Postnatal Growth Of Rat Research Articles

Localization of DLL1- and NICD-positive osteoblasts in cortical bone during postnatal growth in rats

The long bone midshaft expands by forming primary osteons at the periosteal surface of cortical bone in humans and rodents. Osteoblastic bone formation in the vascular cavity in the center of primary osteons is delayed during cortical bone development. The mechanisms of the formation of primary osteons is not fully understood, however. Focusing on NOTCH1 signaling, an inhibitory signaling on osteoblastic bone formation, our immunohistochemical analysis revealed Delta like1 (DLL1), a ligand of NOTCH1, and the NOTCH1 intracellular domain (NICD, an activated form of NOTCH1) immunoreactivity, in the cuboidal osteoblasts lining the bone surface in the vascular cavity of primary osteons during postnatal growth in rats. Interestingly, five days after treatment of primary osteoblasts with ascorbic acid and β glycerophosphate, protein levels of both DLL1 and NICD increased transiently, indicating that DLL1 activates NOTCH1 in primary cultured osteoblasts. Thus, the results imply that DLL1-NOTCH1 signaling in osteoblasts is associated with primary osteonal bone formation.

Effect of <i>in utero</i> exposure to <i>n</i>-hexane extract of <i>Ricinus communis</i> var. minor (RICOM 1013J) on postnatal foetal weight changes in Sprague-Dawley albino rats

In traditional medicine practice among the Bassa people of central Nigeria, the seeds of Ricinus communis (Var. minor) are widely used as anticonceptive agents. This study purposes to evaluate the effect of fetal in-utero exposure to extract of Ricinus communis (var. minor) on postnatal growth in rats. Eighteen (18) adult female rats in proestrous phase of the estrous cycle were divided into 3 groups and allowed to mate with males of proven fertility using a male: female ratio 1:3. Group 1 rats were injected subcutaneously on day 2 of pregnancy with 0.2ml of olive oil and served as control, while group 2 animals received 20mg/kg of the extract on day 2 of conception. The rats in group 3 were similarly administered 20mg/kg of the extract subcutaneously on days 2 and 5 of pregnancy. At birth, body weights of pups were taken on days 0, 7, 14 and 28. The results showed that in utero exposure to Ricinus communis var. minor (RICOM-1013-J) significantly decreased postpartum birth weight (p < 0.05) in the first week of life only, while Days 14 and 28 were normal compared to control. The study showed that in utero exposure to therapeutic doses of Ricinus communis var. minor do not have may have no adverse or deleterious effects on foetal development and postpartum growth in rats.Keywords: Ricinus communis; In-utero; n-Hexane; Postnatal; Foetal; Weight changes

Dietary supplementation with bovine-derived milk fat globule membrane lipids promotes neuromuscular development in growing rats

BackgroundThe milk fat globule membrane (MFGM) is primarily composed of polar phospho- and sphingolipids, which have established biological effects on neuroplasticity. The present study aimed to investigate the effect of dietary MFGM supplementation on the neuromuscular system during post-natal development.MethodsGrowing rats received dietary supplementation with bovine-derived MFGM mixtures consisting of complex milk lipids (CML), beta serum concentrate (BSC) or a complex milk lipid concentrate (CMLc) (which lacks MFGM proteins) from post-natal day 10 to day 70.ResultsSupplementation with MFGM mixtures enriched in polar lipids (BSC and CMLc, but not CML) increased the plasma phosphatidylcholine (PC) concentration, with no effect on plasma phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylserine (PS) or sphingomyelin (SM). In contrast, muscle PC was reduced in rats receiving supplementation with both BSC and CMLc, whereas muscle PI, PE, PS and SM remained unchanged. Rats receiving BSC and CMLc (but not CML) displayed a slow-to-fast muscle fibre type profile shift (MyHCI → MyHCIIa) that was associated with elevated expression of genes involved in myogenic differentiation (myogenic regulatory factors) and relatively fast fibre type specialisation (Myh2 and Nfatc4). Expression of neuromuscular development genes, including nerve cell markers, components of the synaptogenic agrin–LRP4 pathway and acetylcholine receptor subunits, was also increased in muscle of rats supplemented with BSC and CMLc (but not CML).ConclusionsThese findings demonstrate that dietary supplementation with bovine-derived MFGM mixtures enriched in polar lipids can promote neuromuscular development during post-natal growth in rats, leading to shifts in adult muscle phenotype.

