Undernourished Female Rats Research Articles

Exposure to increased levels of estradiol during development can have long-term effects on the response to undernutrition in female rats

Objectives: Undernutrition during development alters the expression of peptides that control energy expenditure and feeding behavior. Estrogens can also modulate these peptides. Here, we analyze whether the early postnatal administration of estradiol modulates the effects of undernutrition on neuroendocrine parameters in adult female Wistar rats. Methods: Control rats were fed a control diet. Undernourished pups were submitted to a restricted diet with half of the undernourished rats receiving 0.4 mg/kg s.c. of estradiol benzoate (EB) from postnatal day (P) 6 until P13. Quantitative real-time polymerase chain reaction was performed to determine expression in the hypothalamus of agouti-related peptide (AgRP), proopiomelanocortin (POMC), neuropeptide Y (NPY), and cocaine- and amphetamine-regulated transcript. Plasma estradiol, testosterone, and adiponectin levels were measured by enzyme-linked immunosorbent assay. Total and acylated ghrelin levels were measured in plasma by radioimmunoassay. Insulin and leptin were measured by mulitplex immunoassays. Results: Undernourishment decreased body weight, fat mass, plasma leptin and insulin levels, and hypothalamic POMC mRNA levels. An increase in orexigenic signals AgRP and NPY mRNA levels, and in plasma adiponectin levels were found in undernourished animals. Early postnatal treatment with EB to undernourished female rats reversed the effects of undernutrition on adult hypothalamic POMC mRNA levels. In addition, neonatal EB treatment to undernourished females significantly decreased adult plasma testosterone, estradiol, and acylated ghrelin levels. Discussion: Our results suggest that increased estradiol during a critical period of development has the capacity to modulate the alterations that undernutrition produces on energy metabolism.

Effects provoked by chronic undernourishment on the fibre type composition and contractility of fast muscles in male and female developing rats.

In this study, we compare the effects of pre- and post-natal food deprivation on the relative proportion of fibre types and contractile responses in the extensor digitorum longus (EDL) muscle of female and male rats at different post-natal ages. EDL muscles from undernourished male (UM) rats showed a higher proportion of Type IIB than IIA fibres and larger normalized twitch responses (with respect to muscle weight) than those of controls (CM). In contrast, EDL muscles from control (CF) and undernourished female rats (UF) showed no significant differences in their fibre type composition and normalized twitch forces at most of the ages analysed. Our data are indicative that the EDL muscles from undernourished males are more susceptible to the effects exerted by low food income than the EDL muscles from female rats. It is proposed that changes in the reactive oxygen species (ROS) concentration and hormonal factors, due to undernutrition, are involved in the alterations observed in the fibre type composition and force production of EDL muscles in undernourished male rats and that estrogens may have an antioxidant protective role on the undernourished EDL muscles in female rats.

Pre-pubertal serum leptin levels and sensitivity to central leptin injection of prenatally undernourished female rats

It has been reported that intrauterine undernutrition is closely associated with the pathogeneses of certain diseases in adulthood; i.e., insulin resistance and diabetes, and that leptin resistance plays a pivotal role in the pathology of such intrauterine growth restriction (IUGR)-related conditions. Therefore, examinations of IUGR-induced leptin resistance in early developmental period are important for protecting against future disease. In this study, the effects of prenatal undernutrition on the serum leptin levels and central leptin responses of rats during the neonatal and/or pre-pubertal period were examined. The 50% food-restricted undernourished dams’ offspring (UNO) exhibited a significantly lower birth weight than the normal nutrition dams’ offspring (NNO). However, the UNO grew rapidly, and their mean body weight had caught up with that of the NNO by postnatal day 8. Thus, there were no significant differences between the body weights of the two groups at postnatal day 12, 16, 20, or 28. The serum leptin levels of the UNO were significantly higher than those of the NNO at postnatal days 20 and 28. At postnatal day 28, no significant difference in the hypothalamic mRNA level of neuropeptide Y, which is the main target of leptin, or that of ObRb, which is the leptin receptor, was detected between the NNO and UNO. The chronic intracerebroventricular injection of leptin attenuated body weight gain in both the NNO and UNO; however, there were no significant differences between the body weights of the two groups at any of the examined postnatal time points, indicating that the UNO and NNO exhibited similar central sensitivity to leptin during the pre-pubertal period. These results suggest that prenatal undernutrition induces leptin resistance until the neonatal to pre-pubertal period and that these alterations might be caused by impaired transportation of leptin to central tissues.

