Male Brown Norway Rats Research Articles

Differential effects of late-life initiation of low-dose enalapril and losartan on diastolic function in senescent Fischer 344 × Brown Norway male rats

No proven pharmacological therapies to delay or reverse age-related diastolic dysfunction exist. We hypothesized that late-life low-dose (non-blood-pressure-lowering) angiotensin-converting enzyme inhibition vs. angiotensin II receptor blockade would be equally efficacious at mitigating diastolic dysfunction in the senescent Fischer 344 × Brown Norway rat. Enalapril (10mg/kg/day; n = 9) initiated at 24months of age and continued for 6months, increased myocardial relaxation (e'), reduced Doppler-derived indices of filling pressure (E/e'), favorably lowered the ratio of phospholamban-SERCA2 and reduced oxidative stress markers, Rac1 and nitrotyrosine, in aged hearts. Treatment with losartan (15mg/kg/day; n = 9) similarly mitigated signs of cardiac oxidative stress, but impairments in diastolic function persisted when compared with untreated rats (n = 7). Our findings favor the idea that the lusitropic benefit of low-dose angiotensin-converting enzyme inhibitor initiated late in life may be related to an antioxidant-mediated modulation of SERCA2, resulting in improved relaxation rather than via overt effects on cardiac structure or blood pressure.

Changes in Rat Sperm Chromatin Integrity and Protamination Levels Following Chronic Treatment with the Chemotherapeutic Cocktail Used to Treat Testicular Cancer.

The incidence of testicular cancer has increased dramatically over the past 50 years such that it has become the most common cancer among young men of reproductive age. Advances in the treatment of this disease, that includes the co-administration of bleomycin, etoposide and cis-platinum (BEP), have brought the cure rate to over 90 percent. This high cure rate, in conjunction with the young age of patients, increases the likelihood that, after treatment, these men desire fathering children. Thus, the impact of the treatment on reproductive function, fertility, and progeny outcome are of particular importance. Results previously published from our laboratory have demonstrated that chronic exposure to BEP for nine weeks in male rats severely affected sperm chromatin integrity and resulted in early postnatal mortality in progeny sired by these animals. We hypothesize that DNA damage resulting from a chronic nine-week exposure to BEP will be repaired following cessation of treatment, such that the subsequent wave of spermatogenesis will produce newly divided germ cells that are unaffected. To test our hypothesis, male Brown Norway rats were treated with 1.8 mg/kg cis-platinum and 9.0 mg/kg etoposide daily by oral gavage and 0.9 mg/kg bleomycin weekly via an intraperitoneal injection for 9 weeks. Control animals were treated in the same fashion with 0.9% saline. Animals were divided into two groups such that one group of animals was euthanized at the end of the treatment period while the other group was euthanized nine weeks post-treatment, after the completion of one entire cycle of spermatogenesis post-treatment. Both the susceptibility of DNA to denaturation, evaluated by the sperm chromatin structure/acridine orange assay, and the number of single and double DNA strand breaks, as measured by the COMET assay, were significantly increased in mature cauda sperm following nine weeks of treatment with BEP. However, cauda sperm from animals nine weeks post-treatment did not show any significant DNA damage, indicating that DNA damage was repaired in the following wave of spermatogenesis. Interestingly, the protamination level in these post-treatment sperm, assessed by the chromomycin A3 (CMA3) assay, revealed a significant decrease in protamine content as demonstrated by an increase in CMA3 fluorescence that was not seen following nine weeks of treatment. These findings demonstrate that the chromatin integrity of cauda sperm is not completely repaired nine weeks post-treatment; we suggest that persistent damage may result in adverse effects on progeny outcome. Supported by CIHR and the REDIH CIHR training program. (platform)

Thalidomide Attenuates Graft Arteriosclerosis of Aortic Transplant in a Rat Model

