Restricted feeding modulates peripheral clocks and nutrient sensing pathways in rats

ABSTRACT Objective: Feeding restriction in rats alters the oscillators in suprachiasmatic, paraventricular, and arcuate nuclei, hypothalamic areas involved in food intake. In the present study, using the same animals and experimental protocol, we aimed to analyze if food restriction could reset clock genes ( Clock, Bmal1 ) and genes involved in lipid metabolism ( Pgc1a, Pparg, Ucp2 ) through nutrient-sensing pathways ( Sirt1, Ampk, Nampt ) in peripheral tissues. Materials and methods: Rats were grouped according to food access: Control group (CG, food ad libitum ), Restricted night-fed (RF-n, food access during 2 h at night), Restricted day-fed (RF-d, food access during 2 h in the daytime), and Day-fed (DF, food access during 12 h in the daytime). After 21 days, rats were decapitated at ZT3 (0900-1000 h), ZT11 (1700-1800 h), or ZT17 (2300-2400 h). Blood, liver, brown (BAT) and peri-epididymal (PAT) adipose tissues were collected. Plasma corticosterone and gene expression were evaluated by radioimmunoassay and qPCR, respectively. Results: In the liver, the expression pattern of Clock and Bmal1 shifted when food access was dissociated from rat nocturnal activity; this phenomenon was attenuated in adipose tissues. Daytime feeding also inverted the profile of energy-sensing and lipid metabolism-related genes in the liver, whereas calorie restriction induced a pre-feeding increased expression of these genes. In adipose tissues, Sirt1 expression was modified by daytime feeding and calorie restriction, with concomitant expression of Pgc1a , Pparg , and Ucp2 but not Ampk and Nampt . Conclusion: Feeding restriction reset clock genes and genes involved in lipid metabolism through nutrient-sensing-related genes in rat liver, brown, and peri-epididymal adipose tissues.

Effect of chronic ethanol exposure on rat ventilatory responses to hypoxia and hypercapnia

OBJECTIVE: The effect of chronic ethanol exposure on chemoreflexes has not been extensively studied in experimental animals. Therefore, this study tested the hypothesis that known ethanol-induced autonomic, neuroendocrine and cardiovascular changes coincide with increased chemoreflex sensitivity, as indicated by increased ventilatory responses to hypoxia and hypercapnia. METHODS: Male Wistar rats were subjected to increasing ethanol concentrations in their drinking water (first week: 5% v/v, second week: 10% v/v, third and fourth weeks: 20% v/v). At the end of each week of ethanol exposure, ventilatory parameters were measured under basal conditions and in response to hypoxia (evaluation of peripheral chemoreflex sensitivity) and hypercapnia (evaluation of central chemoreflex sensitivity). RESULTS: Decreased respiratory frequency was observed in rats exposed to ethanol from the first until the fourth week, whereas minute ventilation remained unchanged. Moreover, we observed an increased tidal volume in the second through the fourth week of exposure. The minute ventilation responses to hypoxia were attenuated in the first through the third week but remained unchanged during the last week. The respiratory frequency responses to hypoxia in ethanol-exposed rats were attenuated in the second through the third week but remained unchanged in the first and fourth weeks. There was no significant change in tidal volume responses to hypoxia. With regard to hypercapnic responses, no significant changes in ventilatory parameters were observed. CONCLUSIONS: Our data are consistent with the notion that chronic ethanol exposure does not increase peripheral or central chemoreflex sensitivity. .

Changes in prolactin secretion in the short- and long-term after adrenalectomy / Efeito da evolução temporal da adrenalectomia na secreção de prolactina

OBJECTIVE: To evaluate the modulation of the hypothalamus-pituitary-adrenal axis (HPA) on prolactin secretion in rats after adrenalectomy (ADX). MATERIALS AND METHODS: Plasma corticosterone, ACTH, and prolactin concentrations were measured by radioimmunoassay in rats after bilateral ADX in the short- (3 hours and 1day) and long-term (3, 7, and 14 days). RESULTS: Animals that underwent ADX showed undetectable corticosterone levels and a triphasic ACTH response with a transient increase (3h), a decrease (1d), and further increase in the long-term after ADX. Sham animals showed a marked increase in corticosterone and ACTH levels three hours after surgery, with a decrease to basal levels thereafter. Plasma prolactin levels were not changed after ADX. CONCLUSION: There are different points of equilibrium in the HPA axis after the glucocorticoid negative feedback is removed. Prolactin plasma secretion is not altered in the short or long- term after ADX, suggesting that the peptidergic neurons essential for prolactin release are not activated after ADX.

