Tonic noradrenergic input to neurons in the dorsal raphe nucleus mediates food intake in male mice.

The dorsal raphe nucleus (DRN) is essential for the control of food intake. Efferent projections from the DRN extend to several forebrain regions that are involved in the control of food intake. However, the neurotransmitters released in the DRN related to the control of food intake are not known. We have previously demonstrated that a tonic α1 action on DRN neurons contributes to satiety in the fed rats. In this study we investigated the participation of norepinephrine (NE) signaling in the DRN in the satiety response. Intra-DRN administration of NE causes an increase in the 2-hour food intake of sated mice, an effect that was blocked by previous administration of yohimbine, an α2 antagonist. Similarly, Intra-DRN administration of clonidine, an α2 agonist, increases food intake in sated mice. This result indicates that in the satiated mice exogenous NE acts on α2 receptors to increase food intake. Furthermore, administration of phenylephrine, an α1 agonist, decreases food intake in fasted mice and prazosin, an α1 antagonist, increases food intake in the sated mice. Taken together these results indicate that, in a satiated condition, a tonic α1 adrenergic action on the DRN neurons inhibits food intake and that exogenous NE administered to the DRN acts on α2 adrenergic receptors to increase food intake. These data reinforce the intricate neuronal functioning of the DRN and its effects on feeding.

Intermittent fasting combined with exercise training reduces body mass and alleviates hypothalamic disorders induced by high-fat diet intake.

High-fat diet consumption causes hypothalamic inflammation, dysregulating the leptin pathway, which, in turn, compromises the modulation of hypothalamic neuronal activities and predisposes obesity development. Intermittent fasting (IF) and exercise training (ET) have been demonstrated as efficient interventions to modulate hypothalamic inflammation and neuronal activity. However, no studies have evaluated whether combining these interventions could induce better results in reestablishing hypothalamic homeostasis disrupted by high-fat diet intake. The 8-week-old male C57BL/6 mice were randomly assigned into 2 groups: sedentary mice fed a standard diet (CT), and sedentary mice fed a high-fat diet (HF). After 8 weeks of an HF diet, part of the HF group (now 16 weeks old) was randomly subjected to different interventions for 6 weeks: HF-IF = HF diet mice submitted to IF; HF-T = HF diet mice submitted to ET; HF-IFT = HF diet mice submitted to IF and ET. All interventions decreased the body weight gain induced by high-fat diet intake, associated with reduced calorie consumption in week 14. Only the HF-IFT group presented improved serum insulin, leptin, resistin, and Tnf-alpha levels concomitantly with decreased hypothalamic inflammation. The HF-IFT group also demonstrated increased Pomc mRNA expression associated with enhanced pSTAT3 expression in the hypothalamic arcuate and ventromedial hypothalamic nuclei. Our data indicate that the beneficial effects of the combination of IF and ET on energy homeostasis are associated with increased leptin sensitivity in the hypothalamic arcuate nucleus and ventromedial hypothalamic nucleus, which is likely due to an improvement in hypothalamic inflammatory pathways in these nuclei.

Protective Effects of Kefir Against Unpredictable Chronic Stress Alterations in Mice Central Nervous System, Heart, and Kidney.

Kefir is a probiotic mixture with anxiolytic and antioxidant properties. Chronic stress can lead to anxiety disorders and increase oxidative damage in organs such as the heart and kidney. In this study, we examined whether kefir ameliorates the anxiety-like behavior of mice submitted to chronic unpredictable stress (CUS) by modulating brain-derived neurotrophic factor (BDNF) and corticosterone levels and whether kefir modifies the oxidative parameters in the heart and kidney of mice. Male Swiss mice received kefir (0.3 mL/100 g/day) or milk for 30 days (gavage). On the 10th day, the mice were submitted to CUS. Behavioral analysis was performed using the elevated plus maze and forced swimming tests. BDNF levels were analyzed in brain tissues. Heart and kidney superoxide dismutase (SOD), catalase, glutathione (GSH), thiobarbituric acid reactive substances (TBARS), 3-nitrotyrosine, metalloproteinase-2 (MMP-2), and plasma corticosterone were evaluated. Kefir reverted the CUS-induced decrease in the time spent in the open arms, the increase in grooming frequency, and decrease in the head dipping frequency, but not the reduced immobility time. CUS decreased the cerebellum BDNF levels and increased corticosterone levels, which were restored by Kefir. Neither catalase and SOD activities nor GSH, TBARS, 3-nitrotyrosine, and MMP-2 were modified by CUS in the heart. In the kidney, CUS increased 3-nitrotyrosine and MMP-2. Kefir increased the antioxidant defense in the heart and kidney of control and CUS mice. These results suggest that kefir ameliorated CUS-induced anxiety-like behavior by modulating brain BDNF and corticosterone levels. Kefir also increased the antioxidant defense of mice heart and kidney.

