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S. scabra is an important forage and extremophilic plant native to the Brazilian Caatinga semiarid region. It has only recently been subjected to omics-based investigations, and the generated datasets offer insights into biotechnologically significant candidates yet to be thoroughly examined. INSs (inositol and its derivatives) and RFO (raffinose oligosaccharide family) pathways emerge as pivotal candidates, given their critical roles in plant physiology. The mentioned compounds have also been linked to negative impacts on the absorption of nutrients in mammals, affecting overall nutritional intake and metabolism. Therefore, studying these metabolic pathways is important not just for plants but also for animals who depend on them as part of their diet. INS and RFO pathways in S. scabra stood out for their abundance of identified loci and enzymes. The enzymes exhibited genomic redundancy, being encoded by multiple loci and various gene families. The phylogenomic analysis unveiled an expansion of the PIP5K and GolS gene families relative to the immediate S. scabra ancestor. These enzymes are crucial for synthesizing key secondary messengers and the RFO precursor, respectively. Transcriptional control of the studied pathways was associated with DOF-type, C2H2, and BCP1 transcription factors. Identification of biological processes related to INS and RFO metabolic routes in S. scabra highlighted their significance in responding to stressful conditions prevalent in the Caatinga environment. Finally, RNA-Seq and qPCR data revealed the relevant influence of genes of the INS and RFO pathways in the S. scabra response to water deprivation. Our study deciphers the genetics and transcriptomics of the INS and RFO in S. scabra, shedding light on their importance for a Caatinga-native plant and paving the way for future biotechnological applications in this species and beyond.
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The study investigated the effects of 48-h water and feed deprivation on blood and the performance of grazing Nellore (Bos indicus) heifers. Twenty-four Nellore heifers (initial body weight [BW]â =â 238â ±â 10 kg; ageâ =â 16â ±â 2 mo), were ranked by initial BW and age and randomly assigned to one of the two treatments: (1) grazing animals with free access to pasture, water, and mineral-mix (CON; nâ =â 12), or (2) the same grazing conditions but deprived of pasture, water, and mineral-mix for 48 h (DPR; nâ =â 12). The paddocks consisted of Urochloa brizantha cv. Marandu, using a continuous and fixed stocking rate. The experiment lasted 225 d, with the first 14 d considered as the adaptation period (days -14 to -1) and the subsequent 211 d as the evaluation period (days 0 to 211). From days 0 to 2, treatments were applied by keeping the DPR heifers in pens and reintegrating them into the experimental area after a 48-h water and feed deprivation. Individual full BW was recorded on days -14, -13, -1, before (day 0) and after (day 2) treatment application, and on days 6, 11, 12, 41, 42, 210, and 211. Blood samples were collected in the morning on days 0, 2, 6, 12, and 211. A treatment effect was detected (Pâ <â 0.001) for shrink BW from days 0 to 2, which was greater (Pâ <â 0.001) in DPR vs. CON heifers. Subsequently, DPR animals were lighter (Pâ <â 0.001) compared with CON heifers by the end of the deprivation period (day 2). From days 4 to 211, DPR was lighter (Pâ <â 0.001) compared with CON heifers after treatment application and for the entire experimental period. In the first 10 d after treatment application (days 2 to 12), DPR heifers showed a partial compensatory average daily gain (ADG; Pâ <â 0.001) compared with CON heifers, while no significant differences were observed in ADG between the treatments from days 12 to 42 and 42 to 211 (Pâ >â 0.420). Overall ADG (days 2 to 211) was greater (Pâ <â 0.001) for DPR vs. CON heifers. All serum variables, except AST, were higher (Pâ <â 0.001) in DPR than in CON heifers on day 2 after treatment application. Our study demonstrates that grazing Nellore heifers subjected to 48-h water and feed deprivation experienced significant alterations in their blood metabolites and BW immediately after the stressful event. Although the deprived heifers partially compensated for their BW loss in the early days post-deprivation, they remained 12 kg lighter than the non-deprived animals throughout the production cycle.
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Throughout evolution, plants have developed different strategies of responses and adaptations that allow them to survive in different conditions of abiotic stress. Aloe vera (L.) Burm.f. is a succulent CAM plant that can grow in warm, semi-arid, and arid regions. Here, we tested the effects of preconditioning treatments of water availability (100, 50, and 25% of soil field capacity, FC) on the response of A. vera to prolonged drought growing in the hyper-arid core of the Atacama Desert. We studied leaf biomass, biochemical traits, and photosynthetic traits to assess, at different intervals of time, the effects of the preconditioning treatments on the response of A. vera to seven months of water deprivation. As expected, prolonged drought has deleterious effects on plant growth (a decrease of 55-65% in leaf thickness) and photosynthesis (a decrease of 54-62% in Emax). There were differences in the morphophysiological responses to drought depending on the preconditioning treatment, the 50% FC pretreatment being the threshold to better withstand prolonged drought. A diurnal increase in the concentration of malic acid (20-30 mg mg-1) in the points where the dark respiration increased was observed, from which it can be inferred that A. vera switches its C3-CAM metabolism to a CAM idling mode. Strikingly, all A. vera plants stayed alive after seven months without irrigation. Possible mechanisms under an environmental context are discussed. Overall, because of a combination of morphophysiological traits, A. vera has the remarkable capacity to survive under severe and long-term drought, and further holistic research on this plant may serve to produce biotechnological solutions for crop production under the current scenario of climatic emergency.
