Fawn-Hooded Rats Research Articles

R-Baclofen Treatment Corrects Autistic-like Behavioral Deficits in the RjIbm(m):FH Fawn-Hooded Rat Strain.

The Fawn-hooded rat has long been used as a model for various peripheral and central disorders and the data available indicate that the social behavior of this strain may be compromised. However, a thorough description of the Fawn-hooded rat is unavailable in this regard. The objective of the present study was to investigate various aspects of the Fawn-hooded rat's social behavior in depth. Our results show that several facets of socio-communicational behavior are impaired in the RjIbm(m):FH strain, including defective ultrasonic vocalizations in pups upon maternal deprivation, reduced social play in adolescence and impaired social novelty discrimination in adulthood. In addition, Fawn-hooded rats exhibited heightened tactile sensitivity and hyperactivity. The defects observed were comparable to those induced by prenatal valproate exposure, a widely utilized model of autism spectrum disorder. Further on, the pro-social drug R-baclofen (0.25-1 mg/kg) reversed the autistic-like defects observed in Fawn-hooded rats, specifically the deficiency in ultrasonic vocalization, tactile sensitivity and social novelty discrimination endpoints. In conclusion, the asocial, hypersensitive and hyperactive phenotype as well as the responsivity to R-baclofen indicate this variant of the Fawn-hooded rat strain may serve as a model of autism spectrum disorder and could be useful in the identification of novel drug candidates.

The protective effects of Dendrobium nobile Lindl. alkaloids (DNLA) against CUMS-induced anxiety/depression and hippocampal transcriptome changes in rats

IntroductionDendrobium is the famous Chinese medicine. Dendrobium nobile Lindl. alkaloids (DNLA) is the active ingredient and has been shown to have anti-aging, anti-Alzheimer's disease, and neuroprotective properties. This study examined effect of DNLA on chronic unpredictable mild stress (CUMS)-induced anxiety and depression in Fawn-Hooded (FH/Wjd) rats, a depression model in comorbid of alcoholism. MethodsFH/Wjd rats were subjected to CUMS for 49 days, followed by treatment with DNLA (20 mg/kg/day, po) for 35 days. The anxiety/depression behaviors, Nissl bodies, neurotransmitters and hypothalamic-pituitary-adrenal axis were examined. RNA-Seq analysis was performed to explore the protection mechanisms. ResultsThe CUMS-induced anxiety/depressive-like behaviors were ameliorated by DNLA in the elevated-plus-maze test, open-field test, and forced swimming test. The CUMS reduced Nissl bodies in the hippocampal CA2 region and cortex was alleviated by DNLA. CUMS disrupted 5-hydroxytryptamine, dopamine and gamma-aminobutyric acid in the brain, which were recovered by DNLA. Increases in serum adrenocorticotropic hormone and corticosterone levels were prevented by DNLA. RNA-Seq revealed CUMS-induced 1607 differentially expressed genes, which were ameliorated with DNLA treatment. KEGG showed the enrichment of Ribosome, Rap1 signaling, Tight junction, and RNA transport pathways. DiscussionFH/Wjd rats were susceptible to CUMS-induced anxiety and depression. DNLA ameliorated CUMS-induced anxiety/depression behaviors and neuronal damage. Multiple mechanisms were involved in the beneficial effects of DNLA, including neurotransmitters, the hypothalamic-pituitary-adrenal axis, and the hippocampal gene expressions.

G9a/GLP Targeting Ameliorates Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is characterized by progressive vascular remodeling of small pulmonary arteries (PAs) causing sustained elevation of PA pressure, right ventricular failure, and death. Similar to cancer cells, PA smooth muscle cells (PASMCs), which play a key role in pulmonary vascular remodeling, have adopted multiple mechanisms to sustain their survival and proliferation in the presence of stress. The histone methyltransferase G9a and its partner protein GLP (G9a-like protein) have been shown to exert oncogenic effects and to serve as a buffer against an exaggerated transcriptional response. Therefore, we hypothesized that upregulation of G9a and GLP in PAH plays a pivotal role in pulmonary vascular remodeling by maintaining the abnormal phenotype of PAH-PASMCs. We found that G9a is increased in PASMCs from patients with PAH as well as in remodeled PAs from animal models. Pharmacological inhibition of G9a/GLP activity using BIX01294 and UNC0642 significantly reduced the prosurvival and proproliferative potentials of cultured PAH-PASMCs. Using RNA sequencing, further exploration revealed that G9a/GLP promotes extracellular matrix production and affords protection against the negative effects of an overactive stress response. Finally, we found that therapeutic treatment with BIX01294 reduced pulmonary vascular remodeling and lowered mean PA pressure in fawn-hooded rats. Treatment of Sugen/hypoxia-challenged mice with BIX01294 also improved pulmonary hemodynamics and right ventricular function. In conclusion, these findings indicate that G9a/GLP inhibition may represent a new therapeutic approach in PAH.

