A low-protein isocaloric diet during gestation affects brain development and alters permanently cerebral cortex blood vessels in rat offspring.

In humans, low birth weight is associated with nonfatal stroke, cardiovascular disease and diabetes at adulthood. The aim of this study was to investigate in rats the effect of early protein restriction, inducing low birth weight, on brain and endocrine pancreas vascularization at birth and to study if such alterations lasted until adulthood. Pregnant rats were fed either 20 or 8% protein isocaloric diets. Control newborns were nursed by their dams fed the 20% protein diet and low protein (LP) pups by dams fed either the 8 or 20% protein diet. The diets given during lactation were maintained until adulthood. The blood vessel density of cerebral cortex analyzed by morphometry in 3-d-old pups from dams fed the 8% protein diet was lower than in control (C). It remained lower at adulthood whether a LP or a C diet was given postnatally. Reduction of vascularization at adulthood induced by the LP diet limited to fetal life seems characteristic for the brain since vascularization of islets of Langerhans was reduced in neonates but normalized at adulthood by a C diet postnatally. Body and brain weights were lower in LP pups and adults. DNA concentration was lower in forebrain and higher in cerebellum in LP pups. In brain of LP adults, DNA, protein, cholesterol and phospholipid concentrations were lower and were restored at adulthood by a normal diet after birth. In conclusion, cerebral cortex of offspring exposed to a LP isocaloric diet during fetal development showed reduced vascularization which remained throughout life.     

Effect of a low-protein diet during pregnancy on skeletal muscle mechanical properties of offspring rats

OBJECTIVE: The main goal of the present study was to investigate the effects of a low-protein diet during gestation on the biomechanical properties of skeletal muscle of offspring rats. METHODS: Male Wistar rats were divided into two groups according to their mothers' diet during pregnancy: a control group (mothers fed with 17% protein) and a low-protein group (mothers fed with 7.8% protein; UN). At birth, all mothers received a standardized meal ad libitum. When the rats were 25 and 90 d old, the soleus and extensor digitorum longus (EDL) muscles were removed from the pups. An analysis of the contractile and series elastic component properties was carried out on both muscles. Histochemical analysis was likewise performed. RESULTS: Group UN presented muscle wasting and diminution of maximum twitch and tetanic tension on the muscle at 25 and 90 d of life. There was an increase in maximal shortening velocity in the soleus and EDL muscles at 25 and 90 d in group UN. Series elastic component stiffness was increased in the soleus muscle, although a diminution of series elastic component stiffness was observed in the EDL at 25 d. With regard to the analysis of the muscle fiber proportions at 25 and 90 d, the UN group presented an increase in the IIa fibers in the soleus, whereas there was an increase in the IIb fibers and a diminution in the IIa fibers in the EDL. CONCLUSION: Low-protein intake during a critical period of development induces changes in the structure and function of skeletal muscle. Such changes may compromise an animal's posture and locomotion.     

Maternal low-protein diet during lactation programmes body composition and glucose homeostasis in the adult rat offspring

Previously we have reported that maternal malnutrition during lactation programmes body weight and thyroid function in the adult offspring. In the present study we evaluated the effect of maternal protein restriction during lactation upon body composition and hormones related to glucose homeostasis in adult rats. During lactation, Wistar lactating rats and their pups were divided into two experimental groups: control (fed a normal diet; 23% protein) and protein-restricted (PR; fed a diet containing 8% protein). At weaning, offspring received a normal diet until they were 180 d old. Body weight (BW) and food intake were monitored. Serum, adrenal glands, visceral fat mass (VFM) and carcasses were collected. PR rats showed lower BW (-13%; P < 0.05), VFM (-33%; P < 0.05), total body fat (-33%; P < 0.05), serum glucose (-7%; P < 0.05), serum insulin (-26%, P < 0.05), homeostasis model assessment index (-20%), but higher total adrenal catecholamine content (+90%; P < 0.05) and serum corticosterone concentration (+51%; P < 0.05). No change was observed in food intake, protein mass or total body water. The lower BW of PR rats is due to a reduction of white fat tissue, probably caused by an increase in lipolysis or impairment of lipogenesis; both effects could be related to higher catecholaminergic status, as well as to hypoinsulinaemia. To conclude, changes in key hormones which control intermediary metabolism are programmed by maternal protein restriction during lactation, resulting in BW alterations in adult rats.     