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Hypothalamic arginine vasopressin (AVP)-containing magnocellular neurosecretory neurons (AVPMNN) emit collaterals to synaptically innervate limbic regions influencing learning, motivational behaviour, and fear responses. Here, we characterize the dynamics of expression changes of two key determinants for synaptic strength, the postsynaptic density (PSD) proteins AMPAR subunit GluA1 and PSD scaffolding protein 95 (PSD95), in response to in vivo manipulations of AVPMNN neuronal activation state, or exposure to exogenous AVP ex vivo. Both long-term water deprivation in vivo, which powerfully upregulates AVPMNN metabolic activity, and exogenous AVP application ex vivo, in brain slices, significantly increased GluA1 and PSD95 expression as measured by western blotting, in brain regions reportedly receiving direct ascending innervations from AVPMNN (i.e., ventral hippocampus, amygdala and lateral habenula). By contrast, the visual cortex, a region not observed to receive AVPMNN projections, showed no such changes. Ex vivo application of V1a and V1b antagonists to ventral hippocampal slices ablated the AVP stimulated increase in postsynaptic protein expression measured by western blotting. Using a modified expansion microscopy technique, we were able to quantitatively assess the significant augmentation of PSD95 and GLUA1 densities in subcellular compartments in locus coeruleus tyrosine hydroxylase immunopositive fibres, adjacent to AVP axon terminals. Our data strongly suggest that the AVPMNN ascending system plays a role in the regulation of the excitability of targeted neuronal circuits through upregulation of key postsynaptic density proteins corresponding to excitatory synapses.
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Sinapses , Tirosina 3-Mono-Oxigenase , Arginina Vasopressina/metabolismo , Hipocampo/metabolismo , Hipotálamo/metabolismo , Sinapses/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Although various studies have investigated osmoadaptations of halophilic fungi to saline conditions, only few analyzed the fungal mechanisms occurring at saturated NaCl concentrations. Halophilic Aspergillus sydowii is a model organism for the study of molecular adaptations of filamentous fungi to hyperosmolarity. For the first time a multi-omics approach (i.e., transcriptomics and metabolomics) was used to compare A. sydowii at saturated concentration (5.13 M NaCl) to optimal salinity (1 M NaCl). Analysis revealed 1,842 genes differentially expressed of which 704 were overexpressed. Most differentially expressed genes were involved in metabolism and signal transduction. A gene ontology multi-scale network showed that ATP binding constituted the main network node with direct interactions to phosphorelay signal transduction, polysaccharide metabolism, and transferase activity. Free amino acids significantly decreased and amino acid metabolism was reprogrammed at 5.13 M NaCl. mRNA transcriptional analysis revealed upregulation of genes involved in methionine and cysteine biosynthesis at extreme water deprivation by NaCl. No modifications of membrane fatty acid composition occurred. Upregulated genes were involved in high-osmolarity glycerol signal transduction pathways, biosynthesis of ß-1,3-glucans, and cross-membrane ion transporters. Downregulated genes were related to the synthesis of chitin, mannose, cell wall proteins, starvation, pheromone synthesis, and cell cycle. Non-coding RNAs represented the 20% of the total transcripts with 7% classified as long non-coding RNAs (lncRNAs). The 42% and 69% of the total lncRNAs and RNAs encoding transcription factors, respectively, were differentially expressed. A network analysis showed that differentially expressed lncRNAs and RNAs coding transcriptional factors were mainly related to the regulation of metabolic processes, protein phosphorylation, protein kinase activity, and plasma membrane composition. Metabolomic analyses revealed more complex and unknown metabolites at saturated NaCl concentration than at optimal salinity. This study is the first attempt to unravel the molecular ecology of an ascomycetous fungus at extreme water deprivation by NaCl (5.13 M). This work also represents a pioneer study to investigate the importance of lncRNAs and transcriptional factors in the transcriptomic response to high NaCl stress in halophilic fungi.
