Heterozygous Rats Research Articles

THE EFFECT OF REPEATED ANTISENSE THERAPY ON VARIOUS VASOACTIVE SYSTEMS IN YOUNG REN-2 TRANSGENIC RATS: PP.29.140

Objective: We demonstrated that single injection of antisense oligodeoxynucleotides (AS) against AT1 receptor had transient antihypertensive effect in TGR. We were interested whether repeated AS therapy will have durable effect on blood pressure (BP) and on the contribution of principle vasoactive systems to BP regulation in this model of ANG II-dependent hypertension. Methods: From the age of 30 days heterozygous Ren-2 rats were injected in 10-day intervals with AS until the age of 60 days. On days 40, 50 and 70 of age, basal BP and acute responses to consecutive blockade of renin-angiotensin (10 mg/kg captopril), sympathetic (5 mg/kg pentolinium) and nitric oxide (NO) (30 mg/kg L-NAME) systems were determined in conscious rats. Results: AS therapy decreased BP and reduced cardiac hypertrophy. Both these effects disappeared after the third AS injection. Captopril-induced BP decrease was higher on day 70 in untreated than in AS-treated TGR, suggesting higher contribution of RAS in established hypertension. On the contrary, AS therapy decreased the contribution of sympathetic system on day 40 (during hypertension development). BP decrease was double after SNS than after RAS blockade. AS-treated animals had higher BP increase after NO blockade on day 40. The impact of NO on BP control increased with age, suggesting its role as a compensatory mechanism against augmented activity of pressor systems. The dependency of principle vasoactive systems on the number of renin gene copies was evaluated in three groups of animals: HanSD (-/-),TGR heterozygous for renin gene (+/−) and homozygous TGR (+/+). The contribution of angiotensin-dependent and nifedipine-sensitive vasoconstriction increased with the number of renin gene copies, while heterozygous and homozygous TGR had reduced NO vasodilatory component. Conclusions: Repeated AS therapy of Ren-2 TGR has transient antihypertensive effect, which correlates with cardiac hypertrophy. Augmented sympathetic activity together with reduced NO activity contribute to hypertension in initial phases, while increased RAS influence prevails in established hypertension.

Quantitative evaluation of experimental choroidal neovascularization by confocal scanning laser ophthalmoscopy: fluorescein angiogram parallels heparan sulfate proteoglycan expression

The objective of the present study was to develop a quantitative method to evaluate laser-induced choroidal neovascularization (CNV) in a rat model using Heidelberg Retina Angiograph 2 (HRA2) imaging. The expression of two heparan sulfate proteoglycans (HSPG) related to inflammation and angiogenesis was also investigated. CNV lesions were induced with argon laser in 21 heterozygous Zucker rats and after three weeks a fluorescein angiogram and autofluorescence exams were performed using HRA2. The area and greatest linear dimension were measured by two observers not aware of the protocol. Bland-Altman plots showed agreement between the observers, suggesting that the technique was reproducible. After fluorescein angiogram, HSPG (perlecan and syndecan-4) were analyzed by real-time RT-PCR and immunohistochemistry. There was a significant increase in the expression of perlecan and syndecan-4 (P < 0.0001) in retinas bearing CNV lesions compared to control retinas. The expression of these two HSPG increased with increasing CNV area. Immunohistochemistry demonstrated that the rat retina damaged with laser shots presented increased expression of perlecan and syndecan-4. Moreover, we observed that the overexpression occurred in the outer layer of the retina, which is related to choroidal damage. It was possible to develop a standardized quantitative method to evaluate CNV in a rat model using HRA2. In addition, we presented data indicating that the expression of HSPG parallels the area of CNV lesion. The understanding of these events offers opportunities for studies of new therapeutic interventions targeting these HSPG.