Effect of feeding lysine and threonine fortified bread during gestation and lactation on growth of the offspring in rats.

White bread, bread fortified with lysine, or with lysine and threonine was fed to female rats as the sole source of protein (13% of diet) during two closely spaced gestation and lactation periods. Comparisons were made with diets containing 13% or 26% casein protein, and a stock diet. Weight changes and food consumption of the mothers were determined, as were birth weights and weaning weights of the offspring. Lysine fortification increased food consumption and decreased weight loss of the mothers during lactation. When threonine was added with the lysine, food consumption during lactation was further increased and maternal weight loss prevented. Average weaning weights for first litters as a function of diet were: bread 17.0 +/- 1.9 g, bread + lysine 26.8 +/- 1.0 g, bread + lysine + threonine 39.8 +/- 3.1 g, 13% casein 42.8 +/- 3.8 g, 26% casein 62.5 +/- 4.7 g, and stock diet 41.5 +/- 7.9 g. First and second litter weaning weights were closely similar for each. Although average birth weights were not greatly affected by dietary treatment, total offspring weight at birth of mothers fed unfortified bread was reduced 40% in the second, as compared to the first litter. This reduction in total offspring weight did not occur in mothers fed amino acid fortified bread.     

The effect of sodium restriction during gestation of offspring brain development in rats

Sodium restrictive diets are today often recommended to women experiencing the normal edema of pregnancy. This study explores some effects of dietary sodium restriction, imposed during pregnancy, on reproductive performance and brain development in resultant offspring. Pregnant Sprague-Dawley rats were fed diets containing either 0.173, 0.067, 0.040, or 0.022% sodium throughout gestation. All other nutrients in the diet were fed at levels in excess of NAS-NRC requirements. At parturition, litters were trimmed to four offspring and mothers fed Purina Rat Chow throughout lactation. Twenty-one days postpartum, offspring were killed and analyses of selected parameters of brain composition made. Rats fed the 0.040 and 0.022% were killed and analyses of selected parameters of brain composition made. Rats fed the 0.040 and 0.022% sodium containing diets during pregnancy consumed less feed, gained less weight, and exhibited altered fluid consumption patterns to rats ingesting the 0.173% sodium control diet. Mothers fed the two diets containing the lowest levels of sodium also had smaller litters, fewer live births, and more stillbirths per litter than control mothers. Birth weights and the number of offspring surviving the lactation period were less in the 0.040 and 0.022% sodium treatment groups. No offspring in the 0.022% sodium diet group survived the lactation period. Brain wet weight, dry weight, cholesterol, protein, and RNA content were decreased in offspring in the 0.040% sodium diet group.     

Effects of low-protein diet on the baroreflex and Bezold-Jarisch reflex in conscious rats

The present study evaluated the effects of a low-protein diet (LP, 6% protein) on cardiovascular reflexes of Male Fisher rats. Three experimental groups, and their respective controls (15% protein), were used: (1) Baroreceptor reflex (BAR); (2) Bezold-Jarisch reflex (BJR); and (3) Prazosin treated. Dietary restriction began after weaning (three weeks) and lasted for a period of five weeks, after which animals were subjected to the experimental protocols. The BAR group was evaluated through injections of phenylephrine (0.5-5.0 microgram/Kg, i.v.) and sodium nitroprusside (0.7-7.0 microgram/Kg, i.v.) while the BJR was evaluated through injections of serotonin (2.5-10 microgram/Kg, i.v.). Our results showed an increased baroreflex gain bradycardia for the LP group (-0.96+/-0.34 vs. -2.12+/-1.06 bpm/mmHg) and a larger bradycardia for the BJR the LP group (160+/-18% greater than controls). Basal cardiovascular parameters were not different between LP and control rats, however LP animals treated with prazosin resulted in a larger fall of blood pressure (-19+/-3 vs. -28+/-5 mmHg). In conclusion, LP rats present an increased responsiveness of BAR and BJR, which could contribute to their normal levels of cardiovascular parameters, in spite of the possible increase in the sympathetic vasomotor tonus observed with the prazosin protocol.     

