Sardinian alcohol-preferring (sP) and Sardinian alcohol-non preferring (sNP) rats have been selectively bred for opposite alcohol preference and consumption. Aiming to verify possible differences at ...the proteomics level between sP and sNP rats, we investigated the salivary proteome by a a liquid chromatography–mass spectrometry top-down–bottom-up integrated approach. For this purpose, submandibular saliva was collected from alcohol-naive sP and sNP rats under isoprenaline stimulation. A total of 200 peptides and proteins were detected and quantified in the two rat lines, 149 of which were characterized in their naturally occurring structure. The data are available via ProteomeXchange with identifier PXD006997. Surprisingly, sP rats exhibited marked quantitative and qualitative differences with respect to sNP rats, namely higher levels of proteoforms originating from submandibular gland protein C, and from submandibular rat protein 2, as well as those of several unidentified peptides and proteins. sP rats expressed some proteins not detectable in sNP rats such as the glutamine and glutamic acid-rich protein (GRP)-CB. The isoform GRP-B, detectable in both rat lines, was more abundant in sNP rats. The submandibular saliva of sNP rats was also characterized by very high levels of GRP-B proteolytic peptides and rat salivary protein 1. Whether these differences could contribute to the opposite alcohol preference and consumption of sP and sNP rats is currently unknown and requires further investigation.
Immune system activation is a common feature of hypertension pathogenesis. However, the mechanisms that initiate this activation are not well understood. Innate immune system recognition and response ...to danger are becoming apparent in many cardiovascular diseases. Danger signals can arise from not only pathogens, but also damage-associated molecular patterns (DAMPs). Our first hypothesis was that the DAMP, mitochondrial DNA (mtDNA), which is recognized by Toll-like receptor 9 (TLR9), is elevated in the circulation of spontaneously hypertensive rats (SHR), and that the deoxyribonuclease enzymes responsible for its degradation have decreased activity in SHR. Based on these novel SHR phenotypes, we further hypothesized that (i) treatment of SHR with an inhibitory oligodinucleotide for TLR9 (ODN2088) would lower blood pressure and that (ii) treatment of normotensive rats with a TLR9-specific CpG oligonucleotide (ODN2395) would cause endothelial dysfunction and increase blood pressure.
We observed that SHR have elevated circulating mtDNA and diminished deoxyribonuclease I and II activity. Additionally, treatment of SHR with ODN2088 lowered systolic blood pressure. On the other hand, treatment of normotensive rats with ODN2395 increased systolic blood pressure and rendered their arteries less sensitive to acetylcholine-induced relaxation and more sensitive to norepinephrine-induced contraction. This dysfunctional vasoreactivity was due to increased cyclooxygenase and p38 mitogen-activated protein kinase activation, increased reactive oxygen species generation, and reduced nitric oxide bioavailability.
Circulating mtDNA and impaired deoxyribonuclease activity may lead to the activation of the innate immune system, via TLR9, and contribute to elevated arterial pressure and vascular dysfunction in SHR.
Modulation of metabotropic glutamate 2 (mGlu2) receptor function has huge potential for treating psychiatric and neurological diseases. Development of drugs acting on mGlu2 receptors depends on the ...development and use of translatable animal models of disease. We report here a stop codon mutation at cysteine 407 in Grm2 (cys407*) that is common in some Wistar rats. Therefore, researchers in this field need to be aware of strains with this mutation. Our genotypic survey found widespread prevalence of the mutation in commercial Wistar strains, particularly those known as Han Wistar. Such Han Wistar rats are ideal for research into the separate roles of mGlu2 and mGlu3 receptors in CNS function. Previous investigations, unknowingly using such mGlu2 receptor-lacking rats, provide insights into the role of mGlu2 receptors in behaviour. The Grm2 mutant rats, which dominate some selectively bred lines, display characteristics of altered emotionality, impulsivity and risk-related behaviours and increased voluntary alcohol intake compared with their mGlu2 receptor-competent counterparts. In addition, the data further emphasize the potential therapeutic role of mGlu2 receptors in psychiatric and neurological disease, and indicate novel methods of studying the role of mGlu2 and mGlu3 receptors.
This article is part of the Special Issue entitled ‘Metabotropic Glutamate Receptors, 5 years on’.
•Discovery of cys407* mutation in Grm2 of Wistar rats.•High prevalence in Han Wistar sub-strains.•Grm2 mutation linked with alcohol-preferring rats.•Grm2 mutation linked with changes in risk taking and emotional behaviour.
