Iron Absorption in Rats Increased by Yeast Glucan

The effects of brewer's yeast cell walls and two of its components, glucan and mannan, on the absorption of ⁵⁹Fe by anemic rats were investigated. After administration of the label, the percentage of ⁵⁹Fe taken up into the blood of group given glucan was generally similar to that of a group given yeast cell walls, both values were higher than in controls. The incorporation of ⁵⁹Fe into the small intestines was higher in the group given glucan than in the controls or a group given a glucan—mannan mixture. Glucan is the main substance in yeast cell walls that increases iron absorption.     

The Effects of Physical Exercise on the Serum Iron Profile in Spontaneously Hypertensive Rats

The purpose of this study was to evaluate the profile of serum iron in spontaneously hypertensive rats after an aerobic physical exercise. To accomplish this, 12 normotensive Wistar rats and 12 spontaneously hypertensive rats were distributed into “physical exercise” and “no physical exercise” groups. The animals in the physical exercise group underwent to an aerobic exercise for a total of 4 weeks. Blood was collected for the analysis of iron. Our results indicate that rats of the physical exercise group had significantly lower serum iron levels after the aerobic exercise protocol compared to the spontaneously hypertensive rats no physical exercise group (F _(3,16) = 4.4915, p < 0.01). No significant difference was found between no physical exercise groups. The results indicated that the difference in iron may be due to an increased demand for iron, prompted by chronic physical exercise. In addition, erythrocytosis has been associated with increased blood pressure in spontaneously hypertensive rats, suggesting that iron reduction may be related to decreased blood pressure in these animals.     

金樱子提取液对糖尿病肾病大鼠的肾脏保护作用

目的:研究金樱子提取液对糖尿病肾病(Diabetic Nephropathy,DN)大鼠的肾脏保护作用。方法:在高糖高脂饲料喂食SD(Sprague-Dawley)大白鼠的基础上腹腔注射链脲佐菌素(streptozotocin,STZ)诱导糖尿病肾病大鼠模型,随机分为糖尿病肾病模型组(DN组)和金樱子治疗组(DN+RLM组),同时另设正常对照组(NC组)和金樱子对照组(NC+RLM组)。检测金樱子提取液对各组大鼠血糖(fasting blood-glucose,FBG)、糖化血红蛋白(glycosylated haemoglobin,GHb)、24小时尿微量白蛋白和尿量、血尿素氮(BUN)、血肌酐(Scr)、胆固醇(TC)、甘油三酯(TG)及肾脏结构的影响。结果:与DN大鼠相比,糖尿病肾病大鼠经金樱子提取液治疗后,大鼠FBG、GHb水平、24 h尿微量白蛋白、24 h尿量、肾脏指数明显降低,血脂紊乱、肾功能损害以及DN肾脏病理明显改善,且无明显副作用。结论:金樱子提取液可明显降低DN大鼠血糖,改善DN大鼠血脂、肾功能紊乱及肾脏病理变化,对糖尿病大鼠肾脏具有较强的保护作用。     

Renal Function in Analgesic Nephropathy

Comprehensive one-day renal function tests in 20 patients with a history of analgesic abuse showed varying degrees of chronic renal failure in all. There was no evidence of a selective defect in proximal tubular function, while a defective concentrating mechanism, usually considered necessary for the diagnosis of analgesic-induced renal damage, could be demonstrated in only 16 patients. A urinary acidification defect associated with a concentrating defect was found in nine cases and was thought to reflect specific collecting duct dysfunction. Urinary ammonium excretion was reduced in 13 subjects, owing to a reduced number of functioning nephrons or inadequate acidification, or both. Low citrate excretion was frequently encountered, and this, as well as defective urinary acidification, may play some part in predisposing patients with analgesic nephropathy to intrarenal calcification and progressive renal failure.     