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Recent studies have suggested that glial cells, especially astrocytes, are involved in balanced hydromineral modulation. In response to increased extracellular Na+ concentration, astrocytic Nax channels are activated, promoting lactate production and release. Furthermore, previous in vitro studies have suggested that lactate and hypertonic Na + solution activate SFO GABAergic neurons involved in the salt-appetite central pathways. Here, we evaluated the role of lactate in dehydration-induced sodium and water intake. To this end, intracerebroventricular microinjection (icv) of l-lactate or α-cyano-4-hydroxycinnamic acid (α-CHCA, MCT lactate transporter inhibitor) was performed in rats subjected to 48 h of water deprivation (WD) and 1 h of partial rehydration after 48 h of WD (WD-PR). The rehydration protocol was used to distinguish the mechanisms of thirst and sodium appetite induced by WD. Then, water and sodium (0.3 M NaCl) intake were evaluated for 2 h. Our results showed that central α-CHCA induced an increase in sodium preference in WD rats. Furthermore, central lactate increased water intake but reduced sodium intake in WD-PR animals. In contrast, central lactate transporter inhibition did not change water or sodium intake in WD-PR rats. Our results suggest that lactate is involved in inhibitory mechanisms that induce sodium intake avoidance in dehydrated rats.
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Nephrogenic diabetes insipidus (NDI) is characterized by the inability to concentrate urine that results in polyuria and polydipsia, despite having normal or elevated plasma concentrations of arginine vasopressin (AVP). In this study, we review the clinical aspects and diagnosis of NDI, the various etiologies, current treatment options and potential future developments. NDI has different clinical manifestations and approaches according to the etiology. Hereditary forms of NDI are mainly caused by mutations in the genes that encode key proteins in the AVP signaling pathway, while acquired causes are normally associated with specific drug exposure, especially lithium, and hydroelectrolytic disorders. Clinical manifestations of the disease vary according to the degree of dehydration and hyperosmolality, being worse when renal water losses cannot be properly compensated by fluid intake. Regarding the diagnosis of NDI, it is important to consider the symptoms of the patient and the diagnostic tests, including the water deprivation test and the baseline plasma copeptin measurement, a stable surrogate biomarker of AVP release. Without proper treatment, patients may developcomplications leading to high morbidity and mortality, such as severe dehydration and hypernatremia. In that sense, the treatment of NDI consists in decreasing the urine output, while allowing appropriate fluid balance, normonatremia, and ensuring an acceptable quality of life. Therefore, therapeutic options include nonpharmacological interventions, including sufficient water intake and a low-sodium diet, and pharmacological treatment. The main medications used for NDI are thiazide diuretics, nonsteroidal anti-inflammatory drugs (NSAIDs), and amiloride, used isolated or in combination.
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Diabetes Insípido Nefrogênico , Diabetes Insípido , Diabetes Mellitus , Arginina Vasopressina/genética , Diabetes Insípido Nefrogênico/diagnóstico , Diabetes Insípido Nefrogênico/etiologia , Diabetes Insípido Nefrogênico/terapia , Humanos , Mutação , Poliúria/diagnóstico , Qualidade de VidaRESUMO
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.
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Desidratação , Núcleo Hipotalâmico Paraventricular , Animais , Arginina Vasopressina/metabolismo , Ingestão de Líquidos , Feminino , Gonadotropinas/metabolismo , Gonadotropinas/farmacologia , Ovário/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Ratos , Fatores de TranscriçãoRESUMO
Spontaneously hypertensive rats (SHRs) ingest more NaCl than normotensive strains. Here we investigated NaCl intake and taste reactivity in adult male SHRs and normotensive Holtzman rats treated or not with AT1 receptor antagonist centrally in euhydrated condition and after fluid depletion. Taste reactivity was measured by the number of orofacial expressions to intra-oral infusions of 0.3 M NaCl. In euhydrated condition, intra-oral infusions of 0.3 M NaCl produced greater number of hedonic responses in SHRs than in normotensive rats, without differences in the number of aversive responses. Compared to euhydrated condition, the treatment with the diuretic furosemide + low dose of captopril (angiotensin converting enzyme blocker) increased the number of hedonic and reduced the number of aversive responses to intra-oral NaCl in normotensive rats, without changing the number of hedonic or aversive responses in SHRs. Losartan (AT1 receptor antagonist, 100 ng/1 µl) injected intracerebroventricularly in SHRs abolished 0.3 M NaCl intake induced by water deprivation + partial rehydration, whereas only transiently (first 30 min of the 60 min test) reduced hedonic responses, without changes in aversive responses to intra-oral NaCl. Losartan intracerebroventricularly also only transiently (first 30 min) reduced the number of hedonic responses to intra-oral NaCl in euhydrated SHRs. The results suggest that NaCl palatability is increased and independent from body fluid balance in SHRs. The results also suggest that central AT1 receptors are part of the mechanisms activated to increase NaCl intake and palatability in SHRs. A partial dissociation between NaCl intake and palatability in SHRs is also suggested.
