Comparison of sleep and chronotype between senior and undergraduate university students.

The university programs for seniors provide a third age perspective in lifelong learning with classes and recreational facilities, and enable students to share their experiences and knowledge. A good sleep quality promotes better cognitive functioning and serves to protect against age-related cognitive declines. Central nervous system reorganization takes place during sleep, and although the influence of sleep quality on memory is not clear, circadian rhythm disorders affect alertness and individual performance. Physiological change during aging need to be clarified to better understand how university might help students. The aim of the present study was to evaluate for the first time the chronotype, the sleep quality and their relationship in senior university students and to compare them with those of undergraduate students. The Morningness-Eveningness Questionnaire (MEQ) and the Pittsburgh Sleep Quality Index (PSQI) were used. The results indicated that approximately 50% of the participants were good sleepers. This percentage was equal in the senior and undergraduate students. The results showed that undergraduate students tended toward eveningness while senior students tended toward morningness. Among the undergraduate students, evening type chronotypes had a tendency toward higher PSQI scores and this affected their daytime function scores, while it did not in the senior students, in whom worsening sleep quality was associated with disturbances such as going to the bathroom and nocturnal awakening. This information would be useful for designing environmental interventions to optimize sleep/work cycles for decreasing age-associated changes in memory in senior students and for improving the academic achievements of undergraduate students.

Effects of bisphenol A treatment during pregnancy on kidney development in mice: a stereological and histopathological study.

Bisphenol A (BPA) is a chemical found in plastics that resembles oestrogen in organisms. Developmental exposure to endocrine-disrupting chemicals, such as BPA, increases the susceptibility to type 2 diabetes (T2DM) and cardiovascular diseases. Animal studies have reported a nephron deficit in offspring exposed to maternal diabetes. The aim of this study was to investigate the prenatal BPA exposure effects on nephrogenesis in a mouse model that was predisposed to T2DM. This study quantitatively evaluated the renal structural changes using stereology and histomorphometry methods. The OF1 pregnant mice were treated with a vehicle or BPA (10 or 100 µg/kg/day) during days 9-16 of gestation (early nephrogenesis). The 30-day-old offspring were sacrificed, and tissue samples were collected and prepared for histopathological and stereology studies. Glomerular abnormalities and reduced glomerular formation were observed in the BPA offspring. The kidneys of the BPA10 and BPA100 female offspring had a significantly lower glomerular number and density than those of the CONTROL female offspring. The glomerular histomorphometry revealed a significant difference between the female and male CONTROL offspring for the analysed glomerular parameters that disappeared in the BPA10 and BPA100 offspring. In addition, the kidney histopathological examination showed typical male cuboidal epithelial cells of the Bowman capsule in the female BPA offspring. Exposure to environmentally relevant doses of BPA during embryonic development altered nephrogenesis. These structural changes could be associated with an increased risk of developing cardiometabolic diseases later in life.

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.

Progressive training effects on neuronal hypothalamic activation in the rat.

The purpose of this study was to examine whether progressive training exercise resulted in changes in neuronal expression of c-Fos in the hypothalamic regions (paraventricular nucleus, supraoptic nucleus and suprachiasmatic nucleus) and subfornical organ of Wistar rats and its relation to hydromineral parameters such as plasma proteins, osmolality and hematocrit. Rats were trained progressively in a running wheel over four days, while control rats were not provided with the opportunity to exercise. c-Fos cellular activity was immunohistochemically stained in accordance with the ABC method. The number of c-Fos immunoreactive cells was counted using standard imaging software. c-Fos in the PVN and SO nuclei was found to be significantly increased in trained rats 1h post-exercise compared with control and 24h post-exercise groups. However, no significant differences were found between trained and control rats in the SQ and SFO. These findings provide useful information of interest for future studies on brain specific regions involved in hydromineral balance in response to progressive exercise.

In utero extracellular dehydration modifies thirst in neonatal rats.

The main aim of this study was to investigate the effect of maternal extracellular dehydration during pregnancy in rats on the development of thirst mechanisms in the offspring. Pregnant rats underwent three episodes of extracellular dehydration induced by injecting s.c. 15ml/kg b.w. of a 20% wt/vol solution of polyethylene glycol (PEG) in saline. The treatment given on days 14, 17 and 20 postconception is thought to induce endocrine and natriophilic responses similar to those elicited by vomiting. The offspring were tested for their responses to three different thirst stimuli at 2, 4 and 6 days of age. Like the controls, the offspring from PEG-treated mothers responded to beta stimulation by isoproterenol at 6 days of age. However, they failed to respond to cellular dehydration (NaCl hypertonic injection) at 2 days of age or to extracellular dehydration by PEG on day 4. In conclusion, offspring exposed to in utero extracellular dehydration do not respond to cellular dehydration at 2 days of age or to extracellular dehydration at 4 days of age, whereas control pups had already developed an appropriate response to these stimuli. According to these results, it therefore seems that in utero conditions determine the development of adaptive thirst responses in offspring.