Erratum for Hu et al., "Effects of 'Healthy' Fecal Microbiota Transplantation against the Deterioration of Depression in Fawn-Hooded Rats".

Erratum for Hu et al., "Effects of 'Healthy' Fecal Microbiota Transplantation against the Deterioration of Depression in Fawn-Hooded Rats".

Effects of 'Healthy' Fecal Microbiota Transplantation against the Deterioration of Depression in Fawn-Hooded Rats.

ABSTRACTDepression is a recurrent, heterogeneous mood disorder occurring in more than 260 million people worldwide. Gut microbiome dysbiosis is associated with the development of depressive-like behaviors by modulating neuro-biochemical metabolism through the microbiome-gut-brain (MGB) axis. Fecal microbiota transplantation (FMT) has been proposed as a potential therapeutic solution for depression, but the therapeutic efficiency and mechanism are unknown. Here, we performed an FMT from Sprague-Dawley (SD) rats (‘healthy’ controls) to Fawn-hooded (FH) rats (depression model). Pre-FMT, the FH rats exhibited significantly elevated depressive-like behaviors and distinct neurotransmitter and cytokine levels compared with SD rats. Post-FMT, FH recipients receiving FH fecal microbiota (FH-FH rats) showed aggravated depressive-like behaviors, while the ones receiving SD microbiota (FH-SD rats) had significantly alleviated depressive symptoms, a significant increase in hippocampal neurotransmitters, and a significant decrease of some hippocampal cytokines than FH-FH rats. SD-FMT resulted in the FH-SD rats’ gut microbiome resembling the SD donors, and a significant shift in the serum metabolome but not the hippocampal metabolome. Co-occurrence analysis suggests that SD-FMT prevented recipients’ depression development via the significant decrease of gut microbial species such as Dialister sp., which led to the recipients’ metabolic modulation in serum and hippocampus through the enteric nervous system, the intestinal barrier, and the blood-brain barrier. Our results provided new data pointing to multiple mechanisms of interaction for the impact of gut microbiome modulation on depression therapy.IMPORTANCE Depression is a chronic, recurrent mental disease, which could make the patients commit suicide in severe cases. Considering that gut microbiome dysbiosis could cause depressive symptoms in animals through the MGB axis, the modification of gut microbiota is expected to be a potential therapy for depression, but the daily administration of probiotics is invalid or transient. In this study, we demonstrated that the gut microbiome transferred from a healthy rat model to a depressive rat model could regulate the recipient’s neurobiology and behavior via the systematic alternation of the depressive gut microbiota followed by the serum and hippocampal metabolism. These results underline the significance of understanding the impact of gut microbiota on mental disorders and suggest that ‘healthy’ microbiota transplantation with the function to solve the host’s cerebral inflammation may serve as a novel therapeutic strategy for depression.

Abstract 9771: Novel Contribution of an Epigenetic Factor "g9a" in Pulmonary Arterial Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a vascular disease characterized by an increased mean pulmonary artery (PA) pressure. Pulmonary artery smooth muscle cells (PASMCs) from PAH patients exhibit a “cancer-like” hyperproliferative and apoptosis-resistant phenotype leading to pulmonary vascular remodeling. It is believed that these alterations are influenced by epigenetic processes. However, it is still not clear which gene are the drivers. “G9a”, a histone methyltransferase, is known to be overexpressed in different types of cancer, promoting cell survival and proliferation. Given the similarities between PAH and cancer, we hypothesized that G9a could be implicated in PAH progression and pathogenesis. Methods and Results: Using Western blot (WB) and immunofluorescence (IF), we showed that G9a is significantly upregulated in distal PAs and isolated PASMCs from PAH patients (n= 6-14, p<0.01). Similarly, G9a was increased (p<0.05) in three PAH animal models: monocrotaline (MCT), fawn-hooded rat (FHR) and mice exposed to chronic hypoxia. In vitro, pharmacological G9A inhibition using BIX01294 reduces PAH-PASMC proliferation (Ki67/ EdU assays, p<0.001) and survival (Annexin V assay, p<0.001). Through RNA sequencing analysis conducted in PAH-PASMCs treated or not with BIX01294, we found that upregulated genes were significantly enriched in “cholesterol biosynthesis” and “autophagy”. Consistently, G9a inhibition was accompanied by an increased lipid accumulation and an impaired autophagy flux as evidenced by the appearance of numerous cytoplasmic vacuoles positive for LC3-II (IF, WB), the accumulation of yellow puncta in PAH-PASMCs expressing the RFP-GFP-LC3 fusion protein, the unaffected LC3-II expression after adding chloroquine and the defect in cathepsin B and D maturation (WB). Same results were seen with UNC0642, another G9A inhibitor. In vivo , we showed that BIX01294 significantly improved established PAH in FHR (reduced RVSP and mPAP, increased SV and CO, by right heart catheterization, and attenuated pulmonary vascular remodeling, p<0,001). Conclusion: We showed that G9a upregulation contributes to the pro-proliferative phenotype of PAH-PASMCs; and its inhibition represents a novel avenue to improve PAH.

