[Directed differentiation of human induced pluripotent stem cells into midbrain]

OBJECTIVE

To establish an efficient protocol for directed differentiation of human induced pluripotent stem cells (hiPSCs) into functional midbrain dopaminergic progenitor cells (DAPs) in vitro.

METHODS

hiPSCs were induced to differentiate into DAPs in two developmental stages. In the first stage (the first 13 days), hiPSCs were induced into intermediate cells morphologically similar to primitive neuroepithelial cells (NECs) in neural induction medium containing a combination of small molecule compounds. In the second stage, the intermediate cells were further induced in neural differentiation medium until day 28 to obtain DAPs. After CM-DiI staining, the induced DAPs were stereotactically transplanted into the right medial forebrain bundle (MFB) of rat models of Parkinson's disease (PD). Eight weeks after transplantation, the motor behaviors of PD rats was evaluated. Immunofluorescence assay of brain sections of the rats was performed at 2 weeks after transplantation to observe the survival, migration and differentiation of the transplanted cells in the host brain microenvironment.

RESULTS

hiPSCs passaged stably on Matrigel showed a normal diploid karyotype, expressed the pluripotency markers OCT4, SOX2, and Nanog, and were positive for alkaline phosphatase. The primitive neuroepithelial cells obtained on day 13 formed dense cell colonies in the form of neural rosettes and expressed the neuroepithelial markers (SOX2, Nestin, and PAX6, 91.3%-92.8%). The DAPs on day 28 highly expressed the specific markers (TH, FOXA2, LMX1A and NURR1, 93.3-96.7%). In rat models of PD, the hiPSCs-DAPs survived and differentiated into TH⁺, FOXA2⁺ and Tuj1⁺ neurons at 2 weeks after transplantation. Eight weeks after transplantation, the motor function of PD rats was significantly improved as shown by water maze test (P < 0.0001) and apomorphine-induced rotation test (P < 0.0001) compared with rats receiving vehicle injection.

CONCLUSION

HiPSCs can be effectively induced to differentiate into DAPs capable of differentiating into functional neurons both in vivo and in vitro. In rat models of PD, the transplanted hiPSCs-DAPs can survive for more than 8 weeks in the MFB and differentiate into multiple functional neurocytes to ameliorate neurological deficits of the rats, suggesting the potential value of hiPSCs-DAPs transplantation for treatment of neurological diseases.

Evaluation of different rat models with intrauterine adhesions and improved technique for its establishment

Uterine adhesion (IUA), a leading cause of uterine infertility, is characterized by endometrial fibrosis. Implementing an appropriate animal model is essential for the research on the mechanisms of IUA. In the present study, we establish and evaluate different intrauterine adhesion modeling procedures in rats to provide a reference for researchers. Rat IUA models were established by mechanical injury, 95% ethanol injection, and dual (mechanical and infectious) injury. After two estrus cycles, the female rats were mated with sexually mature male rats and uterine tissues were obtained on the 5th day of pregnancy. HE staining and immunohistochemical detection of cytokeratin 19 and vimentin were performed to assess the morphology of the endometrium. The Masson staining and the expression of transforming growth factor -β1 and collagen Ι were used to assess the endometrium fibrosis. The expression of integrin avβ3, LIF, and HOXA10 in rat endometrium was used to evaluate the endometrial receptivity. In addition, the efficiency of embryo implantation was examined in the uterus on the 8th day of pregnancy. In conclusion, our study found that mechanical injury caused by the curette can be completely repaired after two estrus cycles. However, dual injury (mechanical injury with infection) and 95% ethanol injection can be used to establish the IUA rat model, and the dual damage is closer to the clinic-pathological characteristics of IUA.

Elevated Pro-inflammatory Cytokine Levels in Acute Reflux Esophagitis Are Reduced by 1,25 Dihydroxy Vitamin D3

BACKGROUND/AIM

Gastric acid reflux into the esophagus can cause irritation and inflammation of the esophagus and progress to reflux esophagitis (RE). Vitamin D3 (VitD3) has anti-inflammatory effects and plays an important regulatory role in adaptive and innate immunity. We hypothesized that VitD3 may play a protective role in RE.

MATERIALS AND METHODS

Seventy male Sprague-Dawley rats were used, and acute RE (n=35) or chronic RE (n=35) were surgically induced. The effects of different doses of VitD3 on morphological changes and alteration of pro-inflammatory cytokine levels were examined in the rat models. Western blot analysis was performed to determine protein expression levels of IL-1β, IL-6, and IL-8 in esophageal tissues. Serum levels of VitD3 and calcium were determined using enzyme-linked immunosorbent assays.

RESULTS

The protein expression of pro-inflammatory cytokines IL-1β, IL-6, and IL-8 was found significantly increased in RE. VitD3 treatment significantly reduced the levels of these pro-inflammatory cytokines in both the low-dose and high-dose VitD3 groups compared to control groups in acute RE, but not chronic RE. Macrographic and histopathological examination revealed various degrees of esophageal impairment in rats following surgical induction of acute or chronic RE in rats. These impairments were not improved by VitD3. Morphological grading of esophageal mucosa showed no significant differences between acute and chronic RE. Elevated serum levels of calcium were observed after VitD3 treatment.

CONCLUSION

IL-1β, IL-6, and IL-8 levels were significantly elevated in RE. The abnormal increase in these important pro-inflammatory cytokines was suppressed by VitD3 in the rat models of acute RE. These novel findings suggest a potential protective role of VitD3 in early-stage RE.

Elucidation of Ischemic Mechanisms of Early Pressure Injury during Post-Decompression and Detecting Methods

Background: Pressure injuries (PIs) generally result from prolonged ischemia through localized skin compression, and ischemia persists and exacerbates damage even post-decompression. The mechanisms of ischemia post-decompression are still unclear, and appropriate methods for detection are lacking. Methods: We used blanchable erythema (BE) and early PI rat models. We assessed the perfusion using Evans Blue (EB) and thrombus formation under a light microscope. Furthermore, we performed a capillary refill time test (CRTT) to detect ischemia after depression coupled with the transparent disk method using a spectrophotometer. Results: Compared with the BE group, the early PI group showed significantly slow and insufficient perfusion, as determined by EB staining (p < 0.001). Histological observations revealed that ischemia during post-decompression of early PI was caused by a greater amount of thrombi. The CRTT results showed that although both groups exhibited varying degrees of insufficient refilling volume, the early PI group had significantly slower refilling than the BE group (p < 0.001), which persisted during the deterioration or disappearance of erythema. Conclusions: Our results showed that persistent ischemia caused by thrombi is an important cause of early PI deterioration post-decompression. Therefore, the performance of CRTT coupled with the transparent disc method may become a promising method for detecting ischemia post-decompression.

Preparation of Codonopsis pilosula polysaccharide microcapsules and its effect and mechanism on skin wound healing in rats

In this study, after optimizing the extraction process of CPP (Codonopsis pilosula polysaccharides), CPPM (CPP microcapsules) were prepared. Subsequently, the structural characteristics and physicochemical properties were studied. The results showed that CPPM is a hollow sac-like structure with rough folds and protuberances and comes in spherical or ellipsoidal shapes with uniform particle size. CPPM has certain swelling degree, low hardness, good adhesion, and stability. Then, the effect of CPPM on wounds repair was investigated by a rat model. The results showed that CPPM could improve the wound healing rate. Histological evaluation showed CPPM could promote neovascularization and fibroblast proliferation. By investigating the healing mechanism, it was found that CPPM increased the hydroxyproline content in granulation tissue and had an excellent antioxidant ability, and then inhibited lipid peroxidation, in addition, it significantly increased the transcript levels of VEGF and miRNA-21 genes, indicating that CPPM play an influential role in vascular remodeling during wound healing by up-regulating the expression of VEGF and miRNA-21 genes.

Development and validation of a modularized external fixator for generating standardized fracture healing micromotions in rats

Aims

To fully verify the reliability and reproducibility of an experimental method in generating standardized micromotion for the rat femur fracture model.

Methods

A modularized experimental device has been developed that allows rat models to be used instead of large animal models, with the aim of reducing systematic errors and time and money constraints on grouping. The bench test was used to determine the difference between the measured and set values of the micromotion produced by this device under different simulated loading weights. The displacement of the fixator under different loading conditions was measured by compression tests, which was used to simulate the unexpected micromotion caused by the rat’s ambulation. In vivo preliminary experiments with a small sample size were used to test the feasibility and effectiveness of the whole experimental scheme and surgical scheme.

Results

The bench test showed that a weight loading < 500 g did not affect the operation of experimental device. The compression test demonstrated that the stiffness of the device was sufficient to keep the uncontrollable motion between fracture ends, resulting from the rat’s daily activities, within 1% strain. In vivo results on 15 rats prove that the device works reliably, without overburdening the experimental animals, and provides standardized micromotion reproductively at the fracture site according to the set parameters.

Conclusion

Our device was able to investigate the effect of micromotion parameters on fracture healing by generating standardized micromotion to small animal models.

Cite this article: Bone Joint Res 2021;10(11):714–722.