Maternal RAS influence on the ontogeny of thirst.

Perillan, C., Costales, M., Vijande, M., and J. Arguelles. Maternal RAS influence on the ontogeny of thirst. Physiol Behav XX (X) 000-000, 2006. The main objective of this study was to investigate the effect of an altered ambiance in utero, on the development of thirst mechanisms in the offspring. Female rats underwent a partial ligature of the aorta (PAL), which induces an intrinsic activation of the renin angiotensin system (RAS), thirst and sodium appetite. A second group of female rats was treated with desoxycorticosterone (DOCA) which depresses the RAS. The offspring of these two groups were tested for their responses to several thirst stimuli at 2, 4 and 6 days of age. The offspring from PAL mothers responded like their controls to cellular dehydration (NaCl hypertonic injection) at 2 days of age, and also did to extracellular dehydration by polyethyleneglycol at 4 days. Nevertheless, they responded more to isoproterenol at 6 days of age in comparison to their control group. The offspring from DOCA treated mothers did not show statistically significant responses (in comparison with vehicle injected pups) to hypertonic NaCl at two days nor to polyethyleneglycol at four days. Water intake at 6 days of age after isoproterenol administration in DOCA was statistically enhanced, but not differently from the response obtained from pseudo-DOCA treated pups. In particular, rats developed in a hypereninemic ambiance (O-PAL) during gestation, responded with higher water intake when treated with a strong RAS and thirst activator (isoproterenol) but responded normally to a more gentle and complex stimulus (PG). Therefore it seems that in utero conditions can determine the chronology and intensity of thirst responses in offspring.

Sodium taste threshold in children and its relationship to blood pressure

Popular science has emphasized the risks of high sodium intake and many studies have confirmed that salt intake is closely related to hypertension. The present mini-review summarizes experiments about salt taste sensitivity and its relationship with blood pressure (BP) and other variables of clinical and familial relevance. Children and adolescents from control parents (N = 72) or with at least one essential hypertensive (EHT) parent (N = 51) were investigated. Maternal questionnaires on eating habits and vomiting episodes were collected. Offspring, anthropometric, BP, and salt taste sensitivity values were recorded and blood samples analyzed. Most mothers declared that they added "little salt" when cooking. Salt taste sensitivity was inversely correlated with systolic BP (SBP) in control youngsters (r = -0.33; P = 0.015). In the EHT group, SBP values were similar to control and a lower salt taste sensitivity threshold. Obese offspring of EHT parents showed higher SBP and C-reactive protein values but no differences in renin-angiotensin-aldosterone system activity. Salt taste sensitivity was correlated with SBP only in the non-obese EHT group (N = 41; r = 0.37; P = 0.02). Salt taste sensitivity was correlated with SBP in healthy, normotensive children and adolescents whose mothers reported significant vomiting during the first trimester (N = 18; r = -0.66; P < 0.005), but not in "non-vomiter offspring" (N = 54; r = -0.18; nonsignificant). There is evidence for a linkage between high blood pressure, salt intake and sensitivity, perinatal environment and obesity, with potential physiopathological implications in humans. This relationship has not been studied comprehensively using homogeneous methods and therefore more research is needed in this field.

Sodium taste threshold in children and its relationship to blood pressure.