Estilos de aprendizagem de estudantes de graduação de diferentes profissões da saúde de uma instituição / Learning styles of health professions undergraduate students from a single institution

Resumo: Introdução: O conceito de estilo de aprendizagem deriva de teorias que consideram que as pessoas aprendem de maneiras diversas e que esse processo é melhor quando as estratégias de ensino e aprendizagem adotadas no ambiente escolar são mais compatíveis com algumas das suas características. Objetivo: Este estudo teve como objetivos determinar, em estudantes ingressantes na mesma instituição de ensino superior, em vários cursos de graduação na área da saúde, a frequência dos diferentes estilos de aprendizagem, categorizados segundo as quatro dimensões do referencial de Felder e Soloman (FS), e detectar eventuais diferenças associadas ao tipo de curso e ao gênero. Método: A população de estudo (N = 283; 190 mulheres) foi composta por ingressantes dos cursos de Medicina, Ciências Biomédicas, Fisioterapia, Fonoaudiologia, Nutrição e Metabolismo e Terapia Ocupacional, com 68,2% deles com idade entre 18 e 20 anos. Os estudantes responderam a um questionário de caracterização sociodemográfica e ao Inventário de Estilos de Aprendizagem (ILS) de FS, que permitiu determinar as frequências dos vários estilos de aprendizagem e as suas relações com o tipo de curso de graduação e o gênero. Resultado: No conjunto de estudantes, houve predomínio dos estilos de aprendizagem "sensorial", "visual", "reflexivo" e "sequencial" nas dimensões "percepção", "entrada", "processamento" e "compreensão" da informação, respectivamente. Não houve, em nenhuma das dimensões, diferença estatisticamente significativa quanto aos estilos de aprendizagem que pudesse ser associada ao tipo de curso e ao gênero, embora as mulheres tenham apresentado significativo predomínio do estilo "reflexivo" na dimensão do "processamento". Conclusão: Não foi possível estabelecer diferenças significativas entre os vários cursos de graduação das profissões da saúde, nem entre homens e mulheres, quanto aos estilos de aprendizagem predominantes nos estudantes, embora as mulheres tenham apresentado frequência significativamente maior do estilo reflexivo. Esses achados devem ser levados em consideração no planejamento das atividades de aprendizagem e, principalmente, no apoio pedagógico, dando oportunidade aos estudantes de conhecer os seus estilos de aprendizagem e ajudando-os a se adaptar melhor às estratégias empregadas em cada instituição.

Abstract: Introduction: The concept of "learning styles" derives from theories postulating that students learn by following diverse pathways and that learning is more effective when the adopted teaching strategies more closely match specific student characteristics and learning preferences. Objectives: To determine, in first-year students attending different undergraduate courses in the health area at the same higher education institution, the frequency of different learning styles, categorized according to the four dimensions of Felder & Soloman (FS) model, and to detect any differences associated with the type of course and gender. Method: The study population (N=283; 190 women) consisted of first-year students attending the Medicine, Biomedical Sciences, Physical Therapy, Speech-Language Pathology, Nutrition and Metabolism, and Occupational Therapy courses, with 68.2% of them aged between 18 and 20 years. The students answered a sociodemographic characterization questionnaire and the FS Index of Learning Styles (ILS) questionnaire, which allowed determining the frequencies of the different learning styles and their associations with the type of undergraduate course and gender. Results: the student group showed a predominance of "Sensory", "Visual", "Reflective" and "Sequential", learning styles, in the "Perception", "Input", "Processing" and "Understanding" dimensions of learning, respectively. There was no statistically significant difference in terms of learning styles, in any of the dimensions, that could be associated with the type of course and gender, although women showed a significant predominance of the "Reflective" style in the "Processing" dimension. Conclusion: It was not possible to establish significant differences between the different undergraduate courses in the health area, or between men and women, regarding the students' predominant learning styles, although women showed a significantly higher frequency of the Reflective style. These findings must be considered when planning learning activities and, mainly, in pedagogical support, giving students the opportunity to learn about their learning styles and helping them to better adapt to the strategies employed in each institution.

