Litter Size In Rats Research Articles

Effects of repeated isoflurane exposure during pregnancy on fetoplacental growth and litter size in rats

Effects of repeated isoflurane exposure during pregnancy on fetoplacental growth and litter size in rats

Abstract 10695: Early Overnutrition in Rats Induces Premature Cardiac Alterations Independently of Blood Pressure: Leptin-TRH Pathway Involvement

Animal models are an interesting tool to evaluate future consequences of early nutritional insults. We described in adult mice that: leptin induces cardiac cTRH, leading to cardiac damage regardless of blood pressure in hyperleptinemic Agouti. Conversely, cTRH in the ob/ob lacking leptin is similar to control and even do not have Left Ventricular Hypertrophy (LVH). Moreover, leptin restitution induces cTRH and later LVH. Also, in C57BL/6 a 3-week subanorexigenic leptin dose induced cTRH and sequent LVH. All this suggests that heart damage in obesity depends on the novel leptin-cTRH pathway. Plus, Leptin directly induces TRH in cell culture (Aisicovich 2019, AHA) To further investigate the impact of early dietary interventions in childhood, we studied rat litter size reduction, a model with a reported increase in body weight, fat, leptin, insulin and cholesterol levels (Stefanidis A, 2012) We hypothesize that leptin rise increases cTRH leading to cardiac damage, independently of hypertension. On postnatal day 4, Wistar rat litters of 11 pups at birth were adjusted to 4 male pups (overnourished ON) or 11 (control C). At weaning, we individualized rats with free access to water and standard diet up to 7 weeks old. The rise in body weight, food consumption, and fat in ON vs C (p<0.02 n=10 ANOVA) confirmed the model. There weren’t any blood pressure differences between groups, still LVH index increased (heart weight/tibia length) (p< 0.01 n=6) in ON vs C. As expected, in ON the higher leptin increased cTRH mRNA (p< 0.01 n=6) as protein [WB (p=0.05 n=3) IHQ (p<0.04 n=6)] vs C. According to cTRH actions, hypertrophic and fibrotic markers TGF-B and Collagens 1 and 3 mRNA increased (p<0.01, n=6) confirmed by IHQ and Sirius red staining (p< 0.01 n=6) Also, echocardiogram showed increases in LV end-diastolic (0.26±0.08 vs 0.61±0.07 ml p <0.01) and end-systolic (0.02±0.02 vs 0.11±0.01 ml p <0.01) volumes, and decreases in LV ejection fraction (94.5±2.2 vs 83.3±1.9 % p <0.01) and SF (54.4±2.6 vs 45.0±2.3 % p <0.02) This could be restored by cTRH inhibition as demonstrated in the cardiac infarct model (Schuman ML, 2021) Our results point out that early overnutrition induces evident cardiac damage already at 7 weeks, independently of blood pressure and mostly driven by the leptin-TRH pathway.

Potent effect of KISS1-54 DNA vaccine compared with KISS1-10 DNA vaccine in inhibiting the fertility of female rats

BackgroundMost studies on immunocastration currently focused on male animals. However, immunization of male animals does not completely inhibit sexual behavior and fertility. This study aimed to compare the immunocastration effect of KISS1 DNA vaccines encoding different lengths of kisspeptins in female rats for effective castration effects on both male and female rats. MethodsFifteen female rats were randomly divided into three groups. The rats in T1 group or T2 group was orally given respectively KISS1-54 or KISS1-10 DNA vaccines with fused tPA signal peptide, and the control group (Group C) was orally administered with empty vector vaccine, at a dose of 5 × 109 CFU/rat at weeks 0, 3 and 6 of the study. Blood samples were collected by retroorbital bleeding before primary immunization and at weeks 3 and 9 after primary immunization. ResultsBoth KISS1-54 and KISS1-10 DNA vaccines induced the body’s humoral immune response, and the anti-kisspeptin antibody titres in the T1 group were significantly higher than that in T2 and C groups (p < 0.05). The rats in T1 group has lower serum kisspeptin and estradiol levels than those in T2 and C groups and smaller litter size of rats than those in the control group after mating (p < 0.05). No significant difference was observed between T2 and C groups. The levels of KISS1 and GPR54 mRNA in the hypothalamus and ovaries of the T1 group were significantly lower than that in control group. However, the levels of KISS1 mRNA in the T2 group were significantly lower than that in the control group only in ovaries (p < 0.05). ConclusionThe oral KISS1-54 DNA vaccine with fused tPA signal peptide was more effective than that KISS1-10 DNA vaccine in suppressing fertility of female rats.

