basal ganglia, thalamus, and hypothalamus in the hypoxemia rats as compared with controls. CONCLUSION: Transient maternal hypoxemia may cause neuronal necrosis in vulnerable regions of the fetal rat brain, including the hippocampus, basal ganglia, thalamus, and hypothalamus.