Subacute and sublethal ingestion of microcystin-LR impairs lung mitochondrial function by an oligomycin-like effect.

Microcystin-LR (MC-LR) is a potent cyanotoxin that can reach several organs. However subacute exposure to sublethal doses of MC-LR has not yet well been studied. Herein, we evaluated the outcomes of subacute and sublethal MC-LR exposure on lungs. Male BALB/c mice were exposed to MC-LR by gavage (30 µg/kg) for 20 consecutive days, whereas CTRL mice received filtered water. Respiratory mechanics was not altered in MC-LR group, but histopathology disclosed increased collagen deposition, immunological cell infiltration, and higher percentage of collapsed alveoli. Mitochondrial function was extensively affected in MC-LR animals. Additionally, a direct in vitro titration of MC-LR revealed impaired mitochondrial function. In conclusion, MC-LR presented an intense deleterious effect on lung mitochondrial function and histology. Furthermore, MC-LR seems to exert an oligomycin-like effect in lung mitochondria. This study opens new perspectives for the understanding of the putative pulmonary initial mechanisms of damage resulting from oral MC-LR intoxication.

Acute exposure to C60 fullerene damages pulmonary mitochondrial function and mechanics.

C60 fullerene (C60) nanoparticles, a nanomaterial widely used in technology, can offer risks to humans, overcome biological barriers, and deposit onto the lungs. However, data on its putative pulmonary burden are scanty. Recently, the C60 interaction with mitochondria has been described in vitro and in vivo. We hypothesized that C60 impairs lung mechanics and mitochondrial function. Thirty-five male BALB/c mice were randomly divided into two groups intratracheally instilled with vehicle (0.9% NaCl + 1% Tween 80, CTRL) or C60 (1.0 mg/kg, FUL). Twenty-four hours after exposure, 15 FUL and 8 CTRL mice were anesthetized, paralyzed, and mechanically ventilated for the determination of lung mechanics. After euthanasia, the lungs were removed en bloc at end-expiration for histological processing. Lung tissue elastance and viscance were augmented in FUL group. Increased inflammatory cell number, alveolar collapse, septal thickening, and pulmonary edema were detected. In other six FUL and six CTRL mice, mitochondria expressed reduction in state 1 respiration [FUL = 3.0 ± 1.14 vs. CTRL = 4.46 ± 0.9 (SEM) nmol O2/min/mg protein, p = 0.0210], ATP production (FUL = 122.6 ± 18 vs. CTRL = 154.5 ± 14 µmol/100 µg protein, p = 0.0340), and higher oxygen consumption in state 4 [FUL = 12.56 ± 0.9 vs. CTRL = 8.26 ± 0.6], generation of reactive oxygen species (FUL 733.1 ± 169.32 vs. CTRL = 486.39 ± 73.1 nmol/100 µg protein, p = 0.0313) and reason ROS/ATP [FUL = 8.73 ± 2.3 vs. CTRL = 2.99 ± 0.3]. In conclusion, exposure to fullerene C60 impaired pulmonary mechanics and mitochondrial function, increased ROS concentration, and decrease ATP production.

Many unique characteristics revealed by the complete mitochondrial genome of the scorpion Tityus serrulatus (Lutz e Mello 1922) (Chelicerata; Arachnida).

This is the first complete mitochondrial genome of a Tityus species, although it is the most medically important genus in South America. Tityus serrulatus (Brazilian yellow scorpion) mtDNA revealed the same gene arrangement of three out of four other mitogenomes published by now for the same family (Centruroides limpidus, Mesobuthus gibbosus, M. martensii and Buthus occitanus). However, it presented many unique characteristics such as possession of Cox1 gene, different from all other protein-coding genes of scorpion mtDNA, starts with an atypical start codon (CTG). Moreover, no tRNA gene have complete typical secondary structure and the Tytius genome presented three non-coding regions longer than 100bp. Also, it contains the smallest scorpion 16S gene reported by now. Phylogenetic analysis using concatenated homologous genes confirmed Buthidae as a monophyletic clade and supports a monophyletic group including T. serrulatus and the other American species, C. limpidus.

Fetal kidney programming by maternal smoking exposure: effects on kidney structure, blood pressure and urinary sodium excretion in adult offspring.