Pathological and immunological differences of arterial thrombi and wall caused by three different periodontal bacterial injections in rat models and proposals on the pathogeneses of vascular diseases

OBJECTIVES

Periodontal bacteria that have been studied show a strong connection to various vascular diseases. Among the many kinds of periodontal bacteria, Porphyromonas gingivalis (Pg) is well examined in the general aspects and in a rat model. However, whether other periodontal bacteria work or react differently is not studied well.

MATERIAL AND METHODS

We chose Aggregatibacter actinomycetemcomitans (Aa) and Prevotella intermedia (Pi) as different types of periodontal bacteria. Low-density and high-density bacterial solutions were injected in the small artery of rats' groins using our rat model. Eighteen limbs of 9 SD male rats (500-650 g) were used. After 7 days, 14-18 days, and 28 days, the rats were sacrificed. A pathological and an immuno-histochemical study was conducted and reported on the low-density group with 12 limbs because the Pi group lacked a high-density study. Immuno-histochemical staining of live Pg was performed on three limbs of three rats at 1 h, 3 h, and 1 week after injection.

RESULTS

The appearances from the acute, at 7 days, to chronic phases, at 28 days, were observed. The differences of the species were certainly observed in the internal elastic lamina (IEL), and immuno-histochemical reactions. The inflammatory reactions, such as cellular distribution or intra-thrombus materials, were similar in all. One week later, we could not see any living bacteria in the specimen or immunological observation.

CONCLUSIONS

The three species were essentially the same, except for Aa's stronger disruption of IEL, and more CD3 (Pan T cell) in Pi and more CD79a (Pan B cell) in Pg. We propose a new concept of a possible mechanism of vascular diseases, in which the work of LPS (lipopolysaccharides) and a toll-like receptor (TLR) is emphasized.

Development of rat metabolic syndrome models: A review

Metabolic syndrome (MetS) has become a global problem. With the increasing prevalence of MetS worldwide, understanding its pathogenesis and treatment modalities are essential. Animal models should allow an appropriate representation of the clinical manifestations of human conditions. Rats are the most commonly used experimental animals for the study. The development of a proper MetS model using rats will contribute to the successful application of research findings to the clinical setting. Various intervention methods are used to induce MetS through diet induction with various compositions, chemicals, or a combination of both. This review will provide a comprehensive overview of several studies on the development of rat MetS models, along with the characteristics of the clinical manifestations resulting from each study.

Nephroprotective Efficacy of Sugammadex in Ischemia-Reperfusion Injury: An Experimental Study in a Rat Model

Background: It is known that ischemia-reperfusion damage in the kidney is one of the most common causes of acute kidney failure. It is also known that reduced renal damage has a nephroprotective effect by reducing the release of inflammatory and vasoactive peptides that cause tissue damage. Therefore, we think that reperfusion caused by ischemia in kidney damage may be an important focus for clinical research.

Methods: A total of 21 healthy 230-250 g female rats were used in our experimental study. During the experiment, animals were randomly divided into three groups, each containing seven rats. Group 1: The group that underwent left nephrectomy with a sham operation. Group 2: Left renal ischemia for 60 minutes, then left nephrectomy followed by 45 minutes of reperfusion. Group 3: Left renal ischemia for 60 minutes, then reperfusion for 45 minutes, followed by left nephrectomy. In this group, sugammadex was given intravenously at a dose of 100 mg/kg at the beginning of reperfusion. In the histomorphological examination, damage findings of tubules atrophy, dilation and cast formation, tubular epithelial brush border loss and vacuolization, presence of fibrosis as interstitial structural change, capillary vasodilatation/congestion and neutrophilic cell infiltrates in interstitial spaces, and morphological changes in glomeruli were evaluated.

Results: When evaluated based on tubular brush border, there were no significant differences between Group 2 and Group 1 (P = 0.454), while the damage in Group 3 was less significant than Group 2 (P = 0.017). When evaluated in terms of tubular vacuolization, there was no significant difference between Group 2 and Group 1 (P = 0.902), while the damage in Group 3 was less significant than Group 2 (P = 0.017).

Conclusion: We believe that 100 mg/kg sugammadex given at the beginning of reperfusion after one hour of ischemic condition on rats has a histochemically detectable nephroprotective effect.

Cardiac Natriuretic Peptide Profiles in Chronic Hypertension by Single or Sequentially Combined Renovascular and DOCA-Salt Treatments

The involvement of natriuretic peptides was studied during the hypertrophic remodeling transition mediated by sequential exposure to chronic hemodynamic overload. We induced hypertension in rats by pressure (renovascular) or volume overload (DOCA-salt) during 6 and 12 weeks of treatment. We also studied the consecutive combination of both models in inverse sequences: RV 6 weeks/DS 6 weeks and DS 6 weeks/RV 6 weeks. All treated groups developed hypertension. Cardiac hypertrophy and left ventricular ANP gene expression were more pronounced in single DS than in single RV groups. BNP gene expression was positively correlated with left ventricular hypertrophy only in RV groups, while ANP gene expression was positively correlated with left ventricular hypertrophy only in DS groups. Combined models exhibited intermediate values between those of single groups at 6 and 12 weeks. The latter stimulus associated to the second applied overload is less effective than the former to trigger cardiac hypertrophy and to increase ANP and BNP gene expression. In addition, we suggest a correlation of ANP synthesis with volume overload and of BNP synthesis with pressure overload-induced hypertrophy after a prolonged treatment. Volume and pressure overload may be two mechanisms, among others, involved in the differential regulation of ANP and BNP gene expression in hypertrophied left ventricles. Plasma ANP levels reflect a response to plasma volume increase and volume overload, while circulating BNP levels seem to be regulated by cardiac BNP synthesis and ventricular hypertrophy.

盐摄入量对腹膜透析大鼠残余肾功能的影响

OBJECTIVE

To assess the effect of salt intake on residual renal function in rats and explore the possible mechanism.

OBJECTIVE

SD rats were 5/6-nephrectomized to induce chronic renal failure followed by peritoneal dialysis for 4 weeks (n=18) or without dialysis treatment (control group; n=18). In both groups, the rats were divided into 3 subgroups and were given lowsalt diet (0.02% NaCl), normal salt diet (0.4% NaCl), and high-salt diet (4% NaCl). After 8 and 12weeks, blood pressure and creatinine and sodium levels in the blood, urine, and peritoneal dialysate of the rats were examined. Glomerular sclerosis, tubulointerstitial fibrosis, and protein expression levels of RAS components (ACE-1, AGT, and AT-1) in renal cortical tissue of the rats were evaluated.

OBJECTIVE

The residual renal function of the rats all decreased especially in rats with high salt intake for 8and 12 weeks. In peritoneal dialysis group, the rats with high-salt diet showed signficiantly increased renal interstitial fibrosis score (P=0.036), glomerular sclerosis index (P=0.045), systolic blood pressure (P=0.004), diastolic blood pressure (P=0.048), and renal expressions of AGT, ACE-1, and AT1 (P < 0.05) as compared with those with normal salt intake. In the rats fed the same high-salt diet, the renal interstitial fibrosis score, glomerular sclerosis index, diastolic blood pressure increase, and renal AGT and ACE-1 expression levels were significantly lower in the peritoneal dialysis group than in the control group (P < 0.05). A positive correlation was noted between the reduction of residual renal function and sodium intake in the rats.

OBJECTIVE

In rats with chronic renal failure, high salt intake promotes the activation of the renal RAS system, increases blood pressure, and agrevates renal fibrosis to accelerate the decline of residual renal function, and peritoneal dialysis partially reduces the damage of residual renal function induced by high-salt diets by removing excessive sodium.

Rat models for low and high adaptive response to exercise differ for stress-related memory and anxiety

Physical exercise and fitness may serve as resilience factors to stress exposure. However, the extreme range in human exercise performance suggests that genetic variation for exercise capacity could be a confounding feature to understanding the connection between exercise and stress exposure. To test this idea, we use laboratory rat models selectively bred for a low and high gain in aerobic running capacity in response to training to examine whether an inherent capacity to respond to physical exercise reflects how stress changes neurobiological functioning and regulates fear-associated memory processing. Utilization of this contrasting rat model system of low and high responders has the potential to guide the interpretation of the reported association with exercise involvement and the reduction of stress-induced anxiety disorders. Our data show that aerobic fitness may be linked to the ability to regulate fear-associated memories. We also show that acquired exercise capacity may play a key role in regulating responses to an acute stressor. Exercise sensitivity plays a significant role in the activation of the plasticity-associated molecule extracellular signal-regulated kinase, changes in stress hormone activity, and anatomical modifications to the noradrenergic locus coeruleus. These data identify a unique operational mechanism that may serve as translational targets for lessening symptoms of stress and anxiety.