Delay in the onset of puberty of intrauterine growth retarded female rats cannot be rescued with hypernutrition after birth

Perinatal undernutrition is known to disturb reproductive development, in particular by delaying the onset of puberty in certain species. Using a rat model, we studied whether hypernutrition after birth can rescue the delayed onset of puberty in intrauterine undernourished female rats. Pregnant rats were divided into two groups: the maternal normal nutrition (mNN, n = 8) and maternal undernutrition (mUN, n = 9) groups. In the mUN group, dams received 50% of the daily food intake of the mNN group from day 15 of pregnancy until delivery. Pups from both the mNN and mUN dams were then separated into two groups, based on their postnatal feeding conditions: control-normal nutrition (control-NN), control-hypernutrition (control-HN), Intrauterine growth retardation (IUGR)-normal nutrition (IUGR-NN), and IUGR-hypernutrition (IUGR-HN). Litter sizes of the hypernutrition groups were controlled to five pups per dam, and normal nutrition groups to 12-13 pups per dam. From postnatal day 30, pups were inspected daily for vaginal opening (VO). The age of VO in the IUGR-NN group was 35.7 ± 2.4 days (mean ± SD), which was significantly delayed compared to that of the control-NN group (33.8 ± 0.8 days). The age of VO in the IUGR-HN group was 35.5 ± 2.3 days, which was significantly delayed compared to that of the control-HN group (33.5 ± 0.8 days). Interestingly, the age of VO did not differ between the IUGR-NN and IUGR-HN groups. In conclusion, maternal undernutrition delays puberty in female offspring, and this delay in puberty cannot be rescued with hypernutrition after birth.

Effects of intrauterine undernutrition on hypothalamic Kiss1 expression and the timing of puberty in female rats

Recent studies have suggested that intrauterine undernutrition is closely associated with the pathogenesis of diseases after birth. Perinatal undernutrition is known to disturb the development of reproductive function and delay the onset of puberty in some species. Using a rat model, we determined the effects of prenatal undernutrition on the development of the hypothalamic kisspeptin system and evaluated whether the alteration of the kisspeptin system contributes to the delayed onset of puberty induced by prenatal undernutrition. We also evaluated the effects of prenatal undernutrition on the developmental changes in serum leptin levels because leptin was a putative positive regulator of the hypothalamic kisspeptin system. We compared the timing of vaginal opening (VO) and the developmental changes in body weight, hypothalamic Kiss1 mRNA levels, and serum leptin concentrations between offspring with prenatal undernutrition (UN offspring) and normal nutrition (NN offspring). After birth, the UN offspring showed rapid growth and had caught up to body weight of the NN offspring by postnatal day 12. After postnatal day 16, the UN offspring showed significantly lower Kiss1 mRNA levels than the NN offspring, despite their significantly higher serum leptin levels (at days 20 and 28). The timing of VO in the UN offspring was delayed compared with that in the NN offspring, and chronic central injection of kisspeptin normalized the timing of VO in the UN offspring. These results suggest that decreased hypothalamic kisspeptin action contributes to the delayed onset of puberty in prenatally undernourished female rats. Increased leptin resistance in the kisspeptin system might be involved in these alterations.