Selective breeding of laboratory rats resulted in changes of their behavior. Concomitantly, the albino strains developed vision related pathologies. These alterations certainly occurred on the ...background of modifications in brain morphology. The aim of the study was to assess and compare volumes of major structures in brains of wild-captive, laboratory albino and laboratory pigmented rats. High resolution T2-weighted images of brains of adult male Warsaw Wild Captive Pisula-Stryjek rats (WWCPS, a model of wild type), laboratory pigmented (Brown Norway strain, BN) and albino rats (Wistar strain, WI) were obtained with a 7T small animal-dedicated magnetic resonance tomograph. Volume quantification of whole brains and 50 brain structures within each brain were performed with the digital Schwarz rat brain atlas and a custom-made MATLAB/SPM8 scripts. Brain volumes were scaled to body mass, whereas volumes of brain structures were normalized to individual brain volumes. Normalized brain volume was similar in WWCPS and BN, but lower in WI. Normalized neocortex volume was smaller in both laboratory strains than in WWCPS and the visual cortex was smaller in albino WI rats than in WWCPS and BN. Relative volumes of phylogenetically older structures, such as hippocampus, amygdala, nucleus accumbens and olfactory nuclei, also displayed certain strain-related differences. The present data shows that selective breeding of laboratory rats markedly affected brain morphology, the neocortex being most significantly altered. In particular, albino rats display reduced volume of the visual cortex, possibly related to retinal degeneration and the development of blindness.
Salt-sensitive hypertension is a major risk factor for cardiovascular disorders. Our previous proteomic study revealed substantial differences in several proteins between Dahl salt-sensitive (SS) ...rats and salt-insensitive consomic SS.13(BN) rats. Subsequent experiments indicated a role of fumarase insufficiency in the development of hypertension in SS rats. In the present study, a global metabolic profiling study was performed using gas chromatography/mass spectrometry (GC/MS) in plasma of SS rats (n=9) and SS.13(BN) rats (n=8) on 0.4% NaCl diet, designed to gain further insights into the relationship between alterations in cellular intermediary metabolism and predisposition to hypertension. Principal component analysis of the data sets revealed a clear clustering and separation of metabolic profiles between SS rats and SS.13(BN) rats. 23 differential metabolites were identified (P<0.05). Higher levels of five TCA cycle metabolites, fumarate, cis-aconitate, isocitrate, citrate and succinate, were observed in SS rats. Pyruvate, which connects TCA cycle and glycolysis, was also increased in SS rats. Moreover, lower activity levels of fumarase, aconitase, α-ketoglutarate dehydrogenase and succinyl-CoA synthetase were detected in the heart, liver or skeletal muscles of SS rats. The distinct metabolic features in SS and SS.13(BN) rats indicate abnormalities of TCA cycle in SS rats, which may play a role in predisposing SS rats to developing salt-sensitive hypertension.
After acute myocardial infarction, early reperfusion is the most effective strategy for reducing cardiac damage and improving clinical outcome. However, restoring blood flow to the ischemic ...myocardium can paradoxically induce injury by itself (reperfusion injury), with microvascular dysfunction being one contributing factor. α
adrenergic receptors have been hypothesized to be involved in this process. To assess α
-related pharmacology, we identified a novel α
antagonist by HTS. The HTS hit showed limited α
selectivity as well as low solubility and was optimized toward BAY-6096, a potent, selective, and highly water-soluble α
antagonist. Key aspects of the optimization were the introduction of a permanently charged pyridinium moiety to achieve very good aqueous solubility and the inversion of an amide to prevent genotoxicity. BAY-6096 dose-dependently reduced blood pressure increases in rats induced by an α
agonist, demonstrating the role of α
receptors in vascular constriction in rats.