Human mesenchymal stem cells in spheroids improve fertility in model animals with damaged endometrium

BackgroundAsherman’s syndrome (AS) is one of the gynecological disorders caused by the destruction of the endometrium. For some cases of AS available surgical methods and hormonal therapy are ineffective. Stem cell transplantation may offer a potential alternative for AS cure.MethodsHuman endometrial mesenchymal stem cells (eMSC) organized in spheroids were transplanted in rats with damaged endometrium modeled on AS. Treatment response was defined as pregnancy outcome and litter size.ResultsApplication of eMSC in spheroids significantly improved the rat fertility with the AS model. eMSC organized in spheroids retain all properties of eMSC in monolayer: growth characteristics, expression of CD markers, and differentiation potential. Synthesis of angiogenic and anti-inflammatory factors drastically increased in eMSC assembled into spheroids.ConclusionsHuman endometrial mesenchymal stem cells (eMSC) can be successfully applied for Asherman’s syndrome (AS) treatment in the rat model. eMSC organized in spheroids were more therapeutically effective than the cells in monolayer. After transplantation of eMSC in spheroids the pregnancy outcome and litter size in rats with AS was higher than in rats that received autologous rat bone marrow cells. It suggests the therapeutic plausibility of heterologous eMSC in case of failure to use autologous cells.

Pemberian Ekstrak Etanol Purwoceng pada Masa Pascaplasentasi Meningkatkan Kinerja Reproduksi Tikus Bunting (SUPPLEMENTATION ETHANOLIC EXTRACT OF PIMPINELLA ALPINA AT POSTPLASENTATION ON PREGNANT RAT IMPROVE REPRODUCTIVE PERFORMANCE)

The study was carried out to observe the effect of ethanolic extract of estrogenic purwoceng given 13-21 days age of pregnancy on reproductive performance such as the weight of ovarium, uterus, placenta, andpups, correlation ratio of corpus luteum number, implantation site number, and litter size in rats. Thepregnant rats were divided in to two groups. One groups cosisted of rats treated with purwoceng (83.33 mg/kg body weight) and the other groups was used as control (no treatment). The ovary, uterus, placenta, andpups were collected and weighed on day 21 of pregnancy. The result showed that the rats given 83,33 mg/kg BW ethanol extract of purwoceng tended to increase the weight of ovarium, uterus, and pups but it didnot increase the weight of plasenta. Number of site of implantation, ratio of implantation site to numberof corpus luteum, and ratio of number of pups to implantation site were higher on rat given 83,33 mg/kgBW ethanol extract of purwoceng. Conclusion of this study is ethanol extract of Pimpinella alpina rootsgiven at postplasentation improve reproductive performance.

Litter size, age-related memory impairments, and microglial changes in rat dentate gyrus: Stereological analysis and three dimensional morphometry

It has been demonstrated that rat litter size affects the immune cell response, but it is not known whether the long-term effects aggravate age-related memory impairments or microglial-associated changes. To that end, we raised sedentary Wistar rats that were first suckled in small or large litters (6 or 12pups/dam, respectively), then separated into groups of 2–3 rats from the 21st post-natal day to study end. At 4months (young adult) or 23months (aged), all individual rats were submitted to spatial memory and object identity recognition tests, and then sacrificed. Brain sections were immunolabeled with anti-IBA-1 antibodies to selectively identify microglia/macrophages. Microglial morphological changes in the molecular layer of the dentate gyrus were estimated based on three-dimensional reconstructions. The cell number and laminar distribution in the dentate gyrus was estimated with the stereological optical fractionator method. We found that, compared to young rat groups, aged rats from large litters showed significant increases in the number of microglia in all layers of the dentate gyrus. Compared to the microglia in all other groups, microglia in aged individuals from large litters showed a significantly higher degree of tree volume expansion, branch base diameter thickening, and cell soma enlargement. These morphological changes were correlated with an increase in the number of microglia in the molecular layer. Young adult individuals from small litters exhibited preserved intact object identity recognition memory and all other groups showed reduced performance in both spatial and object identity recognition tasks. We found that, in large litters, brain development was, on average, associated with permanent changes in the innate immune system in the brain, with a significant impact on the microglial homeostasis of aged rats.