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Captopril , Sódio , Animais , Captopril/farmacologia , Furosemida/farmacologia , Losartan/farmacologia , Masculino , Ratos , Ratos Endogâmicos SHRRESUMO
Water activity (aw) is critical for microbial growth, as it is severely restricted at aw < 0.90. Saturating NaCl concentrations (~5.0 M) induce extreme water deprivation (aw â 0.75) and cellular stress responses. Halophilic fungi have cellular adaptations that enable osmotic balance and ionic/oxidative stress prevention to grow at high salinity. Here we studied the morphology, osmolyte synthesis, and oxidative stress defenses of the halophile Aspergillus sydowii EXF-12860 at 1.0 M and 5.13 M NaCl. Colony growth, pigmentation, exudate, and spore production were inhibited at NaCl-saturated media. Additionally, hyphae showed unpolarized growth, lower diameter, and increased septation, multicellularity and branching compared to optimal NaCl concentration. Trehalose, mannitol, arabitol, erythritol, and glycerol were produced in the presence of both 1.0 M and 5.13 M NaCl. Exposing A. sydowii cells to 5.13 M NaCl resulted in oxidative stress evidenced by an increase in antioxidant enzymes and lipid peroxidation biomarkers. Also, genes involved in cellular antioxidant defense systems were upregulated. This is the most comprehensive study that investigates the micromorphology and the adaptative cellular response of different non-enzymatic and enzymatic oxidative stress biomarkers in halophilic filamentous fungi.
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Background: Central diabetes insipidus (CDI) is an endocrine disorder caused by the failure to produce, transport, orrelease ADH. This disease may show a primary etiology (idiopathic or congenital) or a secondary one (trauma or neoplasms). It is characterized by signs such as polyuria and polydipsia. The definitive diagnosis is obtained by the two-stepwater deprivation test; the absence of adequate urinary concentration in the first stage confirms the diagnosis of diabetesinsipidus and, in the second stage, the response to the application of synthetic desmopressin confirms a central origin.Because CDI is rare in felines, the aim of this study was to report the occurrence of a case of CDI, probably of congenitalprimary origin, in an 8-month-old kitten.Case: An 8-month-old male feline, castrated, 3.2 kg, was brought to consultation with a report of polydipsia, polyuria,smaller size and weight, and lower activity when compared to his brother, for several months. On physical examination,lethargy, body score 2/5, and mild dehydration were noted, as well as deciduous teeth that should have already been replaced. Abdominal ultrasound and laboratory tests were requested, which ruled out chronic kidney disease (CKD), diabetesmellitus (DM), hyperadrenocorticism (HAC), and hyperthyroidism. Due to the fact that urinalysis evidenced hyposthenuria(urinary density [UD] 1.004), CDI was suspected. The patient underwent a water deprivation test and, after 7.5 h, lost4.7% of his initial weight, while UD was 1.012, confirming the diagnosis of DI. The investigation then proceeded to theevaluation of the response to synthetic desmopressin by the application of 5 U IM. Two h later, UD was 1.019, confirming...(AU)
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Animais , Gatos , Diabetes Insípido/diagnóstico , Diabetes Insípido/veterinária , Hipotireoidismo Congênito/veterinária , Desamino Arginina Vasopressina , Poliúria/etiologia , Poliúria/veterinária , Polidipsia/veterináriaRESUMO
Background: Central diabetes insipidus (CDI) is an endocrine disorder caused by the failure to produce, transport, orrelease ADH. This disease may show a primary etiology (idiopathic or congenital) or a secondary one (trauma or neoplasms). It is characterized by signs such as polyuria and polydipsia. The definitive diagnosis is obtained by the two-stepwater deprivation test; the absence of adequate urinary concentration in the first stage confirms the diagnosis of diabetesinsipidus and, in the second stage, the response to the application of synthetic desmopressin confirms a central origin.Because CDI is rare in felines, the aim of this study was to report the occurrence of a case of CDI, probably of congenitalprimary origin, in an 8-month-old kitten.Case: An 8-month-old male feline, castrated, 3.2 kg, was brought to consultation with a report of polydipsia, polyuria,smaller size and weight, and lower activity when compared to his brother, for several months. On physical examination,lethargy, body score 2/5, and mild dehydration were noted, as well as deciduous teeth that should have already been replaced. Abdominal ultrasound and laboratory tests were requested, which ruled out chronic kidney disease (CKD), diabetesmellitus (DM), hyperadrenocorticism (HAC), and hyperthyroidism. Due to the fact that urinalysis evidenced hyposthenuria(urinary density [UD] 1.004), CDI was suspected. The patient underwent a water deprivation test and, after 7.5 h, lost4.7% of his initial weight, while UD was 1.012, confirming the diagnosis of DI. The investigation then proceeded to theevaluation of the response to synthetic desmopressin by the application of 5 U IM. Two h later, UD was 1.019, confirming...