INTRODUCTION: Fetal programming by different insults results in low birth weight and reduction in nephron number increasing the risk for adult development of cardiovascular and renal diseases. Maternal smoking is an important modifiable adverse fetal exposure worldwide and leads to a decrease in the offspring's birth weight. Thus far, the specific adverse fetal smoking exposures and mechanisms underlying these associations on renal development and functional disorder are unclear. METHODS: The present study investigates, in adult male rats, the effect of smoking exposure (Sk) in uteri on blood pressure (BP) by an indirect tail-cuff method using an electrosphygmomanometer, and its association with nephron structure by stereological estimation, immunohistochemical and histological techniques, in parallel with kidney function creatinine and lithium clearance. RESULTS: The current study showed in a 16-week old Sk offspring enhanced arterial blood pressure associated with, reduced urinary sodium excretion and higher TGF-ß1 glomerular expression. Sk glomeruli also presented an upregulated collagen and fibronectin deposition intrinsically related to fibrotic process as compared to age-matched control group. CONCLUSION: Here, we demonstrate that fetal-programmed Sk offspring present pronounced glomerular TGF-ß1 and fibrotic marker expression that may, subsequently, promote a glomerular epithelial-mesenchymal transition activated process in an Sk offspring. Although the precise mechanism responsible for the subsequently renal morphological and functional response in Sk offspring is incompletely known, the current data suggest that changes in renal function are conducive to excess sodium tubule reabsorption that is associated with enhanced TGF-ß1, fibronectin and collagen deposition, intrinsically related to fibrotic process, might potentiate the programming of adult hypertension.

Cue-based and algorithmic learning in common carp: A possible link to stress coping style.

Common carp that had been screened for stress coping style using a standard behavioural test (response to a novel environment) were given a learning task in which food was concealed in one of two compartments, its location randomised between trials and its presence in a given compartment signalled by either a red or a yellow light. All the fish learned to find food quickly, but did so in different ways. Fifty five percent learned to use the light cue to locate food; the remainder achieved the same result by developing a fixed movement routine. To explore this variation, we related learning strategy to stress coping style. Time to find food fell identically with successive trials in carp classified as reactive or proactive, but reactive fish tended to follow the light cue and proactive fish to adopt a fixed routine. Among fish that learned to follow the light, reactive individuals took fewer trials to reach the learning criterion than did proactive fish. These results add to the growing body of information on within-species variation in learning strategies and suggest a possible influence of stress coping style on the use of associative learning as opposed to algorithmic searching during foraging.

Impact of taurine supplementation on blood pressure in gestational protein-restricted offspring: Effect on the medial solitary tract nucleus cell numbers, angiotensin receptors, and renal sodium handling.

OBJECTIVE: The current study considers changes of the postnatal brainstem cell number and angiotensin receptors by maternal protein restriction (LP) and LP taurine supplementation (LPT), and its impact on arterial hypertension development in adult life. METHODS AND RESULTS: The brain tissue studies were performed by immunoblotting, immunohistochemistry, and isotropic fractionator analysis. The current study shows that elevated blood pressure associated with decreased fractional urinary sodium excretion (FENa) in adult LP offspring was reverted by diet taurine supplementation. Also, that 12-day-old LP pups present a reduction of 21% of brainstem neuron counts, and, immunohistochemistry demonstrates a decreased expression of type 1 angiotensin II receptors (AT1R) in the entire medial solitary tract nuclei (nTS) of 16-week-old LP rats compared to age-matched NP and LPT offspring. Conversely, the immunostained type 2 AngII (AT2R) receptors in 16-week-old LP nTS were unchanged. CONCLUSION: The present investigation shows a decreased FENa that occurs despite unchanged creatinine clearance. It is plausible to hypothesize an association of decreased postnatal nTS cell number, AT1R/AT2R ratio and FENa with the higher blood pressure levels found in taurine-deficient progeny (LP) compared with age-matched NP and LPT offspring.

Fetal kidney programming by severe food restriction: effects on structure, hormonal receptor expression and urinary sodium excretion in rats.

INTRODUCTION: The present study investigates, in 23-day-old and adult male rats, the effect of severe food restriction in utero on blood pressure (BP), and its association with nephron structure and function changes, angiotensin II (AT1R/AT2R), glucocorticoid (GR) and mineralocorticoid (MR) receptor expression. MATERIALS AND METHODS: The daily food supply to pregnant rats was measured and one group (n=15) received normal quantity of food (NF) while the other received 50% of that (FR50%) (n=15). Kidneys were processed to AT1R, AT2R, MR, and GR immunolocalization and for western blotting analysis. The renal function was estimated by creatinine and lithium clearances in 12-week-old offspring. RESULTS: By stereological analyses, FR50% offspring present a reduction of nephron numbers (35%) with unchanged renal volume. Expression of AT1R and AT2R was significantly decreased in FR50% while the expression of GR and MR increased in FR50%. We also verified a pronounced decrease in urinary sodium excretion accompanied by increased BP in 12-week-old FR50% offspring. CONCLUSION: The current data suggest that changes in renal function are conducive to excess sodium tubule reabsorption, and this might potentiate the programming of adult hypertension. It is plausible to arise in the current study an association between decreasing natriuresis, reciprocal changes in renal AngII and steroid receptors with the hypertension development found in FR50% compared with age-matched NF offspring.