Objective The purpose of the current study was to evaluate the effects of thalidomide on graft arteriosclerosis. Materials and Methods Male Lewis rats received abdominal aorta grafts from male Brown-Norway rats. The animals were divided into 4 groups: no treatment controls, a low-dose group that received thalidomide (50 mg/kg per day), a middle dose group that received thalidomide (100 mg/kg per day), and a high-dose group that received thalidomide (200 mg/kg per day) by daily intragastric administration. Rats were humanely killed at 60 days after surgery. The grafted aortas were analyzed by histology, immunohistochemistry, and Western blot analysis. The serum was analyzed by an enzyme-linked immunosorbent assay (ELISA). Results The neointimal thickness of the thalidomide treated aortas was significantly thinner compared with that of no treatment aortas ( P < .05). Vascular endothelial growth factor (VEGF), platelet-derived growth factor, and intracellular adhesian molecule (ICAM-1) protein expression in the treatment group were significantly lower than those in the control group ( P < .05). Moreover, thalidomide significantly inhibited the production of VEGF and ICAM-1 in serum ( P < .05). Conclusion Our data suggested that thalidomide can attenuate graft arteriosclerosis so as to protect aortic grafts.

Clarology for Conjugated Carbon Nano-Structures: Molecules, Polymers, Graphene, Defected Graphene, Fractal Benzenoids, Fullerenes, Nano- Tubes, Nano-Cones, Nano-Tori, etc.

Aim: The effects of Guanabenz, an agonist of α2-adrenergic receptors routinely used in human medicine as an antihypertensive drug, were studied on NaIO3-induced retinal pigment epithelium (RPE) degeneration, laser-induced choroidal neovascularization (CNV) and choroidal blood flow, in animal models.Methods: The 35mg/kg NaIO3-induced RPE degeneration rat eyes were instilled with 1% Guanabenz eye drops 3 times a day for 7 days before NaIO3 injection, and then 2 to 4 weeks thereafter. RPE function was measured with c-wave of electroretinogram (ERG). Male Brown Norway rats were anesthetized to receive Nd:YAG laser to break the Bruch’s membrane. One percent Guanabenz eye drops were given likewise. The development of CNV was determined by fluorescein angiography performed on week 2 and week 4 using sodium fluorescein (FA) or fluorescein isothiocyanatedextran (FD70-FA). Colored microsphere technique was used for in vivo experiments to determine the choroidal blood flow in ocular hypertensive (40 mmHg) rabbit eyes.Results: The RPE function was protected significantly by Guanabenz according to the c-wave of ERG. Four weeks after NaIO3 injection, the amplitude of ERG c-wave was 0.422±0.092 millivolts in the control group, 0.103±0.04 millivolts in the NaIO3 group, and 0.254±0.061 millivolts in the Guanabenz+NaIO3 group. There was a significant protection of the ERG c-wave by Guanabenz as compared to NaIO3 group (P<0.01). The angiograms of FD70-FA showed decreased lesion size in the Guanabenz group. Four weeks after laser treatment, the size of the CNV lesion was 2.99±0.18 mm2 in the control group, and 1.24±0.16 mm2 in the Guanabenz group (P<0.01). The choroidal blood flow was significantly increased at 30 and 60 minutes after Guanabenz instillation as compared to corresponding controls. Conclusions: Guanabenz significantly protected RPE from NaIO3-induced degeneration, inhibited the development of CNV in laser-induced rat AMD model and increased choroidal blood flow markedly in vivo.

Serum biomarkers in young adult and aged Brown Norway (BN) rats following episodic (weekly) ozone exposure

Ozone (O3) is an air pollutant that is associated with cardiovascular and respiratory diseases. Older adults are considered to be particularly susceptible to oxidant air pollutants such as O3. Serum biomarkers are being sought that would lead to better predictions of susceptibility in the aged to air pollutants. We exposed young adult (4 month) and aged (20 month) male BN rats (N=7) to air (control) or 0.8 ppm O3 for 6 hr/d, 1 d/wk for 17 wks. Respiratory parameters assessed by unrestrained plethysmography the day after exposure revealed that O3 led to airway‐flow limitation. Rats were terminated 24 hr after the last exposure. Bronchoalveolar fluid macrophages were reduced in aged rats and neutrophils increased in young rats exposed to O3. A panel of 58 protein analytes was quantified in serum, including cytokines, chemokines, and tissue factors (Rules Based Medicine). Age affected 20 analytes, including C‐reactive protein, interferon, factor VII, and macrophage inflammatory protein‐2 (MIP‐2). O3 affected 6 analytes, including fibroblast growth factor (basic), MIP‐2, leukemia inhibitor factor, and haptoglobin. Age by O3 interactions were obtained for MIP‐2 and myoglobin. The data illustrate that serum analytes may be beneficial as biomarkers to assess aging and susceptibility to criteria air pollutants. This is an abstract of a proposed presentation and does not reflect US EPA policy.

