Effects of Gundelia tournefortii L. on biochemical parameters, antioxidant activities and DNA damage in a rat model of experimental obesity / Efeitos de Gundelia tournefortii L. em parâmetros bioquímicos, atividades antioxidantes e danos ao DNA em um modelo de obesidade experimental de rato

The present study was designed to investigate the effects of Gundelia tournefortii L. plant extract on different tissues in terms of DNA damage, biochemical and antioxidant parameter values in rats with high-calorie diets. With this aim, Wistar albino male rats were divided into 4 groups containing 6 rats each and the study was completed over 12 weeks duration. At the end of the implementation process over the 12 weeks, rats were sacrificed and blood and tissue samples were obtained. Analyses were performed on blood and tissue samples. According to results for DNA damage (8-OHdG), in brain tissue the OG2 group was significantly reduced compared to the NC group. For MDA results in liver tissue, OG1 and OG2 groups were determined to increase by a significant degree compared to the control group, while the OG2 group was also increased significantly compared to the obese group. In terms of the other parameters, comparison between the groups linked to consumption of a high calorie diet (HCD) and administration of Gundelia tournefortii L. in terms of antioxidant activities and serum samples obtained statistically significant results. Gundelia tournefortii L. plant extracts had effects that may be counted as positive on antioxidant parameter activity and were especially identified to improve DNA damage and MDA levels in brain tissues. Additionally, consumption of Gundelia tournefortii L. plant extract in the diet may have antiobesity effects; thus, it should be evaluated for use as an effective weight-loss method and as a new therapeutic agent targeting obesity.

O presente estudo foi desenhado para investigar os efeitos do extrato da planta Gundelia tournefortii L. em diferentes tecidos em termos de danos ao DNA, valores de parâmetros bioquímicos e antioxidantes em ratos com dietas hipercalóricas. Com esse objetivo, ratos Wistar albinos machos foram divididos em 4 grupos contendo 6 ratos cada e o estudo foi concluído ao longo de 12 semanas de duração. No final desse processo de implementação, os ratos foram sacrificados e amostras de sangue e tecido foram obtidas. As análises foram realizadas em amostras de sangue e tecido. De acordo com os resultados para danos ao DNA (8-OHdG), no tecido cerebral o grupo OG2 foi significativamente reduzido em comparação com o grupo NC. Para os resultados de MDA no tecido hepático, os grupos OG1 e OG2 aumentaram significativamente em comparação ao grupo controle, enquanto o grupo OG2 também aumentou significativamente em comparação ao grupo obeso. Quanto aos demais parâmetros, a comparação entre os grupos ligados ao consumo de dieta hipercalórica (DC) e à administração de Gundelia tournefortii L. em termos de atividades antioxidantes e amostras de soro obteve resultados estatisticamente significativos. Os extratos de plantas de Gundelia tournefortii L. tiveram efeitos que podem ser considerados positivos na atividade dos parâmetros antioxidantes e foram especialmente identificados para melhorar os danos ao DNA e os níveis de MDA nos tecidos cerebrais. Além disso, o consumo de extrato vegetal de Gundelia tournefortii L. na dieta pode ter efeitos antiobesidade; portanto, deve ser avaliado para uso como um método eficaz de perda de peso e como um novo agente terapêutico voltado para a obesidade.

Deep skin wound healing potential of lavender essential oil and licorice extract in a nanoemulsion form: Biochemical, histopathological and gene expression evidences.

Cutaneous wound healing is one of the public health interests. This study aimed to investigate the effects of nanoemulsion cream containing lavender essential oil and licorice extract on the healing of deep skin wound in a rat model. Eighty-five male Wistar rats were randomly divided into five groups including untreated defects as negative control and defects treated with vehicle ointment, lavender essential oil and licorice extract in emulsion and nanoemulsion forms, and phenytoin 1% as the positive control with an excisional wound on the dorsal neck of each rat. On days 2, 7 and 14 oxidative stress factors were evaluated in wound tissue homogenates. The expression of transforming growth factor-ß (TGF-ß), and type I and type III collagen genes were evaluated. Also, wound tissue samples were processed for Hematoxylin & Eosin and Masson-Trichrome staining. Nanoemulsion reduced the wound area more than other groups significantly. Real-time PCR data demonstrated that nanoemulsion and phenytoin groups have shown the best result in increasing TGF-ß1, Type I and type III collagen genes expression compared to the other groups. Reduction in lipid peroxidation level and increasing in SOD and GPx activity was also significant in the nanoemulsion and phenytoin groups. The formation of granular tissue likewise the appearance of collagen in nanoemulsion and phenytoin groups were faster than the other groups. Nanoemulsion cream containing lavender essential oil and licorice extract exhibited a promising wound healing potential towards the excisional wound model in rats.