Involvement of renal corpuscle microRNA expression on epithelial-to-mesenchymal transition in maternal low protein diet in adult programmed rats.

Prior study shows that maternal protein-restricted (LP) 16-wk-old offspring have pronounced reduction of nephron number and arterial hypertension associated with unchanged glomerular filtration rate, besides enhanced glomerular area, which may be related to glomerular hyperfiltration/overflow and which accounts for the glomerular filtration barrier breakdown and early glomerulosclerosis. In the current study, LP rats showed heavy proteinuria associated with podocyte simplification and foot process effacement. TGF-ß1 glomerular expression was significantly enhanced in LP. Isolated LP glomeruli show a reduced level of miR-200a, miR-141, miR-429 and ZEB2 mRNA and upregulated collagen 1α1/2 mRNA expression. By western blot analyzes of whole kidney tissue, we found significant reduction of both podocin and nephrin and enhanced expression of mesenchymal protein markers such as desmin, collagen type I and fibronectin. From our present knowledge, these are the first data showing renal miRNA modulation in the protein restriction model of fetal programming. The fetal-programmed adult offspring showed pronounced structural glomerular disorders with an accentuated and advanced stage of fibrosis, which led us to state that the glomerular miR-200 family would be downregulated by TGF-ß1 action inducing ZEB 2 expression that may subsequently cause glomeruli epithelial-to-mesenchymal transition.

Early changes of hypothalamic angiotensin II receptors expression in gestational protein-restricted offspring: effect on water intake, blood pressure and renal sodium handling.

The current study examines changes in the postnatal hypothalamic angiotensin receptors by maternal protein restriction (LP), and its impact on in uteri programming of hypertension in adult life. The data show that LP male pup body weight was significantly reduced when compared to that of control (NP) pups. Also, immunoblotting analysis demonstrated a significantly decreased expression of type 1 AngII receptors (AT1R) in the entire hypothalamic tissue extract of LP rats at 12 days of age compared to age-matched NP offspring. Conversely, the expression of the type 2 AngII (AT2R) receptors in 12-day- and 16-week-old LP hypothalamus was significantly increased. The current data show the influence of central AngII administration on water consumption in a concentration-dependent fashion, but also demonstrate that the water intake response to AngII was strikingly attenuated in 16-week-old LP. These results may be related to decreased brain arginine vasopressin (AVP) expression appearing in maternal protein-restricted offspring. The present investigation shows an early decrease in fractional urinary sodium excretion in maternal protein-restricted offspring. The decreased fractional sodium excretion was accompanied by a fall in proximal sodium excretion and occurred despite unchanged creatinine clearance. These effects were associated with a significant enhancement in arterial blood pressure in the LP group, but the precise mechanism of these phenomena remains unknown.

Long-term exercise attenuates blood pressure responsiveness and modulates kidney angiotensin II signalling and urinary sodium excretion in SHR.

Observations have been made regarding the effects of long-term exercise training on blood pressure, renal sodium handling and renal renin-angiotensin-aldosterone (RAS) intracellular pathways in conscious, trained Okamoto-Aoki spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKy) normotensive rats, compared with appropriate age-matched sedentary SHR and WKy. To evaluate the influence of exercise training on renal function and RAS, receptors and intracellular angiotensin II (AngII) pathway compounds were used respectively, and lithium clearance and western blot methods were utilised. The current study demonstrated that increased blood pressure in SHR was blunted and significantly reduced by long-term swim training between the ages of 6 and 16 weeks. Additionally, the investigators observed an increased fractional urinary sodium excretion in trained SHR (SHR(T)) rats, compared with sedentary SHR (SHR(S)), despite a significantly decreased creatinine clearance (C(Cr)). Furthermore, immunoblotting analysis demonstrated a decreased expression of AT1(R) in the entire kidney of T(SHR) rats, compared with S(SHR). Conversely, the expression of the AT2(R), in both sedentary and trained SHR, was unchanged. The present study may indicate that, in the kidney, long-term exercise exerts a modulating effect on AngII receptor expression. In fact, the present study indicates an association of increasing natriuresis, reciprocal changes in renal AngII receptors and intracellular pathway proteins with the fall in blood pressure levels observed in T(SHR) rats compared with age-matched S(SHR) rats.

Early potential impairment of renal sensory nerves in streptozotocin-induced diabetic rats: role of neurokinin receptors.

