Maternal RAS influence on the ontogeny of thirst

Comparison of dipsogenic responses of adult rat offspring as a function of different perinatal programming models

The perinatal environment interacts with the genotype of the developing organism resulting in a unique phenotype through a developmental or perinatal programming phenomenon. However, it remains unclear how this phenomenon differentially affects particular targets expressing specific drinking responses depending on the perinatal conditions. The main goal of the present study was to compare the dipsogenic responses induced by different thirst models as a function of two perinatal manipulation models, defined by the maternal free access to hypertonic sodium solution and a partial aortic ligation (PAL-W/Na) or a sham-ligation (Sham-W/Na). The programmed adult offspring of both perinatal manipulated models responded similarly when was challenged by overnight water dehydration or after a sodium depletion showing a reduced water intake in comparison to the non-programmed animals. However, when animals were evaluated after a body sodium overload, only adult Sham-W/Na offspring showed drinking differences compared to PAL and control offspring. By analyzing the central neurobiological substrates involved, a significant increase in the number of Fos + cells was found after sodium depletion in the subfornical organ of both programmed groups and an increase in the number of Fos + cells in the dorsal raphe nucleus was only observed in adult depleted PAL-W/Na. Our results suggest that perinatal programming is a phenomenon that differentially affects particular targets which induce specific dipsogenic responses depending on matching between perinatal programming conditions and the osmotic challenge in the latter environment. Probably, each programmed-drinking phenotype has a particular set point to elicit specific repertoires of mechanisms to reestablish fluid balance.

Neonatal fluoxetine exposure delays reflex ontogeny, somatic development, and food intake similarly in male and female rats

Serotonin (5-HT) acts as a neuromodulator and plays a critical role in brain development. Changes in 5-HT signaling during the perinatal period can affect neural development and may result in behavioral changes in adulthood; however, further investigations are necessary including both sexes to study possible differences. Thus, the aim of this study was to investigate the impact of neonatal treatment with fluoxetine on the development of male and female offspring. The animals were divided into four groups according to sex and treatment. The experimental groups received fluoxetine at 10 mg·kg-1 (1 μL/g of body weight (bw)) and the animals of control group received saline solution 0.9% (1 μL/g of bw) from postnatal days 1-21. In the neonatal period, reflex ontogeny, somatic development, physical features, and food intake were recorded. In the postnatal period (until day 31) bw and post-weaning food intake were recorded. Chronic administration of fluoxetine in the neonatal period caused a delay in the reflex ontogeny and somatic development, as well as reduction of lactation, post-weaning bw, and post-weaning food intake in rats. No difference was found between the sexes. These changes reaffirm that serotonin plays an important role in regulating the plasticity of the brain during the early development period, but without sex differences.

Selenium supplementation during pregnancy and lactation promotes metabolic changes in Wistar rats' offspring

Epidemiological and animal studies have demonstrated a strong association between selenium (Se) supplementation and metabolic disorders, we aimed to evaluate whether maternal Se supplementation was able to change metabolic parameters in rats' offspring. Moreover, as Se is a deiodinase (DIO) cofactor, we decided to investigate how thyroid hormones (THs) would be involved in such metabolic changes. Thereby, two groups (n = 6, ~250 g) of female Wistar rats underwent isotonic saline or sodium selenite (1 mg/kg, p.o.) treatments. Although there were no significant differences in body weight between groups, the Se treatment during pregnancy and lactation increased milk intake and the visceral white adipose tissue (WAT) in offspring. The rats whose mothers were treated with Se also presented an improvement in the glucose tolerance test and in the glucose-stimulated insulin secretion. Regarding the lipid metabolism, the Se group had a reduction of triglycerides in the liver and in WAT. These metabolic changes were accompanied by an increase in serum triiodothyronine (T3 ) and in DIO 2 expression in brown adipose tissue (BAT). We further demonstrate an increased expression of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) and nuclear respiratory factor-1 (NRF-1) mRNA in the liver. In adulthood offspring, Se supplementation programs thyroid function, glucose homeostasis, and feeding behaviour. Taken together, there is no indication that Se programming causes insulin resistance. Moreover, we conjecture that these metabolic responses are induced by increased thyroxine (T4 ) to T3 conversion by DIO2 in BAT and mediated by altered transcription factors expression associated with oxidative metabolism control in the liver.