Diet‐induced Renal Changes in Zucker Rats Are Ameliorated by the Superoxide Dismutase Mimetic TEMPOL

Diabetic nephropathy is the leading cause of renal failure in the United States. The obese Zucker rat (OZR; fa/fa) is a commonly used model of type 2 diabetes and metabolic syndrome (MetS), and of the nephropathy and renal oxidative stress commonly seen in these disorders. Heterozygous lean Zucker rats (LZRs; fa/+) are susceptible to high-fat diet (HFD)-induced obesity and MetS. The present study was designed to investigate whether 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL), a membrane-permeable radical scavenger, could alleviate the renal effects of MetS in OZR and LZR fed a HFD, which resembles the typical "Western" diet. OZR and LZR were fed a HFD (OZR-HFD and LZR-HFD) or regular diet (OZR-RD and LZR-RD) and allowed free access to drinking water or water containing 1 mmol/l TEMPOL for 10 weeks. When compared to OZR-RD animals, OZR-HFD animals exhibited significantly higher levels of total renal cortical reactive oxygen species (ROS) production, plasma lipids, insulin, C-reactive protein, blood urea nitrogen (BUN), creatinine (Cr), and urinary albumin excretion (P < 0.05); these changes were accompanied by a significant decrease in plasma high-density lipoprotein levels (P < 0.05). The mRNA expression levels of desmin, tumor necrosis factor-alpha (TNF-alpha), nuclear factor kappaB (NFkappaB), and NAD(P)H oxidase-1 (NOX-1) were significantly higher in the renal cortical tissues of OZR-HFD animals; NFkappaB p65 DNA binding activity as determined by electrophoretic mobility shift assay was also significantly higher in these animals. The same trends were noted in LZR-HFD animals. Our data demonstrate that TEMPOL may prove beneficial in treating the early stages of the nephropathy often associated with MetS.

Early-onset GH deficiency results in spatial memory impairment in mid-life and is prevented by GH supplementation

GH levels increase to high concentrations immediately before puberty then progressively decline with age. GH deficiency (GHD) originating in childhood is treated with GH supplementation to foster somatic development during adolescence. It is not clear if or how early GH replacement affects memory in adulthood, or whether it can prevent the cognitive deficits commonly observed in adults with childhood-onset GHD. Rats homozygous for the Dw-4 mutation (dwarf) do not exhibit the normal increase in GH at 4 weeks of age when GH levels normally rise and are used to model childhood or early-onset GHD (EOGHD). One group of these rats was injected with GH from 4 to 14 weeks of age to model GH supplementation during adolescence with GHD beginning in adulthood (adult-onset GHD; AOGHD). Another group received GH from 4 weeks throughout the lifespan to model normal lifespan GH (GH-replete). Age-matched, Dw-4 heterozygous rats (HZ) do not express the dwarf phenotype and were used as controls. At 8 and 18 months of age, spatial learning in the water maze was assessed. At 8 months of age all experimental groups were equally proficient. However, at 18 months of age, the EOGHD group had poor spatial learning compared to the AOGHD, GH-replete, and HZ groups. Our data indicate that GHD during adolescence has negative effects on learning and memory that emerge by middle-age unless prevented by GH supplementation.

Mechanism for the Cardiovascular Action of Intracerebroventricularly Administered Vasoactive Intestinal Polypeptide in Rats

It was investigated whether the secretion of epinephrine, norepinephrine, and arginine vasopressin from the adrenal medulla, sympathetic nerve endings, and posterior pituitary gland, respectively, was involved in the mediation of the pressor effect of intracerebroventricular (icv) administration of vasoactive intestinal polypeptide (VIP) in anesthetized rats. Icv administration of 1 microgram VIP increased mean blood pressure by 21% and heart rate by 17% in Wistar rats although the lesser dose was effective only for increasing heart rate. Simultaneously with the change in blood pressure and heart rate, the concentrations of plasma epinephrine and norepinephrine rose 4 and 10 min after VIP administration. After adrenalectomy, the action of VIP on mean blood pressure or heart rate was unchanged or partially reduced, respectively. Although the cardiovascular action of VIP was observed in control Long-Evans rats as well as in Brattleboro rats homozygous or heterozygous for diabetes insipidus, which hereditarily lacked vasopressin completely or partially, the increase in mean blood pressure after icv administration of VIP was more marked in homozygous than heterozygous rats or Long-Evans rats. These results suggest that the cardiovascular action of centrally administered VIP is mediated by increased sympathetic nerve outflows including stimulation of adrenal epinephrine secretion and is enhanced by the chronic absence of vasopressin secretion from the posterior pituitary gland.