孕期不同时间低蛋白饮食致宫内发育迟缓鼠脑白质细胞凋亡的研究

目的:探讨孕期不同时间给予低蛋白饮食致宫内发育迟缓(IUGR)大鼠脑白质细胞凋亡的影响。方法:怀孕wistar大鼠分为对照组(C组)及孕早期(E组)、孕中期(M组)、孕晚期低蛋白饮食组(L组),测量脑重及体重,观察脑组织损伤,脑细胞凋亡及Caspase-3表达情况。结果:出生时体重:E、M组与C组比较差异有统计学意义(P<0.05);脑重:E、M、L组与C组比较差异有统计学意义(P<0.05)。E组出生时脑损伤病变较轻,2周时加重。细胞凋亡数量:出生时E、M、L组均明显高于C组,随年龄增加凋亡细胞数量逐渐减少,生后4周仅E组明显高于C组。Caspase-3的表达:出生时E、M、L组均明显高于C组,随年龄增加Caspase-3的表达逐渐减少,生后4周仅E组明显高于C组。结论:低蛋白饮食应用越早,脑白质细胞凋亡率越高,持续时间越长。Caspase-3活性增强参与了IUGR的病理过程,与细胞凋亡密切相关。     

Supplementation of bitter melon to rats fed a high-fructose diet during gestation and lactation ameliorates fructose-induced dyslipidemia and hepatic oxidative stress in male offspring

This study examined the impact of maternal high-fructose intake and if metabolic control in the offspring could benefit from supplementing bioactive food components such as bitter melon (BM) to the maternal diet. In Expt. 1, virgin female rats received control (C), high-fructose (F; 60%), or BM-supplemented fructose (FBM; 1%) diet before conception until d 21 of lactation. Weaned male offspring were fed the C diet for 11 wk, forming C/C, F/C, and FBM/C groups. The F/C group had elevated serum insulin, TG, and FFA concentrations and hepatic lipid alterations compared with the C/C and FBM/C groups (P < 0.05). The 2 latter groups did not differ. Expt. 2 had similar dam treatment groups, but offspring were weaned to the C or F diet, forming C/C, C/F, F/F, and FBM/F groups, and the dietary treatment was extended to 20 wk. The hepatic levels of stearyl-CoA desaturase and microsomal TG transfer protein mRNA were lower, but that of PPARγ coactivator 1-α and fibroblast growth factor 21 mRNA and fatty acid binding protein 1 protein were higher in the FBM/F group compared with the C/F and F/F groups (P < 0.05), indicating that maternal BM supplementation may reduce lipogenesis and promote lipid oxidation in offspring. The FBM/F group had significantly higher activities of liver glutathione peroxidase, superoxide dismutase, and catalase than the F/F group. The results indicate that supplementing BM to dams could offset the adverse effects of maternal high-fructose intake on lipid metabolism and antioxidant status in adult offspring.     

A low-protein,high-carbohydrate diet increases de novo fatty acid synthesis from glycerol and glycerokinase content in the liver of growing rats

We had previously shown that adipose tissue increased in rats fed a low-protein, high-carbohydrate (LPHC) diet (6% protein, 74% carbohydrate) without a simultaneous increase in the de novo fatty acids (FA) synthesis. In addition, impairment in insulin signaling in adipose tissues was observed in these rats. For this study, we hypothesized that the insulin signaling pathway is preserved in the livers from these rats, which contributes to an increase in liver lipogenesis and, consequently, an increase in the weight of the adipose tissue. We also hypothesized that glycerol from triacylglycerol is an important substrate for FA synthesis. Our results showed that administration of the LPHC diet induced an increase in the in vivo rate of total FA synthesis (150%) as well as FA synthesis from glucose (270%) in the liver. There were also increased rates of [U-¹⁴C]glycerol incorporation into glyceride-FA (15-fold), accompanied by increased glycerokinase content (30%) compared with livers of rats fed the control diet. The LPHC diet did not change the glycerol-3-phosphate generation from either glucose or glyceroneogenesis. There was an increase in the insulin sensitivity in liver from LPHC-fed rats, as evidenced by increases in IR_β (35%) levels and serine/threonine protein kinase (AKT) levels (75%), and basal (95%) and insulin-stimulated AKT phosphorylation (105%) levels. The LPHC diet also induced an increase in the liver sterol regulatory element-binding protein–1c content (50%). In summary, these data confirmed the hypothesis that lipogenesis and insulin signaling are increased in the livers of LPHC-fed rats and that glycerol is important not only for FA esterification but also for FA synthesis.     