Reflexões sobre a utilização do Teste de Progresso na avaliação programática do estudante / Reflections on the use of the Progress Test in the programmatic student assessment

Resumo: Introdução: O Teste de Progresso (TP) constitui modalidade estabelecida e bem-sucedida de avaliação de conhecimentos do estudante das profissões da saúde, principalmente os de Medicina, com potencial de contribuir substancialmente para as finalidades formativa e informativa (controle de qualidade e indicação de melhoria nos processos de ensino e aprendizagem). Adicionalmente, o TP apresenta características adequadas à sua inclusão em sistemas institucionais de avaliação que privilegiem a finalidade formativa, como a avaliação programática (AP), mas que cumprem também a somativa. Nas escolas que vêm definindo ações visando à introdução da AP em seus cursos de graduação, é necessária a reflexão sobre as fortalezas e limitações da utilização do TP no sistema de avaliação. Desenvolvimento: A partir das considerações de um grupo de trabalho representativo de toda a instituição, incumbido de propor meios de introdução da AP em um novo currículo para o curso de Medicina, contando com assessoria internacional com experiência tanto no TP como na AP, elaborou-se reflexão sobre esse tema, baseada na experiência dos autores e em dados da literatura. Propõe-se que, dentro da perspectiva longitudinal da AP, o TP constitua um dos pilares na avaliação de conhecimentos. O TP pode servir de base para acompanhamento do estudante, no contexto da sua turma (coorte), e seus resultados devem ser discutidos com o mentor que o acompanha e lhe dá suporte. O TP deve ter também papel central na gestão, como fonte de informações para eventual revisão e qualificação do currículo e das suas atividades de ensino e aprendizagem. É previsível que a utilização do TP na AP traga diferentes desafios e barreiras, que serão mais facilmente superados se houver na instituição experiências já consolidadas de aplicação de exames institucionais e de desenvolvimento docente para a elaboração de questões objetivas de boa qualidade. Conclusão: A efetividade do TP dentro do sistema institucional de AP vai depender de medidas que visem aumentar a sua efetividade na avaliação e que estimulem a participação ativa do estudante, refletindo sobre seu desempenho no TP, com o apoio do seu mentor, de modo a se engajar em ações que fomentem a autorregulação da aprendizagem.

Abstract: Introduction: The Progress Test (PT) is a well-established and mostly successful modality of student knowledge assessment in the health professions, mainly those in the medical area, with the potential to contribute substantially to the formative and informative purposes (quality control and indication of improvement in the teaching-learning processes). Additionally, the PT has characteristics that are adequate for its inclusion in institutional evaluation systems that facilitate the formative purpose, such as programmatic assessment (PA), but that also meet the summative purpose. In schools that have defined actions aimed at introducing PA in their undergraduate courses, it is necessary to reflect on the strengths and limitations of using PT in the evaluation system. Development: based on the considerations of a working group representative of the entire institution, tasked with proposing means of introducing PA in a new curriculum for the medical course, with international advice with experience in both PT and PA, we generated a reflection on this topic, based on the authors' experience and data from the literature. It is proposed that, within the longitudinal perspective of the PA, the PT constitutes one of the pillars in the assessment of knowledge. The PT can be used as a basis for monitoring the students, in the context of their class (cohort), and its results should be discussed with the mentors who accompanies and supports them. The PT must also play a central role in management, as a source of information for eventual review and qualification of the curriculum and its teaching-learning activities. It is predictable that the use of the PT in PA will bring different challenges and barriers, which will be more easily overcome if the institution has already consolidated experiences in the application of institutional exams and in faculty development for the production of good quality objective questions. Conclusion: the effectiveness of the PT within the institutional PA system will depend on measures aimed at increasing its effectiveness in the assessment and that encourage the student's active participation, reflecting on their performance in the PT, with the support of their mentor, aiming to engage in actions that encourage learning self-regulation.