Complete knockout of the nociceptin/orphanin FQ receptor in the rat does not induce compensatory changes in μ, δ and κ opioid receptors

The nociceptin/orphanin FQ (N/OFQ) opioid peptide receptor (NOPr) is a new member of the opioid receptor family consisting of μ, δ and κ opioid receptors. The anti-opioid properties of its endogenous ligand, N/OFQ provide the receptor interesting potentials in symptoms and processes related to drug addiction, learning and memory, anxiety and depression, and nociception. Using target-selected N-ethyl-N-nitrosourea (ENU)-driven mutagenesis we recently generated a rat model bearing a premature stop codon in the opioid-like receptor (oprl1) gene, and here we describe the primary characterization of this novel model. Data revealed that [3H]N/OFQ binding to brain slices was completely absent in rats homozygous for the premature stop codon (oprl1−/−). Heterozygous rats displayed an intermediate level of NOPr binding. Oprl1 receptor transcript levels, as determined by Northern blot analysis, were reduced by approximately 50% in oprl1−/− rats compared to wild-type controls (oprl1+/+), and no alternative spliced transcripts were observed. Quantitative autoradiographic mapping of μ, δ and κ opioid receptors using [3H]DAMGO, [3H]deltorphin and [3H]CI-977, respectively, did not show any changes in opioid receptor binding. In conclusion, we present a novel mutant rat lacking NOPr without compensatory changes in μ, δ and κ opioid receptors. We anticipate that this mutant rat will have heuristic value to further understand the function of NOPr.

Generating mutant rats using the Sleeping Beauty transposon system

The laboratory rat is an invaluable animal model for biomedical research. However, mutant rat resource is still limited, and development of methods for large-scale generation of mutants is anticipated. We recently utilized the Sleeping Beauty (SB) transposon system to develop a rapid method for generating insertional mutant rats. Firstly, transgenic rats carrying single transgenes, namely the SB transposon vector and SB transposase, were generated. Secondly, these single transgenic rats were interbred to obtain doubly-transgenic rats carrying both transgenes. The SB transposon was mobilized in the germline of these doubly-transgenic rats, reinserted into another location in the genome and heterozygous mutant rats were obtained in the progeny. Gene insertion events were rapidly and non-invasively identified by the green fluorescence protein (GFP) reporter incorporated in the transposon vector, which utilizes a polyA-trap approach. Mutated genes were confirmed by either linker ligation-mediated PCR or 3′-rapid amplification of cDNA ends (3′RACE). Endogenous expression profile of the mutated gene can also be visualized using the LacZ gene incorporated as a promoter-trap unit in the transposon vector. This method is straightforward, readily applicable to other transposon systems, and will be a valuable mutant rat resource to the biomedical research community.

Early-life sodium exposure unmasks susceptibility to stroke in hyperlipidemic, hypertensive heterozygous Tg25 rats transgenic for human cholesteryl ester transfer protein.