Environmentally persistent free radicals decrease cardiac function before and after ischemia/reperfusion injury in vivo

Exposure to airborne particles is associated with increased cardiovascular morbidity and mortality. During the combustion of chlorine-containing hazardous materials and fuels, chlorinated hydrocarbons chemisorb to the surface of transition metal-oxide-containing particles, reduce the metal, and form an organic free radical. These radical-particle systems can survive in the environment for days and are called environmentally persistent free radicals (EPFRs). This study determined whether EPFRs could decrease left ventricular function before and after ischemia and reperfusion (I/R) in vivo. Male Brown–Norway rats were dosed (8 mg/kg, intratracheal) 24 h prior to testing with particles containing the EPFR of 1, 2-dichlorobenzene (DCB230). DCB230 treatment decreased systolic and diastolic function. DCB230 also produced pulmonary and cardiac inflammation. After ischemia, systolic, but not diastolic function was significantly decreased in DCB230-treated rats. Ventricular function was not affected by I/R in control rats. There was greater oxidative stress in the heart and increased 8-isoprostane (biomarker of oxidative stress) in the plasma of treated vs. control rats after I/R. These data demonstrate for the first time that DCB230 can produce inflammation and significantly decrease cardiac function at baseline and after I/R in vivo. Furthermore, these data suggest that EPFRs may be a risk factor for cardiac toxicity in healthy individuals and individuals with ischemic heart disease. Potential mechanisms involving cytokines/chemokines and/or oxidative stress are discussed.

Cardioprotection in Brown Norway Rats is Linked to Mitochondrial Complex I Preservation

Hearts from Brown Norway (BN) rats are more resistant to ischemia-reperfusion (IR) injury than hearts from Dahl Salt Sensitive (SS) rats. Moreover, introgression of BN chromosome 6 into SS confers IR resistance to the same degree as BN. We hypothesize that mitochondrial complex I preservation is linked to cardioprotection in this consomic rat model. Langendorff-prepared hearts from eight week old male BN, SS6BN and SS rats were subjected to 20 min perfusion, 30 min global ischemia or no ischemia (control), and 30 min reperfusion. Mitochondria were isolated and mitochondrial complex I preservation was measured by Western blotting using complex I NDUFA9 subunit antibody. We found higher protein levels in ischemic BN and SS6BN rat mitochondria compared to SS suggesting better preservation of complex I in BN and SS6BN. In contrast, the non-ischemic groups showed no detectable difference in protein levels. Previous studies have shown that mitochondrial function can be a trigger as well as an effector of cardioprotection. Our data shows that mitochondrial complex I is better preserved in BN and SS6BN than in SS. Since myocardial and mitochondrial functions differ significantly between the more IR-susceptible SS and the more IR-resistant BN and SS6BN strains, this suggests that rat chromosome 6 encodes one or more genes that are critical for mitochondrial function and cardioprotection.

Effect of sensory stimulation in rat barrel cortex, dorsolateral striatum and on corticostriatal functional connectivity

The striatum integrates sensory information to enable action selection and behavioural reinforcement. In the rat, a large topographical projection from the rat barrel cortex to widely distributed areas of the striatum is assumed to be an important structural component supporting these processes. The striatal sensory response is, however, not comprehensively understood at a network level. We used a 10-Hz, 100-ms air puff, allowing undamped movement of multiple whiskers, to look at functional connectivity in contralateral cortex and striatum in response to sensory stimulation. Simultaneous recordings of cortical and striatal local field potentials (LFPs) were made under isoflurane anaesthesia in 15 male Brown Norway rats. Four electrodes were placed in the barrel cortex while the dorsolateral striatum was mapped with a 500-μm resolution, resulting in a maximum of 315 recording positions per animal. Significant event-related responses were unevenly distributed throughout the striatum in 34.8% of positions recorded within this area. Only 10.3% of recorded positions displayed significant total power increases in the LFPs during the stimulation period at the stimulus frequency. This suggests that the responses seen in the LFPs are due to phase rearrangement rather than an amplitude increase in the signal. Analysis of corticostriatal imaginary coherence revealed stimulus-induced changes in the functional connectivity of 12% of corticostriatal pairs, the sensory response of sparsely distributed neuronal ensembles within the dorsolateral striatum is reflected in the phase relationship between the cortical and striatal local fields.