Efficient derivation of knock-out and knock-in rats using embryos obtained by in vitro fertilization.

Rats are effective model animals and have contributed to the development of human medicine and basic research. However, the application of reproductive engineering techniques to rats is not as advanced compared with mice, and genome editing in rats has not been achieved using embryos obtained by in vitro fertilization (IVF). In this study, we conducted superovulation, IVF, and knock out and knock in using IVF rat embryos. We found that superovulation effectively occurred in the synchronized oestrus cycle and with anti-inhibin antiserum treatment in immature rats, including the Brown Norway rat, which is a very difficult rat strain to superovulate. Next, we collected superovulated oocytes under anaesthesia, and offspring derived from IVF embryos were obtained from all of the rat strains that we examined. When the tyrosinase gene was targeted by electroporation in these embryos, both alleles were disrupted with 100% efficiency. Furthermore, we conducted long DNA fragment knock in using adeno-associated virus and found that the knock-in litter was obtained with high efficiency (33.3-47.4%). Thus, in this study, we developed methods to allow the simple and efficient production of model rats.

Quantitative Analysis of UDP-Glucuronosyltransferase Ugt1a and Ugt2b mRNA Expression in the Rat Liver and Small Intestine: Sex and Strain Differences.

UDP-glucuronosyltransferases (UGTs) catalyze the glucuronidation of numerous endogenous and exogenous compounds to facilitate their excretion from the body. Because rats are commonly used in nonclinical studies, information regarding UGT species differences between rats and humans would be helpful for understanding human pharmacokinetics. In this study, we determined the absolute mRNA expressions of Ugt isoforms in the liver and small intestine of male and female Sprague-Dawley, Fischer 344, and Wistar rats. The sum of the mRNA levels of Ugt isoforms expressed in the liver was significantly (P < 0.005) higher than that in the small intestine regardless of the strain and sex. Ugt2b mRNA levels represented approximately 80% of total Ugt mRNA levels in the liver, whereas Ugt1a mRNA levels accounted for almost 90% in the small intestine. Ugt2b2 mRNA was specifically expressed in Wistar rat liver, resulting in 2-fold higher expression of total hepatic Ugt mRNA in Wistar rats than that in the other strains. Wistar rats showed prominently higher Ugt2b3 and Ugt2b8 mRNA levels in the small intestine than the other strains. The difference between sexes was remarkable with regard to hepatic Ugt1a10 in any of the strains, although slight differences between sexes were also observed in multiple Ugt isoforms. Taken together, this study revealed sex and strain differences in mRNA levels of rat Ugts. The data shown here would be useful for the selection of rat strains in nonclinical studies.

Sexual Dimorphism of NADPH Oxidase/H2O2 System in Rat Thyroid Cells; Effect of Exogenous 17ß-Estradiol.

It has long been observed that females are more susceptible to thyroid diseases than males. Epidemiological and experimental data show that actions of hormonal factors-especially estrogens-may explain such disparity. However, the exact cause and mechanisms of this sexual dimorphism remain so far unknown. Therefore, we aimed at evaluating the effect of 17ß-estradiol on the redox balance in thyroids of male and female rats. Expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, i.e., dual oxidase 1 (DUOX1), dual oxidase 2 (DUOX2) and NADPH oxidase 4 (NOX4), and hydrogen peroxide (H2O2) levels were evaluated in the primary cell cultures derived from thyroid glands of adult male or female Wistar rats. The measurement was made before and after treatment with 17ß-estradiol alone or with addition of one of its receptor antagonists. We found that under basal conditions female thyroid cells are exposed to higher concentrations of H2O2, most likely due to NOX/DUOX enzymes activity. Additionally, exogenous 17ß-estradiol stimulated NOX/DUOX expression as well as H2O2 production, and this effect was mainly mediated through ERα. In conclusion, oxidative processes may constitute mechanisms responsible for sexual dimorphism of thyroid diseases. Exogenous 17ß-estradiol may play a crucial pathogenic role in thyroid diseases via oxidative mechanisms, however without any gender differences.