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Animais , Gatos , Desamino Arginina Vasopressina , Diabetes Insípido/diagnóstico , Diabetes Insípido/veterinária , Hipotireoidismo Congênito/veterinária , Polidipsia/veterinária , Poliúria/etiologia , Poliúria/veterináriaRESUMO
Vasopressinergic neurones of the supraoptic (SON) and paraventricular (PVN) nuclei express oestrogen receptor (ER)ß and receive afferent projections from osmosensitive neurones that express ERα. However, which subtype of these receptors mediates the effects of oestradiol on vasopressin (AVP) secretion induced by hydromineral challenge has not yet been demonstrated in vivo. Moreover, AVP secretion induced by hyperosmolality is known to involve activation of TRPV1 (transient receptor potential vanilloid, member 1) in magnocellular neurones, although whether oestradiol modulates expression of this receptor is unknown. Thus, the present study aimed to clarify the mechanisms involved in the modulation exerted by oestradiol on AVP secretion, specifically investigating the involvement of ERß, ERα and TRPV1 receptors in response to water deprivation (WD). We observed that treatment with an ERß agonist potentiated AVP secretion and vasopressinergic neuronal activation induced by WD. This increase in AVP secretion induced by WD was reversed by an ERß antagonist. By contrast to ERß, the ERα agonist did not alter plasma AVP concentrations or activation of AVP neurones in the SON and PVN. Additionally, Fos expression in the subfornical organ was not altered by the ERα agonist. TRPV1 mRNA expression was increased by WD in the SON, although this response was not altered by any treatment. The results of the present study suggest that ERß mediates the effects of oestradiol on AVP secretion in response to WD, indicating that the effects of oestradiol occur directly in AVP neurones without affecting TRPV1.
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Estradiol/farmacologia , Receptor beta de Estrogênio/fisiologia , Neurônios/fisiologia , Vasopressinas/fisiologia , Privação de Água/fisiologia , Animais , Receptor alfa de Estrogênio/agonistas , Receptor alfa de Estrogênio/fisiologia , Receptor beta de Estrogênio/agonistas , Receptor beta de Estrogênio/antagonistas & inibidores , Feminino , Concentração Osmolar , Núcleo Hipotalâmico Paraventricular/química , Núcleo Hipotalâmico Paraventricular/metabolismo , RNA Mensageiro/análise , Ratos , Ratos Wistar , Elastômeros de Silicone , Núcleo Supraóptico/química , Núcleo Supraóptico/metabolismo , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/fisiologia , Vasopressinas/análise , Vasopressinas/sangueRESUMO
Excessive salt intake has been associated with the development or worsening of chronic diseases such as hypertension and spontaneously hypertensive rats (SHR) have a typical increased sodium preference. Estrogens reduce sodium appetite, but we do not know whether such effect relates to alterations in sodium palatability. Here we evaluated the influence of ovarian hormones on orofacial motor responses, an index of palatability, to intra-oral infusion of 0.3â¯M NaCl (IONaCl). Adult female SHR and normotensive Holtzman rats (HTZ) were used. Sodium appetite was produced by water deprivation followed immediately by partial rehydration by drinking water to satiation (WD-PR protocol). Immediately at the end of WD-PR, animals received an IO-NaCl for videotape recording of orofacial motor responses. At the end of IO-NaCl, they had access to two bottles containing 0.3â¯M NaCl and water to ingest (sodium appetite test). Bilateral ovariectomy (OVX) enhanced 0.3â¯M NaCl intake during the sodium appetite test and increased the frequency of orofacial hedonic responses to IO-NaCl in both strains. It had no effect on aversive responses. Estradiol treatment in SHR-OVX decreased hedonic responses and increased aversive responses to IO-NaCl. It also reduced 0.3â¯M NaCl intake during the sodium appetite test, but had no effect on baseline mean arterial pressure and heart rate. The results suggest that ovarian hormones restrain WD-PR-induced sodium appetite by reducing the hedonic properties of sodium taste. The results also suggest that estrogens mediate such reduction, particularly in SHR.