An intrauterine catch-up growth regimen increases food intake and post-natal growth in rats

Nutritional conditions during the intrauterine stage are an important developmental programming factor that can affect the growth and metabolic status during foetal development and permanently alter the phenotypes of newborn offspring and adults. This study was performed to examine the effects of intrauterine catch-up growth (IUCG) on food intake, post-natal body growth and the metabolic status of offspring and growing rats. Control pregnant rats were fed ad libitum during the entire gestation period. For the IUCG regimen, pregnant rats were fed 50% of the food of the controls from pregnancy days 4 through 11 (8 days), followed by ad libitum feeding from pregnancy days 12 through parturition. The birth weight of offspring was not affected by the IUCG regimen. At weaning, offspring from each treatment group were assigned to two groups and given either a normal diet or high-fat diet (HFD) for 12 weeks until 103 days of age. In the normal diet group, the IUCG offspring showed a 9.0% increase (P < 0.05) in total food intake, were 11.2% heavier (p < 0.05) at 103 days of age and had an 11.0% greater (p < 0.05) daily weight gain compared with control offspring. The IUCG regimen did not affect body glucose and lipid metabolism. After exposure to the HFD, the IUCG regimen has not exacerbated metabolic disorders. In conclusion, our findings suggest that the IUCG nutritional regimen during pregnancy can increase the food intake and post-natal body growth of offspring without inducing metabolic disorders such as obesity and insulin resistance. The IUCG nutritional regimen might be used to improve the food intake and post-natal body growth of domestic animals.

Moderate zinc restriction during fetal and postnatal growth of rats: effects on adult arterial blood pressure and kidney

Intrauterine and postnatal zinc restriction may result in an adverse environment for the development of cardiovascular and renal systems. This study evaluated the effects of moderate zinc deficiency during fetal life, lactation, and/or postweaning growth on systolic blood pressure, renal function, and morphology in adult life. Female Wistar rats received low (8 ppm) or control (30 ppm) zinc diets from the beginning of pregnancy up to weaning. After weaning, male offspring of each group of mothers were fed low or control zinc diet. Systolic blood pressure, creatinine clearance, proteinuria, renal morphology, renal apoptosis. and renal oxidative stress state were evaluated after 60 days. Zinc deficiency during pre- and postweaning growth induced an increase in systolic blood pressure and a decrease in the glomerular filtration rate associated with a reduction in the number and size of nephrons. Activation of renal apoptosis, reduction in catalase activity, glutathione peroxidase activity, and glutathione levels and increase in lipid peroxidation end products could explain these morphometric changes. Zinc deficiency through pre- and postweaning growth induced more pronounced renal alteration than postweaning zinc deficiency. These animals showed signs of renal fibrosis, proteinuria, increased renal apoptosis, and higher lipid peroxidation end products. A control diet during postweaning growth did not totally overcome renal oxidative stress damage, apoptosis, and fibrosis induced by zinc deficiency before weaning. In conclusion, zinc deficiency during a critical period of renal development and maturation could induce functional and morphological alterations that result in elevated blood pressure and renal dysfunction in adult life.

Multigeneration reproductive toxicity assessment of 60-Hz magnetic fields using a continuous breeding protocol in rats.