OBJETIVO: Avaliar a modulação do eixo hipotálamo-hipófise-adrenal (HHA) sobre a secreção de prolactina após adrenalectomia (ADX). MATERIAIS E MÉTODOS: Quantificamos por RIE corticosterona, ACTH e prolactina plasmáticos em ratos após curtos (3 horas e 1 dia) e longos (3, 7 e 14 dias) períodos de ADX bilateral. RESULTADOS: Animais ADX mostraram níveis indetectáveis de corticosterona. As concentrações plasmáticas de ACTH apresentaram resposta trifásica: aumento transitório (3h), diminuição (1d) e novo aumento após longos períodos de ADX. Animais Sham mostraram aumento de corticosterona/ACTH após três horas de cirurgia, diminuindo posteriormente aos níveis basais. As concentrações plasmáticas de prolactina não se alteraram após ADX. CONCLUSÃO: Existem diferentes pontos de equilíbrio do eixo HHA após a remoção da retroalimentação negativa exercida pelos glicocorticoides. A secreção de prolactina não se alterou após curtos/longos períodos de ADX, sugerindo que os neurônios peptidérgicos essenciais para a liberação de prolactina não estão ativados durante os diferentes períodos de ADX.

Clinical features and molecular analysis of arginine-vasopressin neurophysin II gene in long-term follow-up patients with idiopathic central diabetes insipidus / Apresentação clínica e análise molecular do gene da arginina-vasopressina neurofisina II de pacientes com diabetes insípido central idiopático com longo seguimento

INTRODUCTION: Central diabetes insipidus (DI) characterized by polyuria, polydipsia and inability to concentrate urine, has different etiologies including genetic, autoimmune, post-traumatic, among other causes. Autosomal dominant central DI presents the clinical feature of a progressive decline of arginine-vasopressin (AVP) secretion. OBJECTIVE: In this study, we characterized the clinical features and sequenced the AVP-NPII gene of seven long-term follow-up patients with idiopathic central DI in an attempt to determine whether a genetic cause would be involved. METHODS: The diagnosis of central DI was established by fluid deprivation test and hyper-tonic saline infusion. For molecular analysis, genomic DNA was extracted and the AVP-NPII gene was amplified by polymerase chain reaction and sequenced. RESULTS: Sequencing analysis revealed a homozygous guanine insertion in the intron 2 (IVS2 +28 InsG) of the AVP-NPII gene in four patients, which represents an alternative gene assembly. No mutation in the code region of the AVP-NPII gene was found. CONCLUSIONS: The homozygous guanine insertion in intron 2 (IVS2 +28 InsG) is unlikely to contribute to the AVP-NPII gene modulation in DI. In addition, the etiology of idiopathic central DI in children may not be apparent even after long-term follow-up, and requires continuous etiological surveillance.

INTRODUÇÃO: O diabetes insípido (DI) central, caracterizado por poliúria, polidipsia e inabilidade em concentrar a urina, apresenta diferentes etiologias, incluindo causas genética, autoimune, pós-traumática, entre outras. O DI central autossômico dominante apresenta a característica clínica de falência progressiva da secreção da arginina-vasopressina (AVP). OBJETIVO: No presente estudo, caracterizou-se a apresentação clínica e sequenciou-se o gene AVP-NPII de sete pacientes com DI central idiopático seguidos de longa data na tentativa de determinar se uma causa genética estava envolvida na etiologia. MÉTODOS: O diagnóstico do DI central foi estabelecido por meio do teste de jejum hídrico e infusão de salina hipertônica. Para a realização da análise molecular, o DNA genômico foi extraído e o gene AVP-NPII foi amplificado pela reação em cadeia da polimerase e, posteriormente, sequenciado. RESULTADOS: A análise do sequenciamento do gene AVP-NPII revelou uma inserção em homozigose de uma guanina no íntron 2 (IVS2 +28 InsG) em quatro pacientes, correspondendo a um arranjo alternativo do gene. Nenhuma mutação da região codificadora do gene AVP-NPII foi encontrada. CONCLUSÕES: A inserção em homozigose de uma guanina no íntron 2 (IVS2 +28 InsG) provavelmente não contribui na modulação do gene AVP-NPII no DI. Adicionalmente, a etiologia do DI central idiopático em crianças pode não se tornar evidente mesmo após um longo período de seguimento, necessitando de contínua vigilância da etiologia.