Identification of Candidate Genes for Generalized Tonic-Clonic Seizures in Noda Epileptic Rat.

The Noda epileptic rat (NER) exhibits generalized tonic-clonic seizures (GTCS). A genetic linkage analysis identified two GTCS-associated loci, Ner1 on Chr 1 and Ner3 on Chr 5. The wild-type Ner1 and Ner3 alleles suppressed GTCS when combined in double-locus congenic lines, but not when present in single-locus congenic lines. Global expression analysis revealed that cholecystokinin B receptor (Cckbr) and suppressor of tumorigenicity 5 (St5), which map within Ner1, and PHD finger protein 24 (Phf24), which maps within Ner3, were significantly downregulated in NER. De novo BAC sequencing detected an insertion of an endogenous retrovirus sequence in intron 2 of the Phf24 gene in the NER genome, and PHF24 protein was almost absent in the NER brain. Phf24 encodes a Gαi-interacting protein involved in GABAB receptor signaling pathway. Based on these findings, we conclude that Cckbr, St5, and Phf24 are strong candidate genes for GTCS in NER.

Methylphenidate and Atomoxetine-Responsive Prefrontal Cortical Genetic Overlaps in "Impulsive" SHR/NCrl and Wistar Rats.

Impulsivity, the predisposition to act prematurely without foresight, is associated with a number of neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). Identifying genetic underpinnings of impulsive behavior may help decipher the complex etiology and neurobiological factors of disorders marked by impulsivity. To identify potential genetic factors of impulsivity, we examined common differentially expressed genes (DEGs) in the prefrontal cortex (PFC) of adolescent SHR/NCrl and Wistar rats, which showed marked decrease in preference for the large but delayed reward, compared with WKY/NCrl rats, in the delay discounting task. Of these DEGs, we examined drug-responsive transcripts whose mRNA levels were altered following treatment (in SHR/NCrl and Wistar rats) with drugs that alleviate impulsivity, namely, the ADHD medications methylphenidate and atomoxetine. Prefrontal cortical genetic overlaps between SHR/NCrl and Wistar rats in comparison with WKY/NCrl included genes associated with transcription (e.g., Btg2, Fos, Nr4a2), synaptic plasticity (e.g., Arc, Homer2), and neuron apoptosis (Grik2, Nmnat1). Treatment with methylphenidate and/or atomoxetine increased choice of the large, delayed reward in SHR/NCrl and Wistar rats and changed, in varying degrees, mRNA levels of Nr4a2, Btg2, and Homer2, genes with previously described roles in neuropsychiatric disorders characterized by impulsivity. While further studies are required, we dissected potential genetic factors that may influence impulsivity by identifying genetic overlaps in the PFC of "impulsive" SHR/NCrl and Wistar rats. Notably, these are also drug-responsive transcripts which may be studied further as biomarkers to predict response to ADHD drugs, and as potential targets for the development of treatments to improve impulsivity.

Differences in Genetic Background Contribute to Pseudomonas Exotoxin A-Induced Hepatotoxicity in Rats.

Pseudomonas aeruginosa exotoxin A (PEA) causes severe hepatotoxicity in experimental animals and is useful in investigations of immune-mediated liver injury. However, strain differences in the sensitivity to PEA-induced hepatotoxicity in rats remains be elucidated. In this study, we determined the severity of PEA-induced hepatotoxicity in six genetically different rat strains. Male LE (Long Evans), Wistar, F344, WKY, BN/SsN and LEW rats were administered a single intravenous injection of PEA (20 µg/kg). Significantly elevated serum ALT and AST levels, massive necrosis and hemorrhage, and numerous TUNEL-positive hepatocytes were observed in BN/SsN rats. In contrast, low levels of ALT and AST as well as mild changes in liver histopathology were observed in Wistar and F344 rats. Moderate levels of hepatic injuries were observed in LE, WKY, and LEW rats. Pro-inflammatory cytokines including TNF-α, IL-2 and IL-6 serum levels were markedly increased in BN/SsN rats compared to Wistar and F344 rats. However, the hepatic levels of low density lipoprotein receptor-related protein (LRP), which functions as the PEA receptor, were not significantly different in each strain. Taken together, we suggest that BN/SsN is the most sensitive rat strain, whereas Wistar and F344 were the most resistant rat strains to PEA-induced liver damage. The different genetic background of rat strains plays an important role in the susceptibility to PEA-induced epatotoxicity that may depend on immune-regulation but not LRP receptor levels.