Regional Brazilian diet-induced pre-natal malnutrition in rats is correlated with the proliferation of cultured vascular smooth muscle cells

Pre-natal malnutrition induces hypertension and insulin resistance, pathologies commonly linked to atherosclerotic disease. The proliferation of vascular smooth muscle cells (SMCs) is important during development of the atherosclerotic plaque. In this work, we investigated whether the serum of pre-natal malnourished Wistar rats could alter the proliferation of aortic and renal artery SMCs in culture. Malnutrition was induced by feeding a basic regional diet available in a rural area of Pernambuco State, Brazil. This diet was rich in carbohydrates and deficient in proteins, lipids, vitamins and minerals, including sodium chloride. Serum was obtained from the blood of 90-day-old control and pre-natal undernourished rats. SMCs from control Wistar rats at the 6th passage were allowed to adhere to plates in Dulbecco's modified Eagle's medium (DMEM) supplemented with fetal calf serum (10%). Subsequently, the SMCs were maintained in DMEM supplemented with rat serum (10%). The number of cells was counted on the 3rd, 6th and 8th days of culture into rat serum. [3H]-thymidine incorporation into SMCs was evaluated after 20 h or 6 days of incubation. The birth weight of male and female undernourished offspring was 25% (p<0.05) and 46% (p<0.05) lower, respectively, than their corresponding control groups. On the 8th day of culture, the number of aortic SMCs in the serum of undernourished male and female rats, as well as renal artery SMCs in the serum of undernourished female rats, was higher than in the serum of control rats. The [3H]-thymidine incorporation was higher in aortic SMCs incubated for 6 days in the serum of undernourished male and female rats. At confluence, the density of aortic SMCs was higher than that of renal artery SMCs. Pre-natal malnutrition produces serum with altered properties that can affect the proliferation of SMCs and may contribute to atherosclerotic disease.

Delayed first cycle in intrauterine growth-retarded and postnatally undernourished female rats: follicular growth and ovulation after stimulation with pregnant mare serum gonadotropin at first cycle.

In the present study we examined the consequences of intrauterine growth retardation and postnatal food restriction on the maturational process of sexual development by studying onset of first cycle. In addition, we investigated the effect of pregnant mare serum gonadotropin (PMSG) on ovarian growth and ovulation in intrauterine growth-retarded (IUGR) and postnatally food-restricted (PFR) rats. Intrauterine growth retardation was induced by uterine artery ligation on day 17 of gestation and food restriction was achieved by enlarging the litter to 20 pups per mother from day 2 after birth until weaning (day 24). In control rats, vaginal opening and the first cycle took place on the same day. In IUGR rats, uncoupling occurred between vaginal opening and the first cycle. Vaginal opening was delayed (P<0.05) and the first cycle was even further delayed (P<0.01) compared with controls. Body weight in IUGR rats was lower (P<0.05) at vaginal opening, but at first cycle and after stimulation with 50 IU PMSG in the first cycle it was similar to that in controls. In the ovaries of IUGR rats, the numbers of primordial (P<0.05), growing (P<0.01) and antral follicles (P<0.01), and the total number of follicles (P<0.01) were lower than in controls after stimulation with 50 IU PMSG at first cycle. The number of corpora lutea in the ovaries of the IUGR rats and the controls was similar and reflected superovulation. In the PFR rats, vaginal opening occurred at the same time as in control rats, but at a lower body weight (P<0.01). First cycle was much delayed (P<0.01), by which time body weight was greater (P<0.01) than that of controls at first cycle. On the basis of the differences in weight and age between PFR rats and controls at first cycle, we performed two studies. In study A, ovaries were analysed histologically 42 h after stimulation with PMSG at first cycle of control rats and age-matched PFR rats. In study B, the ovaries of PFR rats at first cycle and age-matched control rats were examined 42 h after PMSG stimulation. In the ovaries of the PFR rats in study A, a greater total number of follicles (P<0.05) was observed, represented by a greater number of primordial follicles (P<0.01) and a lower number of antral follicles (P<0.05), including corpora lutea. The number of corpora lutea in the ovaries of the PFR rats was significantly lower than that in controls (P<0.01). The total number of follicles in the ovaries of the PFR rats of study B did not differ from the age-matched controls after PMSG stimulation at first cycle, and neither did the number of the follicles in the different classes. We conclude that, in IUGR rats at first cycle, PMSG can induce multiple follicular growth and development followed by superovulation comparable to that in controls, despite a decreased total number of follicles in the ovaries. However, in PFR rats of the same age, the ovary is not capable of responding adequately to PMSG, despite a greater total number of follicles. Stimulation with PMSG at first cycle resulted in follicular growth and superovulation comparable to those in age-matched controls. Undernutrition in different critical time periods around birth in the rat leads to ovarian development in such a way that, in both groups, an increased risk of reduced reproductive capacity can be expected.