Noninvasive Assessment of Fibrosis Following Ischemia/Reperfusion Injury in Rodents Utilizing Na Magnetic Resonance Imaging

Fibrosis is often heterogeneously distributed, and classical biopsies do not reflect this. Noninvasive methods for renal fibrosis have been developed to follow chronic kidney diseases (CKD) and to monitor anti-fibrotic therapy. In this study, we combined two approaches to assess fibrosis regression following renal ischemia-reperfusion injury (IRI): magnetic resonance imaging (MRI) and noninvasive extracellular matrix (ECM) biomarkers. MRI was used to evaluate fibrosis in bilateral IRI in rats after reperfusion at 7, 14, and 21 days. This was performed with ¹HT₁ and T₂* mapping, dynamic contrast-enhanced (DCE)-MRI, and chemical shift imaging (CSI)-²³Na. The degradation of laminin gamma-1 chain (LG1M) and type III collagen (C3M) was measured in urine and plasma. Fibrosis was analyzed in tissue using fibronectin (FN) and alpha-smooth muscle actin (α-SMA) using quantitative polymerase chain reaction qPCR and western blotting. We found increased fibrosis 7 days after reperfusion, which dropped to sham levels after 21 days. Single kidney glomerular filtration rate (skGFR), perfusion (DCE-MRI), and total ²³Na kidney content correlated positively with fibrotic markers FN and α-SMA as well as noninvasive LG1M and C3M. We showed that novel MRI protocols and ECM markers could track fibrogenic development. This could give rise to a multi-parametric practice to diagnose and assess fibrosis whilst treating kidney disease without using invasive methods.

Methylene blue and monosodium glutamate improve neurologic signs after fluoroacetate poisoning

Fluoroacetate (FA) is a tasteless, odorless, water-soluble metabolic poison with severe toxicological effects. Characterized in the mid-1900s, it has been used as a rodenticide but is comparably lethal to all mammals. Many countries have restricted its use, and modern-day accidental human exposures are rare, but recently, concerns have been raised about its application as a chemical weapon with no known antidote. A combined treatment of methylene blue (MB), an antioxidant, and monosodium glutamate (MSG), a precursor of the citric acid cycle substrate alpha-ketoglutarate, has been recommended as an effective countermeasure; however, no peer-reviewed articles documenting the efficacy of this therapy have been published. Using a rodent model, we assessed the effects of MB and MSG on the neurologic, cardiac, and pulmonary systems. Transcriptomic analysis was used to elucidate inflammatory pathway activation and guide bioassays, which revealed the advantages and disadvantages of these candidate countermeasures. Results show that MB and MSG can reduce neurologic signs observed in rats exposed to sodium FA and improve some effects of intoxication. However, while this strategy resolved some signs of intoxication, ultimately it was unable to significantly reduce lethality.

Paeonol at Certain Doses Alleviates Aggressive and Anxiety-Like Behaviours in Two Premenstrual Dysphoric Disorder Rat Models

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS), a common mental health disturbance associated with several periodic psychological symptoms in women. Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for PMS/PMDD patients; however, side effects are inevitable, especially in long-term treatment. In previous studies, the natural compound paeonol in Moutan Cortex was found to play effective roles in central nervous system disorders with its anti-inflammatory, anti-oxidant, and neuroprotective effects. Consequently, we assume that paeonol might produce positive effects in the treatment of PMS/PMDD. In this study, the open-field test (OFT) and elevated plus maze (EPM) and light dark box (LDB) tests were performed in mice to determine the optimal dose of paeonol for treating anxiety. Then, paeonol was used to treat the progesterone withdrawal (PWD) and resident intruder paradigm (RIP) rat models of PMDD. Using these two reliable models, the OFT and EPM, LDB, and composite aggressive tests were performed to evaluate the effect of the drug on behavioural symptoms of PMDD. From the dosage screening results, the optimal anti-anxiety dose of paeonol was identified as 17.5 mg/kg/d for 7 days. With regard to the effect of paeonol on PMDD rat models, a significantly improvement was found in the behavioural symptoms, but the effective dose varied in different models. For the PWD model rats, treatment with 6.05 mg/kg paeonol could significantly improve anxiety and irritability, while that with 24.23 mg/kg paeonol resulted in anxiety-like effects in behavioural tests. In RIP model rats, treatment with 12.11 mg/kg paeonol demonstrated excellent effects in improving anxiety, particularly irritable emotional behaviour. In conclusion, our study indicates that paeonol is a potential therapeutic compound for PMS/PMDD; it is a drug option that helps establish dosage guidance for treatment of this condition.

Inflammation and apoptosis accelerate progression to irreversible atrophy in denervated intrinsic muscles of the hand compared with biceps: proteomic analysis of a rat model of obstetric brachial plexus palsy

In treating patients with obstetric brachial plexus palsy, we noticed that denervated intrinsic muscles of the hand become irreversibly atrophic at a faster than denervated biceps. In a rat model of obstetric brachial plexus palsy, denervated intrinsic musculature of the forepaw entered the irreversible atrophy far earlier than denervated biceps. In this study, isobaric tags for relative and absolute quantitation were examined in the intrinsic musculature of forepaw and biceps on denervated and normal sides at 3 and 5 weeks to identify dysregulated proteins. Enrichment of pathways mapped by those proteins was analyzed by Kyoto Encyclopedia of Genes and Genomes analysis. At 3 weeks, 119 dysregulated proteins in denervated intrinsic musculature of the forepaw were mapped to nine pathways for muscle regulation, while 67 dysregulated proteins were mapped to three such pathways at 5 weeks. At 3 weeks, 27 upregulated proteins were mapped to five pathways involving inflammation and apoptosis, while two upregulated proteins were mapped to one such pathway at 5 weeks. At 3 and 5 weeks, 53 proteins from pathways involving regrowth and differentiation were downregulated. At 3 weeks, 64 dysregulated proteins in denervated biceps were mapped to five pathways involving muscle regulation, while, five dysregulated proteins were mapped to three such pathways at 5 weeks. One protein mapped to inflammation and apoptotic pathways was upregulated from one pathway at 3 weeks, while three proteins were downregulated from two other pathways at 5 weeks. Four proteins mapped to regrowth and differentiation pathways were upregulated from three pathways at 3 weeks, while two proteins were downregulated in another pathway at 5 weeks. These results implicated inflammation and apoptosis as critical factors aggravating atrophy of denervated intrinsic muscles of the hand during obstetric brachial plexus palsy. All experimental procedures and protocols were approved by the Experimental Animal Ethics Committee of Fudan University, China (approval No. DF-325) in January 2015.

Blood-Brain Barrier Disruption as a Potential Target for Therapy in Posterior Reversible Encephalopathy Syndrome: Evidence From Multimodal MRI in Rats

Background: To explore blood-brain barrier disruption in hypertensive posterior reversible encephalopathy syndrome. Methods: The hypertension rat models were successfully established and scanned on 7T micro-MRI. MRI parameter maps including apparent diffusion coefficient, T1 value, and perfusion metrics such as cerebral blood volume, cerebral blood flow, mean transit time and time to peak maps, were calculated. Results: The ADC values of the experimental group were higher than those of the control group both in cortical (P < 0.01) and subcortical (P < 0.05) regions. Voxel-wise analysis of ADC maps localized vasogenic edema primarily to the posterior portion of the brain. The increase in cerebral blood volume and cerebral blood flow values were found in the cortical and subcortical regions of rats with acute hypertension. No correlation was found between perfusion metrics and mean arterial pressure. The Evans blue dye content was higher in the posterior brain region than the anterior one (P < 0.05). Conclusions: Cerebral vasogenic edema resulting from acute hypertension supports the hypothesis of posterior reversible encephalopathy syndrome as the result of blood-brain barrier disruption, which maybe the potential therapeutic target for intervention.

PDCD4 expression in coronary atherosclerosis rat models and its mechanism

This study investigated the expression of programmed cell death protein 4 (PDCD4) in rat models of coronary atherosclerosis (AS) and analyzed its role and mechanism. A total of 80 Wistar rats were selected and divided into the control group (n=40) and research group (n=40) according to the principle of similar body weight, of which coronary AS models were established in rats in the research group. PDCD4 expression in coronary artery tissues was detected using western blotting, and the expression of interleukin-6 (IL-6) and IL-8 in the coronary artery tissues were measured by means of reverse transcription-polymerase chain reaction (RT-PCR). The apoptotic rate of coronary artery smooth muscle cells was determined via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). The relative expression of PDCD4 in coronary artery tissues in the research group was obviously higher than that in the control group, and the difference was statistically significant (t=6.121, P<0.01). In terms of the relative expression of messenger ribonucleic acid (mRNA) of IL-6 in the coronary artery tissues, the research group had a remarkably higher level than the control group, with a statistically significant difference (t=21.03, P<0.01). The difference in the relative expression of IL-8 mRNA between the research group and the control group was statistically significant, of which a much higher level was detected in the research group (t=19.96, P<0.01). The apoptotic rate of smooth muscle cells in the research group was increased notably compared with that in the control group, and the difference was statistically significant (t=5.985, P<0.01). PDCD4 may participate in the formation of coronary AS plaque, and its possible function in the process is to inhibit the proliferation of vascular smooth muscle cells and promote the upregulation of IL-6 and IL-8.

miR-138 expression in oral herpes simplex and its effect on ICP0

This study aimed to investigate the micro ribonucleic acid-138 (miR-138) expression in oral herpes simplex (HS) and its effect on the expression of herpes simplex virus type 1 (HSV-1) lytic gene trans-acting factor infected cell protein 0 (ICP0). Forty-five rat models with oral HS were successfully established (the observation group) and another 40 healthy rats were selected as the control group. The miR-138 expression in serum of rats in the two groups were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). 293T cells infected by HSV-1 were divided into Group A and Group B after 10 days of culture. Group A was transfected by miR-138 mimics and Group B was transfected by miR-138 complementary oligonucleotide inhibitor. The expression levels of miR-138 and ICP0 messenger RNA (mRNA) in the cells of the two groups were detected by RT-PCR, and the expression levels of ICP0 protein were detected by enzyme-linked immunosorbent assay (ELISA). A total of 85 rat models with oral HS were established in this study, but only 45 models were established successfully with a success rate of 56.25%. The expression level of miR-138 in the rat serum in the observation group was higher than that in the control group (P<0.05). In addition, the expression level of ICP0 mRNA in Group A was lower than that in Group B (P<0.05). Moreover, the expression level of ICP0 protein in Group A was lower than that in Group B (P<0.05). Finally, the expression level of miR-138 in HSV was increased, suggesting that the expression of miR-138 may inhibit the expression of ICP0, thus preventing the duplication of HSV-1. Therefore, the expression of miR-138 may be used as a potential therapeutic target for HSV.

