Prenatal exposure to high level of glucocorticoids increases the susceptibility of renal proximal tubular cells to apoptosis induced by uropathogenic Escherichia coli toxins

Role of purinergic signaling pathways in the adaptogenic-like activity of methyl jasmonate in rats exposed to unpredictable chronic mild stress

Objectives Purinergic signaling pathway has been implicated in maladaptation of animals subjected to chronic stress. Previous studies have shown that methyl jasmonate (MJ) exhibited adaptogenic properties in mice exposed to unpredictable chronic mild stress (UCMS) via antioxidant and neuroprotective-related mechanisms. Methods This study evaluated the role of purinergic system in adaptogenic-like activity of MJ. Male Wistar rats were treated intraperitoneally with vehicle (10 mL/kg) or MJ (25, 50, or 100 mg/kg) 30 min prior exposure to UCMS. Thereafter, rats were assessed for swimming endurance in forced swim test (FST) and post-swimming motor coordination on beam walk test (BWT) apparatus. The rats' brains were processed for adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine deaminase, and arginase quantification. Hematological parameters, cholesterol, triglyceride, creatinine, and urea nitrogen were also determined. Results MJ prolonged swimming endurance time and reversed stress-induced post-swimming motor dysfunction. The altered hematological parameters induced by UCMS in rats were significantly (p<0.05) attenuated by MJ. MJ also reversed UCMS-induced alterations of total cholesterol, triglyceride, creatinine, and urea nitrogen levels. MJ averted UCMS-induced alterations in purinergic system by decreasing ATP and ADP hydrolysis, adenosine deaminase, and arginase activities in rats' brains. Conclusions Overall, these findings further suggest that MJ has adaptogenic-like activity in rats exposed to UCMS, which may be related to modulation of the purinergic signaling pathway.

Role of purinergic signaling pathways in the adaptogenic-like activity of methyl jasmonate in rats exposed to unpredictable chronic mild stress

Objectives Purinergic signaling pathway has been implicated in maladaptation of animals subjected to chronic stress. Previous studies have shown that methyl jasmonate (MJ) exhibited adaptogenic properties in mice exposed to unpredictable chronic mild stress (UCMS) via antioxidant and neuroprotective-related mechanisms. Methods This study evaluated the role of purinergic system in adaptogenic-like activity of MJ. Male Wistar rats were treated intraperitoneally with vehicle (10 mL/kg) or MJ (25, 50, or 100 mg/kg) 30 min prior exposure to UCMS. Thereafter, rats were assessed for swimming endurance in forced swim test (FST) and post-swimming motor coordination on beam walk test (BWT) apparatus. The rats' brains were processed for adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine deaminase, and arginase quantification. Hematological parameters, cholesterol, triglyceride, creatinine, and urea nitrogen were also determined. Results MJ prolonged swimming endurance time and reversed stress-induced post-swimming motor dysfunction. The altered hematological parameters induced by UCMS in rats were significantly (p<0.05) attenuated by MJ. MJ also reversed UCMS-induced alterations of total cholesterol, triglyceride, creatinine, and urea nitrogen levels. MJ averted UCMS-induced alterations in purinergic system by decreasing ATP and ADP hydrolysis, adenosine deaminase, and arginase activities in rats' brains. Conclusions Overall, these findings further suggest that MJ has adaptogenic-like activity in rats exposed to UCMS, which may be related to modulation of the purinergic signaling pathway.

Leptin promotes fetal lung maturity and upregulates SP-A expression in pulmonary alveoli type-II epithelial cells involving TTF-1 activation

The placental hormone leptin has important functions in fetal and neonatal growth, and prevents depressed respiration in leptin-deficient mice. The effect of leptin on respiratory distress suffered by low birth weight and premature infants has been studied. However, it is unclear how leptin enhances lung maturity in the fetus and ameliorates neonatal respiratory distress. In the present study, we found that antenatal treatment with leptin for 2 d significantly enhanced the relative alveolus area and improved the maturity of fetal lungs in a rat model of fetal growth restriction (FGR). Mean birth weight and lung wet weight were higher in the leptin-treated group than in the PBS-treated group, indicating promotion of fetal growth. Leptin upregulated the intracellular expression and extracellular secretion of surfactant protein (SP) A in type-II alveolar epithelial cells (AECs) in vivo and in vitro. Dual positive effects of leptin were found on protein expression and transcriptional activity of thyroid transcription factor-1 (TTF-1), a nuclear transcription essential for branching morphogenesis of the lung and expression of SP-A in type-II AECs. Knockdown of TTF-1 by RNA interference indicated that TTF-1 may play a vital role in leptin-induced SP-A expression. These results suggest that leptin may have great therapeutic potential for the treatment of FGR, and leptin-mediated SP-A induction and lung maturity of the fetus are TTF-1 dependent.

