Synaptic plasticity in hippocampal CA1 neurons and learning behavior in acute kidney injury, and estradiol replacement in ovariectomized rats.

BACKGROUND: Neurological complications may occur in patients with acute or chronic renal failure; however, in cases of acute renal failure, the signs and symptoms are usually more pronounced, and progressed rapidly. Oxidative stress and nitric oxide in the hippocampus, following kidney injury may be involved in cognitive impairment in patients with uremia. Although many women continue taking hormone therapy for menopausal symptom relief, but there are also some controversies about the efficacy of exogenous sex hormones, especially estrogen therapy alone, in postmenopausal women with kidney injury. Herein, to the best of our knowledge for the first time, spatial memory and synaptic plasticity at the CA1 synapse of a uremic ovariectomized rat model of menopause was characterized by estradiol replacement alone. RESULTS: While estradiol replacement in ovariectomized rats without uremia, promotes synaptic plasticity, it has an impairing effect on spatial memory through hippocampal oxidative stress under uremic conditions, with no change on synaptic plasticity. It seems that exogenous estradiol potentiated the deleterious effect of acute kidney injury (AKI) with increasing hippocampal oxidative stress. CONCLUSIONS: Although, estrogen may have some positive effects on cognitive function in healthy subjects, but its efficacy in menopause subjects under uremic states such as renal transplantation, needs to be further investigated in terms of dosage and duration.

Angiotensin 1 receptor antagonist attenuates acute kidney injury-induced cognitive impairment and synaptic plasticity via modulating hippocampal oxidative stress.

AIMS: The activation of the angiotensin (Ang) II after acute kidney injury (AKI) triggers oxidative stress and inflammatory cascade which involved not only the kidneys but also the brain. Ang II through the Ang II type 1 receptor (AT1R) may have deleterious effects on hippocampal synaptic transmission and cognitive functions under uremic encephalopathy. The present study was conducted to examine the effects of AT1R antagonist on AKI-induced cognitive and synaptic plasticity impairment. MAIN METHODS: Here, we investigated the effect of AKI and possible pathophysiological roles of AT1R with the selective AT1R antagonist losartan (10 mg/kg/day for consecutive 9 days) on cognitive performance using passive avoidance and Morris water maze tests. In order to understand the synaptic transmission, in vivo short and long-term plasticity were evaluated at the Schaffer collateral-CA1 synapse. Biochemical analysis was also performed to detect possible hippocampal nitric oxide and oxidative stress mechanisms. KEY FINDINGS: Our data provide evidence of hippocampal complication following AKI with increased level of nitrite (P < 0.01 vs. sham) as well as oxidative stress (P < 0.01 vs. sham) that may be responsible for behavioral dysfunction under uremia (spatial memory, P < 0.001; passive avoidance P < 0.01 vs. sham). Losartan treatment effectively protects against cognitive (spatial memory, P < 0.01; passive avoidance P < 0.05 vs. AKI-veh) and synaptic plasticity impairments induced by AKI possibly via modulation of oxidative stress in the hippocampus (P < 0.01 vs. AKI-veh). SIGNIFICANCE: The present study conclusively demonstrated a protective role of AT1R antagonist losartan in hippocampal complication and neurocognitive dysfunction after AKI via modulating oxidative stress.

Nephrogenic acute respiratory distress syndrome: A narrative review on pathophysiology and treatment.

The kidneys have a close functional relationship with other organs especially the lungs. This connection makes the kidney and the lungs as the most organs involved in the multi-organ failure syndrome. The combination of acute lung injury (ALI) and renal failure results a great clinical significance of 80% mortality rate. Acute kidney injury (AKI) leads to an increase in circulating cytokines, chemokines, activated innate immune cells and diffuse of these agents to other organs such as the lungs. These factors initiate pathological cascade that ultimately leads to ALI and acute respiratory distress syndrome (ARDS). We comprehensively searched the English medical literature focusing on AKI, ALI, organs cross talk, renal failure, multi organ failure and ARDS using the databases of PubMed, Embase, Scopus and directory of open access journals. In this narrative review, we summarized the pathophysiology and treatment of respiratory distress syndrome following AKI. This review promotes knowledge of the link between kidney and lung with mechanisms, diagnostic biomarkers, and treatment involved ARDS induced by AKI.

Brain consequences of acute kidney injury: Focusing on the hippocampus.

The high mortality rates associated with acute kidney injury are mainly due to extra-renal complications that occur following distant-organ involvement. Damage to these organs, which is commonly referred to as multiple organ dysfunction syndrome, has more severe and persistent effects. The brain and its sub-structures, such as the hippocampus, are vulnerable organs that can be adversely affected. Acute kidney injury may be associated with numerous brain and hippocampal complications, as it may alter the permeability of the blood-brain barrier. Although the pathogenesis of acute uremic encephalopathy is poorly understood, some of the underlying mechanisms that may contribute to hippocampal involvement include the release of multiple inflammatory mediators that coincide with hippocampus inflammation and cytotoxicity, neurotransmitter derangement, transcriptional dysregulation, and changes in the expression of apoptotic genes. Impairment of brain function, especially of a structure that has vital activity in learning and memory and is very sensitive to renal ischemic injury, can ultimately lead to cognitive and functional complications in patients with acute kidney injury. The objective of this review was to assess these complications in the brain following acute kidney injury, with a focus on the hippocampus as a critical region for learning and memory.

