Differential expression of 10 genes in the hypothalamus of two generations of rats selected for a reaction to humans

Individual behavioral differences are due to an interaction of the genotype and the environment. Phenotypic manifestation of aggressive behavior depends on the coordinated expression of gene ensembles. Nonetheless, the identification of these genes and of combinations of their mutual influence on expression remains a difficult task. Using animal models of aggressive behavior (gray rats that were selected for a reaction to humans; tame and aggressive rat strains), we evaluated the expression of 10 genes potentially associated with aggressiveness according to the literature: Cacna1b, Cacna2d3, Drd2, Egr1, Gad2, Gria2, Mapk1, Nos1, Pomc, and Syn1. To identify the genes most important for the manifestation of aggressiveness, we analyzed the expression of these genes in two generations of rats: 88th and 90th. Assessment of gene expression levels was carried out by real-time PCR in the hypothalamus of tame and aggressive rats. This analysis confirmed that 4 out of the 10 genes differ in expression levels between aggressive rats and tame rats in both generations. Specifically, it was shown that the expression of the Cacna1b, Drd2, Egr1, and Gad2 genes does not differ between the two generations (88th vs 90th) within each strain, but significantly differs between the strains: in the tame rats of both generations, the expression levels of these genes are significantly lower as compared to those in the aggressive rats. Therefore, these genes hold promise for further studies on behavioral characteristics. Thus, we confirmed polygenic causes of phenotypic manifestation of aggressive reactions

Destabilization signs in behavioral and somatovegetative parameters of rats selected for catatonia

The article presents data on destabilization signs in response to selection for catatonia at an organismal level. Experiments were conducted with the unique GC (genetic catatonia) rat strain selected for long passive-defensive freezing. The goal of this study was to detect destabilization signs in the behavioral and somatovegetative parameters of GC rats emerging in response to selection. The destabilization manifested itself as changes in rat attitudes towards humans, as became apparent from the glove test. Altered hormone levels in GC rats were detected: corticosterone concentrations were reduced in feces and increased during handling. The metabolic system showed a decrease in energy stored accompanying the fast (glucose level) and slow (triglyceride level) responses. However, the strains did not differ in the concentration of insulin, which affects glucose transport through the cell membrane. Nor did we find differences between Wistar and GC rats in cholesterol level. This lipid is important for both energy and constructive metabolism. A side effect of selection for catatonia was the worse pelage status in GC rats. The overall physical condition of catatonic rats involved reduced body weight in both neonates and adults. All these changes point to the modification of behavioral and somatovegetative patterns and intensification of the passive-defensive component of selection in GC rats

Proton magnetic resonance spectroscopy of neurometabo­lites in the hippocampi of aggressive and tame male rats

Proportions of major neurometabolites with regard to their total amount in the dorsal region of the hippocampus were studied in adult male rats of populations selected for long for increase and absence of aggressivefearful response to humans and in unselected vivarium- kept rats by 1H magnetic resonance spectrometry. Tame and unselected males showed no significant differences in the proportions of any neurometabolites studied. Differences in the proportions of some neurometabolites were found in aggressive vs. tame and in aggressive vs. unselected animals. Tame animals showed higher pro­portions of GABA, N-acetylaspartate (NAA), and choline derivatives and a lower proportion of phosphoryl­ethanolamine than aggressive ones. It is likely that the elevated content of GABA, one of the main inhibitory neurotransmitters in the brain, lowers excita­tion intensity in tame pups in comparison to aggressive ones. In comparison to unselected animals, aggressive rats demonstrated higher proportions of glutamine, aspartate, phosphorylethanolamine, and lactate and lower proportions of NAA and creatinine+ phosphocreatinine. Aspartate is one of the main excitement transmitter, and its elevated proportion in the brain of aggressive rats may favor more intense excitation than in unselected rats. In contrast, the elevated proportion of glutamine in aggressive rats vs. tame rats may be indicative of (1) a metabolic disturbance in the glutamate–glutamine cycle, which links neural and glial cells, and (2) decrease in the activity of glutaminase, the enzyme converting glutamine to glutamate (GABA precursor). The reduced NAA proportion together with the elevated proportion of glutamine in aggressive rats point to impaired energy metabolism in comparison to unselected animals. The differences in neurometabolite patterns between hippocampi of male rats of the unselec­ted and aggressive populations suggest the existence of different neurobiological mechanisms governing aggression manifestation

Effects of neonatal handling on behavior and stress-response in rats selected for reaction towards humans