Comparison of Allogeneic and Syngeneic Rat Glioma Models by Using MRI and Histopathologic Evaluation.

Research in neurooncology traditionally requires appropriate in vivo animal models, on which therapeutic strategies are tested before human trials are designed and proceed. Several reproducible animal experimental models, in which human physiologic conditions can be mimicked, are available for studying glioblastoma multiforme. In an ideal rat model, the tumor is of glial origin, grows in predictable and reproducible patterns, closely resembles human gliomas histopathologically, and is weakly or nonimmunogenic. In the current study, we used MRI and histopathologic evaluation to compare the most widely used allogeneic rat glioma model, C6-Wistar, with the F98-Fischer syngeneic rat glioma model in terms of percentage tumor growth or regression and growth rate. In vivo MRI demonstrated considerable variation in tumor volume and frequency between the 2 rat models despite the same stereotactic implantation technique. Faster and more reproducible glioma growth occurred in the immunoresponsive environment of the F98-Fischer model, because the immune response is minimized toward syngeneic cells. The marked inability of the C6-Wistar allogeneic system to generate a reproducible model and the episodes of spontaneous tumor regression with this system may have been due to the increased humoral and cellular immune responses after tumor implantation.

Behavioral differences of male Wistar rats from different vendors in vulnerability and resilience to chronic mild stress are reflected in epigenetic regulation and expression of p11.

Outbred rat lines such as Wistar rats are commonly used for models of depressive disorders. Such rats arise from random mating schedules. Hence, genetic drift occurs in outbred populations which could lead to genotypic and phenotypic heterogeneity between rats from different vendors. Additionally, vendor specific rearing conditions could contribute to intrastrain variability. In the present study differences in behavioral responses to the chronic mild stress (CMS) model of depression within Wistar rat strains from different vendors are described. DNA methylation studies and mRNA expression analysis of p11 revealed that the behavioral differences between the substrains are reflected at the epigenetic and genetic level. The results suggest that there are breeder-dependent differences in vulnerability to stress in the CMS model of depression, which might bear on the validity of the model and contribute to contradictory findings and difficulties of replication between laboratories. P11 mRNA expression seems to be differently regulated depending on the quality of the stress response evoked by CMS exposure.

Strain differences in cytochrome P450 mRNA and protein expression, and enzymatic activity among Sprague Dawley, Wistar, Brown Norway and Dark Agouti rats.

Rat cytochrome P450 (CYP) exhibits inter-strain differences, but their analysis has been scattered across studies under different conditions. To identify these strain differences in CYP more comprehensively, mRNA expression, protein expression and metabolic activity among Wistar (WI), Sprague Dawley (SD), Dark Agouti (DA) and Brown Norway (BN) rats were compared. The mRNA level and enzymatic activity of CYP1A1 were highest in SD rats. The rank order of Cyp3a2 mRNA expression mirrored its protein expression, i.e., DA>BN>SD>WI, and was similar to the CYP3A2-dependent warfarin metabolic activity, i.e., DA>SD>BN>WI. These results suggest that the strain differences in CYP3A2 enzymatic activity are caused by differences in mRNA expression. Cyp2b1 mRNA levels, which were higher in DA rats, did not correlate with its protein expression or enzymatic activity. This suggests that the strain differences in enzymatic activity are not related to Cyp2b1 mRNA expression. In conclusion, WI rats tended to have the lowest CYP1A1, 2B1 and 3A2 mRNA expression, protein expression and enzymatic activity among the strains. In addition, SD rats had the highest CYP1A1 mRNA expression and activity, while DA rats had higher CYP2B1 and CYP3A2 mRNA and protein expression. These inter-strain differences in CYP could influence pharmacokinetic considerations in preclinical toxicological studies.

Rat Articular Cartilages Change Their Tissue and Protein Compositions During Perinatal Period.