Effect of intra-hippocampal injection of human recombinant growth hormone on synaptic plasticity in the nucleus basalis magnocellularis-lesioned aged rats.

In this study, we proposed that administration of hippocampal growth hormone in ageing animals with growth hormone deficiency can compensate long-term potentiation and synaptic plasticity in nucleus basalis magnocellularis (NBM)-lesioned rats. Aged male Wistar rats were randomly divided into six groups (seven in each) of sham-operated healthy rats (Cont); NBM-lesioned rats (L); NBM-lesioned rats and intrahippocampal injection of growth hormone vehicle (L + Veh); NBM-lesioned and intrahippocampal injection of growth hormone (10, 20 and 40 µg.2 µl-1) (L + GH). In vivo electrophysiological recording techniques were used to characterize maintenance of long-term potentiation at distinct times (1, 2, 3, 24 and 48 hours) after high-frequency stimulation. The population spike was enhanced significantly for about 48 hours following tetanic stimulation in rats treated with a dose-dependent growth hormone compared to the vehicle group (p < 0.05), possibly through neuronal plasticity and neurogenesis in affected areas.

Effect of intra-hippocampal injection of human recombinant growth hormone on synaptic plasticity in the nucleus basalis magnocellularis-lesioned aged rats / Efeito da injeção intrahipocampal de hormônio do crescimento humano recombinante sobre a plasticidade sináptica em ratos envelhecidos lesados do núcleo basalis magnocellularis

ABSTRACT In this study, we proposed that administration of hippocampal growth hormone in ageing animals with growth hormone deficiency can compensate long-term potentiation and synaptic plasticity in nucleus basalis magnocellularis (NBM)-lesioned rats. Aged male Wistar rats were randomly divided into six groups (seven in each) of sham-operated healthy rats (Cont); NBM-lesioned rats (L); NBM-lesioned rats and intrahippocampal injection of growth hormone vehicle (L + Veh); NBM-lesioned and intrahippocampal injection of growth hormone (10, 20 and 40 µg.2 µl-1) (L + GH). In vivo electrophysiological recording techniques were used to characterize maintenance of long-term potentiation at distinct times (1, 2, 3, 24 and 48 hours) after high-frequency stimulation. The population spike was enhanced significantly for about 48 hours following tetanic stimulation in rats treated with a dose-dependent growth hormone compared to the vehicle group (p < 0.05), possibly through neuronal plasticity and neurogenesis in affected areas.

RESUMO Neste estudo, propusemos que a administração de hormônio hipocampal do crescimento em animais envelhecidos com deficiência de hormônio do crescimento pode compensar a potencialização em longo prazo e a plasticidade sináptica em ratos lesados do núcleo basalis magnocellularis (NBM). Ratos machos Wistar foram divididos aleatoriamente em seis grupos (sete ratos em cada grupo) de ratos falso-operados saudáveis (Cont); ratos lesados do NBM (L); ratos lesados do NBM e injeção intrahipocampal de veículo de hormônio do crescimento (L + Veh); ratos lesados do NBM e injeção de hormônio do crescimento (10, 20 e 40 μg.2 μl-1) (L + GH). Técnicas de registro eletrofisiológico in vivo foram utilizadas para caracterizar a manutenção da potencialização em longo prazo em momentos distintos (1, 2, 3, 24 e 48 horas) após estimulação de alta frequência. O pico populacional aumentou significativamente cerca de 48 horas após a estimulação tetânica em ratos tratados com um hormônio do crescimento dose-dependente, em comparação com o grupo veículo (p <0,05), possivelmente através da plasticidade neuronal e da neogênese nas áreas afetadas.

Rheum turkestanicum rhizomes possess anti-hypertriglyceridemic, but not hypoglycemic or hepatoprotective effect in experimental diabetes.

OBJECTIVE: Rheum turkestanicum (R. turkestanicum) rhizomes have been used in Iranain traditional medicine as an anti-diabetic agent. The purpose of the present investigation was to evaluate the anti-diabetic and antioxidant activities of R. turkestanicum rhizome extract in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Diabetes was induced by a single intraperitoneal injection of 55 mg/kg streptozotocin in male Wistar rats. Diabetic rats received the decoction extract of R. turkestanicum rhizomes at the doses of 200, 400 and 600 mg/kg daily by gavage for 3 weeks. Serum glucose and lipid levels were measured in all groups before diabetes induction and at the end of week 3. Oxidative stress was evaluated in the liver by measurement of malondialdehyde levels and total thiol concentration at the end of the experiment. RESULTS: A significant increase in serum glucose and triglyceride levels was observed in diabetic rats, which was accompanied by increased malondialdehyde levels and decreased total thiol concentration in the liver after 3 weeks. Treatment of diabetic rats with R. turkestanicum rhizome extract at the doses of 200, 400 and 600 mg/kg over a 3-week period did not change serum glucose, hepatic malondialdehyde and total thiol levels in diabetic rats. However, treatment with R. turkestanicum extract significantly decreased serum triglyceride levels in a dose-dependent manner at the end of the experiment. CONCLUSION: R. turkestanicum rhizome extract possess anti-hypertriglyceridemic, but not hypoglycemic or hepatoprotective effect in diabetic rats. Therefore, R. turkestanicum rhizome should be consumed with more caution by diabetic patients.