Blockade of the sonic hedgehog signalling pathway inhibits choroidal neovascularization in a laser-induced rat model

Sonic hedgehog (Shh) signaling has recently been shown to be involved in the pathological angiogenesis in response to tissue hypoxia and ischemic injury. Hypoxia/ischemia is considered to play an important role in the development of choroidal neovascularization (CNV). This study was aimed to examine the effect of blockade of the Shh signaling pathway on CNV and the underlying mechanism. A total of 64 male Brown-Norway (BN) rats were used in this study. One eye of each rat underwent laser photocoagulation. The other eye served as normal control. After the laser treatment, the 64 rats were divided into four groups (n=16 in each group): Blank control group, in which no intravitreal administration was given; cyclopamine group, recombinant Shh N-terminals protein (rShh) group and phosphate-buffered saline (PBS) group, in which cyclopamine (a Shh inhibitor), rShh (a Shh activator) and PBS were intravitreally injected into the laser-treated eyes respectively every other day for a total of four intravitreal injections immediately after the laser treatment. Fourteen days after the intravitreal administration, the changes of CNV-related variables, including positive CNV lesion percentage, CNV membrane area and CNV membrane thickness, were evaluated by fluorescein angiography, indocyanine green angiography and pathological examinations. The mRNA and protein expression of PTCH1, Gli1, HIF-1(α), VEGF and DLL4 in each group on 14 days of CNV model was detected by real-time quantitative PCR and western blot analysis, and the relationship between the Shh cascade and the HIF-1(α)-VEGF-DLL4 cascade in CNV was analyzed. The results showed that the CNV membrane area and the CNV membrane thickness were decreased by 62.5% and 41.9% in the cyclopamine group and increased by 85.7% and 64.3% in the rShh group in comparison to those in the blank control group (P<0.01 for each). There was no significant difference in the CNV membrane area and thickness between the blank control group and PBS group (P=0.102 and P=0.063, respectively). Real-time quantitative PCR revealed a 5.23-, 4.14-, 2.97-, 2.78- and 2.39-fold up-regulation of the mRNA expression of PTCH1, Gli1, HIF-1(α), VEGF and DLL4 genes in the laser-treated eyes compared with the normal control eyes in the control group. In the cyclopamine group, the mRNA and protein expression of Gli1, HIF-1(α), VEGF and DLL4 was significantly down-regulated (P<0.05 for each) while the expression of PTCH1 showed no significant changes at the mRNA (P=0.293) and protein level (P=0.304). The mRNA expression and protein expression (P=0.001 and P=0.021, respectively) of PTCH1, Gli1, HIF-1(α), VEGF and DLL4 was significantly increased in the rShh group when compared with the control group. The expression level of these genes was related to the severity of the CNV. It was concluded that intravitreal administration of cyclopamine can effectively inhibit the formation of laser-induced experimental CNV by down-regulating the expression of the HIF-1(α)-VEGF-DLL4 cascade in CNV. The Shh signaling pathway as an upstream signaling pathway of HIF-1(α)-VEGF-DLL4 cascade is implicated in the development of experimental CNV.