Effects of immobilization stress on kidneys of Wistar male rats: a morphometrical and stereological analysis

This paper verifies the morphological changes induced by immobilization stress on the kidney of rats by using stereological methods. Fifteen 4-week-old Wistar male rats were randomly assigned to control (n = 7) and stressed (n = 8) groups. Stress stimuli were performed over 5 weeks by immobilization of the rats for 2 h daily in a rigid opaque plastic cylinder that restrained their movements. Increases in the adrenal mass index (p < 0.05) and decreases in serum testosterone levels (p < 0.05) demonstrated the efficacy of the stressor stimuli. Stressed rats presented diminished body weight gain when compared to controls (p < 0.05). The mean values of kidney weight, kidney volume, kidney volume index and glomerular volume density were significantly lower in the stressed group (p < 0.05); nevertheless, no significant difference was found in the cortical/medullar ratio or in the volume-weighted mean glomerular volume. The number of glomeruli per kidney was 45% lower in the stressed group (p < 0.0001), but no change in serum creatinine levels was found. However, the morphological alterations may have serious implications predisposing individuals to renal disease and hypertension in adult life.

Prenatal dexamethasone exposure in the common marmoset monkey enhances gene expression of antioxidant enzymes in the aorta of adult offspring

Human epidemiological studies have indicated that low birth weight associated with an adverse intrauterine environment is related to a greater incidence of cardiovascular disorders in later life. In the foetus, endogenous glucocorticoids generally increase if there is intrauterine nutrient deficiency. The consequent glucocorticoid hyperexposure has been hypothesised to cause in utero programming of atherogenic genes. We investigated the effect of oral treatment with the synthetic glucocorticoid dexamethasone during early or late pregnancy in marmoset monkeys on oxidative and antioxidant status in the offspring. Urinary concentrations of F(2)-isoprostanes were quantified as markers for in vivo oxidative stress. Expression of the mRNAs for the antioxidant enzymes cytosolic glutathione peroxidase (GPx-1), phospholipid hydroperoxide glutathione peroxidase (GPx-4), cytosolic Cu,Zn-superoxide dismutase (SOD1), mitochondrial Mn-superoxide dismutase (SOD2), glutathione reductase (GSR), modifier subunit of glutamate-cysteine ligase (GCLM) and catalase were determined in the aorta. Three groups of pregnant marmosets (10 animals per group) were treated orally for one week with vehicle, or with dexamethasone (5 mg/kg daily) during two gestation windows: early dexamethasone group, pregnancy day 42-48, and late dexamethasone group, pregnancy day 90-96. In one male sibling of each litter (10 males per group), aortas were taken at 2 years of age. In the late dexamethasone group a higher aortic mRNA expression for GPx-1 (p < 0.023), MnSOD (p < 0.016), GCLM (p < 0.019) and GSR (p < 0.014) in comparison to the controls was observed. Aortic expression in the early dexamethasone group was statistically significantly higher only for GSR mRNA (p < 0.038). No significant changes in urinary F(2)-isoprostane concentrations between controls, early and late dexamethasone groups at 2 years of age were observed. Hence, prenatal exposure to dexamethasone in the third trimester leads to increased mRNA expression of several aortic antioxidant enzymes in the offspring. This expression pattern was not temporally related to oxidative stress, and it may reflect in utero re-programming of aortic antioxidant gene expression during prenatal glucocorticoid exposure.

Consequences of Intrauterine Growth Restriction for the Kidney

Low birth weight due to intrauterine growth restriction is associated with various diseases in adulthood, such as hypertension, cardiovascular disease, insulin resistance and end-stage renal disease. The purpose of this review is to describe the effects of intrauterine growth restriction on the kidney. Nephrogenesis requires a fine balance of many factors that can be disturbed by intrauterine growth restriction, leading to a low nephron endowment. The compensatory hyperfiltration in the remaining nephrons results in glomerular and systemic hypertension. Hyperfiltration is attributed to several factors, including the renin-angiotensin system (RAS), insulin-like growth factor (IGF-I) and nitric oxide. Data from human and animal studies are presented, and suggest a faltering IGF-I and an inhibited RAS in intrauterine growth restriction. Hyperfiltration makes the kidney more vulnerable during additional kidney disease, and is associated with glomerular damage and kidney failure in the long run. Animal studies have provided a possible therapy with blockage of the RAS at an early stage in order to prevent the compensatory glomerular hyperfiltration, but this is far from being applicable to humans. Research is needed to further unravel the effect of intrauterine growth restriction on the kidney.

Mechanisms of renal damage owing to infection

Urinary tract infection (UTI) is a common bacterial illness in children. It is known to be associated with an increased risk of permanent renal cell damage and scarring which may lead to generation of pathological conditions such as hypertension, pre-eclampsia during pregnancy, renal insufficiency, and end-stage kidney disease. The pathophysiology of renal scarring is still obscure, which makes the prevention of renal damage difficult. During acute infection, there are numerous factors that may contribute to tissue damage. Inflammatory responses are activated by host defense mechanisms as well as by specific bacterial virulence factors. Understanding of these complex mechanisms would be helpful to better identify children at high risk of developing renal scarring following UTI.