Abstract 16770: The Epigenetic Modifier EP300: A New Corner Stone in the Regulation of Both Vascular Remodeling and Right Ventricle Failure in Pulmonary Arterial Hypertension

Introduction: Pulmonary Arterial Hypertension (PAH) is characterized by excessive proliferation and resistance to apoptosis of pulmonary artery (PA) smooth muscle cells (PASMCs), leading to progressive increases in pulmonary vascular resistance, and ultimately right ventricular (RV) failure and death. Thanks to omics technologies, we made tremendous progress in understanding gene misregulation during disease processes and identified the epigenetic factor EP300 as a critical player in pathological processes like proliferation/apoptosis and hypertrophy/fibrosis all of which are critical features of both PA remodeling and RV failure in PAH. We hypothesized that EP300 is upregulated in PAH and contributes to both PA remodeling and RV failure. Methods and Results: By Western blot (WB) and immunofluorescence (IF), we found that EP300 is up-regulated in isolated PASMCs and distal PAs from PAH patients (n=11-14) compared to controls (n=8-10) (p<0.01). Similar results were observed in 3 PAH animal models, namely the monocrotaline (MCT), the Sugen/Hypoxia (Su/Hx) and the Fawn-Hooded rat (FHR) (p<0.05). In vitro, pharmacological inhibition of EP300 using CCS-1477 reduces PAH-PASMC proliferation (Ki67 labeling & WB PCNA; p<0.05) and resistance to apoptosis (Annexin V assay & WB Survivin; p<0.05). These effects were confirmed at the molecular level by RNA-Seq analysis. In addition, increased EP300 expression was observed in hypertrophied and failed RV from PAH patients, as well as in rats injected with MCT or subjected to pulmonary artery banding (WB, p<0.05). In animal models, EP300 negatively correlates with CO and positively correlates with RVEDP, cardiomyocyte surface area and fibrosis. Finally, we demonstrated that inhibition of EP300 using CCS-1477 or SGC-CBP30 significantly improved established PAH (right heart catheterization) in two animal models (MCT and FHR). Conclusion: EP300 upregulation contributes to both pulmonary vascular remodeling and RV dysfunction seen in PAH and its inhibition represents a promising therapeutic avenue.

Brucine N-Oxide Reduces Ethanol Intake and Preference in Alcohol-Preferring Male Fawn-Hooded Rats.

Alcohol use disorder places a heavy burden on global public health systems and thus is in urgent need of improved pharmacotherapies. Previously, our group has demonstrated that 30mg/kg of the indole alkaloid brucine significantly attenuates alcohol-drinking behavior; however, the high toxicity, poor water solubility, short half-life, and limited therapeutic window of brucine restrain its clinical application as an antialcoholism medication. We subsequently hypothesized that the oxide of brucine (brucine N-oxide) would produce a similar behavioral effect without the risk profile associated with brucine. Male Fawn-Hooded rats with high innate alcohol preference underwent 2-bottle choice procedures (Experiments 1 to 3). Experiment 1 examined the effects of 7 daily BNO injections of 0, 30, 50, or 70mg/kg (s.c.) on voluntary alcohol consumption (n=9/group). Experiment 2 evaluated the impact of a single dose of 0 or 70mg/kg BNO on the increased alcohol intake induced by a 4-day alcohol deprivation (n=8/group). Experiment 3 tested the effect of 7 daily BNO injections of 0 or 70mg/kg (s.c.) on sucrose preference (n=6/group). Experiment 4 measured the median lethal dose (LD50) values of BNO and brucine to compare their acute toxicity in rats. Experiment 5 tested whether BNO (0, 30, 50, and 70mg/kg, s.c.) affected locomotor activity using an open-field paradigm (n=8/group). Finally, Experiment 6 evaluated the possible conditioned rewarding effects of 0, 30, 50, and 70mg/kg BNO using the conditioned place preference paradigm (n=6/group). BNO administration dose-dependently attenuated alcohol consumption without affecting food intake, total fluid consumption, or the natural preference for a sucrose solution, with 70mg/kg BNO reducing consumption by 22.8%. A single dose of 70mg/kg BNO significantly inhibited the alcohol deprivation effect. The LD50 values of BNO and brucine in rats were determined to be 1,103.5±177.0mg/kg and 264.6±17.7mg/kg, respectively. Finally, BNO administration did not affect spontaneous locomotor activity or induce a place preference. BNO may help to control excessive alcohol use and should be considered a treatment strategy for future study and development.