The effects of high level ascorbic acid on pregnancy rate and litter size in rats

The effects of high dose ascorbic acid on pregnancy rate and litter size in rats were investigated in this study. For this purpose, forty rats were used. The animals were randomly divided into four groups as control (n = 10) and treatment (n = 30). The rats were randomly assigned to three groups in treatment group. Within this group, 15 females and 15 males were used. Females in Groups 1 and 3, and males in Groups 1 and 2 were administered 1.5 g/kg body weight vitamin C high dose ascorbic acid orally, in drinking water, freshly prepared daily for 15 days. The results showed that the use of high dose ascorbic acid in male groups (1 and 2) caused an insignificant increment on pregnancy rate and litter size when compared to the control groups and Group 3. Thus, the use of high dose ascorbic acid may reduce fertilizing capability of sperm. On account of this, pregnancy rate may be falling away. Key words: Rat, ascorbic acid, pregnancy rate, litter size.

Influence of litter size on the postnatal growth of rat pups: Is there a rationale for litter-size standardization in toxicity studies?

The standardization of rodent litter sizes (or culling) in reproductive toxicity studies has become a common practice because it is believed that litter size affects pup postnatal growth and development. A claim has also been made that culling on postnatal day 4 or earlier reduces litter-size-induced variability in the pup growth thereby making statistical detection of toxic effects more sensitive. Although these statements remain controversial, culling has been either recommended or considered optional in current proposals for new OECD guidelines for reproductive/developmental toxicity testing. This study was undertaken to provide data useful for a discussion on the need for culling in reproductive toxicity testing. Along this line, we investigated the effects of rat litter size on maternal body weight gain during pregnancy and lactation as well as on pup growth, somatic maturation and survival to weaning (PND 21). Two-hundred-forty-one untreated pregnant rats (Wistar, Bor:spf, TOR) delivered litters with 1-13 pups, being 10 the most frequent (24%) litter size. Pup mortality was 5.4%, 3.0% and 0.4% in the first, second and third postnatal weeks, respectively. Maternal and pup body weight gains, and the day of appearance of milestones of somatic maturation (fur development, incisor eruption and eye opening) were examined in a subset of litters/mothers (N=180) in which all pups survived to PND 21. An inverse relationship between litter size and pup body weight was found on day of birth (PND 1) and thereafter until PND 21. Delays in the attainment of maturational milestones as litter size increases were also found. These observations indicated that the rate of growth and development of rat pups during suckling period is dependent on the litter size. The consequences of litter-size standardization in toxicity studies are discussed in the light of these findings. Alternative procedures to attenuating litter-size-induced variability in pup growth or its impact on toxicity data evaluation are presented as well.

Manipulation of rat litter size during suckling influences cortical spreading depression after weaning and at adulthood

Nutritional conditions early in life constitute one environmental factor that can influence brain electrophysiological features. Cortical spreading depression (SD) is a brain electrophysiological phenomenon that can be altered by the early nutritional status of organism. SD-velocity changes were presently studied in young (30–40 days old) and adult (90–120 days) rats suckled in litters formed by 3, 6, or 12 pups (called respectively small (S), medium (M) and large (L) litters). Body weights and SD propagation velocities in the 3 groups varied, respectively in an inverse and direct way, in relation to the litter sizes. The present investigation provides the first systematic description of the effectiveness of favorable and unfavorable lactation conditions (respectively suckling in Sand L litters) in altering cortical SD-propagation. The results confirm previous evidence in favor of permanent or at least long-lasting SD-changes associated to the prevailing nutritional status during the period of fast brain development.

Energy metabolism of young rats after early postnatal overnutrition.