Articular cartilage (AC) covers the surface of bones in joints and functions as a cushion against mechanical loading. The tissue contains abundant extracellular matrix (ECM), which mainly consists of proteoglycans (PG) and collagen (COL) fibres. The property of AC is gradually changing by ageing with gravity loading. To know the property change of AC by initial gravity loading during short period after birth, we performed histological assays and proteomics assay on the AC of the femoral condyle in knee joints of perinatal rats. The water content (%) was significantly decreased in neonate AC compared with fetal AC. During the perinatal stages (E19 and P0), the localizations of glycosaminoglycan (GAG) and type I and II COLs were homogeneous. The density of chondrocytes was significantly decreased in the deeper layers comparing with the surface layer in neonate AC. In addition, we found a drastic change in the protein expression pattern on proteomic analysis. The expressions of ECM components were relatively increased in neonate AC compared with fetal AC.

Slc:Wistar outbred rats show close genetic similarity with F344 inbred rats.

Although Slc:Wistar rats are used widely in biomedical research as outbred rats, close similarities in growth curves, survival rates, and immunological and biochemical phenotypes have been reported between Slc:Wistar and F344 inbred rats. We reported previously that nine genetic variations that were fixed in Slc:Wistar rats had identical genotypes in F344 rats. Here, we examined the genetic characteristics of Slc:Wistar rats using 27 simple-sequence length polymorphism (SSLP) markers and compared them with other Wistar stocks available in Japan and with some F344 strains. Among 27 SSLP loci, 23 (85%) were fixed in the Slc:Wistar rats, which was the highest among the other Wistar stocks. The 23 fixed loci shared identical genotypes with corresponding loci in F344 rats. Further, the predominant allele types in the unfixed loci had allele frequencies as high as 80%, and these alleles were identical in the F344 rats. When the nine genetic variations reported previously are added, a total of 32 (89%) out of the 36 loci examined were fixed and identical in the Slc:Wistar and F344 rat genomes. These findings indicate the low genetic variation in Slc:Wistar rats and the high genetic similarity between the Slc:Wistar and F344 inbred rats. This study demonstrates the importance of characterizing outbred rats and the need to pay ample attention to the genetic characteristics the Slc:Wistar rats for their proper use.

Effects of physical exercise on the P38MAPK/REDD1/14-3-3 pathways in the myocardium of diet-induced obesity rats.

Obesity is associated with myocardial insulin resistance and impairment of the mammalian target of rapamycin (mTOR) signaling pathway. The activation of the mTOR cascade by exercise has been largely shown in skeletal muscle, but insufficiently analyzed in myocardial tissue. In addition, little is known regarding the mTOR upstream molecules in the hearts of obese animals and even less about the role of exercise in this process. Thus, the present study was aimed to evaluate the effects of physical exercise on P38 Mitogen-Activated Protein Kinase (P38MAPK) phosphorylation and the REDD1 (regulated in development and DNA damage responses 1) and 14-3-3 protein levels in the myocardium of diet-induced obesity (DIO) rats. After achievement of DIO and insulin resistance, Wistar rats were divided in 2 groups: sedentary obese rats and obese rats performed treadmill running (50-min/day, 5 days per week velocity of 1.0 km/h for 2 months). Forty-eight hours after the final physical exercise, the rats were killed, and the myocardial tissue was removed for Western blot analysis. DIO increased the REDD1 protein levels and reduced the 14-3-3 protein levels and P38MAPK, mTOR, P70S6k (p70 ribosomal S6 protein kinase), and 4EBP1 (4E-binding protein-1) phosphorylation. Interestingly, physical exercise reduced the REDD1 protein levels and increased the 14-3-3 protein levels and P38MAPK, mTOR, P70S6k, and 4EBP1 phosphorylation. Moreover, exercise increased the REDD1/14-3-3 association in the heart. Our results indicate that the phospho-P38MAPK, REDD1, and 14-3-3 protein levels were reduced in the myocardium of obese rats and that physical exercise increased the protein levels of these molecules.

Differences in hematologic variables in rats of the same strain but different origin.