Early-life risk factor exposure increases aortic atherosclerosis and blood pressure in humans and animal models; however, limited insight has been gained as to end-organ complications. We investigated the effects of early-life Na exposure (0.23% versus 0.4% NaCl regular rat chow) on vascular disease outcomes using the inbred, transgenic [hCETP](25) Dahl salt-sensitive hypertensive rat model of male-predominant coronary atherosclerosis, Tg25. Rather than the expected increase in coronary heart disease, fetal 0.4% Na exposure (< or =2 g of Na per 2-kcal/d diet) induced adult-onset stroke in both sexes (ANOVA P<0.0001), with earlier stroke onset in Tg25 females. Analysis of later onset of 0.4% Na exposure resulted in decreased stroke risk and later stroke onset despite longer 0.4% Na exposure durations, which indicates increasing risk with earlier onset of 0.4% Na exposure. Histological analysis of stroke-positive rat brains revealed cerebral cortical hemorrhagic infarctions, microhemorrhages, neuronal ischemia, and microvascular injury. Ex vivo MRI of stroke-positive rat brains detected cerebral hemorrhages, microhemorrhages, and ischemia with middle cerebral artery distribution and cerebellar noninvolvement. Ultrasound microimaging detected carotid artery disease. Prestroke analysis detected neuronal ischemia and decreased mass of isolated cerebral but not cerebellar microvessels. Early-life Na exposure exacerbated hypertension and unmasked stroke susceptibility, with greater female vulnerability in hypertensive, hyperlipidemic Tg25 rats. The reproducible modeling in stroke-prone Tg25 rats of carotid artery disease, cerebral hemorrhagic infarctions, neuronal ischemia, microhemorrhages, and microvascular alterations suggests a pathogenic spectrum with causal interrelationships. This "mixed-stroke" spectrum could represent paradigms of ischemic-hemorrhagic transformation and/or a microangiopathic basis for the association of ischemic lesions, microhemorrhages, and strokes in humans. Together, the data reveal early-life Na exposure to be a significant modifier of hypertension and stroke disease course and hence a potentially modifiable prevention target that deserves systematic study.

Suppression of prostate cancer in a transgenic rat model via γ‐tocopherol activation of caspase signaling

Epidemiological data indicate that intake of one form of vitamin E, gamma-tocopherol, may reduce prostate cancer risk, and several in vitro studies have demonstrated that gamma-tocopherol can inhibit prostate cancer cell growth. The purpose of the present study was to confirm effects of gamma-tocopherol on prostate cancer in the transgenic rat for adenocarcinoma of prostate (TRAP) model established in our laboratory. In Experiment 1, heterozygous male TRAP rats 5 weeks of age received alpha-tocopherol at the concentration of 50 mg/kg in the diet, or gamma-tocopherol at 50 or 100 mg/kg for 10 weeks. In Experiment 2, TRAP rats of 3 weeks of age were given gamma-tocopherol at 50, 100, or 200 mg/kg diet for 7 weeks. gamma-Tocopherol did not affect body weight gain, organ weights or serum levels of either testosterone or estradiol. However, quantitative evaluation of prostatic lesions demonstrated significantly suppression of sequential progression from PIN to adenocarcinoma in a dose-dependent manner, along with clear activation of caspases 3 and 7 in the ventral lobe in both experiments. The present study clearly demonstrated that gamma-tocopherol suppresses prostate tumor progression in an in vivo TRAP model, and could be a candidate chemopreventive agent for human prostate cancer.

The role of vasopressin in hypothalamo-pituitary-adrenal axis regulation during lactation