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Estradiol/farmacologia , Cloreto de Sódio/administração & dosagem , Privação de Água , Animais , Feminino , Ovariectomia , Distribuição Aleatória , Ratos Endogâmicos SHR , Ratos Sprague-Dawley , Paladar/fisiologiaRESUMO
NEW FINDINGS: What is the central question of this study? The central goal of this study was to understand the effects of central angiotensin-(1-7) on basal and osmotically stimulated water intake in rats. What is the main finding and its importance? This study demonstrated that central administration of angiotensin-(1-7) did not induce thirst in basal conditions but increased water intake after osmotic stimulation, such as water deprivation and salt loading. These results indicate a new function for this peptide, which, in turn, allows for future research on the mechanisms through which angiotensin-(1-7) influences osmotic thirst. Angiotensin-(1-7) [Ang-(1-7)] is generated by type 2 angiotensin-converting enzyme (ACE2) and binds to the MAS receptor. Although it is well known that Ang-(1-7) functionally antagonizes the effects of the classical renin-angiotensin system in several situations, the role of Ang-(1-7) in hydromineral homeostasis is not clear. The aim of this study was to assess the role of Ang-(1-7) on neuroendocrine responses to hyperosmolality in rats. Male Wistar rats were divided into the following three groups: control; 24 h of water deprivation (WD); and 24 h of salt loading (SL; 1.8% NaCl). Intracerebroventricular (i.c.v.) injections of Ang-(1-7) or vehicle were given to assess water intake and plasma concentration of vasopressin. Additionally, the brains from control and WD groups were collected to evaluate gene expression in the subfornical organ (SFO), paraventricular nucleus (PVN) and supraoptic nucleus (SON). It was found that i.c.v. Ang-(1-7) did not change water and salt intake in control rats; however, Ang-(1-7) increased water intake after WD and SL, with no change in salt intake. Plasma vasopressin was not changed by i.c.v. Ang-(1-7) in control or WD rats. Moreover, WD increased Mas gene expression in the SON and PVN, with no changes in Ace2 mRNA levels. In conclusion, Ang-(1-7) increases thirst after osmotic stimuli, indicating that a previous sensitization to its action is necessary. This finding is consistent with the increased Mas gene expression in the PVN and SON after water deprivation.
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Angiotensina I/administração & dosagem , Ingestão de Líquidos/efeitos dos fármacos , Pressão Osmótica , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Fragmentos de Peptídeos/administração & dosagem , Órgão Subfornical/efeitos dos fármacos , Núcleo Supraóptico/efeitos dos fármacos , Sede/efeitos dos fármacos , Enzima de Conversão de Angiotensina 2 , Animais , Injeções Intraventriculares , Masculino , Núcleo Hipotalâmico Paraventricular/metabolismo , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/metabolismo , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Ratos Wistar , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Cloreto de Sódio/administração & dosagem , Órgão Subfornical/metabolismo , Núcleo Supraóptico/metabolismo , Regulação para Cima , Vasopressinas/sangue , Privação de ÁguaRESUMO
Water deprivation (WD) induces changes in plasma volume and osmolality, which in turn activate several responses, including thirst, the activation of the renin-angiotensin system (RAS) and vasopressin (AVP) and oxytocin (OT) secretion. These systems seem to be influenced by oestradiol, as evidenced by the expression of its receptor in brain areas that control fluid balance. Thus, we investigated the effects of oestradiol treatment on behavioural and neuroendocrine changes of ovariectomized rats in response to WD. We observed that in response to WD, oestradiol treatment attenuated water intake, plasma osmolality and haematocrit but did not change urinary volume or osmolality. Moreover, oestradiol potentiated WD-induced AVP secretion, but did not alter the plasma OT or angiotensin II (Ang II) concentrations. Immunohistochemical data showed that oestradiol potentiated vasopressinergic neuronal activation in the lateral magnocellular PVN (PaLM) and supraoptic (SON) nuclei but did not induce further changes in Fos expression in the median preoptic nucleus (MnPO) or subfornical organ (SFO) or in oxytocinergic neuronal activation in the SON and PVN of WD rats. Regarding mRNA expression, oestradiol increased OT mRNA expression in the SON and PVN under basal conditions and after WD, but did not induce additional changes in the mRNA expression for AVP in the SON or PVN. It also did not affect the mRNA expression of RAS components in the PVN. In conclusion, our results show that oestradiol acts mainly on the vasopressinergic system in response to WD, potentiating vasopressinergic neuronal activation and AVP secretion without altering AVP mRNA expression.