Cisplatin-Induced Nephrotoxicity; Protective Supplements and Gender Differences

Cisplatin (CDDP) has been widely used as a chemotherapeutic agent for solid tumors. The most common side effect of CDDP is nephrotoxicity, and many efforts have been made in the laboratory and the clinic to employ candidate adjuvants to CDDP to minimize this adverse influence. Many synthetic and herbal antioxidants as well as trace elements have been investigated for this purpose in recent years and a variety of positive and negative results have been yielded. However, no definitive supplement has so far been proposed to prevent CDDP-induced nephrotoxicity; however, this condition is gender related and the sex hormone estrogen may protect the kidney against CDDP damage. In this review, the results of research related to the effect of different synthetic and herbal antioxidants supplements are presented and discussed with suggestions included for future work.

Renal ischemia/reperfusion injury; from pathophysiology to treatment.

Ischemia/reperfusion injury (IRI) is caused by a sudden temporary impairment of the blood flow to the particular organ. IRI usually is associated with a robust inflammatory and oxidative stress response to hypoxia and reperfusion which disturbs the organ function. Renal IR induced acute kidney injury (AKI) contributes to high morbidity and mortality rate in a wide range of injuries. Although the pathophysiology of IRI is not completely understood, several important mechanisms resulting in kidney failure have been mentioned. In ischemic kidney and subsequent of re-oxygenation, generation of reactive oxygen species (ROS) at reperfusion phase initiates a cascade of deleterious cellular responses leading to inflammation, cell death, and acute kidney failure. Better understanding of the cellular pathophysiological mechanisms underlying kidney injury will hopefully result in the design of more targeted therapies to prevent and treatment the injury. In this review, we summarize some important potential mechanisms and therapeutic approaches in renal IRI.

The preventive effects of diminazene aceturate in renal ischemia/reperfusion injury in male and female rats.

Background. Angiotensin-converting enzyme 2/angiotensin (1-7)/Mas receptor (ACE2/Ang-1-7/MasR) appears to counteract most of the deleterious actions of angiotensin-converting enzyme/angiotensin II/angiotensin II receptor 1 (ACE/Ang II/AT1R) in renal ischemia/reperfusion (I/R) injury but ACE2 activity and its levels are sexually dimorphic in the kidney. This study was designed to evaluate the effects of activation endogenous ACE2 using the diminazene aceturate (DIZE) in renal I/R injury in male and female rats. Methods. 36 Wistar rats were divided into two groups of male and female and each group distinct to three subgroups (n = 6). I/R group was subjected to 45 min of bilateral ischemia and 24 h of reperfusion, while treatment group received DIZE (15 mg/kg/day) for three days before the induction of I/R. The other group was assigned as the sham-operated group. Results. DIZE treatment in male rats caused a significant decrease in blood urea nitrogen (BUN), creatinine, liver functional indices, serum malondialdehyde (MDA), and increase kidney nitrite levels (P < 0.05), and in female rats a significant increase in creatinine and decrease serum nitrite levels compared to the I/R group (P < 0.05). Conclusions. DIZE may protect the male kidney from renal I/RI through antioxidant activity and elevation of circulating nitrite level.

Medical risk factors of diabetes mellitus among professional drivers.

BACKGROUND: Road transport drivers are one of the professional groups whose activities have a strong impact of public safety. In view of the natural professional activity, the drivers are at a higher risk of obesity, hypertension and hyperlipidemia, and carbohydrate metabolism disorders such as diabetes mellitus. MATERIALS AND METHODS: Medical documentation was the source of data for the reported study. It derived from medical examinations of 1903 drivers applying for driving license. RESULTS: Hyperglycemia was found in 52.1% of the drivers, 9.1% of them were in diabetic stage, and with HbA1C criteria 77.6% of these drivers were in this stage. Excessive body weight was recorded in 65.6% of the study population, 44.8% were diagnosed with overweight and 20.8% with obesity. High blood pressure was recorded in 16.4% of drivers. CONCLUSION: High prevalence of excessive body weight and high blood pressure and hyperlipidemia are risk factors for diabetes mellitus in professional drivers that indicates a need to undertake multidimensional actions target on this particular profession and involving various health care sectors. Prophylactic and detailed pre-placement examinations should be considered, depending on the rate and the intensity of disorders. These should be coupled with an introduction of primary and secondary prophylactic activities and monitoring of relevant treatment.