Event Abstract Back to Event The role of vasopressin in hypothalamo-pituitary-adrenal axis regulation during lactation Subodh Kumar Jain1, 2*, Zsuzsa Mergl2, Istvan Barna2, 3, Mario Engelmann3 and Dóra Zelena2 1 Dr.H.S.Gour University, Department of Zoology, India 2 Hungarian Academy of Sciences, Hungary 3 Otto-von-Guericke-Universität, Germany Adaptation to stress is a basic phenomenon in life and the hypothalamo-pituitary-adrenal axis (HPA) plays a crutial role in it. Lactation is a chronic load therefore HPA axis is constantly active. Here we examined the role of vasopressin (AVP) in HPA axis regulation during lactation using the natural AVP knockout Brattleboro rat. Virgin and lactating, homo- and heterozygous (control) AVP-deficient rats were compared. Heterozygous dams showed all somatic signs of chronic stress (elevated adrenal weight and involuted thymuses) compared to virgins. The lack of AVP prevented the adrenal gland hyperplasia only. Corticotrop releasing hormone mRNA level in the hypothalamic paraventricular nucleus (PVN) was elevated in heterozygous dams, but not in AVP-deficient mothers. The adrenocorticotropin (ACTH) percursor proopiomelanocortin mRNA level in the adenohypophysis was elevated in dams as well as in AVP-deficient virgins without interaction. Resting plasma ACTH levels were unchanged, while corticosterone levels were elevated in heterozygous dams without changes in AVP-deficient dams. The oxytocin mRNA in the PVN was higher in AVP-deficient virgins but lactation induced further rise in both genotypes. Our results support the view that lactation leeds to the development of chronic stress state. The regulatory role of AVP was only partial. Oxytocin elevation may compensate the missing AVP, however the functional restitution is not complete. Conference: 12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009. Presentation Type: Poster Presentation Topic: Homeostatic regulatory mechanisms Citation: Jain S, Mergl Z, Barna I, Engelmann M and Zelena D (2009). The role of vasopressin in hypothalamo-pituitary-adrenal axis regulation during lactation. Front. Syst. Neurosci. Conference Abstract: 12th Meeting of the Hungarian Neuroscience Society. doi: 10.3389/conf.neuro.01.2009.04.013 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Feb 2009; Published Online: 25 Feb 2009. * Correspondence: Subodh Kumar Jain, Dr.H.S.Gour University, Department of Zoology, Sagar - 470 003, India, subjain@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Subodh Kumar Jain Zsuzsa Mergl Istvan Barna Mario Engelmann Dóra Zelena Google Subodh Kumar Jain Zsuzsa Mergl Istvan Barna Mario Engelmann Dóra Zelena Google Scholar Subodh Kumar Jain Zsuzsa Mergl Istvan Barna Mario Engelmann Dóra Zelena PubMed Subodh Kumar Jain Zsuzsa Mergl Istvan Barna Mario Engelmann Dóra Zelena Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Life History of Cones in the Rhodopsin-Mutant P23H-3 Rat: Evidence of Long-term Survival

To follow the status of cones over the life of the P23H-3 transgenic rat, while the rod population is depleted. P23H-3 heterozygous and Sprague-Dawley (SD) control rats were raised in dim, cyclic light from postnatal day (P)10 to P540. Retinas were examined for cone density, cone outer segment (OS) length, cone axon and soma morphology, and the amplitude of rod and cone components of the electroretinogram (ERG) were determined. In the P23H-3 retina, cone density followed a developmental pattern, increasing from P10 until P20, declining during early adult life (to P150), then steadying at levels found in the SD retina until P540. Cone OSs elongated to P30 and then slowly shortened during late adulthood; at P350 and P540, cone OSs were significantly shorter than in the background SD strain. Cone axons shortened slowly throughout adult life as the outer nuclear layer thinned. The rod a-wave declined steadily in the P23H-3 retina from P10, falling below amplitudes seen in the SD strain from early life. By contrast, the cone b-wave maintained amplitude at SD levels, until P380. Despite the ongoing loss of rod function and numbers, cone numbers in the P23H-3 retina were maintained at levels found in the SD rat to the oldest age examined, and cone function and OS morphology were maintained for approximately 1 year, indicating a long period of cone independence. The long period of cone survival creates an opportunity to induce self-repair, if the stress causing their dysfunction can be reduced.