Assuntos
Desidratação/fisiopatologia , Estradiol/uso terapêutico , Estrogênios/uso terapêutico , Neurônios/efeitos dos fármacos , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Núcleo Supraóptico/efeitos dos fármacos , Desequilíbrio Hidroeletrolítico/prevenção & controle , Animais , Arginina Vasopressina/agonistas , Arginina Vasopressina/análise , Arginina Vasopressina/metabolismo , Comportamento Animal/efeitos dos fármacos , Desidratação/terapia , Ingestão de Líquidos/efeitos dos fármacos , Terapia de Reposição de Estrogênios , Feminino , Hidratação , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Ovariectomia/efeitos adversos , Núcleo Hipotalâmico Paraventricular/metabolismo , Núcleo Hipotalâmico Paraventricular/patologia , Área Pré-Óptica/efeitos dos fármacos , Área Pré-Óptica/metabolismo , Área Pré-Óptica/patologia , Ratos Wistar , Órgão Subfornical/efeitos dos fármacos , Órgão Subfornical/metabolismo , Órgão Subfornical/patologia , Núcleo Supraóptico/metabolismo , Núcleo Supraóptico/patologia , Núcleo Vestibular Lateral/efeitos dos fármacos , Núcleo Vestibular Lateral/metabolismo , Núcleo Vestibular Lateral/patologia , Desequilíbrio Hidroeletrolítico/sangue , Desequilíbrio Hidroeletrolítico/etiologia , Desequilíbrio Hidroeletrolítico/fisiopatologiaRESUMO
Animal-based measures of thirst are currently absent from animal welfare monitoring schemes due to the lack of a well-validated indicator applicable for on-farm use. In the present study, an on-farm test based on voluntary water consumption from an unfamiliar open drinker was validated in a (semi-)commercial setting. To investigate the effect of thirst on water consumption, we subjected 4 flocks of 1,500 broilers to either 0 or 12 h of water deprivation and subsequently measured the amount of water that small subgroups consumed after the deprivation period (first experiment). Broilers that were water deprived before the test drank more than control broilers (P < 0.001). In a second experiment, a similar test was performed using 20 commercial broiler flocks in Belgium and Brazil. After a pretreatment water consumption test, the birds were subjected to 0 or 6 h of water deprivation, and a posttreatment water consumption test was conducted. Only in Brazil, deprived birds drank significantly more than controls in the posttreatment water consumption test (P < 0.001). A tendency for a difference was found in Belgium (P = 0.083). Pre- and posttreatment water consumption was higher in Brazil than in Belgium (P < 0.001). Stocking density and temperature influenced, respectively, the pretreatment and the control's posttreatment water consumption in Brazil, but not in Belgium. These results indicate that the water consumption test is sufficiently sensitive to discriminate between control and 12 h deprived flocks, and in Brazil even between control and 6 h deprived birds. The location of the test within the house did not affect the amount of water consumed in either experiment, suggesting that this variable does not have to be standardized. However, the amount of water consumed by broilers able to drink freely for a long period depended on indoor climatic variables (in Brazil only) and possibly genotype. This suggests that these variables need to be considered when interpreting the test outcome in terms of the thirst level experienced by the broilers.
Assuntos
Criação de Animais Domésticos/métodos , Galinhas/fisiologia , Ingestão de Líquidos , Sede , Privação de Água/fisiologia , Bem-Estar do Animal , Animais , Bélgica , BrasilRESUMO
Conflicting results have been obtained by several groups when studying the effects of streptozotocin (STZ)-treated rats in the elevated plus-maze (EPM). Since thirst is a prominent feature in STZ-induced diabetic-like condition, we studied whether the walls of the closed arms of the EPM, by limiting the search for water in the environment, may contribute to the observed differential behavioral outcomes. The aim of this study was to ascertain whether visual barriers within the EPM have an influence on the behavior of STZ-treated rats in this test of anxiety. A striking similarity between STZ-treated (50 mg/kg, i.p., in two consecutive days) and water deprived rats (72 h) was found in exploratory behavior in the EPM, showing an anxiolytic-like profile. However the anxiolytic response of STZ-treated rats exposed to the EPM shifts into an anxiogenic profile when they are subsequently tested in the open-field test, which unlike the EPM is devoid of visual barriers. Likewise, water deprived rats (72 h) also showed an anxiogenic profile when they were exposed to the open-field test. Our results indicate that experimental outcomes based on EPM observations can be misleading when studying physiological or pathological conditions, e.g. diabetes, in which thirst may increase exploratory behavior.