Treatment with the essential amino acid L-tryptophan reduces masticatory impairments in experimental cerebral palsy

Purpose Children with cerebral palsy (CP) often exhibit difficulties in feeding resulting from deficits in chewing. This study investigates the therapeutic potential of L-tryptophan (TRI) to reduce deficits in chewing in rats subjected to an experimental model of CP.Methods A total of 80 Wistar albino rats were used. Pups were randomly assigned to 4 experimental groups: Control Saline, Control TRI, CP Saline, and CP TRI groups. The experimental model of CP was based on the combination of perinatal anoxia associated with postnatal sensorimotor restriction of the hind limbs. TRI was administered subcutaneously during the lactation period. Anatomical and behavioral parameters were evaluated during maturation, including body weight gain, food intake, chewing movements, relative weight and the distribution of the types of masseter muscle fibers.Results The induction of CP limited body weight gain, decreased food intake and led to impairment in the morphological and functional parameters of chewing. Moreover, for a comparable amount of food ingested, CP TRI animals grew the most. In addition, supplementation with TRI improved the number of chewing movements, and increased the weight and proportion of type IIB fibers of the masseter in rats subjected to CP.Conclusion These results demonstrate that experimental CP impaired the development of mastication and that TRI supplementation increased masticatory maturation in animals subjected to CP.

The effects of experimental gestational hypertension on maternal blood pressure and fluid intake and pre-weanling hypothalamic neuronal activity

To examine the fetal programming effects of maternal hypertension, natriophilia and hyperreninemia [experimentally induced in rats by partial inter-renal aortic ligature (PAL) prior to mating] fos immunoreactivity was studied in 6-day-old offspring of PAL and control mothers. The purposes of the present set of experiments were twofold. The first was to characterize the effects of PAL on the mother's arterial blood pressure and intake of salt (1.8% NaCl solution) and water over the course of gestation. Second, was to study the pattern of neuronal activation in key brain areas of 6-day-old offspring treated with the dipsogen isoproterenol that were from PAL and control mothers. Beta-adrenergic receptor agonist-treated pups allowed the determination whether there were neuroanatomical correlates within the neural substrates controlling thirst and the enhanced water intake evidenced by the isoproterenol treated pups of PAL mothers. Hydromineral ingestive behavior along with blood pressure and heart rate of PAL (M-PAL) and control (M-sPAL) dams throughout gestation was studied. Higher salt and water intakes along with blood pressures and heart rates were found during gestation and lactation in the M-PAL group. Maternal PAL evoked significantly increased isoproterenol-elicited Fos staining in brain regions (e.g. subfornical organ, organum vasculosum of the lamina terminalis, supraoptic nucleus, hypothalamic paraventricular nucleus and median preoptic nucleus) of 6-day-old pups, which is the age of animals shown enhanced thirst responses in PAL offspring. These results indicate that PAL is compatible with pregnancy, producing a sustained increase in blood pressure and heart rate, along with increased water and salt intake. The present study demonstrates that the neural substrates involved in cardiovascular homeostasis and fluid balance in adult rats are responsive in six-day-old rats, and can be altered by fetal programming.

Offspring’s hydromineral adaptive responses to maternal undernutrition during lactation

Early development, throughout gestation and lactation, represents a period of extreme vulnerability during which susceptibility to later metabolic and cardiovascular injuries increases. Maternal diet is a major determinant of the foetal and newborn developmental environment; maternal undernutrition may result in adaptive responses leading to structural and molecular alterations in various organs and tissues, such as the brain and kidney. New nephron anlages appear in the renal cortex up to postnatal day 4 and the last anlages to be formed develop into functional nephrons by postnatal day 10 in rodents. We used a model of undernutrition in rat dams that were food-restricted during the first half of the lactation period in order to study the long-term effects of maternal diet on renal development, behaviour and neural hydromineral control mechanisms. The study showed that after 40% food restriction in maternal dietary intake, the dipsogenic responses for both water and salt intake were not altered; Fos expression in brain areas investigated involved in hydromineral homeostasis control was always higher in the offspring in response to isoproterenol. This was accompanied by normal plasma osmolality changes and typical renal histology. These results suggest that the mechanisms for the control of hydromineral balance were unaffected in the offspring of these 40% food-restricted mothers. Undernutrition of the pups may not be as drastic as suggested by dams’ restriction.

Alimentary Epigenetics: A Developmental Psychobiological Systems View of the Perception of Hunger, Thirst and Satiety

Hunger, thirst and satiety have an enormous influence on cognition, behavior and development, yet we often take for granted that they are simply inborn or innate. Converging data and theory from both comparative and human domains, however, supports the conclusion that the phenomena hunger, thirst and satiety are not innate but rather emerge probabilistically as a function of experience during individual development. The metatheoretical perspective provided by developmental psychobiological systems theory provides a useful framework for organizing and synthesizing findings related to the development of the perception of hunger, thirst and satiety, or alimentary interoception. It is argued that neither developmental psychology nor the psychology of eating and drinking have adequately dealt with the ontogeny of alimentary interoception and that a more serious consideration of the species-typical developmental system of food and fluid intake and the many modifications that have been made therein is likely necessary for a full understanding of both alimentary and emotional development.