Drinking and arterial blood pressure responses to ANG II in young and old rats

We investigated water drinking and arterial blood pressure responses to intravenous infusions of ANG II in young (4 mo), middle-aged adult (12 mo), and old (29 mo) male Brown Norway rats. Infusions of ANG II began with arterial blood pressure either at control levels or at reduced levels following injection of the vasodilator minoxidil. Under control conditions, mean arterial pressure (MAP) in response to ANG II rose to the same level for all groups, and middle-aged and old rats drank as much or more water in response to ANG II compared with young rats, depending on whether intakes were analyzed using absolute or body weight-adjusted values. When arterial blood pressure first was reduced with minoxidil, MAP in response to ANG II stabilized at significantly lower levels compared with control conditions for all groups. Young rats drank significantly more water under reduced pressure conditions compared with control conditions, while middle-aged and old rats did not. Urine volume in response to ANG II was lower, while water balance was higher, under conditions of reduced pressure compared with control conditions. Baroreflex control of heart rate was substantially reduced in old rats compared with young and middle-aged animals. In summary, young rats appear to be more sensitive to the inhibitory effects of increased arterial blood pressure on water drinking than are older animals.

Role and possible mechanism of regulators of G-protein signaling 5 in development of experimental choroidal neovascularization

To observe the role and possible mechanism of regulators of G-protein signaling 5 (RGS5) in the development of experimental choroidal neovascularization (CNV). It was an experimental study. A total of 88 male Brown Norway (BN) rats underwent the 532 nm photocoagulation to set up the CNV model. Forty of them were sort by time after the photocoagulation as follows: 1 d (n = 6), 3 d (n = 6), 7 d (n = 7) and 14 d (n = 21), then 48 of them were divided by treatment factor: intravitreal injection of physiological saline or Avastin. Nineteen of them served as the controls. The expression of RGS5 and VEGF were examined by immunofluorescence, western blot and reverse transcription polymerase chain reaction (RT-PCR). The thickness and area of CNV were qualified by histopathological sections and choroidal flatmounts. All of the results were analyzed by Student's t-test. (1) The expression of RGS5 and VEGF proteins: there was no statistical significance in gray-scale value of RGS5 between 14 d group (0.899 ± 0.057) and control group (0.820 ± 0.032), although RGS5 expression reached a peak at 14 days (t = 2.079, P > 0.05). There was statistical significance in gray-scale value of VEGF between 7 d group (0.600 ± 0.031) and control group (0.382 ± 0.036), and VEGF expression reached a peak at 7 days (t = 7.959, P < 0.01). (2) The expression of RGS5 and VEGF mRNAs: the RGS5 mRNA expression decreased at 1 day (0.763 ± 0.035) and 3 days (0.725 ± 0.054) in comparison with the control (0.886 ± 0.047, t = 3.646, 3.888; P < 0.05, 0.05), and reached a peak at 14 days after photocoagulation (t = 2.194, P > 0.05). There was statistical significance in gray-scale value of VEGF between 7 d group (0.855 ± 0.029) and control group (0.274 ± 0.039), and VEGF expression reached a peak at 7 days after photocoagulation (t = 20.709, P < 0.01). (3) The changes of thickness and area of CNV: the thickness and area of CNV were significantly decreased (t = 2.616, 15.179; P < 0.05, 0.01) after intravitreal injection with Avastin. RGS5 and VEGF coexpressed in the area of CNV, and RGS5 expressed later than VEGF. The expression of RGS5 was decreased when CNV was inhibited by anti-VEGF treatment. Therefore, it is possible that RGS5 may be involved in VEGF-regulated CNV formation.

Targeting therapy of pigment epithelium derived factor mediated by ultrasound activated immunoliposome for choroidal neovascularization