Endothelial nitric oxide synthase (eNOS) is critical in the regulation of vascular function, and can generate both nitric oxide (NO) and superoxide (O2*−), which are key mediators of cellular ...signalling. In the presence of Ca2+/calmodulin, eNOS produces NO, endothelial-derived relaxing factor, from l-arginine (l-Arg) by means of electron transfer from NADPH through a flavin containing reductase domain to oxygen bound at the haem of an oxygenase domain, which also contains binding sites for tetrahydrobiopterin (BH4) and l-Arg. In the absence of BH4, NO synthesis is abrogated and instead O2*− is generated. While NOS dysfunction occurs in diseases with redox stress, BH4 repletion only partly restores NOS activity and NOS-dependent vasodilation. This suggests that there is an as yet unidentified redox-regulated mechanism controlling NOS function. Protein thiols can undergo S-glutathionylation, a reversible protein modification involved in cellular signalling and adaptation. Under oxidative stress, S-glutathionylation occurs through thiol-disulphide exchange with oxidized glutathione or reaction of oxidant-induced protein thiyl radicals with reduced glutathione. Cysteine residues are critical for the maintenance of eNOS function; we therefore speculated that oxidative stress could alter eNOS activity through S-glutathionylation. Here we show that S-glutathionylation of eNOS reversibly decreases NOS activity with an increase in O2*− generation primarily from the reductase, in which two highly conserved cysteine residues are identified as sites of S-glutathionylation and found to be critical for redox-regulation of eNOS function. We show that eNOS S-glutathionylation in endothelial cells, with loss of NO and gain of O2*− generation, is associated with impaired endothelium-dependent vasodilation. In hypertensive vessels, eNOS S-glutathionylation is increased with impaired endothelium-dependent vasodilation that is restored by thiol-specific reducing agents, which reverse this S-glutathionylation. Thus, S-glutathionylation of eNOS is a pivotal switch providing redox regulation of cellular signalling, endothelial function and vascular tone.
Social buffering is a phenomenon in which stress in an animal is ameliorated when the subject is accompanied by a conspecific animal(s) during exposure to distressing stimuli. We previously reported ...that in male Wistar rats, the presence of another Wistar rat mitigates conditioned fear responses to an auditory conditioned stimulus (CS). Subsequent analyses revealed several characteristics of this social buffering of conditioned fear responses. However, information regarding the specificity of accompanying conspecifics is still limited. In the present study, we assessed whether rats of other strains could induce social buffering in Wistar rats. When a fear-conditioned Wistar subject was re-exposed to the CS alone, we observed increased freezing and decreased investigation and walking, as well as elevated corticosterone levels. The presence of a Wistar, Sprague–Dawley, or Long–Evans rat blocked these responses, suggesting that social buffering was induced by these strains of rats. In contrast, a Fischer 344 rat did not induce social buffering in the Wistar subject. We further found that an inbred Lewis rat induced social buffering whereas a Brown Norway rat, a strain that has been established independently from Wistar rats, did not. These results suggest that the difference in origin, rather than the inbred or outbred status of the associate rat, seemed to account for the lack of social buffering induced by the F344 rats. Based on these findings, we conclude that strains of an accompanying conspecific can affect the efficacy of social buffering in rats.
•Wistar, Sprague–Dawley, and Long–Evans rats induced social buffering in Wistar rats.•Lewis rat induced social buffering in Wistar rats.•Fischer 344 or Brown Norway rats did not induce social buffering in Wistar rats.•The strain of an accompanying conspecific affects the efficacy of social buffering.
Background:
Risk‐taking, measured with laboratory tasks such as the Balloon Analog Risk Task (BART), is associated with real‐life manifestations of risky behaviors, which may be an important ...component of inherited liability to alcohol use disorders. To identify genomic factors that influence these traits, the current study (i) characterized performance of a rodent version of the BART in multiple inbred rat strains, (ii) tested the degree to which performance was under genetic control, (iii) explored sex differences in performance, and (iv) evaluated the risk‐taking behavior of F1 progeny of high‐risk‐ and low‐risk‐taking strains to examine modes of inheritance.
Methods:
Male and female rats (N = 100) from 5 inbred strains (Wistar‐Furth, Fischer‐344, Lewis, Spontaneously Hypertensive, Brown Norway) and Wistar‐Furth × Fischer‐344 hybrids were tested in the rat‐BART, as well as in tests of locomotor activity, sucrose preference, and general motivation.
Results:
About 55% of the variance in risk‐taking behavior was attributable to heritable factors. The Fischer‐344 strain was the most risk‐taking and the most variable in responding. The mating of low‐risk‐taking Wistar‐Furth and Fischer‐344 rats produced progeny that behaved most like the Fischer‐344 strain. Consistent with prior research in this laboratory (Jentsch et al., 2010), all rats were sensitive to changes in both risk and reinforcement parameters in the rat‐BART; rats decreased voluntary risk‐taking in the face of increasing risk and increased lever pressing when reinforcement probabilities were reduced.
Conclusions:
Our results endorse a moderately heritable pattern of risk‐taking behavior in rats. The behavior of the hybrid progeny suggests a polygenic model with most gene effects transmitted by mode of dominant inheritance. The identification of high‐risk and low‐risk strains allows for isolation of quantitative trait loci associated with task performance and for probing the relationships between risk‐taking and dimensions of alcohol use disorders.
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