Male and female reproductive functions have been proposed as possibly sensitive targets for the biological effects of 60-Hz (power frequency) magnetic fields (MF). However, experimental data relevant to this hypothesized association are very limited. In the present study, the "reproductive assessment by continuous breeding" design was used to identify possible effects of MF exposure on reproductive performance, fetal development, and early postnatal growth in rats. Groups of age-matched Sprague-Dawley rats (40 breeding pairs/group) were exposed continuously (18.5 hr per day) to linearly polarized, transient-free 60-Hz MF at field strengths of 0 Gauss (G; sham control), 0.02 G, 2.0 G, or 10.0 G. An additional group of 40 breeding pairs received intermittent (1 hr on/1 hr off) exposure to 10.0 G fields. F0 breeding pairs were exposed to MF or sham fields for 1 week prior to mating, during a 14-week period of cohabitation, and during a 3-week holding period after cohabitation. The duration of the cohabitation period was selected to be sufficient for the delivery of five litters in the sham control group. Pups from the final F1 litter from each breeding pair were exposed to MF or sham fields until sexual maturity, were cohabitated in MF or sham fields for 7 days with nonsiblings from the same exposure group, and were held in the MF or sham fields for 22 days to permit delivery of F2 pups for evaluation. No evidence of exposure-related toxicity was identified in any rat in the F0, F1, or F2 generations. Fetal viability and body weights in all litters of groups exposed to MF were comparable to those of sham controls. No significant differences between sham controls and MF-exposed groups were seen in any measure of reproductive performance (litters/breeding pair, percent fertile pairs, latency to parturition, litter size, or sex ratio) in either the F0 or F1 generation. Exposure of Sprague-Dawley rats to 60-Hz MF strengths of up to 10.0 G either during their peak reproductive period (F0) or during gestation and throughout their life span (F1) has no biologically significant effects on reproductive performance. These results do not support the hypothesis that exposure to pure, linearly polarized 60-Hz MF is a significant reproductive or developmental toxicant.

Melanocortins and opioids modulate early postnatal growth in rats

This study was undertaken to investigate the effects of melanocortins and opioids on rat early postnatal body and organ growth. Among melanocortins tested desacetyl-α-melanocyte-stimulating hormone (α-MSH) at dosages of 0.3 and 3 μg/g/day was effective in stimulating neonatal growth with a weight gain of 7 and 5.6%, respectively, after 2 weeks of treatment. Likewise, a weight rise of 4.2 and 3% was obtained with 3 μg/g/day of both α-MSH and Nle 4- d-Phe 7 α-MSH. As far as opioids were concerned, while N-acetyl-β-endorphin (β-End) was ineffective, the activity of β-End was dependent on dosage. Indeed, newborns treated with 0.03 μg/g/day showed a slight, but significant, increase in weight, whereas a marked decrease in growth followed treatment with 0.3 and, mainly, 3 μg/g/day, with a final weight loss of 3.4 and 5.5%, respectively. All melanocortins exerted a positive action on muscular and brain trophism and, in addition, desacetyl-α-MSH also induced a rise of fat deposits. On the contrary, while the 0.03 μg/g/day β-End dose caused an increase in muscular and brain weight, the higher dosages of the opioid were detrimental, not only for muscle and brain, but also for both liver and spleen weight. A slight, although significant ( P < 0.05), enhancement of serum dehydroepiandrosterone sulfate (DHEAS) level was found after the injection of 0.3 μg/g desacetyl-α-MSH, whereas both the 0.3 and 3 μg/g doses of desacetyl-α-MSH and the 3 μg/g dose of α-MSH determined the rise of plasma androstenedione ( P < 0.05). All tested melanocortins and opioids failed to modify the concentrations of corticosterone. Our results suggest that melanocortins and opioids can modulate early postnatal growth in rats either by direct or indirect mechanisms.

Alteration of maternal growth hormone levels during pregnancy influences both fetal and postnatal growth in rats.

To study the effects of exogenous growth hormone (GH) administration to the mother on fetal growth, dwarf rats with an isolated GH deficiency were given daily s.c. injections of GH throughout pregnancy. Fetuses were heavier in GH-treated mothers (p < 0.001), and pups from GH-treated mothers continued to grow faster (p < 0.001) than pups from control mothers throughout the postnatal growth period through to weaning. In normal Wistar rats, administration of a potent antiserum to somatostatin to pregnant rats increased the mean birth weight of the offspring (p < 0.01). Administration of GH to the mothers also significantly increased birth weight (p < 0.05), but administration of antiserum to rat GH resulted in a significant retardation of both fetal and placental growth (p < 0.001). These data suggest that maternal GH status is significantly involved in the growth of the fetal rat.