Assuntos
Ansiedade/psicologia , Comportamento Animal/fisiologia , Diabetes Mellitus Experimental/psicologia , Comportamento Exploratório/fisiologia , Sede/fisiologia , Animais , Glicemia/metabolismo , Peso Corporal/fisiologia , Ingestão de Líquidos , Masculino , Ratos , Ratos Wistar , Privação de Água/fisiologiaRESUMO
The effects of the in vivo administration of baclofen on renal tubular transport and aquaporin-2 (AQP2) expression were evaluated. In conscious animals kept in metabolic cages, baclofen (0.01-1mg/kg, s.c.) induced a dose-dependent increment in the urine flow rate (UFR) and in sodium and potassium excretion, associated with an increased osmolal clearance (Closm), a diminished urine to plasma osmolality ratio (Uosm/Posm) and a decrease in AQP2 expression. The above mentioned baclofen effects on functional parameters were corroborated by using conventional renal clearance techniques. Additionally, this model allowed the detection of a diminution in glucose reabsorption. Some experiments were performed with water-deprived or desmopressin-treated rats kept in metabolic cages. Either water deprivation or desmopressin treatment decreased the UFR and increased the Uosm/Posm. Baclofen did not change the Uosm/Posm or AQP2 expression in desmopressin-treated rats; but it increased the UFR and diminished the Uosm/Posm and AQP2 expression in water-deprived animals. These results indicate that in vivo administration of baclofen promotes alterations in proximal tubular transport, since glucose reabsorption was decreased. The distal tubular function was also affected. The increased Closm indicates an alteration in solute reabsorption at the ascending limb of the Henle's loop. The decreased Uosm/Posm and AQP2 expression in controls and in water-deprived, but not in desmopressin-treated rats, lead us to speculate that some effect of baclofen on endogenous vasopressin availability could be responsible for the impaired urine concentrating ability, more than any disturbance in the responsiveness of the renal cells to the hormone.
Assuntos
Baclofeno/administração & dosagem , Baclofeno/farmacologia , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/fisiologia , Animais , Aquaporina 2/metabolismo , Estado de Consciência , Desamino Arginina Vasopressina/farmacologia , Relação Dose-Resposta a Droga , Regulação da Expressão Gênica/efeitos dos fármacos , Túbulos Renais/metabolismo , Masculino , Ratos , Ratos Wistar , Água/metabolismoRESUMO
Prenatal stresses such as water deprivation affect developmental process of embryo. This study evaluated the effects of water deprivation in pregnant mother on histological parameters of testis of offspring. Pregnant rats were divided into two groups (control and experimental). In experimental animals, water was removed from the ewes for 48h at the end of third trimester of gestation (19-21th days). Histopathology and histomorphic analysis and also TUNEL assay on offspring's testes were performed at pubertal age (60 days). The sperm motility either compared between two groups. The results showed that prenatal water deprivation induced histopathological alteration such as epithelium vacuolization, sloughing and detachments (P<0.01). Morphometrical data showed that prenatal water deprivation decreased tubular diameter and reduce epithelium height (P<0.01). Johnsen's score showed poor spermatogenesis in experimental group (P=0.001). The percent of germ cell apoptosis was increased in offspring's testes of rats born to mothers exposed to stress during pregnancy (P=0.000). The increased number of Multinucleated cells in the seminiferous lumen (P=0.000) in parallel with decreased number of sertoli cells (P=0.03) showed adverse effect of prenatal water deprivation on blood testis barrier. Present study revealed that prenatal water deprivation had injurious effect on developmental process of testes that affects on both germ cells and sertoli cells and had noxious effect on sperm parameters. These data confirm that prenatal stress disrupts normal spermatogenesis of offspring.
El estrés prenatal, como la privación del agua, afecta el proceso de desarrollo embrionario. Este estudio evaluó los efectos de la falta de agua en la rata preñada sobre los parámetros histológicos del testículo de las crías. Las ratas preñadas fueron divididas en dos grupos (control y experimental). En los animales de experimentación, se eliminó el agua durante 48 h al final del término de la gestación (19-21 días). Junto al análisis histopatológico e histomorfométrico se realizó el ensayo TUNEL en los testículos de las crías en la edad puberal (60 días). La motilidad de los espermatozoides se comparó entre los dos grupos. Los resultados mostraron que la privación de agua prenatal induce alteraciones histopatológicas tales como vacuolización del epitelio, descamación y desunión (P<0,01). Los datos morfométricos mostraron que con la privación de agua prenatal hubo disminución del diámetro tubular y se redujo la altura del epitelio (P<0,01). El score de Johnsen mostró una espermatogénesis deficiente en el grupo experimental (p = 0,001). El porcentaje de apoptosis de las células germinales se incrementó en los testículos de las crías de las ratas nacidas de madres expuestas a estrés durante el embarazo (p = 0,000). Un aumento del número de células multinucleadas en el lumen seminífero (P = 0,000) junto a la disminución del número de células de Sustento (P = 0,03) demostró el efecto adverso de la privación de agua prenatal en la barrera hemato-testicular. El presente estudio reveló que la falta de agua prenatal tuvo un efecto perjudicial en el proceso de desarrollo de los testículos, lo que afecta a las células germinales y los sustentocitos, y tuvo un efecto nocivo sobre los parámetros seminales. Estos datos confirman que el estrés prenatal altera la espermatogénesis normal de la descendencia.