PIM1 (Moloney Murine Leukemia Provirus Integration Site) Inhibition Decreases the Nonhomologous End-Joining DNA Damage Repair Signaling Pathway in Pulmonary Hypertension.

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by the narrowing of pulmonary arteries (PAs). It is now established that this phenotype is associated with enhanced PA smooth muscle cells (PASMCs) proliferation and suppressed apoptosis. This phenotype is sustained in part by the activation of several DNA repair pathways allowing PASMCs to survive despite the unfavorable environmental conditions. PIM1 (Moloney murine leukemia provirus integration site) is an oncoprotein upregulated in PAH and involved in many prosurvival pathways, including DNA repair. The objective of this study was to demonstrate the implication of PIM1 in the DNA damage response and the beneficial effect of its inhibition by pharmacological inhibitors in human PAH-PASMCs and in rat PAH models. Approach and Results: We found in vitro that PIM1 inhibition by either SGI-1776, TP-3654, siRNA (silencer RNA) decreased the phosphorylation of its newly identified direct target KU70 (lupus Ku autoantigen protein p70) resulting in the inhibition of double-strand break repair (Comet Assay) by the nonhomologous end-joining as well as reduction of PAH-PASMCs proliferation (Ki67-positive cells) and resistance to apoptosis (Annexin V positive cells) of PAH-PASMCs. In vivo, SGI-1776 and TP-3654 given 3× a week, improved significantly pulmonary hemodynamics (right heart catheterization) and vascular remodeling (Elastica van Gieson) in monocrotaline and Fawn-Hooded rat models of PAH. We demonstrated that PIM1 phosphorylates KU70 and initiates DNA repair signaling in PAH-PASMCs and that PIM1 inhibitors represent a therapeutic option for patients with PAH.

A new inbred strain of Fawn-Hooded rats demonstrates mania-like behavioural and monoaminergic abnormalities

The Fawn-Hooded (FH) rat carries a gene mutation that results in a dysfunctional serotoninergic system. However, previous studies have reported differing features between the FH/Wjd and FH/Har strains. We aimed to compare the behavioural and neurobiological features of FH/HamSlc rats with those of Fischer 344 rats. We performed the open field, elevated minus-maze, Y-maze spontaneous alternation, and forced swim tests to investigate behavioural alterations. We also assessed neurobiological characteristics by quantifying monoamines and their related compounds in the prefrontal cortex, hippocampus, and striatum using high-performance liquid chromatography with an electrochemical detection system. FH/HamSlc rats showed hyperactivity and a high impulsivity tendency in the open field and the elevated minus maze test, but no cognitive dysfunction. In addition, the hyperactivity was suppressed immediately after the forced swim test. FH/HamSlc rats showed low dopamine levels, but high dopamine turnover in the striatum. Serotonin and noradrenaline levels were low in the prefrontal cortex and the hippocampus of FH/HamSlc rats, but high serotonin turnover was observed in the prefrontal cortex, hippocampus, and striatum. FH/HamSlc rats show (1) mania-like behavioural characteristics that are different from those of other strains of FH rats; (2) stimulus dependent suppression of hyperactivity similar to the clinical findings that exercise alleviates the symptoms of bipolar disorder; and (3) monoaminergic dysregulation such as monoamine imbalance and hyperturnover that may be associated with mania-related behavioural characteristics. Thus, the FH/HamSlc rat is a new animal model for mania including bipolar disorder.

Metabolic Remodeling in the Pressure-Loaded Right Ventricle: Shifts in Glucose and Fatty Acid Metabolism-A Systematic Review and Meta-Analysis.