Postnatal growth in rats prenatally exposed to cigarette smoke or carbon monoxide

Postnatal growth in rats prenatally exposed to cigarette smoke or carbon monoxide

Dietary alpha-linolenic acid deficiency in the rat. I. Effects on reproduction and postnatal growth.

The effects of a dietary alpha-linolenic acid (18 : 3 n-3) deficiency on reproduction and postnatal growth in rats were studied during 3 successive gestations and 4 successive generations. Female rats received respectively a semi-synthetic diet in which the lipids were incorporated either as sunflower oil at 1.5% (deficient diet) or as soya oil at 1.87% (control diet). Both diets supplied the same amount of linoleic acid (18 : 2 n-6) (940 mg/100 g of diet), but the sunflower oil supplied 22 times less alpha-linolenic acid than the soya diet (6 mg vs 130 mg/100 g of diet). The results showed that, in our experimental conditions, the alpha-linolenic acid deficiency had no effect on fecundity (% of pregnant females), fertility (number of pups/litter), pup birth weight, food intake and weight of pregnant or lactating females, or pup growth during suckling. However, this deficiency did cause abnormally high rates of perinatal mortality from birth to postpartum day 3, namely on the average, for successive gestations: 18.5% in deficient pups vs 5.2% in the controls, and for successive generations: 16.6% in deficient pups vs 5.3% in the controls. Rat n-3 PUFA requirement during reproduction has been discussed; it appears to be more than 100 mg/100 g of feed. But this need should also be estimated in relation to n-6 PUFA supply; for female rats during reproduction, the ratio n-6: n-3 should be less than 10.

Embryonic and postnatal growth of rat and mouse

(1) The investigation yielded several general growth principles, i.e., types of growth occurring rather frequently: (a) allometric growth, (b) a non-changing growth rate, persisting when the growth rate changes in the majority of tissues, (c) a growth rate equal to that of the whole embryo, (d) absence of growth and (e) jumps, i.e., changes in the volume or surface of organs completed within about half a day or less and probably due to changes in the cell volume or surface area; these histological changes tend to start simultaneously with the changes in growth rate. (2) Growth constants tend to have a value of about 2.0 in the prenatal period, as in the post-natal period. During development, however, their value increases slightly but significantly. (3) Further arguments are given for the mitosis-regulating model described in Part III. (4) The mitosis-regulating model combined with the general growth principles derived here and in earlier parts of this report constitute a comprehensive model for the genetiv regulation of the growth process.

Embryonic and postnatal growth of rat and mouse

(1) Data on the embryonic growth of several organs and of many different types of tissue in the mouse and rat are presented. (2) The concept developmental age is introduced, because it leads to an age estimate that is better correlated with the developmental stage. (3) The general growth pattern of the organs and tissues studied agrees with that found for the whole animal, consisting of phases with exponential growth separated by breaks. In the majority of the organs the breaks occur at the same time as in the whole animal. (4) The decrease in the growth rate at the end of phase EII is definitely smaller in the majority of the organs than in the whole animal. (5) Breaks occurring at other times than those found in the whole animal seem to take place in a few organs, and in the mouse at the embryonic age of about 17 days in a large number of organs.

Effect of extirpation of the cervical sympathetic ganglia on postnatal growth of rats

Bilateral extirpation of the superior cervial sympathetic ganglia during the first months of life in young rats caused retardation in growth by 40–60%. Division of preganglionic sympathetic fibers and mock operations produced no significant changes. Normal growth and development of the skeleton were disturbed in the ganglionectomized rats: the zone of growth of the proximal end of the tibia in the ganglionectomized animals was much narrower than in the intact controls and delay in the spread of secondary centers of ossification was observed.

The embryonic and postnatal growth of rat and mouse

The embryonic and postnatal growth of rat and mouse

The embryonic and postnatal growth of rat and mouse

The embryonic and postnatal growth of rat and mouse

The embryonic and postnatal growth of rat and mouse

The embryonic and postnatal growth of rat and mouse