Genetically Epilepsy-Prone Rats Display Anxiety-Like Behaviors and Neuropsychiatric Comorbidities of Epilepsy

Epilepsy is associated with a variety of neuropsychiatric comorbidities, including both anxiety and depression. Despite high occurrences of depression and anxiety seen in human epilepsy populations, little is known about the etiology of these comorbidities. Experimental models of epilepsy provide a platform to disentangle the contribution of acute seizures, genetic predisposition, and underlying circuit pathologies to anxious and depressive phenotypes. Most studies to date have focused on comorbidities in acquired epilepsies; genetic models, however, allow for the assessment of affective phenotypes that occur prior to onset of recurrent seizures. Here, we tested male and female genetically epilepsy-prone rats (GEPR-3s) and Sprague-Dawley controls in a battery of tests sensitive to anxiety-like and depressive-like phenotypes. GEPR-3s showed increased anxiety-like behavior in the open field test, elevated plus maze, light-dark transition test, and looming threat test. Moreover, GEPR-3s showed impaired prepulse inhibition of the acoustic startle reflex, decreased sucrose preference index, and impaired novel object recognition memory. We also characterized defense behaviors in response to stimulation thresholds of deep and intermediate layers of the superior colliculus (DLSC), but found no difference between strains. In sum, GEPR-3s showed inherited anxiety, an effect that did not differ significantly between sexes. The anxiety phenotype in adult GEPR-3s suggests strong genetic influences that may underlie both the seizure disorder and the comorbidities seen in epilepsy.

Annexin A7 Levels Increase in Rats With Traumatic Brain Injury and Promote Secondary Brain Injury

The incidence of traumatic brain injury (TBI) has been increasing annually. Annexin A7 is a calcium-dependent phospholipid binding protein. It can promote melting of the cell membrane. Recent studies have shown that it plays an important role in atherosclerosis, other cardiovascular diseases, and a variety of tumors. However, few studies of ANXA7 in TBI have been performed. We here observed how ANXA7 changes after TBI and discuss whether brain injury is associated with the use of ANXA7 antagonist intervention. Experimental Results: 1. After TBI, ANXA7 levels were higher than in the sham group, peaking 24 h after TBI. 2. The use of siA7 was found to reduce the expression of A7 in the injured brain tissue, and also brain edema, BBB damage, cell death, and apoptosis relative to the sham group. Conclusion: ANXA7 promotes the development of secondary brain injury (SBI) after TBI.

A Conformational Change in C-Reactive Protein Enhances Leukocyte Recruitment and Reactive Oxygen Species Generation in Ischemia/Reperfusion Injury

Introduction

C-reactive protein circulates as a pentameric protein (pCRP). pCRP is a well-established diagnostic marker as plasma levels rise in response to tissue injury and inflammation. We recently described pro-inflammatory properties of CRP, which are mediated by conformational changes from pCRP to bioactive isoforms expressing pro-inflammatory neo-epitopes [pCRP* and monomeric C-reactive protein (mCRP)]. Here, we investigate the role of CRP isoforms in renal ischemia/reperfusion injury (IRI).

Methods

Rat kidneys in animals with and without intraperitoneally injected pCRP were subjected to IRI by the time of pCRP exposure and were subsequently analyzed for monocyte infiltration, caspase-3 expression, and tubular damage. Blood urea nitrogen (BUN) was analyzed pre-ischemia and post-reperfusion. CRP effects on leukocyte recruitment were investigated via intravital imaging of rat-striated muscle IRI. Localized conformational CRP changes were analyzed by immunohistochemistry using conformation specific antibodies. 1,6-bis(phosphocholine)-hexane (1,6-bisPC), which stabilizes CRP in its native pentameric form was used to validate CRP effects. Leukocyte activation was assessed by quantification of reactive oxygen species (ROS) induction by CRP isoforms ex vivo and in vitro through electron spin resonance spectroscopy. Signaling pathways were analyzed by disrupting lipid rafts with nystatin and subsequent ROS detection. In order to confirm the translational relevance of our findings, biopsies of microsurgical human free tissue transfers before and after IRI were examined by immunofluorescence for CRP deposition and co-localization of CD68⁺ leukocytes.

Results

The application of pCRP aggravates tissue damage in renal IRI. 1,6-bisPC reverses these effects via inhibition of the conformational change that leads to exposure of pro-inflammatory epitopes in CRP (pCRP* and mCRP). Structurally altered CRP induces leukocyte–endothelial interaction and induces ROS formation in leukocytes, the latter can be abrogated by blocking lipid raft-dependent signaling pathways with Nystatin. Stabilizing pCRP in its native pentameric state abrogates these pro-inflammatory effects. Importantly, these findings are confirmed in human IRI challenged muscle tissue.

Conclusion

These results suggest that CRP is a potent modulator of IRI. Stabilizing the native pCRP conformation represents a promising anti-inflammatory therapeutic strategy by attenuation of leukocyte recruitment and ROS formation, the primary pathomechanisms of IRI.

Oxytocin and Migraine Headache

This article reviews material presented at the 2016 Scottsdale Headache Symposium. This presentation provided scientific results and rationale for the use of intranasal oxytocin for the treatment of migraine headache. Results from preclinical experiments are reviewed, including in vitro experiments demonstrating that trigeminal ganglia neurons possess oxytocin receptors and are inhibited by oxytocin. Furthermore, most of these same neurons contain CGRP, the release of which is inhibited by oxytocin. Results are also presented which demonstrate that nasal oxytocin inhibits responses of trigeminal nucleus caudalis neurons to noxious stimulation using either noxious facial shock or nitroglycerin infusion. These studies led to testing the analgesic effect of intranasal oxytocin in episodic migraineurs-studies which did not meet their primary endpoint of pain relief at 2 h, but which were highly informative and led to additional rat studies wherein inflammation was found to dramatically upregulate the number of oxytocin receptors available on trigeminal neurons. This importance of inflammation was supported by a series of in vivo rat behavioral studies, which demonstrated a clear craniofacial analgesic effect when a pre-existing inflammatory injury was present. The significance of inflammation was further solidified by a small single-dose clinical study, which showed analgesic efficacy that was substantially stronger in chronic migraine patients that had not taken an anti-inflammatory drug within 24 h of oxytocin dosing. A follow-on open label study examining effects of one month of intranasal oxytocin dosing did show a reduction in pain, but a more impressive decrease in the frequency of headaches in both chronic and high frequency episodic migraineurs. This study led to a multicountry double blind, placebo controlled study studying whether, over 2 months of dosing, "as needed" dosing of intranasal oxytocin by chronic and high frequency migraineurs would reduce the frequency of their headaches compared to a 1-month baseline period. This study failed to meet its primary endpoint, due to an extraordinarily high placebo rate in the country of most of the patients (Chile), but was also highly informative, showing strong results in other countries and strong post hoc indications of efficacy. The results provide a strong argument for further development of intranasal oxytocin for migraine prophylaxis.

Adipose depot-specific effects of ileal interposition surgery in UCD-T2D rats: unexpected implications for obesity and diabetes

Ileal interposition (IT) surgery delays the onset of diabetes in a rat model of type-2 diabetes (UCD-T2DM). Here, to gain a deeper understanding of the molecular events underlying the effects of IT surgery, we examined the changes in the proteome of four white adipose depots (retroperitoneal, mesenteric, inguinal, and epididymal) and plasma-free fatty acid profile in pre-diabetic rats 1.5 months following IT or sham surgery. The IT-mediated changes were exerted mainly in mesenteric fat and spanned from delayed adipocyte maturation to a neuroendocrine remodeling. Conversely, inguinal, retroperitoneal, and epididymal depots showed opposite trends consistent with increased adipocyte maturation and adipogenesis development prior to overt signs of diabetes, probably orchestrated by peroxisome proliferator-activated receptor gamma signaling and higher plasma n-6/n-3 free fatty acid ratios. The resulting scenario suggests a targeted use of surgical strategies that seek to delay or improve diabetes in order to manipulate adipose depot-specific responses to maximize the duration and beneficial effects of the surgery.