Activity of Oxytocinergic Neurons in the Supraoptic Nucleus under Stimulation of α2‐Adrenoceptors in Brattleboro Rats

Vasopressin (AVP) deficient homozygous Brattleboro rats exhibit severe osmotic challenges due to waterless chronic hypernatremia and hyperosmolality. We investigated the effect of xylazine, an alpha2-adrenoceptor agonist, on the activity of oxytocinergic (OXY) neurons in the supraoptic nucleus (SON) of homozygous (di/di), heterozygous (di/+), and control (+/+) rats. Ninety minutes after saline (0.1 mL/100 g b.w., i.p.) or xylazine injection (10 mg/kg, i.p.) rats were anaesthetized with pentobarbital (50 mg/kg i.p.) and sacrificed by transcardial perfusion with fixative. Activity of OXY neurons was evidenced by nuclear Fos protein immunoreactivity. Fos/OXY colabelings were analyzed on 40-mum thick coronal sections using computerized light microscope. As expected, plasma osmolality and water intake revealed high heterogenity within the di/di group of rats. Fos expression in SON of di/di rats was correlated with osmolality of each rat. In saline-treated rats, maximum activation of Fos reached around 4% in +/+, 20% in di/+ rats, and as much as 60% in di/di rats. Xylazine activated in SON about 70% of OXY-ergic neurons in +/+, 60% in di/+ rats, and more than 80% in di/di rats. The present findings indicate that in spite of the high spontaneous activity of SON OXY-ergic neurons due to the AVP deficiency in di/di rats, many of the silent OXY-ergic neurons in the SON remained acceptable for alpha2-adrenoceptor stimulation.

Deficiency in endothelin receptor B reduces proliferation of neuronal progenitors and increases apoptosis in postnatal rat cerebellum.

Endothelins regulate cellular functions in the mammalian brain through the endothelin receptors A and B (EDNRA and EDNRB). In this study, we investigated the role of EDNRB on cell proliferation in the cerebellum by using the spotting lethal (sl) rat, which carries a naturally occurring deletion in the EDNRB gene. Proliferating cells in the three genotypes, wild-type (+/+), heterozygous (+/sl) and homozygous mutant (sl/sl) rats were labelled by intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) at postnatal day 2. The density of BrdU-positive cells (per mm(2)) in the external germinal layer of sl/sl rats (Mean +/- SEM, 977 +/- 388) was significantly reduced compared to +/+ (4915 +/- 631) and +/sl (2304 +/- 557) rats. Subsequently, we examined the effects of EDNRB mutation on neural apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP nick end-labelling assay. This showed that the density of apoptotic cells in the cerebella of sl/sl rats (9.3 +/- 0.5/mm(2)) was significantly more increased than +/+ rats (4 +/- 0.7). The expression of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) were measured with standard ELISA, but were unchanged in all genotypes. These results suggest that ENDRB mediates neural proliferation and have anti-apoptotic effects in the cerebellum of the postnatal rat, and that these effects are independent of changes in the expression of BDNF and GDNF. Our findings will lead to better understanding of the morphological changes in the cerebellum of Hirschsprung's disease patients with congenital EDNRB mutation.

Nephrotoxic serum nephritis in nude rats: the roles of host immune reactions in the accelerated type.

By immunization with rabbit immunoglobulins and the injection of a subnephritogenic dose of rabbit nephrotoxic serum (NTS), accelerated-type nephrotoxic serum nephritis (NTN) was induced in heterozygous (rnu/+) rats but not in athymic nude (rnu/rnu) rats. By transferring rat antibody against rabbit immunoglobulins, marked proteinuria was induced also in nude rats (202.0 +/- 98.4 mg/day on day 3) as in rnu/+ rats (122.6 +/- 35.3 mg/day on day 3). No marked differences in histological findings could be found between both groups. The most marked increase in the number of intraglomerular infiltrating cells was observed in heterozygous rats indicating that the presence of thymus-derived cells leads to the accumulation of more cells in glomeruli. We conclude that humoral immunity alone is enough to accelerate the pathogenic mechanism which induces glomerular injury with heavy proteinuria in this model.