Renal Effects and Underlying Molecular Mechanisms of Long-Term Salt Content Diets in Spontaneously Hypertensive Rats

Several evidences have shown that salt excess is an important determinant of cardiovascular and renal derangement in hypertension. The present study aimed to investigate the renal effects of chronic high or low salt intake in the context of hypertension and to elucidate the molecular mechanisms underlying such effects. To this end, newly weaned male SHR were fed with diets only differing in NaCl content: normal salt (NS: 0.3%), low salt (LS: 0.03%), and high salt diet (HS: 3%) until 7 months of age. Analysis of renal function, morphology, and evaluation of the expression of the main molecular components involved in the renal handling of albumin, including podocyte slit-diaphragm proteins and proximal tubule endocytic receptors were performed. The relationship between diets and the balance of the renal angiotensin-converting enzyme (ACE) and ACE2 enzymes was also examined. HS produced glomerular hypertrophy and decreased ACE2 and nephrin expressions, loss of morphological integrity of the podocyte processes, and increased proteinuria, characterized by loss of albumin and high molecular weight proteins. Conversely, severe hypertension was attenuated and renal dysfunction was prevented by LS since proteinuria was much lower than in the NS SHRs. This was associated with a decrease in kidney ACE/ACE2 protein and activity ratio and increased cubilin renal expression. Taken together, these results suggest that LS attenuates hypertension progression in SHRs and preserves renal function. The mechanisms partially explaining these findings include modulation of the intrarenal ACE/ACE2 balance and the increased cubilin expression. Importantly, HS worsens hypertensive kidney injury and decreases the expression nephrin, a key component of the slit diaphragm.     

Paeoniflorin Prevents Diabetic Nephropathy in Rats

The aim of this study was to test the hypothesis that paeoniflorin prevents the progression of diabetic nephropathy by modulating the inflammatory process. Sprague–Dawley rats were divided into 5 groups: nondiabetic control rats; untreated diabetic model (DM) rats; and DM rats treated with 5, 10, or 20 mg/kg paeoniflorin in drinking water once daily. Rats received a single intravenous injection of streptozotocin to induce diabetes; 9 wk after injection, rats began the 8-wk daily paeoniflorin treatment regimen. Compared with that of nonDM controls, the urinary albumin:creatinine ratio was increased significantly in untreated DM rats; this ratio was decreased in DM rats treated with 5, 10, or 20 mg/kg paeoniflorin compared with that of untreated DM rats. In addition, paeoniflorin treatment effectively suppressed glomerular hypertrophy; blood glucose; the expression of transforming growth factor β, type IV collagen, and intercellular adhesion molecule 1; and renal infiltration of macrophages compared with levels in untreated DM rats. Furthermore, renal nuclear factor κB activity was increased in untreated but not paeoniflorin-treated DM rats. In conclusion, our data suggest that the preventive effects of paeoniflorin may be mediated by its antiinflammatory actions.Abbreviations: DM, diabetic model; ECM, extracellular matrix; ICAM1, intercellular adhesion molecule 1; MCP1, monocyte chemoattractant protein 1; NFκB, nuclear factor κB; TGFβ, transforming growth factor βDiabetic nephropathy is the most common cause of endstage renal disease and high mortality in humans. Adequate control of blood glucose may slow the rate of its progression, but it is still difficult to achieve strict glycemic control for diabetic patients in the longer term, due at least in part to the limitations of available therapeutic approaches.³ Recent studies have suggested the emerging role of inflammatory processes in the pathogenesis of diabetic nephropathy in addition to other well-known mechanisms.In human renal disease, transforming growth factor β (TGFβ) may mediate the buildup of tissue extracellular matrix (ECM) proteins.¹⁷ This cytokine reportedly stimulated ECM protein accumulation in diabetic tissues by upregulating the production of ECM proteins or by downregulating the production of ECM-degrading enzymes.²⁶ Renal levels of TGFβ1 increase in both experimental and human diabetes. In addition, TGFβ1 induces the synthesis of ECM components including collagen types I, III, and IV and fibronectin.^2,5Intercellular adhesion molecule 1 (ICAM1) is a key adhesion molecules. In addition, the ICAM1-dependent infiltration of macrophages into the kidney is very important in the pathogenesis of diabetic nephropathy.¹⁸ In addition, the expression of ICAM1 is rapidly induced and maintained for a long time in renal tissues after induction of diabetes in experimental type 1 diabetic rats.^14,20 Macrophage infiltration was blocked by antiICAM1 antibody, confirming that ICAM1 mediates macrophage infiltration into the diabetic kidney.⁶ Furthermore, ICAM1-deficient mice were protected from renal injury after the induction of diabetes, suggesting that the inflammatory process is a critical factor for the development of diabetic nephropathy.²¹Despite the availability of treatments that lower blood glucose and blood pressure, many diabetic patients are still prone to developing kidney failure, which no currently available therapies can reverse.²⁴ Therefore a search is needed for new therapeutic approaches—based on novel mechanisms of action—to the treatment of diabetic nephropathy. Paeoniflorin is a monoterpene glucoside and a component of the total glucoside extract obtained from the root of Paeonia lactiflora.²⁸ This extract was approved for marketing in China in 1998.²³ As a disease-modifying drug, the total glucoside extract of peony has both antiinflammatory and immune-regulatory effects and is used in the treatment of rheumatoid arthritis, hepatitis, systemic lupus erythematosus, and mesenteric hyperplastic nephritis.^8,9,27 The goal of this study is to address whether paeoniflorin might prevent the progression of diabetic nephropathy through the inhibition of the inflammatory processes including TGFβ, type IV collagens, and ICAM1 expression, monocyte chemoattractant protein 1 (MCP1), nuclear factor κB (NFκB) activation, and macrophage infiltration.     