Interplay Between Phosphorylation and O-GlcNAcylation of Sarcomeric Proteins in Ischemic Heart Failure

Post-translational modifications (PTMs) of sarcomeric proteins could participate to left ventricular (LV) remodeling and contractile dysfunction leading in advanced heart failure (HF) with altered ejection fraction. Using an experimental rat model of HF (ligation of left coronary artery) and phosphoproteomic analysis, we identified an increase of desmin phosphorylation and a decrease of desmin O-N-acetylglucosaminylation (O-GlcNAcylation). We aim to characterize interplay between phosphorylation and O-GlcNAcylation for desmin in primary cultures of cardiomyocyte by specific O-GlcNAcase (OGA) inhibition with thiamet G and silencing O-GlcNAc transferase (OGT) and, in perfused heart perfused with thiamet G in sham- and HF-rats. In each model, we found an efficiency of O-GlcNAcylation modulation characterized by the levels of O-GlcNAcylated proteins and OGT expression (for silencing experiments in cells). In perfused heart, we found an improvement of cardiac function under OGA inhibition. But none of the treatments either in in vitro or ex vivo cardiac models, induced a modulation of desmin, phosphorylated and O-GlcNAcylated desmin expression, despite the presence of O-GlcNAc moities in cardiac desmin. Our data suggests no interplay between phosphorylation and O-GlcNAcylation of desmin in HF post-myocardial infarction. The future requires finding the targets in heart involved in cardiac improvement under thiamet G treatment.

Maternal Protein Restriction Induces Alterations in Hepatic Unfolded Protein Response-Related Molecules in Adult Rat Offspring

Intrauterine growth restriction (IUGR) leads to the development of metabolic syndrome in adulthood. To explore the potential mechanisms of metabolic imprinting, we investigated the effect of malnutrition in utero on hepatic unfolded protein response (UPR)-related genes in IUGR offspring. An IUGR rat model was developed by feeding a low-protein diet to pregnant rats. The expression levels and activity of hepatic UPR genes were analysed by quantitative PCR (qPCR) arrays and western blotting. The hepatic UPR molecules heat-shock 70-kDa protein 4l (Hspa4l), mitogen-activated protein kinase 10 (Mapk10), and endoplasmic reticulum to nucleus signalling 2 (Ern2) were markedly downregulated in IUGR foetuses, but the expression of Mapk10 and Ern2 returned to normal levels at 3 weeks postnatal. In contrast, cAMP responsive element binding protein 3-like 3 (Creb3l3) was upregulated in hepatic tissues at embryo 20(E20), then restored to normal in adulthood (12 weeks). The protein levels of activating transcription factor 2 (Atf2) and Atf6, two key factors of the UPR pathway, were upregulated in the livers of IUGR foetuses, and the latter remained upregulated until 12 weeks. Combined with our previous findings showing an increase in hepatic gluconeogenesis enzymes in IUGR offspring, we speculated that aberrant intrauterine milieu impaired UPR signalling in hepatic tissues; these alterations early in life might contribute to the predisposition of IUGR foetuses to adult metabolic disorders.

Single-Gene Congenic Strain Reveals the Effect of Zbtb16 on Dexamethasone-Induced Insulin Resistance

BACKGROUND

Glucocorticoids (GCs) are potent therapeutic agents frequently used for treatment of number of conditions, including hematologic, inflammatory, and allergic diseases. Both their therapeutic and adverse effects display significant interindividual variation, partially attributable to genetic factors. We have previously isolated a seven-gene region of rat chromosome 8 sensitizing to dexamethasone (DEX)-induced dyslipidemia and insulin resistance (IR) of skeletal muscle. Using two newly derived congenic strains, we aimed to investigate the effect of one of the prime candidates for this pharmacogenetic interaction, the Zbtb16 gene.

METHODS

Adult male rats of SHR-Lx.PD5^PD-Zbtb16 (n = 9) and SHR-Lx.PD5^SHR-Zbtb16 (n = 8) were fed standard diet (STD) and subsequently treated with DEX in drinking water (2.6 µg/ml) for 3 days. The morphometric and metabolic profiles of both strains including oral glucose tolerance test, triacylglycerols (TGs), free fatty acids, insulin, and C-reactive protein levels were assessed before and after the DEX treatment. Insulin sensitivity of skeletal muscle and visceral adipose tissue was determined by incorporation of radioactively labeled glucose.

RESULTS

The differential segment of SHR-Lx.PD5^SHR-Zbtb16 rat strain spans 563 kb and contains six genes: Htr3a, Htr3b, Usp28, Zw10, Tmprss5, and part of Drd2. The SHR-Lx.PD5^PD-Zbtb16 minimal congenic strain contains only Zbtb16 gene on SHR genomic background and its differential segment spans 254 kb. Total body weight was significantly increased in SHR-Lx.PD5^PD-Zbtb16 strain compared with SHR-Lx.PD5^SHR-Zbtb16 , however, no differences in the weights of adipose tissue depots were observed. While STD-fed rats of both strains did not show major differences in their metabolic profiles, after DEX treatment the SHR-Lx.PD5^PD-Zbtb16 congenic strain showed increased levels of TGs, glucose, and blunted inhibition of lipolysis by insulin. Both basal and insulin-stimulated incorporation of radioactively labeled glucose into skeletal muscle glycogen were significantly reduced in SHR-Lx.PD5^PD-Zbtb16 strain, but the insulin sensitivity of adipose tissue was comparable between the two strains.

CONCLUSION

The metabolic disturbances including impaired glucose tolerance, dyslipidemia, and IR of skeletal muscle observed after DEX treatment in the congenic SHR-Lx.PD5^PD-Zbtb16 reveal the Zbtb16 locus as a possible sensitizing factor for side effects of GC therapy.

Genetic Fine-Mapping and Identification of Candidate Genes and Variants for Adiposity Traits in Outbred Rats

OBJECTIVE

Obesity is a major risk factor for multiple diseases and is in part heritable, yet the majority of causative genetic variants that drive excessive adiposity remain unknown. Here, outbred heterogeneous stock (HS) rats were used in controlled environmental conditions to fine-map novel genetic modifiers of adiposity.

METHODS

Body weight and visceral fat pad weights were measured in male HS rats that were also genotyped genome-wide. Quantitative trait loci (QTL) were identified by genome-wide association of imputed single-nucleotide polymorphism (SNP) genotypes using a linear mixed effect model that accounts for unequal relatedness between the HS rats. Candidate genes were assessed by protein modeling and mediation analysis of expression for coding and noncoding variants, respectively.

RESULTS

HS rats exhibited large variation in adiposity traits, which were highly heritable and correlated with metabolic health. Fine-mapping of fat pad weight and body weight revealed three QTL and prioritized five candidate genes. Fat pad weight was associated with missense SNPs in Adcy3 and Prlhr and altered expression of Krtcap3 and Slc30a3, whereas Grid2 was identified as a candidate within the body weight locus.

CONCLUSIONS

These data demonstrate the power of HS rats for identification of known and novel heritable mediators of obesity traits.

Age and Sex Interact to Mediate the Effects of Intermittent, High-Dose Ethanol Exposure on Behavioral Flexibility

Human alcoholics have been shown to have impaired cognitive control over actions and increased reliance on habitual response strategies. While it is unclear in humans whether these differences predate ethanol exposure or result from chronic drinking, data from animal studies suggest that ethanol acts to promote the development of inflexible behaviors. Here, we investigated how intermittent exposure to high doses of ethanol impacts the ability to flexibly regulate behavior in a habit model. As adolescence, may represent a period of increased drug taking and developmental vulnerability that may impact adult behavior, we compared the effects of high-dose ethanol exposure during adolescence to exposure during adulthood in male and female rats. Our findings indicated that the effects of intermittent, high-dose ethanol exposure on habitual behavior is mediated by age and sex such that ethanol exposure during adolescence promoted the use of habitual response strategies in adult females, but not males, and that the opposite pattern emerged following intermittent, high-dose ethanol exposure in adult rats.

Dammarane Sapogenins Ameliorates Neurocognitive Functional Impairment Induced by Simulated Long-Duration Spaceflight

Increasing evidence indicates the occurrence of cognitive impairment in astronauts under spaceflight compound conditions, but the underlying mechanisms and countermeasures need to be explored. In this study, we found that learning and memory abilities were significantly reduced in rats under a simulated long-duration spaceflight environment (SLSE), which includes microgravity, isolation confinement, noises, and altered circadian rhythms. Dammarane sapogenins (DS), alkaline hydrolyzed products of ginsenosides, can enhance cognition function by regulating brain neurotransmitter levels and inhibiting SLSE-induced neuronal injury. Bioinformatics combined with experimental verification identified that the PI3K-Akt-mTOR pathway was inhibited and the MAPK pathway was activated during SLSE-induced cognition dysfunction, whereas DS substantially ameliorated the changes in brain. These findings defined the characteristics of SLSE-induced cognitive decline and the mechanisms by which DS improves it. The results provide an effective candidate for improving cognitive function in spaceflight missions.

Rat Models of Ventricular Fibrillation Following Acute Myocardial Infarction

A number of animal models have been designed in order to unravel the underlying mechanisms of acute ischemia-induced arrhythmias and to test compounds and interventions for antiarrhythmic therapy. This is important as acute myocardial infarction (AMI) continues to be the major cause of sudden cardiac death, and we are yet to discover safe and effective treatments of the lethal arrhythmias occurring in the acute setting. Animal models therefore continue to be relevant for our understanding and treatment of acute ischemic arrhythmias. This review discusses the applicability of the rat as a model for ventricular arrhythmias occurring during the acute phase of AMI. It provides a description of models developed, advantages and disadvantages of rats, as well as an overview of the most important interventions investigated and the relevance for human pathophysiology.