Oficina para elaboração de testes de múltipla escolha de ciências básicas aplicadas: relato de experiência / Workshop on item writing to assess basic sciences in health professional education: an experience report

Resumo: Introdução: A avaliação do estudante é componente essencial de todo programa educacional. O aprendizado das ciências básicas é fundamental para dar sentido ao que se aprende na fase clínica da formação de um profissional em saúde. Entretanto, a maioria dos treinamentos de elaboradores de testes de múltipla escolha (TME) é voltada à formulação de questões clínicas e não inclui abordagem específica para questões das ciências básicas. Relato de experiência: Foi realizada uma oficina para a capacitação docente na elaboração de TME de aplicação dos conhecimentos de ciências básicas, visando à elaboração de uma prova a ser aplicada no final do ciclo básico de seis cursos da saúde. O material instrucional foi elaborado pelos autores, que ofereceram uma oficina no formato on-line. Um diferencial dessa capacitação foi a aplicação de modelos de elaboração de enunciados com contextos definidos, utilizando momentos de preparo assíncronos e encontro síncrono. Após a oficina, aplicaram-se questionários sobre a satisfação e aprendizagem dos participantes. A maioria avaliou a oficina como boa ou muito boa e referiu aumento da percepção de capacidade para elaborar TME, e, ao final, somente 7% se sentiram pouco preparados para elaborar um TME seguindo as boas práticas. Houve melhora na qualidade dos TME elaborados, tendo como referencial os índices de dificuldade e discriminação. Discussão: Existem evidências do valor do desenvolvimento do corpo docente na melhoria da qualidade das questões produzidas. O formato de oficina proposto foi bem avaliado pelos participantes e contribuiu para a qualidade das questões de provas aplicadas ao final do ciclo básico. Conclusão: Estratégias como a descrita qualificam as avaliações dentro da escola e contribuem para a organização de provas externas.

Abstract: Introduction: Student assessment is an essential component of all educational programs. Basic science learning is essential for making clinical knowledge meaningful to healthcare students. However, most item writer training is focused on the formulation of clinical questions and does not include a specific approach to basic science questions. Experience Report: Workshops on item writing for knowledge application on basic sciences were carried out with the aim of planning a test to be applied at the end of the basic cycle of six health courses. The instructional material was prepared by the authors, who offered online workshops. A differential of this training was the application of models of item lead-in elaboration with defined contexts, using moments of asynchronous preparation and synchronous encounter. After each workshop, surveys were applied to assess participants' satisfaction and learning. Most participants rated the workshop as good or very good and reported an increase in their perceived ability to prepare single best answer multiple-choice questions. At the end, only 7% reported they were not prepared to write an item following good practices. There was an improvement in the quality of the items prepared, using the difficulty and discrimination indexes as a reference. Discussion: There is evidence of the value of faculty development in improving the quality of the questions produced. The proposed workshop format was well evaluated by the participants and contributed to the quality of tests applied to students at the end of the basic science cycle. Conclusion: Strategies such this qualify assessments within the school and contribute to the organization of external exams.

Alterations in Kidney Structures Caused by Age Vary According to Sex and Dehydration Condition.

Aging is a complex biological process, resulting in gradual and progressive decline in structure and function in many organ systems. Our objective is to determine if structural changes produced by aging vary with sex in a stressful situation such as dehydration. The expression of Slc12a3 mRNA in the renal cortex, α-smooth muscle actin (α-SMA), and fibronectin was evaluated in male and female rats, aged 3 and 18 months, submitted and not submitted to water deprivation (WD) for 48 h, respectively. When comparing ages, 18-month-old males showed a lower expression of Slc12a3 mRNA than 3-month-old males, and control and WD 18-month-old male and female rats exhibited a higher expression of α-SMA than the respective 3-month-old rats. Fibronectin was higher in both control and WD 18-month-old males than the respective 3-month-old males. In females, only the control 18-month-old rats showed higher fibronectin than the control 3-month-old rats. When we compared sex, control and WD 3-month-old female rats had a lower expression of Slc12a3 mRNA than the respective males. The WD 18-month-old male rats presented a higher expression of fibronectin and α-SMA than the WD 18-month-old female rats. When we compared hydric conditions, the WD 18-month-old males displayed a lower relative expression of Slc12a3 mRNA and higher α-SMA expression than the control 18-month-old males. Aging, sex, and dehydration lead to alterations in kidney structure.