BackgroundRight ventricular (RV) failure because of chronic pressure load is an important determinant of outcome in pulmonary hypertension. Progression towards RV failure is characterized by diastolic dysfunction, fibrosis and metabolic dysregulation. Metabolic modulation has been suggested as therapeutic option, yet, metabolic dysregulation may have various faces in different experimental models and disease severity. In this systematic review and meta‐analysis, we aimed to identify metabolic changes in the pressure loaded RV and formulate recommendations required to optimize translation between animal models and human disease.Methods and ResultsMedline and EMBASE were searched to identify original studies describing cardiac metabolic variables in the pressure loaded RV. We identified mostly rat‐models, inducing pressure load by hypoxia, Sugen‐hypoxia, monocrotaline (MCT), pulmonary artery banding (PAB) or strain (fawn hooded rats, FHR), and human studies. Meta‐analysis revealed increased Hedges’ g (effect size) of the gene expression of GLUT1 and HK1 and glycolytic flux. The expression of MCAD was uniformly decreased. Mitochondrial respiratory capacity and fatty acid uptake varied considerably between studies, yet there was a model effect in carbohydrate respiratory capacity in MCT‐rats.ConclusionsThis systematic review and meta‐analysis on metabolic remodeling in the pressure‐loaded RV showed a consistent increase in glucose uptake and glycolysis, strongly suggest a downregulation of beta‐oxidation, and showed divergent and model‐specific changes regarding fatty acid uptake and oxidative metabolism. To translate metabolic results from animal models to human disease, more extensive characterization, including function, and uniformity in methodology and studied variables, will be required.

Combined deficiency of RAB32 and RAB38 in the mouse mimics Hermansky-Pudlak syndrome and critically impairs thrombosis

AbstractThe biogenesis of lysosome related organelles is defective in Hermansky-Pudlak syndrome (HPS), a disorder characterized by oculocutaneous albinism and platelet dense granule (DG) defects. The first animal model of HPS was the fawn-hooded rat, harboring a spontaneous mutation inactivating the small guanosine triphosphatase Rab38. This leads to coat color dilution associated with the absence of DGs and lung morphological defects. Another RAB38 mutant, the cht mouse, has normal DGs, which has raised controversy about the role of RAB38 in DG biogenesis. We show here that murine and human, but not rat, platelets also express the closely related RAB32. To elucidate the parts played by RAB32 and RAB38 in the biogenesis of DGs in vivo and their effects on platelet functions, we generated mice inactivated for Rab32, Rab38, and both genes. Single Rab38 inactivation mimicked cht mice, whereas single Rab32 inactivation had no effect in DGs, coat color, or lung morphology. By contrast, Rab32/38 double inactivation mimicked severe HPS, with strong coat and eye pigment dilution, some enlarged lung multilamellar bodies associated with a decrease in the number of DGs. These organelles were morphologically abnormal, decreased in number, and devoid of 5-hydroxytryptamine content. In line with the storage pool defect, platelet activation was affected, resulting in severely impaired thrombus growth and prolongation of the bleeding time. Overall, our study demonstrates the absence of impact of RAB38 or RAB32 single deficiency in platelet biogenesis and function resulting from full redundancy, and characterized a new mouse model mimicking HPS devoid of DG content.

Mitochondrial HSP90 Accumulation Promotes Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a vascular remodeling disease with a poor prognosis and limited therapeutic options. Although the mechanisms contributing to vascular remodeling in PAH are still unclear, several features, including hyperproliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs), have led to the emergence of the cancer-like concept. The molecular chaperone HSP90 (heat shock protein 90) is directly associated with malignant growth and proliferation under stress conditions. In addition to being highly expressed in the cytosol, HSP90 exists in a subcellular pool compartmentalized in the mitochondria (mtHSP90) of tumor cells, but not in normal cells, where it promotes cell survival. We hypothesized that mtHSP90 in PAH-PASMCs represents a protective mechanism against stress, promoting their proliferation and resistance to apoptosis. Expression and localization of HSP90 were analyzed by Western blot, immunofluorescence, and immunogold electron microscopy. In vitro, effects of mtHSP90 inhibition on mitochondrial DNA integrity, bioenergetics, cell proliferation and resistance to apoptosis were assessed. In vivo, the therapeutic potential of Gamitrinib, a mitochondria-targeted HSP90 inhibitor, was tested in fawn-hooded and monocrotaline rats. We demonstrated that, in response to stress, HSP90 preferentially accumulates in PAH-PASMC mitochondria (dual immunostaining, immunoblot, and immunogold electron microscopy) to ensure cell survival by preserving mitochondrial DNA integrity and bioenergetic functions. Whereas cytosolic HSP90 inhibition displays a lack of absolute specificity for PAH-PASMCs, Gamitrinib decreased mitochondrial DNA content and repair capacity and bioenergetic functions, thus repressing PAH-PASMC proliferation (Ki67 labeling) and resistance to apoptosis (Annexin V assay) without affecting control cells. In vivo, Gamitrinib improves PAH in two experimental rat models (monocrotaline and fawn-hooded rat). Our data show for the first time that accumulation of mtHSP90 is a feature of PAH-PASMCs and a key regulator of mitochondrial homeostasis contributing to vascular remodeling in PAH.