Nephrotoxic serum nephritis in nude rats: the roles of host immune reactions

A description is made of renal lesions in rats induced by heterologous (rabbit) nephrotoxic serum with or without subsequent host immune reactions against it and the effects of immune reactions on the course of classical nephrotoxic serum (Masugi) nephritis are discussed. The disease was induced by injecting congenitally athymic ACI nude rats (rnu/rnu) and their normal heterozygous littermates (rnu/+) with rabbit anti-rat glomerular basement membrane (GBM) antiserum. In the autologous phase, rat IgG and immunoglobulins were localized in a linear pattern along capillary walls only in nephritic heterozygous rats. In the indirect plaque-forming cell (PFC) assay against rabbit immunoglobulins in the autologous phase, significantly more PFC could be detected in nephritic heterozygous rats than in nephritic nude rats. The nude and heterozygous rats were essentially the same with respect to the amount of urinary protein, histological change and clinical course. At least in classical nephrotoxic serum nephritis in rats, host immune reactions against GBM bound heterologous nephrotoxic serum were concluded to have no effect on the course of the disease.

Hyperbilirubinemia's protective effect against cisplatin nephrotoxicity in the Gunn rat

Gunn rats, deficient in the enzyme uridine diphosphate glucuronyl transferase, were used to investigate the effects of unconjugated hyperbilirubinemia in cisplatin nephrotoxicity. The effect of bilirubin on the antineoplastic activity of cisplatin in osteosarcoma cell lines was also determined. The in vivo model involved three groups of rats (n=6 rats/group): homozygous Gunn rats (j/j), heterozygous Gunn rats (j/+), and congenic Wistar rats. On day 0, all rats were given 4 mg/kg cisplatin intraperitoneally. Blood was sampled on days 0, 3, and 5 for bilirubin, BUN, and creatinine and kidneys were taken on day 5. Cell culture was performed in four canine osteosarcoma cell lines using the average concentrations of bilirubin for homozygous Gunn rats at day 0 and 3. Bilirubin was added to cell lines alone and with cisplatin. Cell viability was assessed using the CellTiter Blue assay. Serum bilirubin levels were highly elevated in Gunn j/j, moderately elevated in Gunn j/+, and undetectable in Wistar rats at day 0. Bilirubin provided a nephroprotective effect, with significantly lower BUN and creatinine in Gunn j/j when compared with Wistar rats at day 5. Histological grading demonstrated preservation of the S3 segment in Gunn j/j when compared with Wistar rats (P<0.05). Bilirubin had no significant effect on the antineoplastic effect of cisplatin at either concentration in the four cell lines (P<0.001). Hyperbilirubinemia in the Gunn rat provided marked preservation of renal function and histology in a cisplatin nephrotoxicity model. Exogenous bilirubin did not interfere with the antineoplastic activity of cisplatin in vitro.

Serotonin transporter dosage modulates long-term decision-making in rat and human

Decision-making plays an important role in everyday life and is often disturbed in psychiatric conditions affected by the common human serotonin transporter promoter length polymorphism (5-HTTLPR). This raises the hypothesis that decision-making is modulated by the serotonergic system, but currently it is unclear how the 5-HTTLPR affects central serotonergic functioning. We tested healthy human volunteers genotyped for the 5-HTTLPR in the Iowa Gambling Task (IGT), which is one of the most frequently used neuropsychological tasks to assess decision-making. Furthermore, we tested female homozygous (SERT −/−) and heterozygous (SERT +/−) serotonin transporter knockout rats in a rodent version of the IGT. Women homozygous for the short (s) allele of the 5-HTTLPR were found to choose more disadvantageously than women homozygous for the long allele of the 5-HTTLPR as the IGT progressed. In the rat, SERT −/− and SERT +/− were associated with advantageous decision-making compared to SERT +/+ as the IGT progressed. Combining the human and rat observations, we show that SERT dosage affects the maintenance of a once established choice option, irrespective of the choice (advantageous or disadvantageous) that has been made. We postulate that the SERT-mediated effects relate to deficits in the processing of choice outcome to guide subsequent choices in this gamble-based test, and that SERT −/− and SERT +/− rodent models in combination with studies in humans can be used to provide insight in the modulatory effects of 5-HTTLPR.