High-fat diet changes the behavioural and hormonal responses to water deprivation in male Wistar rats.

NEW FINDINGS: What is the central question of this study? What is the effect of an obesogenic diet on the control of hydromineral balance in rats? What is the main finding and its importance? The results showed that, when dehydrated, rats fed a high-fat diet drink less water than their control-diet-fed counterparts. Changes in aquaporin-7 and peroxisome proliferator-activated receptor α expression in the white adipose tissue might be involved. ABSTRACT: High-fat diet (HFD) increases fat accumulation, glycaemia and blood triglycerides and is used as a model to study obesity. Besides the metabolic changes, obesity likely affects water intake. We assessed the effects of HFD on behavioural and hormonal responses to water deprivation. Additionally, we measured if the adipose tissue is differentially affected by water deprivation in control and HFD-fed rats. HFD rats showed a decreased basal water intake when compared to control-fed rats. When subjected to 48 h of water deprivation, as expected, both control and HFD rats drank more water than the hydrated rats. However, the increase in water intake was lessened in HFD dehydrated rats. Similarly, the increase in haematocrit in dehydrated rats was less pronounced in HFD dehydrated rats. These results suggest that HFD diminishes drinking behaviour. White adipose tissue weight, glycaemia and plasma glycerol concentration were increased in HFD rats; however, after 48 h of water deprivation, these parameters were significantly decreased in dehydrated HFD rats, when compared to controls. The increase in adipose tissue caused by HFD may mitigate the effects of dehydration, possibly through the increased production of metabolic water caused by lipolysis in the adipocytes. Oxytocin possibly mediates the lipolytic response, since both its secretion and receptor expression are affected by dehydration in both control and HFD rats, which suggests that oxytocin signalling is maintained in these conditions. Changes in mediators of lipolysis, such as aquaporin-7 and peroxisome proliferator-activated receptor α, might contribute to the different effects observed in control and HFD rats.

Nicotine exposure through breastfeeding affects brain-derived neurotrophic factor and synaptic proteins levels in the brain of stressed adult female mice.

Nicotine has been used during pregnancy and lactation as a tobacco harm reduction strategy. However, it is unclear whether nicotine exposure during a critical development period negatively impacts stress responses in adulthood. This study investigated how nicotine, administered via breastfeeding, affects the brain-derived neurotrophic factor (BDNF), synaptic proteins levels, and anxiety-like behavior in adult female mice subjected to stress. Female Swiss mice were exposed to saline or nicotine (8 mg/kg/day) through breastfeeding between their fourth and 17th postnatal days (P) via implanted osmotic mini pumps. The unpredictable chronic mild stress (UCMS) protocol was performed during their adulthood (P65) for 10 consecutive days, followed by the elevated plus maze (EPM) test 1 day after the protocol. Animals were euthanized and their blood, collected for plasma corticosterone measurements and their brain structures, dissected for BDNF and synaptic proteins analyses. We found no significant differences in corticosterone levels between groups (Saline/Non-stress, Nicotine/Non-stress, Saline/Stress, and Nicotine/Stress). The UCMS protocol hindered weight gain. Mice exposed to nicotine through breastfeeding with or without the UCMS protocol in adulthood showed higher grooming and head dipping frequency; decreased BDNF levels in cerebellum and striatum; increased postsynaptic density protein 95 (PSD-95), synapsin I, and synaptophysin levels in cerebellum; and decreased PSD-95 and synapsin I levels in brainstem. Our results indicate that nicotine exposure through breastfeeding leads to long-lasting behavioral effects and synaptic protein changes, most of which were independent of the UCMS protocol, even after a long nicotine-free period, highlighting the importance of further studies on nicotine exposure during development.

Arcuate AgRP, but not POMC neurons, modulate paraventricular CRF synthesis and release in response to fasting.