Popular science has emphasized the risks of high sodium intake and many studies have confirmed that salt intake is closely related to hypertension. The present mini-review summarizes experiments about salt taste sensitivity and its relationship with blood pressure (BP) and other variables of clinical and familial relevance. Children and adolescents from control parents (N = 72) or with at least one essential hypertensive (EHT) parent (N = 51) were investigated. Maternal questionnaires on eating habits and vomiting episodes were collected. Offspring, anthropometric, BP, and salt taste sensitivity values were recorded and blood samples analyzed. Most mothers declared that they added "little salt" when cooking. Salt taste sensitivity was inversely correlated with systolic BP (SBP) in control youngsters (r = -0.33; P = 0.015). In the EHT group, SBP values were similar to control and a lower salt taste sensitivity threshold. Obese offspring of EHT parents showed higher SBP and C-reactive protein values but no differences in renin-angiotensin-aldosterone system activity. Salt taste sensitivity was correlated with SBP only in the non-obese EHT group (N = 41; r = 0.37; P = 0.02). Salt taste sensitivity was correlated with SBP in healthy, normotensive children and adolescents whose mothers reported significant vomiting during the first trimester (N = 18; r = -0.66; P < 0.005), but not in "non-vomiter offspring" (N = 54; r = -0.18; nonsignificant). There is evidence for a linkage between high blood pressure, salt intake and sensitivity, perinatal environment and obesity, with potential physiopathological implications in humans. This relationship has not been studied comprehensively using homogeneous methods and therefore more research is needed in this field.

Thirst changes in offspring of hyperreninemic rat dams.

The aim of this study was to investigate the changes in thirst dependence on the renin-angiotensin system (RAS), in offspring of hyperreninemic, hyperdipsic, and natriophilic rat dams. Female rats underwent a partial aortic ligature between the renal arteries (PAL) or were sham-operated (SHAM). At 6 days of age, offspring of PAL (O-PAL) and SHAM (O-SHAM) dams were injected with isoproterenol (subcutaneously, 500 microg/kg body weight) or vehicle. Pretreatment with captopril (intraperitoneally, 50 mg/kg) on isoproterenol-induced thirst was also studied. Plasma renin activity in dams and hematocrit and osmolality in pups were measured. O-PAL had a greater water intake than O-SHAM. However, they responded similarly to isoproterenol or isoproterenol with captopril pretreatment. Only minor differences in hematocrit and osmolality were found between O-SHAM and O-PAL rats after isoproterenol or vehicle treatment. Beta-adrenergic or angiotensinergic responsivity seems not to be altered in offspring of hyperrenimic, hyperdipsic, and natriophilic dams. Nevertheless, other thirst responses of offspring may be critically dependent upon uterine conditions.

Quantitative histochemical assessment of oxidative metabolism in the subfornical organ after partial aortic ligature in rats.

Circumventricular organs are considered to be involved in hydromineral homeostatic responses. In this study we used quantitative histochemistry of cytochrome oxidase to evaluate the oxidative metabolic activity of the subfornical organ of rats with a partial aortic occlusion. These rats showed a significant increase in water intake from the second day after the ligature, while natriophilia was already significant on the first day. Greater levels of cytochrome oxidase activity were found in subfornical organs of partial aortic ligated rats when compared with control, providing further evidence for the involvement of this circumventricular structure in fluid homeostasis at least in this hyperdipsic, hypernatriophilic, hyperreninemic and hypertensive experimental model.

Partial aortic ligature induces selective long-term c-fos like immunoreactivity in the organum vasculosum of the lamina terminalis, medial preoptic area and choroid plexus in the rat.

Partial aortic ligature causes an increase in water and sodium intake. Circumventricular brain regions are known to be involved in the regulation of these processes. In this work we use c-fos-like immunoreactivity to detect active areas involved in the long-term control of increased water and sodium intake due to partial aortic ligature. A significant increase in water intake was found on the first day after the induction, while natriophilia was observed on the fourth day. c-fos-like immunoreactivity was found selectively in the subfornical organ, the organum vasculosum of the lamina terminalis, the medial preoptic area, and the choroid plexus of the third ventricle. Present results provide further evidence for the involvement of circumventricular organs and the preoptic area in the regulation of hydromineral balance. Moreover, they suggest a maintained and long-term regulation of sodium intake by these same brain areas.

Adult offspring long-term effects of high salt and water intake during pregnancy.

Offspring from dams subjected to hypereninemia, hyperdipsia, and natriophilia by partial aortic ligation (PAL) showed a long-term modification of their ingestive behavior. These rats, upon reaching adulthood, showed an increased appetite for low-concentration saline solutions (0.1 M) when compared to control rats. They also presented a high intake of a medium concentration NaCl solution (0.45 M) after having been offered a very aversive highly concentrated NaCl solution (1.0 M) along with water for 2 days. An increase was also observed in their salt/water intake ratio following two different thirst challenges, 24-h fluid deprivation or sodium depletion by furosemide treatment. The demonstration of the long-term effect of pregnancy history on salt preference in adult offspring draws attention to the possible physiopathological aspects that may be of relevance, considering the well-established relationship between salt intake and hypertension, a disease most commonly occurring in the adult and aged population.