目的 研究超声联合载色素上皮源性因子(PEDF)免疫纳米脂质体对脉络膜新生血管(CNV)的靶向治疗作用.方法 以CNV内皮细胞上血管内皮生长因子受体-2(VEGFR-2)为靶向位点,将其配体寡肽连接到纳米脂质体上,再反向装载PEDF,制备能与CNV内皮细胞特异性结合的免疫纳米脂质体.对48只BN大鼠右眼行半导体倍频激光(波长为532nm)光凝术建立CNV模型.光凝后7d,实验组鼠尾静脉分别注射游离PEDF、载PEDF脂质体、载PEDF免疫脂质体,联合眼局部超声波辐照20s,并设立玻璃体腔注射PEDF组和对照组.光凝后14d,脉络膜巩膜冰冻切片观察免疫脂质体对CNV的靶向性.FITC-右旋糖酐标记脉络膜巩膜铺片行新生血管定量分析.结果 载PEDF免疫脂质体可特异性靶向结合CNV.CNV与FITC标记的PEDF免疫纳米脂质体结合而呈现绿色荧光,正常脉络膜血管不显现荧光.玻璃体腔注射PEDF组及鼠尾静脉注射游离PEDF、载PEDF脂质体、载PEDF免疫脂质体组CNV面积均较对照组减少,差异有统计学意义(P＜0.05).超声联合PEDF免疫纳米脂质体组对CNV的抑制作用强于玻璃体腔注射PEDF组(P＜0.05).结论 动物实验证实PEDF免疫纳米脂质体可特异性结合CNV细胞,超声可增强PEDF免疫纳米脂质体对CNV的抑制作用,该方法有望为眼新生血管的治疗提供新途径。

Changes in aortic stiffness related to elastic fiber network anomalies in the Brown Norway rat during maturation and aging

Adult Brown Norway (BN) rats exhibit numerous internal elastic lamina (IEL) ruptures in the abdominal aorta (AA) and a lower aortic elastin-to-collagen ratio (E/C) compared with other strains. We studied here AA mechanical properties in BN compared with control strains. AA stiffness (assessed by plotting elastic modulus/wall-stress curves obtained under anesthesia), thoracic aorta elastin and collagen contents, and IEL ruptures in AA were measured in male BN and LOU rats aged 6, 10, and 15 wk. The Long Evans (LE) control strain was compared with BN at more advanced ages (15, 28, and 64 wk). At all ages, aortic E/C was lower in BN than in control strains. At 6 wk, AA stiffness was greater in BN than in LOU. In both strains, AA stiffness decreased between 6 and 10 wk, more so in BN than in LOU, and then increased, reaching similar values at 15 wk. BN AA stiffness was not different from that of LE at 15 and 28 wk, but was significantly lower at 64 wk. The increased stiffness in young BN rat AA may be due to the decreased E/C. IEL rupture onset in the BN around 7-8 wk, which decreases stiffness, as suggested by its pharmacological modulation, abolished such differences by 15 wk. Thereafter, age-related AA stiffness increased less in BN than in LE, likely due to the numerous IEL ruptures. We conclude that, in the BN rat, the lower E/C and the presence of IEL ruptures have opposing effects on arterial stiffness.

Intramuscular testosterone and trenbolone enanthate elevates hemoglobin concentrations

Testosterone enanthate (TE) increases serum testosterone (T), prostate mass, and hemoglobin (Hb) in orchidectomized (ORX) rodents. Trenbolone enanthate (TREN) is a synthetic analogue of T which does not undergo 5‐alpha reduction or aromatization; suggesting that it may increase Hb without inducing prostate enlargement. Our purpose was to determine whether TREN administration results in elevated circulating trenbolone (TR) and elevated Hb without prostate enlargement. Thirty‐five 10 month old male Brown Norway rats were randomized into Sham+vehicle (V), ORX+V, ORX+T, and ORX+TREN groups and received weekly drug injections for 42 days. Injections of TE, resulted in elevated serum concentrations of T compared to other treatments (p&lt;0.05). Whereas, injections of TREN increased serum TR levels without increasing serum T (p&lt;0.05). Prostate mass was 78% lower in ORX and 30% lower in TR groups vs. SHAM (p&lt;0.05); while prostate mass in ORX+T was nearly double SHAM (p&lt;0.05). Both T and TREN elevated Hb by 11% compared to ORX (p&lt;0.05). Ultimately, ORX+TREN elevated Hb concentrations and reduced prostate mass; suggesting that TR may selectively activate androgen receptors. Supported by a VA Merit Award (SEB).