BACKGROUND: Electrophysiological studies in the mammalian kidney have identified two major classes of sensory receptors of the afferent renal nerves; chemoreceptors (CR) and mechanoreceptors (MR). The localization of calcitonin gene-related peptide (CGRP) and substance P (SP) in these renal pelvic sensory neurons provides an anatomical basis for a possible functional interaction between the two neuropeptides and SP receptor. The present study was performed to examine the possible changes in the responsiveness of renal sensory SP and CGRP receptors in rats with streptozotocin (STZ)-induced diabetes mellitus. Due to the crucial role of renal pelvic SP and CGRP receptors in the activation of renal sensory neurons by various stimuli, we examined whether the responsiveness of MR or CR activation and the dorsal root ganglia content of neuropeptides and neurokinin 1 receptors (NK(1)R) were altered in diabetic rats compared with non-diabetic rats. METHODS: Afferent renal nerve activity (ARNA) was recorded from the peripheral portion of the cut end of one renal nerve branch placed on a bipolar silver wire electrode. T(13) dorsal root ganglia (DRG) immunoreactivity was performed to NK(1)R, SP and CGRP. RESULTS: The results of the current study confirmed that the stimulation of renal MR and CR elicited a renorenal reflex response, and that the renal pelvic administration of SP and CGRP increased ipsilateral ARNA and contralateral urinary sodium excretion with no changes in arterial pressure. We also found a decrease in NK(1)R expression followed by an increase in SP and CGRP levels in the DRG of diabetic rats. The ARNA response, produced by renal pelvic MR and CR stimulation, was found to be significantly attenuated in the STZ-induced diabetic model. Conclusions. These data may indicate a compensatory synthesis and/or abnormal axonal delivery of neurokinins from the cell body to synaptic portions of the neuron as the underlying reason for attenuated ARNA in renal sensory neurons of diabetic rats.

Expression of renin-angiotensin system signalling compounds in maternal protein-restricted rats: effect on renal sodium excretion and blood pressure.

BACKGROUND: Intrauterine growth restriction due to low maternal dietary protein during pregnancy is associated with retardation of foetal growth, renal alterations and adult hypertension. The renin-angiotensin system (RAS) is a coordinated hormonal cascade in the control of cardiovascular, renal and adrenal function that governs body fluid and electrolyte balance, as well as arterial pressure. In the kidney, all the components of the renin-angiotensin system including angiotensin II type 1 (AT1) and type 2 (AT2) receptors are expressed locally during nephrogenesis. Hence, we investigated whether low protein diet intake during pregnancy altered kidney and adrenal expression of AT1(R) and AT2(R) receptors, their pathways and if the modified expression of the RAS compounds occurs associated with changes in urinary sodium and in arterial blood pressure in sixteen-week-old males' offspring of the underfed group. METHODS: The pregnancy dams were divided in two groups: with normal protein diet (pups named NP) (17% protein) or low protein diet (pups LP) (6% protein) during all pregnancy. RESULTS: The present data confirm a significant enhancement in arterial pressure in the LP group. Furthermore, the study showed a significantly decreased expression of RAS pathway protein and Ang II receptors in the kidney and an increased expression in the adrenal of LP rats. The detailed immunohistochemical analysis of RAS signalling proteins in the kidney confirm the immunoblotting results for both groups. The present investigation also showed a pronounced decrease in fractional urinary sodium excretion in maternal protein-restricted offspring, compared with the NP age-matched group. This occurred despite unchanged creatinine clearance. CONCLUSIONS: The current data led us to hypothesize that foetal undernutrition could be associated with decreased kidney expression of AT(R) resulting in the inability of renal tubules to handle the hydro-electrolyte balance, consequently causing arterial hypertension.

Thymus hyperplasia after resolution of hypercortisolism in ACTH-dependent Cushing's syndrome: the importance of thymic vein catheterization.

Thymic hyperplasia has been described after the resolution of hypercortisolism from several etiologies, causing great diagnostic dilemmas. We describe a case where the catheterization of the thymic vein was essential for the differential diagnosis of a thymic enlargement in an adrenalectomized patient with ACTH-dependent Cushing's syndrome. The patient was a 48-year-old female with clinical and laboratorial data suggesting Cushing's disease. She underwent a transsphenoidal surgery with no tumor visualization and no remission of the syndrome. Histopathological studies disclosed a normal pituitary. She underwent a bilateral adrenalectomy and 8 months later a chest CT showed an increase of left thymic lobe, which was previously non-existent. After a negative (111)In-pentetreotide scintigraphy, the patient underwent simultaneous and bilateral catheterism of the petrosus sinuses and catheterization of the thymic and inominate veins and no ACTH gradient was shown among the sites of collection. She did not undergo thoracotomy and a follow-up was established. During the evolution, there was a spontaneous regression of the thymic lesion 38 months after the diagnosis. The ACTH gradient during the catheterization of thymic vein was essential for the differential diagnosis of the thymic enlargement tumor after hypercortisolism resolution in ACTH-dependent Cushing's syndrome, especially in this case, where the ACTH source was occult, thus avoiding an invasive surgical procedure for a benign entity with spontaneous resolution.