It is known that neonatal handling may cause longterm changes in neurobiological and behavioral phenotypes. Neonatal handling of rats selected for enhanced aggressiveness towards humans (“aggressive” rats of generation 44) significantly mitigated aggression and stress responsiveness. However, levels of corticosterone in stress in intact aggressive rats of later generations (70s) were lower than in generation 44, which differed little from the corresponding value in “tame” rats, selected in the opposite direction, for the absence of aggressiveness towards humans. The study was conducted with Norway rat populations of the 75th generation of selection for aggressive and tame behavior, respectively. The goal was to find out whether the decrease in stress response in aggressive rats at the current stage of selection was accompanied by a decrease in the influence of handling on aggressiveness. It was found that neonatal handling of aggressive animals caused a significant decrease in aggressiveness, although considerably smaller than in generation 44. In both aggressive and tame rats, the blood corticosterone level at stress was getting back to the basal level for a longer time than in the corresponding control groups. Neonatal handling decreased the amount of mRNA for the glucocorticoid receptor (GR) in the hippocampus of aggressive rats but did not affect significantly the amount of mRNA for the corticotropin-releasing hormone (CRH) in the hypothalamus. However, higher contents of CRH mRNA were recorded in aggressive rats than in tame ones in the control groups. However, no differences in glucocorticoid receptor mRNA  were found between the strains in contrast to earlier generations. It was shown that neonatal handling was beneficial for maternal behavior in tame rats. Thus, the results obtained in the 75th generation of selection indicate that the effect of handling on aggressiveness weakens with decreasing stress responsiveness in aggressive rats. This is likely to be related to the changing amount of GR in the hippocampus and stronger glucocorticoidmediated feedback at the current stage of selection. The minor prolongation of the stress response appears to be related to the stressing component of neonatal handling rather than to changes in maternal care

The microRNA-29 family in cartilage homeostasis and osteoarthritis

MicroRNAs have been shown to function in cartilage development and homeostasis, as well as in progression of osteoarthritis. The objective of the current study was to identify microRNAs involved in the onset or early progression of osteoarthritis and characterise their function in chondrocytes. MicroRNA expression in mouse knee joints post-DMM surgery was measured over 7 days. Expression of miR-29b-3p was increased at day 1 and regulated in the opposite direction to its potential targets. In a mouse model of cartilage injury and in end-stage human OA cartilage, the miR-29 family were also regulated. SOX9 repressed expression of miR-29a-3p and miR-29b-3p via the 29a/b1 promoter. TGFβ1 decreased expression of miR-29a, b and c (3p) in primary chondrocytes, whilst IL-1β increased (but LPS decreased) their expression. The miR-29 family negatively regulated Smad, NFκB and canonical WNT signalling pathways. Expression profiles revealed regulation of new WNT-related genes. Amongst these, FZD3, FZD5, DVL3, FRAT2, CK2A2 were validated as direct targets of the miR-29 family. These data identify the miR-29 family as microRNAs acting across development and progression of OA. They are regulated by factors which are important in OA and impact on relevant signalling pathways

Relating the Chondrocyte Gene Network to Growth Plate Morphology: From Genes to Phenotype

During endochondral ossification, chondrocyte growth and differentiation is controlled by many local signalling pathways. Due to crosstalks and feedback mechanisms, these interwoven pathways display a network like structure. In this study, a large-scale literature based logical model of the growth plate network was developed. The network is able to capture the different states (resting, proliferating and hypertrophic) that chondrocytes go through as they progress within the growth plate. In a first corroboration step, the effect of mutations in various signalling pathways of the growth plate network was investigated

Enhancement of COPD biological networks using a web-based collaboration interface

The construction and application of biological network models is an approach that offers a holistic way to understand biological processes involved in disease. Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory disease of the airways for which therapeutic options currently are limited after diagnosis, even in its earliest stage. COPD network models are important tools to better understand the biological components and processes underlying initial disease development. With the increasing amounts of literature that are now available, crowdsourcing approaches offer new forms of collaboration for researchers to review biological findings, which can be applied to the construction and verification of complex biological networks. We report the construction of 50 biological network models relevant to lung biology and early COPD using an integrative systems biology and collaborative crowd-verification approach. By combining traditional literature curation with a data-driven approach that predicts molecular activities from transcriptomics data, we constructed an initial COPD network model set based on a previously published non-diseased lung-relevant model set. The crowd was given the opportunity to enhance and refine the networks on a website ( https://bionet.sbvimprover.com/) and to add mechanistic detail, as well as critically review existing evidence and evidence added by other users, so as to enhance the accuracy of the biological representation of the processes captured in the networks. Finally, scientists and experts in the field discussed and refined the networks during an in-person jamboree meeting. Here, we describe examples of the changes made to three of these networks: Neutrophil Signaling, Macrophage Signaling, and Th1-Th2 Signaling. We describe an innovative approach to biological network construction that combines literature and data mining and a crowdsourcing approach to generate a comprehensive set of COPD-relevant models that can be used to help understand the mechanisms related to lung pathobiology. Registered users of the website can freely browse and download the networks