肾康注射液对伴高同型半胱氨酸血症高血压肾病患者肾功能和心功能的影响

目的:探讨肾康注射液对伴高同型半胱氨酸血症的高血压肾病患者心、肾功能的影响。方法:采用随机数字表法将76例高血压肾病伴高同型半胱氨酸血症患者随机分成研究组和对照组,每组各38例。两组均予以常规治疗措施,研究组则在上述基础上联合肾康注射液方案,持续治疗4周。观察比较两组治疗前后肾功能指标[血肌酐(SCr)、血尿素氮(BUN)、内生肌酐清除率(Ccr)]、肾损伤标志物[血清β2-微球蛋白(β2-MG)、血清胱抑素C(Cys-C)]、心功能指标[左室射血分数(LVEF)、心室舒张期末内径(LVIDd)、左心室收缩末期内径(LVIDs)]、炎性因子[C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)]及动脉粥样硬化危险因子[同型半胱氨酸(Hcy)、内皮素]水平及不良反应的发生情况。结果:治疗4周后,两组患者部分肾功能指标(SCr、BUN)、肾损伤标志物(血清β2-MG、血清Cys-C)、部分心功能指标(LVIDd、LVIDs)、炎性因子(CRP、TNF-α、IL-6)及动脉粥样硬化危险因子(Hcy、内皮素)水平均较治疗前明显降低,且研究组以上指标均显著低于对照组(P均0.05);LVEF及Ccr水平则较治疗前明显提升,且研究组以上指标均显著高于对照组,差异均有统计学意义(P均0.05)。两组患者均无不良反应发生(P0.05)。结论:肾康注射液用于高血压肾病伴高同型半胱氨酸血症患者的临床治疗对延缓其肾损伤进程、改善患者心、肾功能及降低动脉粥样硬化形成风险等具有积极意义。     

Increased Expression of the Very Low-Density Lipoprotein Receptor Mediates Lipid Accumulation in Clear-Cell Renal Cell Carcinoma