Suboptimal intake of magnesium in rats. Effects during growth and gestation

To investigate the interaction of magnesium depletion and source of protein and the effect of this interaction on growth, female weanling Sprague-Dawley rats were fed diets based on 20% casein or 20% soy protein isolate which contained eithe adequate (800 mg/kg) or suboptimal (200 mg/kg) levels of magnesium. The initial suboptimal level of approximately 100 mg/kg magnesium was increased to approximately 200 mg/kg magnesium on day 6 of the study. The nutritional stress of rapid growth resulted in clinical signs of deficiency including audiogenic seizures in the animals fed the casein diet which was low in magnesium. Some clinical manifestations of deficiency persisted through almost all of the 6-week growth period. The lower nutritional quality of soy protein isolate and/or the components of soy which depress mineral bioavailability resulted in a higher rate of alopecia and skin sores in the rats fed the soy low magnesium diet than in those fed the casein low magnesium one. Growth retardation in the magnesium deficient animals occurred during the post-weaning growth phase. Gestational weight gain was also depressed by low magnesium intake to a greater extent than has been previously reported in response to a mild magnesium restriction. Because of recent reports of suboptimal intakes of magnesium by humans, further research of combined effects of subacute magnesium deficiency and utilization of foods containing soy protein is needed.     

Iron status of suckling rats as influenced by maternal diet during gestation and lactation

1. Two experiments are reported. In Expt 1, pregnant Sprague-Dawley rats (200-220 g) were given purified diets containing 35, 75, 150 or 300 mg Fe/kg throughout gestation and lactation. In Expt 2, the levels of Fe given were 250 and 300 mg/kg diet. 2. Litters were standardized at birth to contain seven pups. On day 20 of lactation blood, milk, spleen and liver were collected for Fe analysis. 3. A dietary Fe concentration of 35 mg/kg maintained maximum weight gain, food intake, liver and spleen weight, haemoglobin concentration and packed cell volume in the growing maternal rat through 20 d of lactation. Dam liver and spleen Fe concentrations were maximized between 75 and 250 mg Fe/kg diet. 4. Pups (20-d-old) nursed by dams given 35 mg Fe/kg tended to have lower body and organ weights compared to other groups. Liver and spleen Fe concentrations increased with increasing maternal dietary Fe and were significantly increased between 150 and 250 mg Fe/kg.     

亚慢性镧暴露对大鼠海马氨基酸类神经递质表达影响

目的探讨镧对大鼠神经行为影响及海马组织氨基酸类神经递质释放的改变。方法健康成年雌性Wistar大鼠24只,随机分为对照组及低、中、高剂量染镧组（0.25%、0.50%、1.00% LaCl₃）,仔鼠自母鼠怀孕至断乳后1个月饮用不同剂量氯化镧;穿梭箱实验检测仔鼠神经行为改变,高效液相色谱法检测仔鼠海马中兴奋性氨基酸递质及抑制性氨基酸递质含量。结果与对照组比较,中、高剂量染镧组仔鼠接受电击时间、主动逃避潜伏期时间[分别为（26.00±8.11）、（36.38±5.88）与（6.50±2.45）、（9.38±3.50）s]］均延长,差异有统计学意义（P<0.05）,表现出学习记忆损伤;与对照组比较,中、高剂量染镧组仔鼠海马兴奋性氨基酸递质谷氨酸（Glu）、天冬氨酸（Asp）含量[分别为（8.16±2.16）、（12.05±4.86）与（8.91±3.48）、（12.33±4.57）μmol/gpro]升高,中、高剂量染镧组仔鼠海马抑制性氨基酸递质甘氨酸（Gly）、γ-氨基丁酸（GABA）、牛磺酸（Tau）含量[分别为（9.95±3.41）、（13.25±5.03）、（10.93±3.53）、（14.50±4.90）与（10.10±3.18）、（13.78±5.28）μmol/gpro]升高,差异有统计学意义（P<0.05）;呈剂量效应关系。结论亚慢性镧染毒可导致仔鼠学习记忆能力下降,其机制可能与仔鼠海马组织内兴奋性及抑制性氨基酸神经递质含量升高有关。     