BACKGROUND: The activation of the hypothalamic-pituitary-adrenal (HPA) axis is essential for metabolic adaptation in response to fasting. However, the neurocircuitry connecting changes in the peripheral energy stores to the activity of hypothalamic paraventricular corticotrophin-releasing factor (CRFPVN) neurons, the master controller of the HPA axis activity, is not completely understood. Our main goal was to determine if hypothalamic arcuate nucleus (ARC) POMC and AgRP neurons can communicate fasting-induced changes in peripheral energy stores, associated to a fall in plasma leptin levels, to CRFPVN neurons to modulate the HPA axis activity in mice. RESULTS: We observed increased plasma corticosterone levels associate with increased CRFPVN mRNA expression and increased CRFPVN neuronal activity in 36 h fasted mice. These responses were associated with a fall in plasma leptin levels and changes in the mRNA expression of Agrp and Pomc in the ARC. Fasting-induced decrease in plasma leptin partially modulated these responses through a change in the activity of ARC neurons. The chemogenetic activation of POMCARC by DREADDs did not affect fasting-induced activation of the HPA axis. DREADDs inhibition of AgRPARC neurons reduced the content of CRFPVN and increased its accumulation in the median eminence but had no effect on corticosterone secretion induced by fasting. CONCLUSION: Our data indicate that AgRPARC neurons are part of the neurocircuitry involved in the coupling of PVNCRF activity to changes in peripheral energy stores induced by prolonged fasting.

Prolonged Activation of Brain CB2 Signaling Modulates Hypothalamic Microgliosis and Astrogliosis in High Fat Diet-Fed Mice.

Low-grade inflammation of the hypothalamus is associated with the disturbance of energy balance. The endocannabinoid system has been implicated in the development and maintenance of obesity as well as in the control of immune responses. The type 2 cannabinoid receptor (CB2) signaling has been associated with anti-inflammatory effects. Therefore, in high fat diet (HFD)-induced obese mice, we modulated CB2 signaling and investigated its effects on energy homeostasis and hypothalamic microgliosis/astrogliosis. We observed no effect on caloric intake and body weight gain in control diet-fed animals that received prolonged icv infusion of the CB2 receptor agonist HU308. Interestingly, we observed a decrease in glucose tolerance in HFD-fed animals treated with HU308. Prolonged icv infusion of HU308 increases astrogliosis in the ventromedial nucleus (VMH) of obese animals and reduced HFD-induced microgliosis in the hypothalamic arcuate (ARC) but not in the paraventricular (PVN) or VMH nuclei. These data indicate that central CB2 signaling modulates glucose homeostasis and glial reactivity in obesogenic conditions, irrespective of changes in body weight.

Effects of gonadotropin inducible ovarian transcription factor 1 in the paraventricular nucleus on fluid intake after dehydration of ovariectomized female rats.

NEW FINDINGS: What is the central question of this study? Giot1, the gene for gonadotropin inducible ovarian transcription factor 1 (GIOT1), is upregulated in osmotically challenged rats: does Giot1 gene expression in the paraventricular nucleus have a role in controlling fluid intake following dehydration and what is the role of ovarian hormones in the modulation of GIOT1 actions? What is the main finding and its importance? GIOT1 acts to regulate water and salt intake as well as hormone secretion after dehydration. The identification of genes that participate in the hormone and behavioural responses involved with hydromineral homeostasis is essential for future exploration of novel drug targets for the treatment of metabolic disease. ABSTRACT: In order to maintain body fluid balance after dehydration, hypothalamic neurons of the paraventricular nucleus (PVN) are activated to promote secretion of vasopressin (AVP) and oxytocin (OXT) from the neurohypophysis, and to modulate the behavioural allostatic responses of thirst and salt appetite. Gonadotropin inducible transcription factor (GIOT1) is a Krüppel-type zinc finger protein induced by gonadotropins and oestradiol (E2). This transcription factor is expressed in the hypothalamus, specifically in the PVN where expression of Giot1 mRNA increases following hydromineral challenges such as water deprivation or salt loading, although its physiological role is not clear. We hypothesize that GIOT1 has a central role in the integrated homeostatic and allostatic responses to disturbances in hydromineral balance, especially in the presence of female gonadal hormones. Female rats with intact ovaries or ovariectomized rats were subjected to specific microinjection of a lentiviral vector mediating Giot1 knockdown in the PVN. Three weeks after injection, rats were subjected to 48 h water deprivation, and thereafter water and salt intake were evaluated. Giot1 knockdown in PVN reduced water and saline intake as well as AVP and OXT secretion. Furthermore, Giot1 knockdown had profound effects on gene expression in the PVN, reducing the abundance of transcripts encoded by the Avp, Oxt, Nr4a1 and Crh genes. In conclusion, the present study shows for the first time that GIOT1 in the PVN regulates both transcription and fluid intake, although any connection to ovarian hormones remains to be established.