BACKGROUND: Wistar rats are frequently used in toxicologic studies; however, the impact of animal source on hematologic reference intervals (RI) is not known. OBJECTIVE: The purpose of this study was to compare hematologic data of Wistar rats obtained from 2 breeders and to calculate preliminary RI for the Sysmex XT-2000iV hematology analyzer. METHODS: Blood collected in EDTA from 75 10-13-week-old rats (male, n = 38; female, n = 37) from breeder 1 and 60 rats (male, n = 30; female, n = 30) from breeder 2 was analyzed using a Sysmex XT-2000iV hematology analyzer. Results were analyzed for differences using a t-test or Mann-Whitney U-test. Sex-specific 95% RI were calculated for rats from both breeders. RESULTS: Significant breeder-specific differences were found for WBC, RBC, platelet, lymphocyte, monocyte, eosinophil, and reticulocyte counts and MCV, MCH, MPV, and plateletcrit for both sexes, and for HCT and hemoglobin concentration for female rats. The greatest differences (P < .0001) between rats from breeders 1 and 2, respectively, were found for WBC (female: 2.2-5.9 × 10(9) /L vs 4.2-9.4 × 10(9) /L 38; male: 3.4-9.5 vs 6.4-14.4 × 10(9) /L), lymphocyte (female: 1.7-4.8 × 10(9) /L vs 3.4-8.2 × 10(9) /L; male: 2.6-7.8 vs 5.2-12.4 × 10(9) /L), and platelet (female: 591-836 × 10(9) /L vs 804-1282 × 10(9) /L; male: 573-998 × 10(9) /L vs 861-1247 × 10(9) /L) counts. CONCLUSION: Differences in hematologic RI between Wistar rats obtained from different breeders underscore the need to evaluate untreated control animals for comparison, rather than using historical RI, to detect compound-related effects in preclinical safety studies. Valid RI for control animals are needed and should be verified when using a new supplier to avoid misinterpretation of data. Low reference limits for some variables, such as WBC counts, in rats from one source may preclude their use in studies in which detection of leukopenia is required.

SHRSP/Izm and WKY/NCrlCrlj rats having a missense mutation in Abcg5 deposited plant sterols in the body, but did not change their biliary secretion and lymphatic absorption-comparison with Jcl:Wistar and WKY/Izm rats.

We had previously found plant sterols deposited in the bodies of stroke-prone spontaneously hypertensive rats (SHRSP)/Sea and Wistar Kyoto (WKY)/NCrlCrlj rats that had a missense mutation in the Abcg5 cDNA sequence that coded for ATP-binding cassette transporter (ABC) G5. We used SHRSP/Izm, WKY/NCrlCrlj, and WKY/Izm rats in the present study to determine the mechanisms for plant sterol deposition in the body. Jcl:Wistar rats were used as a control strain. A diet containing 0.5% plant sterols fed to the rats resulted in plant sterol deposition in the body of SHRSP/Izm, but not in WKY/Izm or Jcl:Wistar rats. Only a single non-synonymous nucleotide change, G1747T, resulting in a conservative cysteine substitution for glycine at amino acid 583 (Gly583Cys) in Abcg5 cDNA was identified in the SHRSP/Izm and WKY/NCrlCrlj rats. However, this mutation was not found in the WKY/Izm or Jcl:Wistar rats. No significant difference in the biliary secretion or lymphatic absorption of plant sterols was apparent between the rat strains with or without the missense mutation in Abcg5 cDNA. Our observations suggest that plant sterol deposition in rat strains with the missense mutation in Abcg5 cDNA can occur, despite there being no significant change in the biliary secretion or lymphatic absorption of plant sterols.

Behavioral effects of bidirectional selection for behavior towards human in virgin and lactate Norway rats.

Although numerous studies have demonstrated strong differences in behavioral, hormonal and neurobiological characteristics between male rats selected for elimination (tame) and enhancement (aggressive) of aggressiveness towards humans, few studies have examined changes in female behavior under this selection. The objective of the current work was to evaluate the effects of bidirectional selection for aggressiveness towards humans on behavioral profiles of virgin and lactating rats compared with the behavior in tame, aggressive and unselected (wild-type) females. The behavior of virgin females was studied using the light-dark box, the startle response test and the modified glove test. Tame females were less anxious and more tolerant towards humans than unselected and aggressive rats. Principal component analysis of all behavioral parameters produced three independent factors, explaining 66.37% of the total variability. The measures of behavior towards humans and the measures of anxiety mainly loaded on PC1 (first principal component) which separated the tame females from the unselected and aggressive ones. These data suggest the genetic correlation between the selected behavior towards humans and anxiety-related behavior in virgin rats. No significant effect of line was found for PC2 scores, associated with risk assessment behavior. Measurements of freezing behavior mainly loaded on PC3, and this component separated rats of different genetic groups from each other. The behavior of lactating rats was studied in maternal defense and pup retrieval tests. Females of selected lines did not significantly differ in behavioral measurements of these tests and were characterized by higher maternal motivation than unselected rats. It is suggested that long-term breeding of tame and aggressive rats in captivity has reduced the threshold for maternal behavior.