Late-onset endothelin receptor blockade in hypertensive heterozygous REN-2 transgenic rats

Our previous studies in heterozygous Ren-2 transgenic rats (TGR) have shown that early treatment with selective endothelin (ET) A receptor blockade is superior to nonselective ET A/B receptor blockade. The aim of this study was to evaluate the role of the ET system in male heterozygous TGR with established hypertension (late-onset treatment). TGR and control Hannover Sprague–Dawley (HanSD) rats were fed a high-salt diet and were treated concomitantly with the nonselective ET A/B receptor blocker bosentan or the selective ET A receptor blocker atrasentan from day 52 of age on. Survival rate was partly increased by bosentan and fully normalized with atrasentan. Bosentan transiently decreased blood pressure (BP), whereas atrasentan significantly reduced BP as early as one week after the start of the treatment. This effect persisted for the whole experimental period. Atrasentan also substantially reduced cardiac hypertrophy, proteinuria, glomerulosclerosis and left ventricle ET-1 content. Bosentan improved and atrasentan almost restored podocyte architecture and reversed changes in podocyte phenotype represented by the expression of CD 10, desmin and vimentin. Our results demonstrate that selective ET A receptor blockade has more favorable effects than nonselective ET A/B receptor blockade and, unlike observed in homozygous TGR, ET A receptor blockade has similar effects in heterozygous rats with established hypertension as in young animals with developing hypertension.

Increased osmotic fragility of erythrocytes in chronically jaundiced rats after phototherapy.

Littermate homozygous (jj) and heterozygous (Jj) Gunn rats, were irradiated with blue fluorescent light for 18 hours continuously. The incident irradiance was 1.5 mWatts/cm2 in the 420--480 nm band pass. The influence of the irradiance on circulating erthrocytes was studied by testing their osmotic fragility before and after the irradiance. The non-jaundiced, Jj, animals did not exhibit any increase in the osmotic fragility of their erythrocytes. The osmotic fragility of the erythrocytes from jaundiced, jj, animals was the same as the Jj animals prior irradiance. However, the fragility of the erythrocytes from the jj animals was significantly increased after the 18 hours of irradiance. The results indicated that the photodynamic action of bilirubin may be present in vivo.

Heredity mode of genetic polymorphism in aldehyde oxidase activity in Donryu strain rats

Donryu strain rats show genetic polymorphisms in the aldehyde oxidase gene, resulting in the phenotypic expression of ultrarapid metabolizers with homozygous nucleotide sequences (337G, 2604C), extensive metabolizers with heterozygous nucleotide sequences (377G/A, 2604C/T), and poor metabolizers with homozygous nucleotide sequences (377A, 2604T). In the mating experiments the ratio of the number of ultrarapid metabolizers, extensive metabolizers, and poor metabolizers rats in the F1 generation from the heterozygous F0 extensive metabolizers male and female rats was roughly 0.6 : 1.5 : 1, and the ratio converged to approximately 1 : 2 : 1 in the F2 generation from the heterozygous F1 extensive metabolizers male and female rats. On the contrary, all the F2 generation from homozygous F1 ultrarapid metabolizers male and female rats or from homozygous F1 poor metabolizers male and female rats had the ultrarapid metabolizers or the poor metabolizers genotypes and phenotypes. The genotypes completely agreed with the phenotypes in all individuals of F0, F1, and F2 generations. The results indicate that the genetic polymorphism of aldehyde oxidase in Donryu strain rats obeys Mendelian heredity. The reason for a low ratio of the ultrarapid metabolizers rats in the commercially available Donryu strain rats — not more than several per cent — compared with the ratio expected from the Mendelian rule is unknown.