Restricted feeding modulates peripheral clocks and nutrient sensing pathways in rats.

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. 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.

Hormonal and neural responses to restraint stress in an animal model of perimenopause in female rats.

The present study investigated the hormonal and neural responses to stress in a perimenopause animal model induced by 4-vinylcyclohexene diepoxide (VCD), which induces progressive follicular depletion in rodents, allowing studies on the transition to ovarian failure. Female rats, aged 28 days old, were s.c. injected for 15 consecutive days with corn oil or VCD. At 85 ± 5 days after the onset of treatment, the jugular vein was cannulated in the afternoon of metoestrus and in next morning (dioestrus) at 10.00 am, rats were subjected to 30 minutes of restraint stress. Blood samples were withdrawn before (-5 minutes), during (2, 5, 15 and 30 minutes) and after (45, 60 and 90 minutes) stress and plasma prolactin, progesterone and corticosterone levels were measured. Animals were perfused, brains processed for c-Fos/tyrosine hydroxylase (TH) in the locus coeruleus (LC) and c-Fos/corticotrophin-releasing factor (CRF) in the paraventricular nucleus (PVN). In unstressed rats the density of ß-endorphin fibres was assessed in LC and PVN. In VCD-treated rats, stress-induced prolactin peak was higher, basal and peak progesterone levels were lower, and both levels of corticosterone were similar to controls. However, the recovery period was longer for both adrenal hormones. In VCD-treated rats the number of c-Fos/TH and c-Fos/CRF-immunoreactive neurones was higher whereas the density of ß-endorphin fibres was lower in LC and PVN. We surmise that the hyperactivity of the LC and PVN neurones in VCD-treated rats may be a result of the lower progesterone levels that resulted in the decrease of ß-endorphin content in both nuclei, thus impairing the negative-feedback mechanism in the recovery period.

STAT3 but Not ERK2 Is a Crucial Mediator Against Diet-Induced Obesity via VMH Neurons.

Leptin plays an important role in the protection against diet-induced obesity (DIO) by its actions in ventromedial hypothalamic (VMH) neurons. However, little is known about the intracellular mechanisms involved in these effects. To assess the role of the STAT3 and ERK2 signaling in neurons that express the steroidogenic factor 1 (SF1) in the VMH in energy homeostasis, we used cre-lox technology to generate male and female mice with specific disruption of STAT3 or ERK2 in SF1 neurons of the VMH. We demonstrated that the conditional knockout of STAT3 in SF1 neurons of the VMH did not affect body weight, food intake, energy expenditure, or glucose homeostasis in animals on regular chow. However, with high-fat diet (HFD) challenge, loss of STAT3 in SF1 neurons caused a significant increase in body weight, food intake, and energy efficiency that was more remarkable in females, which also showed a decrease in energy expenditure. In contrast, deletion of ERK2 in SF1 neurons of VMH did not have any impact on energy homeostasis in both regular diet and HFD conditions. In conclusion, STAT3 but not ERK2 signaling in SF1 neurons of VMH plays a crucial role in protection against DIO in a sex-specific pattern.

Physiological and Transcriptomic Changes in the Hypothalamic-Neurohypophysial System after 24 h of Furosemide-Induced Sodium Depletion.