Early postnatal overnutrition (PNO) induced by restricting litter size in rats leads to increased body-weight (BW) and body-fat gain in later life. PNO rats are used as an animal model of moderate obesity and early hyperinsulinism. We investigated whether the increased adiposity could be due to a decreased energy expenditure. Male newborn Wistar rats were raised in litters of either two (SL) or twelve pups (NL), weaned at 4 weeks of age and subsequently fed ad libitum. BW was recorded continuously until 12 weeks of age. Daily energy intake, total daily energy expenditure (EE, measured by indirect calorimetry) and body composition were measured in weaned pups at 5, 8 and 12 weeks of age. SL rats displayed increased BW compared with NL rats from week 2 to 5 and again from week 10 to 12. Lean body mass, body fat and protein content and total EE were increased in SL rats at week 5. The same linear correlation described the relationship between BW and total EE in NL and SL rats. At week 8 to 12 no differences in energy metabolism could be found, but the total fat content was increased in SL rats at week 12. Energy balance, i.e. assimilated energy minus EE, was no different between SL and NL at any time that it was measured. We conclude that although PNO rats display increased adiposity in early life, there seem to be no long-lasting effects on energy metabolism in later life, even if a tendency to increased adiposity can still be detected.

Relationship between fetal weight and litter size in rats: Application to reproductive toxicology studies

The inverse relationship between mammalian fetal weight and litter size has been discussed by many authors, but their opinions reveal no agreement at all. As in toxicity studies of reproduction, both parameters must be correctly evaluated. We investigated the existence of such a relationship in 2466 fetuses from 203 litters of Sprague-Dawley CD control rats. The frequency distribution of fetal weights had a normal adjustment. From the mean weight of fetuses in each litter, the mean fetal weights in each litter size and correlation coefficent were calculated and the regression line was plotted; the correlation coefficient ( r = −0.677) was highly significant ( P = 0.002), which made evident that there was an inverse relationship between fetal weight and litter size. If fetal weight/litter size inverse relationship is not taken into account when toxicity on the fetal weight is analyzed, wrong conclusions may be reached if the test substance reduces the litter size, provoking embryofoetal mortality. The iatrogenic decrement in fetal weight can be masked by an increment due to the litter size reduction. We suggest that in all three segments of reproductive toxicity studies, litter size must be considered as a covariate to the effect of the test substance on the fetal weight, in order to perform a correct analysis of covariance (ANCOVA), in addition to the dose factor commonly used in common ANOVA.

Postnatal undernutrition slows development of bronchiolar epithelium in rats.

The lung's small conducting airways are sites of dysfunction early in the course of chronic lung diseases that are prevalent in humans; furthermore, there is evidence that aspects of childhood environment may adversely influence small airway function in adulthood. Because there is considerable early postnatal morphological maturation of the bronchiolar epithelium in rats, these considerations led to the present study in which we assessed the effect of early postnatal undernutrition in rats on the anatomic development of the bronchiolar epithelium. We found undernutrition, produced by increasing rat litter size shortly after birth, led to delayed development of the mitochondria and rough endoplasmic reticulum of bronchiolar Clara cells. Of particular interest, underfeeding resulted in considerably diminished mitosis by Clara cells, decreased nuclear numerical density of bronchiolar ciliated cells, evidence of diminished conversion of Clara cells to ciliated cells, and an abnormal cellular composition of the small airway epithelium that persisted well beyond the period of underfeeding. We conclude that early neonatal events can have long-term effects on the bronchiolar epithelium.

Does exposure of preovulatory oocytes to ultrasonic radiation affect reproductive performance?

Ultrasonography of preovulatory oocytes has been reported to lead to reduced litter size in rats. Because of the growing popularity of ultrasound-guided follicular aspiration in human in vitro fertilization programs, further study of ultrasonic radiation's effect on the preovulatory oocyte is warranted. We used 106 virgin Sprague-Dawley rats which, on the evening of proestrus, received ultrasonic radiation of sham treatment after the onset of the luteinizing hormone (LH) surge. No differences were found between control (C) and experimental (US) animals in pregnancy rate, number of corpora lutea, implantations, pups, and mean pup and placental weights at autopsy on day 22 of pregnancy. Ultrasonic radiation applied to meiotically active, preovulatory oocytes did not affect the reproductive performance of these rats.

Prenatal alcohol exposure: abnormalities in placental growth and fetal amino acid uptake in the rat.

On day 20 of gestation, after ethanol feeding (27% ethanol calories, 25% protein), placental weights, DNA, RNA and water content were greater than in controls pair-fed an isocaloric diet without ethanol or those ad lib fed a pellet diet of similar composition. Rat litter size and fetal body, liver and brain weights were similar in all groups. In vivo fetal amino acid accumulation was significantly lower after alcohol exposure despite similar placental uptake. These results indicate that both placental hyperplasia and abnormal fetal amino acid uptake occur at a low alcohol dose when fetal body weight is unaffected.