Comparative effects of stressors on behavioral and neuroimmune responses of fawn-hooded (FH/Wjd) and Wistar rats: Implications for models of depression

Patients with depression and rodent models of depression show increased cytokines and activated microglia. Fawn Hooded (FH/Wjd) rats have long been used as a model of depression based on their depressive-like behaviors, high basal corticosterone levels and altered serotonergic levels, but little is known about the neuroimmune function in this model. To test whether depressive-like behaviors relate to dysfunction of the neuroimmune system, depressive-like behaviors in the forced swim test (FST) and corticosterone (CORT) response to the swim test were compared in male Fawn Hooded versus Wistar rats, and cytokine levels in plasma and brain and plasma CORT in response to lipopolysaccharide (LPS, an endotoxin that activates the neuroimmune system) or 1 h restraint were measured. Fawn Hooded rats had more depressive-like behaviors in the FST (decreased swim time and increased immobility) and increased overall plasma CORT compared with Wistar rats. Additionally, Fawn Hooded rats exhibited blunted brain and plasma cytokine response to LPS compared with Wistar rats, an effect that might be related to the blunted plasma CORT response to LPS. No strain differences were found on these measures in response to restraint stress. These results suggest that Fawn Hooded rats have a depressive-like phenotype potentially more closely associated with serotonin dysregulation and a dysregulated HPA axis and remain a relevant model for further defining the role of these systems in depressive conditions.

Attenuation of ethanol abstinence-induced anxiety- and depressive-like behavior by the phosphodiesterase-4 inhibitor rolipram in rodents.

Withdrawal symptoms stand as a core feature of alcohol dependence. Our previous results have shown that inhibition of phosphodiesterase-4 (PDE4) decreased ethanol seeking and drinking in alcohol-preferring rodents. However, little is known about whether PDE4 is involved in ethanol abstinence-related behavior. The objective of this study was to characterize the role of PDE4 in the development of anxiety- and depressive-like behavior induced by abstinence from ethanol exposure in different animal models. Using three rodent models of ethanol abstinence, we examined the effects of rolipram, a prototypical, selective PDE4 inhibitor, on (1) anxiety-like behavior induced by repeated ethanol abstinence in the elevated plus maze test in fawn-hooded (FH/Wjd) rats, (2) anxiety-like behavior in the open-field test and light-dark transition test following acute ethanol abstinence in C57BL/6J mice, and (3) anxiety- and depressive-like behavior induced by protracted ethanol abstinence in the elevated plus maze, forced-swim, and tail-suspension tests in C57BL/6J mice. Pretreatment with rolipram (0.1 or 0.2mg/kg) significantly increased entries and time spent in the open arms of the elevated plus maze test in rats with repeated ethanol abstinence. Similarly, in mice with acute ethanol abstinence, administration of rolipram (0.25 or 0.5mg/kg) dose-dependently increased the crossings in the central zone of the open-field test and duration and transitions on the light side of the light-dark transition test, suggesting anxiolytic-like effects of rolipram. Consistent with these, chronic treatment with rolipram (0.1, 0.3, or 1.0mg/kg) increased entries in the open arms of the elevated plus maze test; it also reduced the increased duration of immobility in both the forced-swim and tail-suspension tests in mice after protracted ethanol abstinence, suggesting antidepressant-like effects of rolipram. These results provide the first demonstration for that PDE4 plays a role in modulating the development of negative emotional reactions associated with ethanol abstinence, including anxiety and depression. PDE4 inhibitors may be a novel class of drugs for treatment of alcoholism.