Executive Summary: variation in susceptibility to ozone-induced health effects in rodent models of cardiometabolic disease

Seven million premature deaths occur annually due to air pollution worldwide, of which ∼80% are attributed to exacerbation of cardiovascular disease (CVD), necessitating greater attention to understanding the causes of susceptibility to air pollution in this sector of population. We used rat models of CVD with or without obesity and compared them to healthy strains to examine the risk factors of ozone-induced lung injury and inflammation. We examined functional, biochemical and molecular changes in several organs to evaluate how physiological factors as well as compensatory antioxidant reserves modulate processes by which ozone injury is influenced by underlying disease. In this study, we highlight key findings of this series of reports. We show that underlying cardiopulmonary insufficiency in genetically predisposed rats appears to increase the effective ozone dose; thus dosimetry is one factor contributing to exacerbated ozone effects. We further show that antioxidant reserve in airway lining fluid modulates ozone-induced damage such that strains with the least antioxidant reserve incur the greatest injury. And finally, we show that the inflammatory response to ozone is governed by a cluster of genes involved in regulating cytokine release, trafficking of inflammatory cells and processes related to cellular apoptosis and growth. All such processes are influenced not only by ozone dosimetry and the lung antioxidant milieu but also by the strain-specific genetic factors. In using a comprehensive systems biology research approach, our data reveal key risk factors for--and strategies to reduce risk of--air pollution mortality among those with CVD.

Clinical and pathological manifestations of cardiovascular disease in rat models: the influence of acute ozone exposure

Rodent models of cardiovascular diseases (CVD) and metabolic disorders are used for examining susceptibility variations to environmental exposures. However, cross-model organ pathologies and clinical manifestations are often not compared. We hypothesized that genetic CVD rat models will exhibit baseline pathologies and will thus express varied lung response to acute ozone exposure. Male 12-14-week-old healthy Wistar Kyoto (WKY), Wistar (WIS), and Sprague-Dawley (SD) rats and CVD-compromised spontaneously hypertensive (SH), fawn-hooded hypertensive (FHH), stroke-prone SH (SHSP), obese SH heart-failure (SHHF), obese diabetic JCR (JCR) rats were exposed to 0.0, 0.25, 0.5, or 1.0 ppm ozone for 4 h and clinical biomarkers, and lung, heart and kidney pathologies were compared immediately following (0-h) or 20-h later. Strain differences were observed between air-exposed CVD-prone and WKY rats in clinical biomarkers and in kidney and heart pathology. Serum cholesterol was higher in air-exposed obese SHHF and JCR compared to other air-exposed strains. Ozone did not produce lesions in the heart or kidney. CVD-prone and SD rats demonstrated glomerulopathy and kidney inflammation (WKY = WIS = SH < SD = SHSP < SHHF < JCR = FHH) regardless of ozone. Cardiac myofiber degeneration was evident in SH, SHHF, and JCR, while only JCR tends to have inflammation in coronaries. Lung pathology in air-exposed rats was minimal in all strains except JCR. Ozone induced variable alveolar histiocytosis and bronchiolar inflammation; JCR and SHHF were less affected. This study provides a comparative account of the clinical manifestations of disease and early-life organ pathologies in several rat models of CVD and their differential susceptibility to lung injury from air pollutant exposure.

Variability in ozone-induced pulmonary injury and inflammation in healthy and cardiovascular-compromised rat models

The molecular bases for variability in air pollutant-induced pulmonary injury due to underlying cardiovascular (CVD) and/or metabolic diseases are unknown. We hypothesized that healthy and genetic CVD-prone rat models will exhibit exacerbated response to acute ozone exposure dependent on the type and severity of disease. Healthy male 12-14-week-old Wistar Kyoto (WKY), Wistar (WS) and Sprague Dawley (SD); and CVD-compromised spontaneously hypertensive (SH), Fawn-Hooded hypertensive (FHH), stroke-prone spontaneously hypertensive (SHSP), obese spontaneously hypertensive heart failure (SHHF) and obese JCR (JCR) rats were exposed to 0.0, 0.25, 0.5, or 1.0 ppm ozone for 4 h; pulmonary injury and inflammation were analyzed immediately following (0-h) or 20-h later. Baseline bronchoalveolar lavage fluid (BALF) protein was higher in CVD strains except for FHH when compared to healthy. Ozone-induced increases in protein and inflammation were concentration-dependent within each strain but the degree of response varied from strain to strain and with time. Among healthy rats, SD were least affected. Among CVD strains, lean rats were more susceptible to protein leakage from ozone than obese rats. Ozone caused least neutrophilic inflammation in SH and SHHF while SHSP and FHH were most affected. BALF neutrophils and protein were poorly correlated when considering the entire dataset (r = 0.55). The baseline and ozone-induced increases in cytokine mRNA varied markedly between strains and did not correlate with inflammation. These data illustrate that the degree of ozone-induced lung injury/inflammation response is likely influenced by both genetic and physiological factors that govern the nature of cardiovascular compromise in CVD models.

Strain differences in antioxidants in rat models of cardiovascular disease exposed to ozone

We examined the hypothesis that antioxidant substances and enzymes in lung, heart and in bronchoalveolar lavage fluid (BALF) are altered in response to O3 in cardiovascular disease and/or metabolic syndrome (CVD)-prone rat models. CVD strains [spontaneously hypertensive (SH), SH stroke-prone (SHSP), SHHF/Mcc heart failure obese (SHHF), insulin-resistant JCR:LA-cp obese (JCR) and Fawn-Hooded hypertensive (FHH)] were compared with normal strains [Wistar, Sprague-Dawley (SD) and Wistar Kyoto (WKY)]. Total glutathione (GSH + GSSG or GSx), reduced ascorbate (AH2), uric acid (UA) and antioxidant enzymes were determined in lung, heart and BALF immediately (0 h) or 20-h post 4-h nose-only exposure to 0.0, 0.25, 0.5 and 1.0 ppm O3. Basal- and O3-induced antioxidant substances in tissues varied widely among strains. Wistar rats had a robust O3-induced increase in GSx and AH2 in the lung. Two CVD strains (JCR and SHHF) had high basal levels of AH2 and GSx in BALF as well as high basal lung UA. Across all strains, high BALF GSx was only observed when high BALF AH2 was present. CVD rats tended to respond less to O3 than normal. High-basal BALF AH2 levels were associated with decreased O3 toxicity. In summary, large differences were observed between both normal and CVD rat strains in low-molecular weight antioxidant concentrations in lung, BALF and heart tissue. Wistar (normal) and JCR and SHHF (CVD) rats appeared to stand out as peculiar in terms of basal- or O3-induced changes. Results elucidate interactions among antioxidants and air pollutants that could enhance understanding of cardiopulmonary disease.

Rat models of cardiometabolic diseases: baseline clinical chemistries, and rationale for their use in examining air pollution health effects

Individuals with cardiovascular and metabolic diseases (CVD) are shown to be more susceptible to adverse health effects of pollutants. Rodent models of CVD are used for examining susceptibility variations. CVD models developed by selective inbreeding are shown to represent the etiology of human disease and metabolic dysfunction. The goal of this article was to review the origin and the pathobiological features of rat models of varying CVD with or without metabolic syndrome and healthy laboratory rat strains to allow better interpretation of the data regarding their susceptibility to air pollutant exposures. Age-matched healthy Sprague-Dawley (SD), Wistar (WIS) and Wistar Kyoto (WKY), and CVD-prone spontaneously hypertensive (SH), Fawn-Hooded hypertensive (FHH), SH stroke-prone (SHSP), SHHF/Mcc heart failure obese (SHHF) and insulin-resistant JCR:LA-cp obese (JCR) rat models were considered for this study. The genetics and the underlying pathologies differ between these models. Normalized heart weights correlated with underlying cardiac disease while wide differences exist in the number of white blood cells and platelets within healthy strains and those with CVD. High plasma fibrinogen and low angiotensin converting enzyme activity in FHH might relate to kidney disease and associated hypertension. However, other obese strains with known kidney lesions do not exhibit decreases in ACE activity. The increased activated partial thromboplastin time only in SHSP correlates with their hemorrhagic stroke susceptibility. Increases plasma lipid peroxidation in JCR might reflect their susceptibility to acquire atherosclerosis. These underlying pathologies involving CVD and metabolic dysfunction are critical in interpretation of findings related to susceptibility variations of air pollution health effects.

Differential Effect of Electroacupuncture on Inflammatory Adipokines in Two Rat Models of Obesity

Chronic inflammation is known to be associated with visceral obesity and insulin resistance which are characterized by altered levels of production of pro- and anti-inflammatory adipokines. The dysregulation of the production of inflammatory adipokines and their functions in obese individuals leads to a state of chronic low-grade inflammation and may promote obesity-linked metabolic disorders and cardiovascular diseases such as insulin resistance, metabolic syndrome, and atherosclerosis. Electroacupuncture (EA) was tested to see if there was a difference in its effect on pro- and anti-inflammatory adipokine levels in the blood serum and the white adipose tissue of obese Zucker fatty rats and high-fat diet-induced obese Long Evans rats. In the two rat models of obesity, on Day 12 of treatment, repeated applications of EA were seen to have had a significant differential effect for serum tumor necrosis factor-α, adiponectin, the adiponectin:leptin ratio, and blood glucose. For the adipose tissue, there was a differential effect for adiponectin that was on the borderline of significance. To explore these changes further and how they might affect insulin resistance would require a modification to the research design to use larger group sizes for the two models or to give a greater number of EA treatments.