Clear-cell renal cell carcinoma (RCC) is, in most cases, caused by loss of function of the tumor suppressor gene von Hippel–Lindau, resulting in constitutive activation of hypoxia-inducible factor (HIF)-1α and expression of hypoxia-induced genes in normoxic conditions. Clear-cell RCC cells are characterized histologically by accumulation of cholesterol, mainly in its ester form. The origin of the increased cholesterol remains unclear, but it is likely explained by an HIF-1α-driven imbalance between cholesterol uptake and excretion. Here, we showed that expression of the very low-density lipoprotein receptor (VLDL-R) was significantly increased in clear-cell RCC human biopsies compared with normal kidney tissue. Partial knockdown of HIF-1α in clear-cell RCC cells significantly reduced the VLDL-R expression, and knockdown of either HIF-1α or VLDL-R reduced the increased lipid accumulation observed in these cells. We also showed increased uptake of fluorescently labeled lipoproteins in clear-cell RCC cells, which was significantly reduced by knockdown of HIF-1α or VLDL-R. Taken together, our results support the concept that the pathological increase of HIF-1α in clear-cell RCC cells upregulates VLDL-R, which mediates increased uptake and accumulation of lipids. These results explain the morphological characteristics of clear-cell RCC, and open up novel possibilities for detection and treatment of clear-cell RCC.     

西格列汀通过增加肾组织中SOCS 1和Podocalyxin的表达改善糖尿病肾病大鼠肾功能

目的:探讨西格列汀对糖尿病肾病大鼠肾功能及肾组织中细胞因子信号传导负调控因子1(Suppressors of cytockine signaling,SOCS 1)和足细胞特异蛋白抗体(Podocalyxin)表达的影响。方法:将大鼠随机分为4组:对照组,模型组,西格列汀组和贝那普利组。模型组、西格列汀组和贝那普利组采用腹腔注射链脲佐菌素建立模型,对照组给予腹腔注射等量生理盐水。造模成功后,西格列汀组(n=8)和贝那普利组(n=8)分别灌胃给予7 mg/kg/d的西格列汀和贝那普利。模型组(n=8)和对照组(n=10)均给予等体积的蒸馏水灌胃,连续8周。检测并对比各组大鼠代谢相关指标,肾组织纤维化程度指标,肾组织中炎症因子水平以及Podocalyxin、SOCS 1和结蛋白(Desmin)表达。结果:干预8周后,与对照组对比,模型组空腹血糖、糖化血红蛋白、甘油三酯、总胆固醇、24 h尿蛋白排泄率、肌酐、体重、肾组织转化生长因子-β1(Transforming growth factor,TGF-β1)、白介素(Interleukin,IL)-6、IL-1β、SOCS 1和Desmin水平均显著增加,Ⅳ型胶原蛋白(Collagen-Ⅳ,C-Ⅳ)、纤维连接蛋白(Fibronectin,FN)、层黏连蛋白(Laminin,LN)和Podocalyxin水平显著降低(P0.05);与模型组对比,西格列汀组和厄贝沙坦组空腹血糖、糖化血红蛋白、甘油三酯、总胆固醇、24 h尿蛋白排泄率、肌酐、体重、肾组织TGF-β1、IL-6、IL-1β和Desmin水平均显著降低,Podocalyxin和SOCS 1蛋白表达增加(P0.05)。但厄贝沙坦组与西格列汀组以上各指标对比差异无统计学意义(P0.05)。结论:西格列汀可能通过增加Podocalyxin和SOCS 1蛋白表达,降低肾组织中炎症因子和Desmin蛋白表达,进而改善糖尿病肾病大鼠肾纤维化和肾功能。     

Chronic Treatment with Atrial Natriuretic Peptide in Spontaneously Hypertensive Rats: Beneficial Renal Effects and Sex Differences

Objective

The aim of this study was to investigate the effects of chronic treatment with atrial natriuretic peptide (ANP) on renal function, nitric oxide (NO) system, oxidative stress, collagen content and apoptosis in kidneys of spontaneously hypertensive rats (SHR), as well as sex-related differences in the response to the treatment.

Methods

10 week-old male and female SHR were infused with ANP (100 ng/h/rat) or saline (NaCl 0.9%) for 14 days (subcutaneous osmotic pumps). Systolic blood pressure (SBP) was recorded and diuresis and natriuresis were determined. After treatment, renal NO synthase (NOS) activity and eNOS expression were evaluated. Thiobarbituric acid-reactive substances (TBARS), glutathione concentration and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in the kidney. Collagen was identified in renal slices by Sirius red staining and apoptosis by Tunel assay.