Progression of hypertension and kidney disease in aging fawn-hooded rats is mediated by enhanced influence of renin–angiotensin system and suppression of nitric oxide system and epoxyeicosanoids

ABSTRACTThe fawn-hooded hypertensive (FHH) rat serves as a genetic model of spontaneous hypertension associated with glomerular hyperfiltration and proteinuria. However, the knowledge of the natural course of hypertension and kidney disease in FHH rats remains fragmentary and the underlying pathophysiological mechanisms are unclear. In this study, over the animals’ lifetime, we followed the survival rate, blood pressure (telemetry), indices of kidney damage, the activity of renin–angiotensin (RAS) and nitric oxide (NO) systems, and CYP450-epoxygenase products (EETs). Compared to normotensive controls, no elevation of plasma and renal RAS was observed in prehypertensive and hypertensive FHH rats; however, RAS inhibition significantly reduced systolic blood pressure (137 ± 9 to 116 ± 8, and 159 ± 8 to 126 ± 4 mmHg, respectively) and proteinuria (62 ± 2 to 37 ± 3, and 132 ± 8 to 87 ± 5 mg/day, respectively). Moreover, pharmacological RAS inhibition reduced angiotensin (ANG) II and increased ANG 1–7 in the kidney and thereby may have delayed the progression of kidney disease. Furthermore, renal NO and EETs declined in the aging FHH rats but not in the control strain. The present results, especially the demonstration of exaggerated vascular responsiveness to ANG II, indicate that RAS may contribute to the development of hypertension and kidney disease in FHH rats. The activity of factors opposing the development of hypertension and protecting the kidney declined with age in this model. Therefore, therapeutic enhancement of this activity besides RAS inhibition could be attempted in the therapy of human hypertension associated with kidney disease.

Elevated Aminopeptidase P Attenuates Cerebral Arterial Responses to Bradykinin in Fawn-Hooded Hypertensive Rats.

Cerebral arterial myogenic and autoregulatory responses are impaired in Fawn Hooded hypertensive (FHH) rats. Cerebral autoregulatory responses are restored in the congenic rat strain in which a segment of chromosome 1 from the Brown Norway (BN) rat was transferred into the FHH genetic background (FHH.1BN). The impact of this region on cerebral arterial dilator responses remains unknown. Aminopeptidase is a gene that was transferred into the FHH genetic background to generate the FHH.1BN rats and is responsible for degradation of the vasodilator bradykinin. Thus, we hypothesized that FHH rats will have increased aminopeptidase P levels with impaired cerebral arterial responses to bradykinin compared to BN and FHH.1BN rats. We demonstrated higher cerebral arterial expression of aminopeptidase P in FHH compared to BN rats. Accordingly, we demonstrated markedly impaired cerebral arterial dilation to bradykinin in FHH compared to BN rats. Interestingly, aminopeptidase P expression was lower in FHH.1BN compared to FHH rats. Decreased aminopeptidase P levels in FHH.1BN rats were associated with increased cerebral arterial bradykinin-induced dilator responses. Aminopeptidase P inhibition by apstatin improved cerebral arterial bradykinin dilator responses in FHH rats to a level similar to FHH.1BN rats. Unlike bradykinin, cerebral arterial responses to acetylcholine were similar between FHH and FHH.1BN groups. These findings indicate decreased bradykinin bioavailability contributes to impaired cerebral arterial dilation in FHH rats. Overall, these data indicate an important role of aminopeptidase P in the impaired cerebral arterial function in FHH rat.

Bleeding Diathesis in Fawn Hooded Rats-Possible Implications for Invasive Procedures and Refinement Strategies.

Simple SummaryThe Fawn Hooded (FH) rat population is commonly used in biomedical research. It is widely acknowledged that the FH rat has a bleeding disorder, which may lead to abundant bleeding. However, the clinical consequences of this bleeding disorder have not been described in current literature. During our study, surgical procedures on FH rats led to an unanticipated loss of animals due to abundant bleeding. Adjustments made to minimize the impact of this disorder in animals undergoing invasive procedures are described. It is strongly recommended to take the bleeding diathesis into account when performing invasive procedures in FH rats and to apply the described refinements.The Fawn hooded (FH) rat is commonly used in biomedical research. It is widely acknowledged that the FH rat has a bleeding disorder; leading to abundant bleedings. Although this bleeding disorder is investigated to model the storage pool defect; its impact on commonly performed invasive laboratory procedures has not yet been described. Our research group experienced clinically significant consequences of this bleeding disorder following invasive procedures (including intraperitoneal injections and neurocranial surgery) in the Rjlbm: FH stock. The clinical consequences of the surgical and anesthetic protocols applied; are described including the subsequent procedural refinements applied to minimize the impact of this disorder. It is strongly recommended to take the bleeding diathesis into account when performing invasive procedures in FH rats and to apply the suggested refinement of procedures.