BACKGROUND/AIMS: Furosemide is a loop diuretic widely used in clinical practice for the treatment of oedema and hypertension. The aim of this study was to determine physiological and molecular changes in the hypothalamic-neurohypophysial system as a consequence of furosemide-induced sodium depletion. METHODS: Male rats were sodium depleted by acute furosemide injection (10 and 30 mg/kg) followed by access to low sodium diet and distilled water for 24 h. The renal and behavioural consequences were evaluated, while blood and brains were collected to evaluate the neuroendocrine and gene expression responses. RESULTS: Furosemide treatment acutely increases urinary sodium and water excretion. After 24 h, water and food intake were reduced, while plasma angiotensin II and corticosterone were increased. After hypertonic saline presentation, sodium-depleted rats showed higher preference for salt. Interrogation using RNA sequencing revealed the expression of 94 genes significantly altered in the hypothalamic paraventricular nucleus (PVN) of sodium-depleted rats (31 upregulated and 63 downregulated). Out of 9 genes chosen, 5 were validated by quantitative PCR in the PVN (upregulated: Ephx2, Ndnf and Vwf; downregulated: Caprin2 and Opn3). The same genes were also assessed in the supraoptic nucleus (SON, upregulated: Tnnt1, Mis18a, Nr1d1 and Dbp; downregulated: Caprin2 and Opn3). As a result of these plastic transcriptome changes, vasopressin expression was decreased in PVN and SON, whilst vasopressin and oxytocin levels were reduced in plasma. CONCLUSIONS: We thus have identified novel genes that might regulate vasopressin gene expression in the hypothalamus controlling the magnocellular neurons secretory response to body sodium depletion and consequently hypotonic stress.

Anxiety-like behavior and neuroendocrine changes in offspring resulting from gestational post-traumatic stress disorder.

Exposure to stressful environmental events during the perinatal period can increase vulnerability to psychopathologies that cause neuroendocrine changes associated with deficits in emotional behavior that can appear early in life. Post-traumatic stress disorder (PTSD) is a frequent, chronic, and disabling disorder that negatively impacts the emotional, social, and cognitive behaviors of affected individuals. Thus, we induced PTSD in pregnant rats by applying inescapable footshocks and then investigated the behavioral parameters similar to anxiety in offspring at prepubertal age, in addition to the plasma levels of maternal and offspring corticosterone and expression of glucocorticoid receptors (GR) in the offspring's hippocampus. With the dams, maternal behavior, open field, and object recognition tests were performed. With the male and female offspring, we performed the following: quantification of ultrasonic vocalizations, elevated plus-maze test, evaluation of exploratory activity in the open field, and hole board test, as well as plasma corticosterone measurements and Western blotting for GR. Our results showed that gestational PTSD affected maternal behavior, led to anxiety-like symptoms, increased corticosterone levels, and increased GR expression in the offspring's hippocampus. Therefore, our data can contribute to the understanding of the onset of early (childhood and juvenile/pre-pubertal phases) anxiety owing to exposure to a traumatic event during the gestation period.

Effects of endogenous H2S production inhibition on the homeostatic responses induced by acute high-salt diet consumption.

The gaseous modulator hydrogen sulfide (H2S) is synthesized, among other routes, by the action of cystathionine-γ-lyase (CSE) and importantly participates in body fluid homeostasis. Therefore, the present study aimed to evaluate the participation of H2S in behavioral, renal and neuroendocrine homeostatic responses triggered by the acute consumption of a high Na+ diet. After habituation, adult male Wistar rats were randomly distributed and maintained for seven days on a control [CD (0.27% of Na+)] or hypersodic diet [HD (0.81% of Na+)]. CD and HD-fed animals were treated with DL-Propargylglycine (PAG, 25 mg/kg/day, ip) or vehicle (0.9% NaCl in equivalent volume) for the same period. At the end of the experiment, animals were euthanized for blood and tissue collection. We demonstrated that a short-term increase in dietary Na+ intake, in values that mimic the variations in human consumption (two times the recommended) significantly modified hydroelectrolytic homeostasis, with repercussions in the hypothalamic-neurohypophysial system and hypothalamic-pituitary-adrenal axis function. These findings were accompanied by the development of a clear inflammatory response in renal tubular cells and microvascular components. On the other hand, the inhibition of the endogenous production of H2S by CSE provided by PAG treatment prevented the inflammation induced by HD. In the kidney, PAG treatment induced the overexpression of inducible nitric oxide synthase in animals fed with HD. Taken together, these data suggest, therefore, that HD-induced H2S production plays an important proinflammatory role in the kidney, apparently counter regulating nitric oxide actions in renal tissue.

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.