Reduced skeletal muscle function is associated with decreased fiber cross-sectional area in the Cy/+ rat model of progressive kidney disease

BACKGROUND

The combination of skeletal muscle wasting and compromised function plays a role in the health decline commonly observed in chronic kidney disease (CKD) patients, but the pathophysiology of muscle mass/strength changes remains unclear. The purpose of this study was to characterize muscle properties in the Cy/+ rat model of spontaneously progressive CKD.

METHODS

Leg muscle function and serum biochemistry of male Cy/+ (CKD) rats and their nonaffected littermates (NLs) were assessed in vivo at 25, 30 and 35 weeks of age. Architecture and histology of extensor digitorum longus (EDL) and soleus (SOL) muscles were assessed ex vivo at the conclusion of the experiment. We tested the hypothesis that animals with CKD have progressive loss of muscle function, and that this functional deficit is associated with loss of muscle mass and quality.

RESULTS

Thirty-five-week-old CKD rats produced significantly lower maximum torque in ankle dorsiflexion and shorter time to maximum torque, and longer half relaxation time in dorsiflexion and plantarflexion compared with NL rats. Peak dorsiflexion torque (but not plantarflexion torque) in CKD remained steady from 25 to 35 weeks, while in NL rats, peak torque increased. Mass, physiologic cross-sectional area (CSA) and fiber-type (myosin heavy chain isoform) proportions of EDL and SOL were not different between CKD and NL. However, the EDL of CKD rats showed reduced CSAs in all fiber types, while only MyHC-1 fibers were decreased in area in the SOL.

CONCLUSIONS

The results of this study demonstrate that muscle function progressively declines in the Cy/+ rat model of CKD. Because whole muscle mass and architecture do not vary between CKD and NL, but CKD muscles show reduction in individual fiber CSA, our data suggest that the functional decline is related to increased muscle fiber atrophy.

Establishment of C6 brain glioma models through stereotactic technique for laser interstitial thermotherapy research

OBJECTIVE

To establish C6 brain glioma models using stereotactic technique, and to study effects of laser interstitial thermotherapy (LITT) in rat models of glioma.

METHODS

C6 glioma cells were cultured in dulbecco's minimum essential medium (DMEM) cell culture medium. The in vitro C6 cell cultures were stereotaxically implanted into the right caudate nucleus of rat brain. Presence of tumor was confirmed with Factor VIII R, hematoxylin-eosin stain, staining of glial fibrillary acid protein, and S-100 immunohistochemistry. After magnetic resonance (MR) scanning and correction of tumor location, the models were divided into groups according to the treating time and laser power (2-10 W). Semiconductor laser optical fibers were inserted in tumors for LITT. Cortex's temperature conducted from the center target was measured using infrared thermograph, and deep-tissue temperature around the target was measured using a thermocouple.

RESULTS

Rat C6 gliomas were inoculated with optimized stereotactic technique. These gliomas resembled human glioma in terms of histopathological features. Such models are more reliable and reproducible, with 100% yield of intracranial tumor and no extracranial growth extension. The difference between cortex temperature conducted from center target and deep-tissue temperature around target was not statistically significant.

CONCLUSION

The rat C6 brain glioma model established in the study was a perfect model to study LITT of glioma. Infrared thermograph technique measured temperature conveniently and effectively. The technique is noninvasive, and the obtained data could be further processed using software used in LITT research. To measure deep-tissue temperature, combining thermocouple with infrared thermograph technique would present better results.

Assessing Susceptibility to Epilepsy in Three Rat Strains Using Brain Metabolic Profiling Based on HRMAS NMR Spectroscopy and Chemometrics

The possibility that a metabolomic approach can inform about the pathophysiology of a given form of epilepsy was addressed. Using chemometric analyses of HRMAS NMR data, we compared several brain structures in three rat strains with different susceptibilities to absence epilepsy: Genetic Absence Epilepsy Rats from Strasbourg (GAERS), Non Epileptic Control rats (NEC), and Wistar rats. Two ages were investigated: 14 days postnatal (P14) before the onset of seizures and 5 month old adults with fully developed seizures (Adults). The relative concentrations of 19 metabolites were assessed using (1)H HRMAS NMR experiments. Univariate and multivariate analyses including multiblock models were used to identify the most discriminant metabolites. A strain-dependent evolution of glutamate, glutamine, scyllo-inositol, alanine, and glutathione was highlighted during cerebral maturation. In Adults, data from somatosensory and motor cortices allowed discrimination between GAERS and NEC rats with higher levels of scyllo-inositol, taurine, and phosphoethanolamine in NEC. This epileptic metabolic phenotype was in accordance with current pathophysiological hypothesis of absence epilepsy (i.e., seizure-generating and control networks) and putative resistance of NEC rats and was observed before seizure onset. This methodology could be very efficient in a clinical context.

What is the Optimal Duration of Middle-Cerebral Artery Occlusion Consistently Resulting in Isolated Cortical Selective Neuronal Loss in the Spontaneously Hypertensive Rat?

Introduction and objectives: Selective neuronal loss (SNL) in the reperfused penumbra may impact clinical recovery and is thus important to investigate. Brief proximal middle cerebral artery occlusion (MCAo) results in predominantly striatal SNL, yet cortical damage is more relevant given its behavioral implications and that thrombolytic therapy mainly rescues the cortex. Distal temporary MCAo (tMCAo) does target the cortex, but the optimal occlusion duration that results in isolated SNL has not been determined. In the present study, we assessed different distal tMCAo durations looking for consistently pure SNL.

Methods: Microclip distal tMCAo (md-tMCAo) was performed in ~6-month old male spontaneously hypertensive rats (SHRs). We previously reported that 45 min md-tMCAo in SHRs results in pan-necrosis in the majority of subjects. Accordingly, three shorter MCAo durations were investigated here in decremental succession, namely 30, 22, and 15 min (n = 3, 3, and 7 subjects, respectively). Recanalization was confirmed by MR angiography just prior to brain collection at 28 days and T2-weighted MRI was obtained for characterization of ischemic lesions. NeuN, OX42, and GFAP immunohistochemistry appraised changes in neurons, microglia, and astrocytes, respectively. Ischemic lesions were categorized into three main types: (1) pan-necrosis; (2) partial infarction; and (3) SNL.

Results: Pan-necrosis or partial infarction was present in all 30 min and 22 min subjects, but not in the 15 min group (p < 0.001), in which isolated cortical SNL was consistently present. MRI revealed characteristic hyperintense abnormalities in all rats with pan-necrosis or partial infarction, but no change in any 15 min subject.

Conclusion: We found that 15 min distal MCAo consistently resulted in pure cortical SNL, whereas durations equal or longer than 22 min consistently resulted in infarcts. This model may be of use to study the pathophysiology of cortical SNL and its prevention by appropriate interventions.

Intra-articular injection of dexketoprofen in rat knee joint: histopathologic assessment of cartilage & synovium

BACKGROUND & OBJECTIVES

Effective pain control following outpatient surgical procedures is an important aspect of patient discharge. This study was carried out with an aim to investigate the histopathological effects of intra-articular dexketoprofen trometamol injection in knee joint on synovium and cartilage in an experimental rat model.

METHODS

In each of 40 rats, the right knee was designated as the study group and the left knee as the control group (NS group). Under aseptic conditions, 35 rats received an injection of 0.25 ml (6.25 mg) dexketoprofen trometamol into the right knee joint and an injection of 0.25 ml 0.9 per cent normal saline solution into the left knee joint. On the 1st, 2nd, 7th, 14th, and 21st days after intra-articular injection, rats in specified groups were sacrificed by intraperitoneal injection of 120 mg/kg sodium thiopental. Knee joints were separated and sectioned for histopathological examination. Inflammatory changes in the joints were recorded according to a grade scale.

RESULTS

No significant difference in terms of pathological changes both in synovium and cartilage was observed between the NS group and the study group on days 1, 2, 7, 14 and 21 after intra-articular injection of dexketoprofen or saline in the knee joint.

INTERPRETATION & CONCLUSIONS

The findings showed no evidence of significant histopathological damage to the cartilage and synovia for a period up to 21 days following intra-articular administration of dexketoprofen trometamol in the knee joints of rats.