Characterizing the Cardioprotective Phenotype of Brown Norway Rats: Importance of Optimal Ischemia Duration

The degree of cardiac ischemia‐reperfusion (IR) injury in Brown Norway (BN) and Dahl Salt Sensitive (SS) rats is remarkably different, with BN hearts being more resistant to IR injury than SS [1]. The objective of our study was to determine the role of varying ischemic duration on genome‐dependent cardioprotection in these two inbred rat strains. Langendorff‐prepared hearts from eight week old male BN and SS rats were perfused at constant pressure (90 mmHg) at 37ºC with crystalloid buffer solution. Isovolumetric left ventricular pressure, heart rate and coronary flow were measured before, during and after 25, 30 or 35 min of global no‐flow ischemia, and infarct size was determined at 120 min reperfusion. We found that longer ischemic periods were associated with worse functional recovery and larger infarct size by the end of reperfusion in both strains. However, the genetic background differentially modified this relationship such that optimal distinction between BN and SS strongly depended on ischemia time. These data suggest that differences in IR injury with varying ischemia duration affect the ability to investigate genome‐dependent cardioprotective pathways. Therefore, the choice of an optimal ischemia time [2] plays a crucial role during investigation of myocardial IR injury using this genetic model.

Resveratrol Affects Bone Minerals and Strength in Aging Hindlimb Suspended Rats

No studies have investigated the role of resveratrol supplementation on age‐related bone loss. Aging is also associated with unloading of bone due to increased bed rest. Hindlimb suspension (HLS) of rats stimulates mechanical unloading of bones. The study objective was to determine the effects of resveratrol supplementation on bones in aging ambulatory (AMB) and HLS rats. Mature adult (6mo) and old (32mo) Fischer Brown Norway male rats were kept AMB or HLS. Rats were than randomly assigned (n=7/group) to received a daily oral gavage of 12.5mg/kg bwt/d trans‐resveratrol or deionized water in 1 milliliter of 0.1% carboxymethylcellulose. At the end of 14 d, the femur and tibia were collected. Bone mineral content (BMC) was measured by ashing at 600°C. Bone calcium (Ca) and phosphorus (P) were determined by inductively coupled plasma optical emission spectrometry. Bone strength measurements were determined by three‐point bending test. In AMB rats, resveratrol supplementation decreased bone strength indicated by reduced tibial ultimate failure energy (p=0.02) in old rats and reduced femoral Young's modulus (YM) (p=0.02) in both mature and old rats. In HLS rats, resveratrol supplementation decreased tibial Ca (p=0.02), P (p=0.02), and strength indicated by lower ultimate stiffness (p=0.04) and YM (p=0.045) in mature rats. Based on our results resveratrol supplementation does not appear to benefit bone.

Experimental study on the inhibitory effect of bevacizumab on choroidal neovascularization in rat

Objective To observe the inhibitory effects and characteristics of intravitreal injection with bevacizumab on laser-induced choroidal neovascularization (CNV).Methods Twelve male brown norway (BN) rats were divided into the bevacizumab group and control group with six rats in each group.One eye of rats were received a series of 8 diode laser esions around optic disc to induce CNV,then the rats in bevacizumab group and control group underwent intravitreal injection with 2 μl bevacizumab and ringer's lactate.On days 7,14,and 21,the morphology and leakage of CNV were observed by fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA).On day 21 after photocoagulation,thephotocoagulated eyes were enucleated and processed for histopathologie examination,including hematoxylin and eosin (H&E) staining and immunohistochemistry staining for vascular endothelial growth factor (VEGF).Results On day 7 after photocoagulation,ICGA showed that CNV developed in the bevacizumab group and the control group.FFA showed that leakage intensity in the bevacizumab group was significantly lower than that in the control group,but the bevacizumab group gradually increased over time.The mean thickness of CNV significantly decreased in the bevacizumab group.The CNV in the bevacizumab group were negative for VEGF according to the result of immmuohistochemistry staining.Conclusions Early intravitreal injection with 2 μl bevacizumab can reduce the thickness of CNV and inhibit the leakage of CNV.However,bevacizumab could neither block the formation of CNV,nor suppress the permeability permanently.Combined other therapies with bevacizumab may be more potential to treat CNV effectively. Key words: Choroidal neovascularization/drug therapy; Angiogenesis inhibitors/therapeutic use; Antibodies,monoclonal/therapeutic use; Antibodies,monoclonal/administration & dosage; Disease models,animal