The Role of Nitric Oxide System in The Regulation of Renal Function During Prehypertensive and Hypertensive Period in Fawn‐Hooded Rat

Objective: Fawn-Hooded (FH) rat strain represents unique model of hypertension with renal failure. Normotensive FHL rats serve as a control whereas FHH develop early hypertension and exhibit increased susceptibility to renal disease due to impaired autoregulatory efficiency of the kidney. Aim of this study was to examine the influence of nitric oxide (NO) system in FHL and FHH rats in prehypertensive and hypertensive period. Design and method: 3 and 9 months old FHH and FHL rats were anesthetized, NO synthase inhibitor (L-NAME) were infused via jugular vein in dose 50 μg/kg of body weight and mean arterial pressure (MAP), renal blood flow (RBF), glomerular filtration rate (GFR), urine flow (UF) and sodium excretion responses were measured. Results: FHH rats exhibited significantly higher basal MAP compare to FHL in 3 month (123 ± 2,9 vs. 101 ± 2,5 mmHg) and also in 9 month (141 ± 2,1 vs. 102 ± 2,4 mmHg). Young FHH had higher basal RBF than FHL (6,5 ± 0,2 vs. 5,4 ± 0,5 ml/min/g) although older FHH rats had slightly lower RBF compare to FHL (3,7 ± 0,5 vs. 4,9 ± 0,5 ml/min/g) and also GFR (0,47 ± 0,07 vs. 0,66 ± 0,09 ml/min/g). L-NAME administration led to similar responses in both ages in MAP, RBF and GFR but hypertensive FHH had significantly lower increase in UF (from 3,7 ± 0,4 to 13,6 ± 2,5 µl/min/g) compare to FHL (from 4,4 ± 0,8 to 29,7 ± 2,6 µl/min/g) and also in sodium excretion (from 0,19 ± 0,07 to 1,57 ± 0,54 µmol/min/g) than in FHL (from 0,14 ± 0,08 to 3,77 ± 0,57 µmol/min/g). Conclusions: This study indicates that FHH rats with developed hypertension exhibit impaired renal hemodynamics and tubular function that may be caused by relative NO deficiency in the kidney.

The role of 5-HT2B receptors in development of valvulopathy, cardiomyopathy, and pulmonary hypertension in Fawn-Hooded rats

Patients with serotonin interference and carcinoid syndrome producing hyperserotoninaemia are prone to develop cardiac valvulopathies. Elevated serotonin levels have also been linked to pulmonary hypertension (PH) via induction of pulmonary vasoconstriction and proliferation of pulmonary artery smooth muscle cells. Fawn-Hooded rats were used, which genetically exhibit a platelet storage pool disease, hence are unable to store serotonin in platelets. In vivo hemodynamic measurements (Millar catheter) were used to characterize pulmonary artery systolic pressure (PAPs) along with echocardiographic examination. Cardiac fibrosis was evaluated by Masson's trichrome staining. Serotonin receptor expression was measured by qRT-PCR. Proliferation and serotonin receptor expression in response to various stimulations were evaluated in cultured cardiac fibroblasts. Fawn-Hooded rats presented with elevated PAPs starting at three months of age compared to age-matched control Brown Norway rats. Once developed, elevated PAPs did not further deteriorate. PH was reduced by treatment with the 5-HT2B inhibitor terguride, as evidenced by normalised right ventricle-body weight ratio (a marker of right ventricular hypertrophy), PAPs and pulmonary acceleration time (echocardiography). Histology revealed progressive valvulopathy with inappropriate presence of chondrocytes and fibrosis in the aortic and mitral valves in Fawn-Hooded rats. Progressive fibrosis did not limit to the valves, but pervaded left ventricular (LV) myocardial interstitium. These findings were associated with increased transaortic gradient, a marker of aortic stenosis, progressive LV dilation with systolic/diastolic impairment, evaluated by echocardiography. In response to serotonin and fetal calf serum Brown Norway-derived cardiac fibroblasts showed increased proliferation and upregulation of 5-HT2B receptor (RT-PCR), which was reversible with terguride. Fawn-Hooded rats developed both PH and cardiac valvulopathy. Both PH and cardiac valvulopathy were attenuated by treatment with the 5-HT2B antagonist terguride.