β-endorphin concentrations in the hypothalamus, pituitary and plasma of streptozotocin-diabetic rats with and without insulin substitution therapy

The concentrations of β-endorphin like immunoreactivity (β-END) in the hypothalamus, pituitary and plasma were studied in rats of either sex, one month after induction of diabetes by single iv injection of streptozotocin. As controls, both normal and undernourished rats, weight-matched with diabetic rats, were used. Diabetic male and female rats had a marked depletion of β-END stores in the hypothalamus and neurointermediate lobe (NIL) but not in the anterior pituitary. Depletion of β-END was reversed to normal by insulin replacement therapy. Severe undernourishment was not as effective as diabetes to reduce β-END stores in the hypothalamus and NIL. A significant reduction of β-END was observed only in the NIL of undernourished female rats. Plasma β-END and β-lipotropin (β-LPH) concentrations were not significantly altered in diabetic rats. These results indicate that the lack of insulin may affect β-END synthesis in the hypothalamus and NIL.

Metabolism of adenine nucleotides, nucleic acids and proteins in the liver, brain and kidney of 21-day-old progeny of undernourished female rats.

The metabolism of adenine nucleotides, nucleic acids, and proteins was investigated and compared in the liver, brain, and kidney of the 21-day-old progeny of rats which were well fed (control group) or undernourished during their whole lifetime (experimental group). The in vivo content of various nucleotides (ATP-ADP, cAMP, 5'AMP, and adenosine), the incorporation of radioactive precursor into various nucleotide fractions, and the specific activity of various nucleotides increased considerably in the liver, brain, and kidney of the progeny in the experimental group. Nucleic acid and protein content failed to increase normally in these organs of the progeny in the experimental group. The synthesis of DNA and RNA increased in the liver, brain, and kidney of experimental group progeny. These results suggest that maternal dietary restriction prolonged or blocked the G and S phase of the cell cycle in the liver, brain, and kidney of the progeny of dietary restricted rats.

The influence of nutrition on variation in length of estrous cycle in female rats

The present studies were performed to determine the variation in length of the estrous cycle of undernourished female rats. The two groups studied received 4% and 8% protein diets, the first one group ad libitum and the second one controlled in quantity so that the animals of the two groups have the same growth rate.

Maternal dietary deficiency and its effect on the metabolism of nucleic acids and proteins. "Effect of exchanging the young, during the lactation period, between the control and undernourished female rats".

The effect of maternal dietary deficiency on the metabolism of nucleic acids and proteins was studied by exchanging the pups of control and undernourished dams during the lactation period. In the pups of control dams fostered by undernourished dams during the lactation period (E3), it was observed that the body and organ weight, and RNA, DNA, and protein content failed to increase normally. Contrary to this, the free leucine and nucleotide contents were higher and their specific activities lower in the plasma and various organs of the E3 group as compared with the control group.Specific activity of protein was higher in the liver, brain, kidney, and lung, and was lower in the spleen and heart of the E3 group as compared with the control group. Specific activity of RNA was higher in the liver, spleen, and lung, and was lower in the brain, kidney, and heart of the E3 group as compared with the control group.In the pups of undernourished dams fostered by the control dams during the lactation period (E1), the body and organ weights, the RNA, DNA, and protein content, the content of free leucine and nucleotides as well as their specific activities, and the specific activity of protein and RNA were partially or completely restored. However, the DNA content of the brain remained unchanged in comparison with those pups of undernourished dams nursed by their own mother (E2). In the brain, kidney, spleen, and lung of the E1 group, the specific activity of RNA increased considerably and even exceeded the control values.The radioactivity results discussed above clearly demonstrate an accelerated metabolism of protein and RNA in the various organs of the E3 group and a partial or complete normalization in the E1 group.

Quantitative Changes in DNA, RNA, and Protein Content of the Various Organs of the Young of Undernourished Female Rats

Quantitative Changes in DNA, RNA, and Protein Content of the Various Organs of the Young of Undernourished Female Rats