Results

Female SHR showed lower SBP, oxidative stress, collagen content and apoptosis in kidney, and higher renal NOS activity and eNOS protein content, than males. ANP lowered SBP, increased diuresis, natriuresis, renal NOS activity and eNOS expression in both sexes. Renal response to ANP was more marked in females than in males. In kidney, ANP reduced TBARS, renal collagen content and apoptosis, and increased glutathione concentration and activity of GPx and SOD enzymes in both sexes.

Conclusions

Female SHR exhibited less organ damage than males. Chronic ANP treatment would ameliorate hypertension and end-organ damage in the kidney by reducing oxidative stress, increasing NO-system activity, and diminishing collagen content and apoptosis, in both sexes.     

Nitric Oxide Synthase in Spontaneously Hypertensive Rats

Since its discovery by Furchgott and Zawadzki in 1980 [18], endothelium-derived relaxing factor (EDRF) has been shown to play a central role in the cardiovascular system [10]. The endothelial product is chemically equivalent to nitric oxide (NO) [23, 40] or a biochemical congener thereof [48]. Fifteen years ago, this small, simple and highly toxic molecule was known as a lengthy list of environmental pollutants found in unsavory haunts such as smoke and smog, and even as destroyer of ozone, suspected carcinogen, and precursor of acid rain. In addition, NO seems an unlikely biological jack of all trades for most of the body's functions are regulated by extraordinarily large and complex proteins and compounds. But over the past decade, diverse lines of evidence have converged to show that this sometime poison is a fundamental player in the everyday business of the human body.     

Outcomes of Renal Transplantation in HIV-1 Associated Nephropathy

Introduction

Several studies have demonstrated that renal transplantation in HIV positive patients is both safe and effective. However, none of these studies have specifically examined outcomes in patients with HIV-associated nephropathy (HIVAN).

Methods

Medical records of all HIV-infected patients who underwent kidney transplantation at Johns Hopkins Hospital between September 2006 and January 2014 were reviewed. Data was collected to examine baseline characteristics and outcomes of transplant recipients with HIVAN defined pathologically as collapsing focal segmental glomerulosclerosis (FSGS) with tubulo-interstitial disease.

Results and Discussion

During the study period, a total of 16 patients with HIV infection underwent renal transplantation. Of those, 11 patients were identified to have biopsy-proven HIVAN as the primary cause of their end stage renal disease (ESRD) and were included in this study. They were predominantly African American males with a mean age of 47.6 years. Seven (64%) patients developed delayed graft function (DGF), and 6 (54%) patients required post-operative dialysis within one week of transplant. Graft survival rates at 1 and 3 years were 100% and 81%, respectively. Acute rejection rates at 1 and 3 years were 18% and 27%, respectively. During a mean follow up of 3.4 years, one patient died.

Conclusions

Acute rejection rates in HIVAN patients in this study are higher than reported in the general ESRD population, which is similar to findings from prior studies of patients with HIV infection and ESRD of various causes. The high rejection rates appear to have no impact on short or intermediate term graft survival.     

Renalase Protects against Contrast-Induced Nephropathy in Sprague-Dawley Rats

Background

Contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired acute renal failure. Oxidative stress, apoptosis and inflammation play crucial roles in CIN. Renalase is a newly discovered monoamine oxidase from the kidney. We hypothesize that renalase could protect against CIN through anti-oxidation, anti-inflammation and anti-apoptosis pathways.

Methods

We tested our hypothesis in vivo with a rat model of Ioversol-induced CIN and in vitro. Sprague-Dawley rats were divided into 4 groups (n = 6 per group): control group, Ioversol group (rats subjected to Ioversol-induced CIN), Ioversol plus vehicle group (CIN rats pretreated with vehicle) and Ioversol plus renalase group (CIN rats pretreated with 2 mg/kg recombinant renalase). HK2 cells were treated with Ioversol or H₂O₂.