The effects of early protein malnutrition and environmental stimulation on behavioral and biochemical parameters in rats

The present study investigated the effects of protein malnutrition and environmental stimulation on biochemical and behavioral parameters in rats. The concentrations of polyamines in the frontal cortex, striatum, and hippocampus, as well as plasma corticosterone levels, were measured. The exploratory behavior was analyzed using the elevated plus-maze (EPM) test. Rats received either 16 percent (well-nourished - W) or 6 percent (malnourished - M) protein diets and were divided into stimulated or non-stimulated groups. Malnutrition increased corticosterone levels and decreased plasma protein and anxiety. Non-stimulated rats tested in the EPM had increased corticosterone levels and decreased frontal cortex, striatum and hippocampus protein and polyamines contents. Stimulation decreased open arm entries in the EPM in M animals and increased closed arm entries in the W ones. Stimulation increased frequency and time spent in risk-assessment behaviors. These results suggest that both malnutrition and EPM testing are distressing situations, as indicated by increased corticosterone levels. These results are consistent with lower anxiety and/or higher impulsiveness in M animals.

Doppler e marcadores séricos maternos na predição de complicações da gestação / Doppler and maternal serum screening in the prediction of pregnancy complications

OBJETIVO: Comparar a eficácia do Doppler das artérias uterinas e de marcadores séricos maternos na predição de complicações da gestação. MATERIAIS E MÉTODOS: Trata-se de um estudo prospectivo com 49 primigestas, incluídas no estudo na 18ª semana, sendo coletada a amostra sanguínea para a realização das dosagens séricas, realizadas pelo método de quimioluminescência (alfa-fetoproteína, gonadotrofina coriônica humana e óxido nítrico) e radioimunoensaio (peptídio atrial natriurético). O Doppler das artérias uterinas foi realizado entre 24-26 semanas, determinando a presença ou ausência de incisura na onda de velocidade de fluxo. Na análise estatística utilizou-se o teste de Mann-Whitney, para amostras não-paramétricas, e o teste exato de Fisher, para parâmetros qualitativos. RESULTADOS: Os valores de sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo foram, respectivamente, de 8,3 por cento, 97,0 por cento, 50,0 por cento e 74,4 por cento para a alfa-fetoproteína; 8,3 por cento, 87,9 por cento, 20,0 por cento e 72,5 por cento para a gonadotrofina coriônica humana; 16,7 por cento, 97,0 por cento, 33,3 por cento e 76,2 por cento para o peptídio atrial natriurético; e 16,7 por cento, 93,9 por cento, 50,0 por cento e 75,6 por cento para o óxido nítrico. A sensibilidade do Doppler foi de 75,0 por cento, especificidade de 63,6 por cento, valor preditivo positivo de 57,1 por cento e valor preditivo negativo de 87,5 por cento. CONCLUSÃO: O Doppler das artérias uterinas é melhor preditor de complicações da gestação quando comparado a alguns marcadores séricos em populações de baixo risco.

OBJECTIVE: To compare the effectiveness of uterine artery Doppler and maternal serum screening in the prediction of pregnancy complications. MATERIALS AND METHODS: Prospective study with 49 primigravidae at their 18th gestational week, when a blood sample was collected for serum dosage by chemiluminescence (alpha-fetoprotein, human chorionic gonadotropin and nitric oxide) and radioimmunoassay (atrial natriuretic peptide). Uterine artery Doppler was performed between the 24th and 26th gestational weeks, for determining the presence or absence of notch in the flow velocity waveform. The non-parametric Mann-Whitney test was utilized for statistical analysis, and the Fisher exact test for analysis of qualitative parameters. RESULTS: Sensitivity, specificity, positive and negative predictive values were, respectively, 8.3 percent, 97.0 percent, 50.0 percent and 74.4 percent for alpha-fetoprotein; 8.3 percent, 87.9 percent, 20.0 percent and 72.5 percent for human chorionic gonadotropin; 16.7 percent, 97.0 percent, 33.3 percent and 76.2 percent for atrial natriuretic peptide; and 16.7 percent, 93.9 percent, 50.0 percent and 75.6 percent for nitric oxide. The uterine artery Doppler sensitivity was 75.0 percent, specificity 63.6 percent, positive predictive value 57.1 percent, and negative predictive value 87.5 percent. CONCLUSION: Uterine artery Doppler is an effective method for prediction of pregnancy complications as compared with maternal serum screening in low risk populations.