The early days of NK cells: an example of how a phenomenon led to detection of a novel immune receptor system - lessons from a rat model

In this review, I summarize some of the early research on NK cell biology and function that led to the discovery of a totally new receptor system for polymorphic MHC class I molecules. That NK cells both could recognize and kill tumor cells but also normal hematopoietic cells through expression of MHC class I molecules found a unifying explanation in the “missing self” hypothesis. This initiated a whole new area of leukocyte receptor research. The common underlying mechanism was that NK cells expressed receptors that were inhibited by recognition of unmodified “self” MHC-I molecules. This could explain both the killing of tumor cells with poor expression of MHC-I molecules and hybrid resistance, i.e., that F1 hybrid mice sometimes could reject parental bone marrow cells. However, a contrasting phenomenon termed allogeneic lymphocyte cytotoxicity in rats gave strong evidence that some of these receptors were activated rather than inhibited by recognition of polymorphic MHC-I. This was soon followed by molecular identification of both inhibitory and stimulatory Ly49 receptors in mice and rats and killer cell immunoglobulin-like receptors in humans that could be either inhibited or activated when recognizing their cognate MHC-I ligand. Since most of these receptors now have been molecularly characterized, their ligands and the intracellular pathways leading to activation or inhibition identified, we still lack a more complete understanding of how the repertoire of activating and inhibitory receptors is formed and how interactions between these receptors for MHC-I molecules on a single NK cell are integrated to generate a productive immune response. Although several NK receptor systems have been characterized that recognize MHC-I or MHC-like molecules, I here concentrate on the repertoires of NK receptors encoded by the natural killer cell gene complex and designed to recognize polymorphic MHC-I molecules in rodents, i.e., Ly49 (KLRA) receptors.

Efficacy of kilohertz-frequency and conventional spinal cord stimulation in rat models of different pain conditions

OBJECTIVES

The aim was to compare the effects of high-frequency spinal cord stimulation (HF-SCS) at subparesthetic intensity with conventional SCS in rat models of different types of pain. In addition, microrecordings of afferent activity in the dorsal columns during both types of SCS were performed to elucidate their mode of action.

MATERIALS AND METHODS

Miniature SCS electrodes were implanted in all rats. One group was submitted to the spared nerve injury procedure (SNI) and another to inflammatory pain after carrageenan injection into a hind paw. All animals were tested for hypersensitivity to normally innocuous tactile and thermal stimuli. One group of normal healthy rats was submitted to acute nociceptive (pinch, heat) pain. Microrecording of afferent activity in the gracile nucleus (GN) was performed in a group of nerve-lesioned rats responding to conventional SCS.

RESULTS

HF-SCS at 500, 1,000, or 10,000 Hz at subparesthetic amplitudes produced similar reductions in hypersensitivity due to nerve lesion as did conventional SCS at 50 Hz. HF-SCS showed no effect on thermal pain. A trial to rescue non-responders to conventional SCS using HF-SCS was not successful. There were no effects either of conventional or of HF-SCS on acute or inflammatory pain. Conventional SCS produced massive activation in the GN but no activation during HF-SCS, though normal peripherally evoked afferent activity remained.

CONCLUSIONS

Conventional SCS proved equally effective to HF-SCS in various pain models. As no activity is conveyed rostrally in subparesthetic HF-SCS, we hypothesize that its mechanisms of action are primarily segmental.

Peritraumatic startle response predicts the vulnerability to develop PTSD-like behaviors in rats: a model for peritraumatic dissociation

Peritraumatic dissociation, a state characterized by alteration in perception and reduced awareness of surroundings, is considered to be a risk factor for the development of post-traumatic stress disorder (PTSD). However, the predictive ability of peritraumatic dissociation is questioned for the inconsistent results in different time points of assessment. The startle reflex is an objective behavioral measurement of defensive response to abrupt and intense sensory stimulus of surroundings, with potential to be used as an assessment on the dissociative status in both humans and rodents. The present study examined the predictive effect of acoustic startle response (ASR) in different time points around the traumatic event in an animal model of PTSD. The PTSD-like symptoms, including hyperarousal, avoidance, and contextual fear, were assessed 2–3 weeks post-trauma. The results showed that (1) the startle amplitude attenuated immediate after intense footshock in almost half of the stress animals, and (2) the attenuated startle responses at 1 h but not 24 h after stress predicted the development of severe PTSD-like symptoms. These data indicate that the startle alteration at the immediate period after trauma, including 1 h, is more important in PTSD prediction than 24 h after trauma. Our study also suggests that the startle attenuation immediate after intense stress may serve as an objective measurement of peritraumatic dissociation in rats.

Marrow mesenchymal stromal cells reduce methicillin-resistant Staphylococcus aureus infection in rat models

BACKGROUND AIMS

Staphylococci account for a large proportion of hospital-acquired infections, especially among patients with indwelling devices. These infections are often caused by biofilm-producing strains, which are difficult to eradicate and may eventually cause bacteremia and metastatic infections. Recent evidence suggests that mesenchymal stem cells can enhance bacterial clearance in vivo.

METHODS

In this study, a rat model with carboxymethyl cellulose pouch infection was used to analyze the efficacy of bone marrow-derived mesenchymal stromal cells (BMSCs) against the methicillin-resistant Staphylococcus aureus.

RESULTS

The results showed that the administration of BMSCs effectively reduced the number of bacterial colonies and the expression of many cytokines and chemokines (such as interleukin [IL]-6, IL-1β, IL-10 and CCL5). Unlike the fibroblast control groups, the pouch tissues from the BMSC-treated rats showed the formation of granulations, suggesting that the healing of the wound was in progress.

CONCLUSIONS

The results indicate that the treatment of BMSCs can reduce methicillin-resistant S aureus infection in vivo, thereby reducing the inflammatory response.

Neuro-glial and systemic mechanisms of pathological responses in rat models of primary blast overpressure compared to "composite" blast

A number of experimental models of blast brain injury have been implemented in rodents and larger animals. However, the variety of blast sources and the complexity of blast wave biophysics have made data on injury mechanisms and biomarkers difficult to analyze and compare. Recently, we showed the importance of rat position toward blast generated by an external shock tube. In this study, we further characterized blast producing moderate traumatic brain injury and defined "composite" blast and primary blast exposure set-ups. Schlieren optics visualized interaction between the head and a shock wave generated by external shock tube, revealing strong head acceleration upon positioning the rat on-axis with the shock tube (composite blast), but negligible skull movement upon peak overpressure exposure off-axis (primary blast). Brain injury signatures of a primary blast hitting the frontal head were assessed and compared to damage produced by composite blast. Low to negligible levels of neurodegeneration were found following primary blast compared to composite blast by silver staining. However, persistent gliosis in hippocampus and accumulation of GFAP/CNPase in circulation was detected after both primary and composite blast. Also, markers of vascular/endothelial inflammation integrin alpha/beta, soluble intercellular adhesion molecule-1, and L-selectin along with neurotrophic factor nerve growth factor-beta were increased in serum within 6 h post-blasts and persisted for 7 days thereafter. In contrast, systemic IL-1, IL-10, fractalkine, neuroendocrine peptide Orexin A, and VEGF receptor Neuropilin-2 (NRP-2) were raised predominantly after primary blast exposure. In conclusion, biomarkers of major pathological pathways were elevated at all blast set-ups. The most significant and persistent changes in neuro-glial markers were found after composite blast, while primary blast instigated prominent systemic cytokine/chemokine, Orexin A, and Neuropilin-2 release, particularly when primary blast impacted rats with unprotected body.

Frequency-dependent effects of vibration on physiological systems: experiments with animals and other human surrogates

Occupational exposure to vibration through the use of power- and pneumatic hand-tools results in cold-induced vasospasms, finger blanching, and alterations in sensorineural function. Collectively, these symptoms are referred to as hand-arm vibration syndrome (HAVS). Currently the International Standards Organization (ISO) standard ISO 5349-1 contains a frequency-weighting curve to help workers and employers predict the risk of developing HAVS with exposure to vibration of different frequencies. However, recent epidemiological and experimental evidence suggests that this curve under-represents the risk of injuries to the hands and fingers induced by exposure to vibration at higher frequencies (>100 Hz). To improve the curve, better exposure-response data need to be collected. The goal of this review is to summarize the results of animal and computational modeling studies that have examined the frequency-dependent effects of vibration, and discuss where additional research would be beneficial to fill these research gaps.

Rat Mcs5a is a compound quantitative trait locus with orthologous human loci that associate with breast cancer risk

Breast cancer risk is a polygenic trait. To identify breast cancer modifier alleles that have a high population frequency and low penetrance we used a comparative genomics approach. Quantitative trait loci (QTL) were initially identified by linkage analysis in a rat mammary carcinogenesis model followed by verification in congenic rats carrying the specific QTL allele under study. The Mcs5a locus was identified by fine-mapping Mcs5 in a congenic model. Here we characterize the Mcs5a locus, which when homozygous for the Wky allele, reduces mammary cancer risk by 50%. The Mcs5a locus is a compound QTL with at least two noncoding interacting elements: Mcs5a1 and Mcs5a2. The resistance phenotype is only observed in rats carrying at least one copy of the Wky allele of each element on the same chromosome. Mcs5a1 is located within the ubiquitin ligase Fbxo10, whereas Mcs5a2 includes the 5' portion of Frmpd1. Resistant congenic rats show a down-regulation of Fbxo10 in the thymus and an up-regulation of Frmpd1 in the spleen. The association of the Mcs5a1 and Mcs5a2 human orthologs with breast cancer was tested in two population-based breast cancer case-control studies (approximately 12,000 women). The minor alleles of rs6476643 (MCS5A1) and rs2182317 (MCS5A2) were independently associated with breast cancer risk. The minor allele of rs6476643 increases risk, whereas the rs2182317 minor allele decreases risk. Both alleles have a high population frequency and a low penetrance toward breast cancer risk.