Results

The results showed that pretreatment with renalase attenuated the deterioration of renal function, tubular necrosis, oxidative stress, apoptosis and inflammation (P<0.05). Furthermore, renalase protected HK2 cells against the cytotoxicity of Ioversol and suppressed Caspase-3 activity, oxidative stress and apoptosis induced by H₂O₂.

Conclusion

Recombinant renalase protected CIN in rats through anti-oxidation, anti-apoptosis and anti-inflammation mechanisms.     

Alteration of Cerebral Taurine Biosynthesis in Spontaneously Hypertensive Rats

Abstract: Cerebral taurine biosynthesis in a spontaneously hypertensive rat (SHR) has been studied. Cysteine sulfinic acid (CSA) and cysteic acid (CA), possible key intermediates in taurine biosynthesis, were found in the rat brain, whereas no cysteamine-cystamine was detected. In the brain of SHR, a statistically significant decrease in the contents of CSA, CA, and taurine was noted in the cerebellum, hypothalamus, and striatum as compared with normotensive Wistar Kyoto rats. Similarly, it was demonstrated that the activity of cysteine dioxygenase, the enzyme catalyzing cysteine to CSA, was attenuated significantly in the same brain areas of SHR. In contrast, no alteration in the activity of CSA decarboxylase, the enzyme converting CSA to hypotaurine or CA to taurine, was observed. A decline in the percent conversion of [¹⁴C]cysteine to [¹⁴C]taurine was found also in tissue homogenates from the cerebellum, hypothalamus, and striatum of SHR, indicating that the declines in taurine content may be due to an attenuation of taurine biosynthesis, possibly at the step involving cysteine dioxygenase.     