The effect of oxytocin antibodies on the litter size in rats

Oxytocin antibody (OT-AB) was produced to synthetic OT in rabbits and rats by immunizing with OT coupled to bovine serum albumin by glutaraldehyde. The plasma was screened for antibody to OT by the use of OT 1S1I in double antibody and dialysis procedures. The actively immunized rats were bred with normal male rats of proved fertility. Mean litter size was 8.7 ± 1.0 (S.E.) in actively immunized rats as compared to 11.7 ± 0.4 in controls (P 0.025). Length of gestation was virtually identical in both groups, but lactation seemed impaired in the treated group and there were many pups dead. In another experiment the female rats were passively immunized to OT. The mean litter size for the control rats for passively immunized rats was 11.4 ± 1.0 and for the OT-AB injected group 10.8 ± 1.0. The difference between the litter size in the actively immunized rats and the other groups was highly significant (P 0.025). This study emphasizes that (1) OT improves the fertility rate in rats, possibly by an effect on sperm transport and implantation, and (2) OT is necessary for normal lactation. The study also suggests that the neutralization of OT increases the incidence of fetal abnormalities during parturition.

Aspects of oral development in relation to litter size in rats.

Aspects of oral development in relation to litter size in rats.

Effect of litter size upon milk yield and litter weight gains in rats.

SummaryA study is reported concerning the influence of litter size in rats on the estimated milk yields and litter weight gains on days 14 to 20, and on the DNA of the mammary glands on day 20. On day 14 of lactation, the mean milk yield increased from 5.6 g with 2 to 16.4 g with 12 in the litter. The milk yield in most groups increased until the 18th day, then decreased on day 20. The milk available/pup on day 14 was 2.8 g for the 2-pup litters and declined gradually to 1.4 g for the 12-pup litters. The litter weight on day 14 was 68.3 g for litters of 2 and increased gradually to 287.1 g for litters of 12. The gain per pup was greatest for litters of 2 and then declined with increasing litter number. At the 20th day, the DNA for litters of 2 was 8.9 mg/100 g bw and increased gradually with increasing litter size to 13.6 mg for litters of 12. The RNA also increased with increasing litter size up to 10.

Uterine metabolic status during pregnancy and litter size in rats.

Uterine metabolic status during pregnancy and litter size in rats.

Normal pregnancy and litter size in rats injected with fetal placentas.

No reduction in the number of rats with pregnancies nor in the number of fetuses per pregnancy could be demonstrated when groups of Sprague-Dawley females were injected with placental tissue in various forms and then mated to Long-Evans males. The placental preparations were either: (1) homogenates of fetal placentas removed from Long-Evans rats; (2) whole cells of fetal placentas derived from the same Long-Evans male with which the injected female was mated; or (3) cells of fetal placenta (derived from the same Long-Evans male with which the injected female was mated) homogenized with Freund's adjuvant.

Action of adrenocorticotropin on pregnancy and litter size in rats.

Previously it was reported that adrenocorticotropin (ACTH) displayed the ability to restrict the action of estradiol-17ß in uterine growth and of progesterone in decidual development. This study concerns the influence of a highly purified and potent preparation of ACTH on pregnancy and litter size in albino rats of known reproductive vigor. Experimental procedures consisted of injecting ACTH prior to, immediately after mating and 11 days after mating. These data indicate that ACTH has the ability to reduce litter size and produce a large number of stillbirths. The most marked effects were observed when ACTH was injected on the day of mating and for 6 subsequent days. Normally, the litter size of nontreated controls is 9.6 ± 0.5. The daily injection of 2.0 and 4.0 mg ACTH daily for 7 days after mating effected reduced litters, 5.0 ± 1.7 and 3.9 ± 1.5, respectively. Furthermore, such treatment produced 27 stillborns on the 2.0-mg dosage and 39 on the 4.0-mg treatment. ACTH administered to adrenalectomized rats neither modified pregnancy nor litter size. ACTH given to intact rats effected a decrease in the fetal body weights. Such was not observed in the adrenalectomized groups nor in the ACTH-treated, adrenalectomized series. These data strongly indicate that the effects observed are mediated by way of the adrenal glands, and additional evidence is offered supporting the contention that there are numerous interactions among hormones of adrenal cortex and the ovaries.