Identification of genetic modifiers of behavioral phenotypes in serotonin transporter knockout rats.

BACKGROUND: Genetic variation in the regulatory region of the human serotonin transporter gene (SLC6A4) has been shown to affect brain functionality and personality. However, large heterogeneity in its biological effects is observed, which is at least partially due to genetic modifiers. To gain insight into serotonin transporter (SERT)-specific genetic modifiers, we studied an intercross between the Wistar SERT-/- rat and the behaviorally and genetically divergent Brown Norway rat, and performed a QTL analysis. RESULTS: In a cohort of >150 intercross SERT-/- and control (SERT+/+) rats we characterized 12 traits that were previously associated with SERT deficiency, including activity, exploratory pattern, cocaine-induced locomotor activity, and abdominal and subcutaneous fat. Using 325 genetic markers, 10 SERT-/--specific quantitative trait loci (QTLs) for parameters related to activity and exploratory pattern (Chr.1,9,11,14), and cocaine-induced anxiety and locomotor activity (Chr.5,8) were identified. No significant QTLs were found for fat parameters. Using in silico approaches we explored potential causal genes within modifier QTL regions and found interesting candidates, amongst others, the 5-HT1D receptor (Chr. 5), dopamine D2 receptor (Chr. 8), cannabinoid receptor 2 (Chr. 5), and genes involved in fetal development and plasticity (across chromosomes). CONCLUSIONS: We anticipate that the SERT-/--specific QTLs may lead to the identification of new modulators of serotonergic signaling, which may be targets for pharmacogenetic and therapeutic approaches.

Activation of ERK and JNK MAP kinases in optic nerves of rats exposed to global cerebral ischemia.

OBJECTIVES: To determine the influence of global cerebral ischemia on the activation of extracellular-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK) in optic nerves of rats exposed to different reperfusion periods. MATERIALS AND METHODS: Transient global cerebral ischemia (20-min duration) was induced by the four-vessel occlusion method. After different reperfusion periods (5 and 10 min; 1; 6 and 12 h after ischemia), optic nerves were extracted and ERK and JNK activation signals were determined by Western immunoblot analyses. RESULTS: The activation signals of ERK and JNK were detected within first 10 min of reperfusion, but striking activation for both enzymes was found 1 h after ischemia. After a transient decrease, the activation of ERK returned to peak level after 12 h of reperfusion in the second wave of kinase activation. In that period, a slight increase of JNK activation was registered. CONCLUSION: Our results demonstrated for the first time that ERK and JNK were activated in rat optic nerves during early and later periods of reperfusion, suggesting their potential active role in the response of cerebral white matter tissue to ischemic injury.

Transcriptional responses to reinforcing effects of cocaine in the rat hippocampus and cortex.

The psychostimulant effects of cocaine are thought to result from its ability to block dopamine (DA) uptake and increase DA levels in ventral striatum. In addition, cocaine causes biochemical changes in the brain areas involved in learning and memory, including hippocampus and cortex, whose role in drug reinforcement is now being actively investigated. Thus, we studied molecular events in the hippocampus and frontal cortex of rats treated with cocaine conditioned place preference (CPP) paradigm. After exposure to cocaine conditioning (cocaine paired), cocaine alone (cocaine non-paired) or saline rats were tested for place conditioning. Cocaine (10 mg/kg) caused increases in time spent in the drug-paired compartment. By using microarray analyses, we examined gene expression in the hippocampi and frontal cortices of cocaine-paired rats, cocaine non-paired and saline-treated controls. Our study revealed that 214 transcripts were differentially regulated in the hippocampi of cocaine-paired rats. These include genes that play roles in protein phosphorylation, RNA processing and protein synthesis, ubiquitin-dependent protein degradation and cytoskeleton organization. In contrast, 39 genes were differently expressed in the frontal cortex. Our data support the possibility that molecular changes in the hippocampus might participate in the formation and maintenance of memory patterns induced by cocaine in the brain. Differences in the transcriptional responses in the hippocampus and cortex suggest the primary importance of the hippocampus for recent memory processing associated with cocaine-induced CPP.