Renal Function and Hematology in Rats with Congenital Renal Hypoplasia

Renal hypoplasia due to a congenitally reduced number of nephrons progresses to chronic kidney disease and may cause renal anemia, given that the kidneys are a major source of erythropoietin in adults. Hypoplastic kidney (HPK) rats have only about 20% of the normal number of nephrons and develop CKD. This study assessed the renal function and hematologic changes in HPK rats from 70 to 210 d of age. HPK rats demonstrated deterioration of renal excretory function, slightly macrocytic erythropenia at all days examined, age-related increases in splenic hemosiderosis accompanied by a tendency toward increased hemolysis, normal plasma erythropoietin levels associated with increased hepatic and decreased renal erythropoietin production, and maintenance of the response for erythropoietin production to hypoxic conditions, with increased interstitial fibrosis at 140 d of age. These results indicate that increases in splenic hemosiderosis and the membrane fragility of RBC might be associated with erythropenia and that hepatic production of erythropoietin might contribute to maintaining the blood Hgb concentration in HPK rats.Abbreviations: CKD, chronic kidney disease; HGN, hypogonadism; HPK, hypoplastic kidneyApproximately 10% to 13% of the general population has chronic kidney disease (CKD), including an estimated 13.3 million people in Japan.^13,15,20 Moreover, more than 1.1 million patients worldwide require maintenance dialysis, and that number continues to increase.²⁴ Determining the pathogenesis of CKD, identifying clinical makers of early stages of CKD, and developing effective methods to treat CKD are required, especially given that CKD has been reported to be a risk factor for cardiovascular disease, with high mortality rates.^11,13,15 Patients with CKD are frequently anemic, due to a low level of erythropoietin and inhibition of erythropoiesis.^12,27 The decreased production of erythropoietin may result from the transdifferentiation of interstitial fibroblasts to myofibroblasts, resulting in increased production of extracellular matrix in the kidneys.^4,29 The number of nephrons in the kidneys at birth varies greatly,^5,19 and a congenital reduction in number of nephrons is thought to be related to the occurrence and prognosis of CKD.^9,17,18,21 Therefore, a CKD animal model with a reduced number of nephrons is useful for studying the pathophysiology of and treatments for CKD.Affected rats in the hypogonadism (HGN) inbred strain are characterized by male sterility due to hypogonadism,^37,41 reduced female fertility due to ovarian hypoplasia,^30,31 and progressive renal dysfunction due to bilateral hypoplastic kidneys (HPK).^32,33 These defects are controlled by a single autosomal recessive gene, hgn.^38,40 Linkage analysis and sequencing of candidate genes revealed a 25-bp duplicated insertion mutation in exon 7 of Astrin/Spag5, which encodes a microtubule-associated protein.³⁹ Because this mutation causes a premature terminal codon resulting in a truncated Astrin protein that lacks the primary spindle-targeting domain, the cause of the phenotype is considered to be a loss-of-function type mutation of the Astrin gene.^38,39 The recovery of normal fertility and renal function in homozygous mutant rats by a transgene comprising normal Astrin cDNA indicates that Astrin is required for normal testicular and renal development.²²The HGN strain was isolated from the sixth filial generation of a polygenic hydronephrotic rat strain derived from the original stock of the Wistar–Imamichi rat closed colony.⁴¹ Because the occurrence of hydronephrosis would influence renal development and function, we established another hypogonadism strain (HGN II) that was directly derived from the original closed colony.³⁶ The HGN II strain has been maintained by inbreeding between carriers, and the mutated gene responsible for the phenotype in the HGN II strain is identical to that in the HGN strain.³⁹ The affected rats of the HGN II strain show a similar phenotype as that of the HGN strain with regard to hypogonadism and HPK.^35,36Although male HPK rats in the HGN and HGN II strains have only about 20% of the nephrons present in normal kidney, the total glomerular filtration rate per kidney is compensated by hyperfiltration of individual glomeruli.^32,36 However, continuous glomerular hyperfiltration and functional overload of individual nephrons can result in a deterioration in renal excretion. Histologically, HPK rats demonstrate glomerular hypertrophy and dilation of the renal tubules.^32,36 As these rats age, cast formation in tubular lumen, glomerular sclerosis, and cellular infiltration into interstitial tissue occur.^33,35 In addition, age-related features of renal deterioration, including polyposia, polyuria, azotemia, albuminuria, and hypertension, follow,³⁵ and secondary hyperparathyroidism, osteodystrophy, and anemia emerge at advanced age in HPK rats.³³ Therefore HPK rats are a model for studying how a congenitally reduced nephron mass may induce CKD and secondary renal diseases, and HPK rats might be useful for identifying biomarkers related to these diseases. Because our previous studies in HPK rats^33,35 provided only limited information about the progression of CKD and renal anemia, the current study was designed to analyze multiple parameters related to renal function and hematology and to characterize the anemic tendencies in 70- to 210-d-old HPK rats. We found that the hematologic condition of HPK rats is characterized by reduced renal excretive function, erythropenia, increased hemolysis in the spleen, progressive renal fibrosis, and maintenance of normal plasma erythropoietin concentrations.     

Spatial Memory in Spontaneously Hypertensive Rats (SHR)

The spontaneously hypertensive rat (SHR) is an established animal model of ADHD. It has been suggested that ADHD symptoms arise from deficits in executive functions such as working memory, attentional control and decision making. Both ADHD patients and SHRs show deficits in spatial working memory. However, the data on spatial working memory deficits in SHRs are not consistent. It has been suggested that the reported cognitive deficits of SHRs may be related to the SHRs’ locomotor activity. We have used a holeboard (COGITAT) to study both cognition and activity in order to evaluate the influence of the activity on the cognitive performance of SHRs. In comparison to Wistar-Kyoto (WKY) rats, SHRs did not have any impairment in spatial working memory and reference memory. When the rats’ locomotor activity was taken into account, the SHRs’ working memory and reference memory were significantly better than in WKY rats. The locomotor activity appears to be a confounding factor in spatial memory tasks and should therefore be controlled for in future studies. In the SHR model of ADHD, we were unable to demonstrate an impairment of working memory which has been reported in patients with ADHD.