Spontaneous Fibrosarcoma with Pleomorphic Appearance in an Aged Brown Norway Rat

An 18-month-old male Brown Norway (BN) rat showed a grayish-white subcutaneous mass in the right cheek. Histologically, the mass was composed of highly pleomorphic cells producing collagen. Immunohistochemical analysis showed that the tumor cells were strongly positive for vimentin and partially positive for Ki-67; however, they were negative for ED-1, ED-2, S-100, cytokeratin, desmin and myoglobin. Ultrastructurally, the cytoplasms of the tumor cells contained well-developed rough endoplasmic reticulum. Thus, the tumor had no characteristic feature other than collagen production and was diagnosed as a fibrosarcoma.

Chronic ingestion of 2-deoxy- d-glucose induces cardiac vacuolization and increases mortality in rats

Calorie restriction (CR), the purposeful reduction of energy intake with maintenance of adequate micronutrient intake, is well known to extend the lifespan of laboratory animals. Compounds like 2-deoxy- d-glucose (2DG) that can recapitulate the metabolic effects of CR are of great interest for their potential to extend lifespan. 2DG treatment has been shown to have potential therapeutic benefits for treating cancer and seizures. 2DG has also recapitulated some hallmarks of the CR phenotype including reduced body temperature and circulating insulin in short-term rodent trials, but one chronic feeding study in rats found toxic effects. The present studies were performed to further explore the long-term effects of 2DG in vivo. First we demonstrate that 2DG increases mortality of male Fischer-344 rats. Increased incidence of pheochromocytoma in the adrenal medulla was also noted in the 2DG treated rats. We reconfirm the cardiotoxicity of 2DG in a 6-week follow-up study evaluating male Brown Norway rats and a natural form of 2DG in addition to again examining effects in Fischer-344 rats and the original synthetic 2DG. High levels of both 2DG sources reduced weight gain secondary to reduced food intake in both strains. Histopathological analysis of the hearts revealed increasing vacuolarization of cardiac myocytes with dose, and tissue staining revealed the vacuoles were free of both glycogen and lipid. We did, however, observe higher expression of both cathepsin D and LC3 in the hearts of 2DG-treated rats which indicates an increase in autophagic flux. Although a remarkable CR-like phenotype can be reproduced with 2DG treatment, the ultimate toxicity of 2DG seriously challenges 2DG as a potential CR mimetic in mammals and also raises concerns about other therapeutic applications of the compound.

PD0325901, a Mitogen-Activated Protein Kinase Kinase Inhibitor, Produces Ocular Toxicity in a Rabbit Animal Model of Retinal Vein Occlusion

PD0325901, a selective inhibitor of mitogen-activated protein kinase kinase (MEK), was associated with the occurrence of ocular retinal vein occlusion (RVO) during clinical trials in patients with solid tumors. As previous animal safety studies in rats and dogs did not identify the eye as a target organ of toxicity, this work was conducted to develop a rabbit model of ocular toxicity with PD0325901. Dutch-Belted rabbits were administered a single intravitreal injection of PD0325901 (0.5 or 1 mg/eye) or saline control, and ophthalmic examinations and retinal angiography were conducted over a 2-week period post-dose. In addition, mechanism of ocular toxicity was further explored in rat with microarray analysis. PD0325901 treatment produced RVO with retinal vasculature leakage and hemorrhage within 48-h postinjection in Dutch-Belted rabbits. Subsequent retinal detachment and degeneration were also detected on day 8 postinjection. To evaluate the potential mechanism(s) of PD0325901-mediated RVO, male Brown Norway rats were orally administered PD0325901 (45 mg/kg/day) up to 5 days and retinal tissue was collected for gene array analysis. Although PD0325901 did not produce clinical evidence of RVO in rats, retinal gene expression suggested an increased oxidative stress and inflammatory response, endothelium and blood-retinal barrier damage, and prothrombotic effects. Moreover, soluble endothelial protein C receptor (sEPCR), a biomarker for RVO, was elevated in human umbilical vascular endothelial cells (HUVECs) cultured with PD0325901. This work has developed a rabbit model of PD0325901-induced RVO that may be used to characterize the cellular and molecular mechanisms of this effect in humans.