A methyl-deficient diet fed to rat dams during the peri-conception period programs glucose homeostasis in adult male but not female offspring

Methyl deficiencies have been implicated in metabolic programming during the periods of oocyte and embryo development. Semisynthetic methyl-deficient diets (MD) with no folic acid, 0.05% choline, and approximately one-half the recommended content of methionine were fed to female rats for 3 wk prior to mating and for the first 5 d of gestation. During the period of MD feeding, plasma homocysteine concentrations were approximately twice those of rats fed the complete (CON) diet. From d 5, both groups received a complete semipurified AIN diet until birth. On d 8, plasma homocysteine concentrations did not differ between the 2 groups. Thereafter, dams and offspring were fed a nonpurified diet for the remainder of the experiment. At 6 mo of age, the homeostatic model assessment (HOMA) index of the male MD offspring tended to be 32% higher (P = 0.053) and peak insulin during an oral glucose tolerance test (oGTT) was 39% higher (P < 0.05) compared with the male CON offspring. There was no difference in the response to an oGTT in the female offspring at 6 mo of age. The increased HOMA index of male MD offspring persisted to 12 mo of age. The peak glucose concentration during oGTT was 23% higher (P < 0.05) in MD compared with the CON males despite 39% greater (P < 0.05) peak insulin concentrations. This study shows that in rats, a physiologically relevant methyl-deficient diet fed during the period of oocyte maturation and preimplantation development programs gender-specific changes in glucose handling by the offspring.     

A maternal high-fat diet represses the expression of antioxidant defense genes and induces the cellular senescence pathway in the liver of male offspring rats

Maternal high-fat (HF) diet feeding is associated with increased risk of developing metabolism-related diseases in adult offspring, including chronic liver disease. The present study tested the hypothesis that maternal HF diet leads to a decreased antioxidant defense capacity and causes cellular senescence in liver of adult offspring rats, which might increase risk of developing chronic liver disease. Timed-pregnant Sprague Dawley rats were fed a HF diet (45% of energy from fat) or a control (C) diet (16% of energy from fat) during gestation and lactation. The resulting offspring were fed a C diet after weaning to generate 2 offspring groups: C diet-fed offspring of dams fed C diet (C/C) and C diet-fed offspring of dams fed a HF diet (HF/C). At 12 wk of age, male rats were killed and samples were collected for analysis. Maternal HF diet significantly increased plasma TG and hepatic TBARS concentrations and the size of hepatic lipid droplets in offspring rats. The expression of antioxidant defense genes, such as glutathione peroxidase-1, Cu/Zn superoxide dismutase (Sod1), paraoxonase enzymes (Pon1, Pon2, and Pon3), were significantly lower in the liver of HF/C pups than in C/C pups. The expression of Inhibitor of cyclin dependent Kinase 4a (p16INK4a), a marker of cellular senescence, and cyclooxygenase-2 (Cox2), a proinflammatory marker, was significantly higher in the HF/C offspring group than in the C/C offspring group. Western-blot analysis shows that cyclin D1 and phosphorylated retinoblastoma protein were significantly lower in HF/C offspring than in C/C offspring. The results provide the first evidence to our knowledge that maternal HF diet might alter antioxidant defense capacity and program the p16INK4a-dependent cellular senescence in the liver of adult offspring.