Attractin Gene Deficiency in Rats Leads to Impairments in Both Activity and Spatial Learning and Memory

Pyridoxine supplementation before puberty ameliorates MAM-induced cognitive and sensorimotor gating impairments

Schizophrenia is a kind of neurodevelopmental mental disorder in which patients begin to experience changes early in their development, typically manifesting around or after puberty and has a fluctuating course. Environmental disturbances during adolescence may be a risk factor for schizophrenia-like deficits. As a better treatment option, preventive intervention prior to schizophrenia may be more beneficial than direct treatment. More effective stress-relieving interventions during the critical puberty period may prevent schizophrenia-like neuronal changes and the transition to schizophrenia in adulthood. Pyridoxine deficiency alters the function of NMDA (n-methyl-D-aspartic acid) receptors and plays a key role in learning and memory. In this study, we prepared a progeny model of schizophrenia by exposing pregnant rats to methoxymethanol acetate (MAM) on gestational day 17. The offspring rats were injected intraperitoneally with pyridoxine daily from birth to prepuberty PND12-PND21), and behavioral changes in the offspring rats were observed in adulthood. Cannabinoid receptor interacting protein 1 (CNRIP1) and cannabinoid receptor-1 (CB1R), which regulate memory, cognitive and motor activity, were detected in the prefrontal cortex (PFC) and hippocampus of the offspring rats, and the cell proliferation in the hippocampal dentate gyrus (DG) was also observed. The results showed that the MAM rats spent less time the open arm in the elevated plus maze test, decreased discrimination coefficient in novel object recognition test, and decreased prepulse inhibition, while the MAM rats supplemented with pyridoxine in prepuberty did not show any of the above abnormal behavioral changes in adulthood. By examining related proteins in the PFC and hippocampus, we found that only CB1R protein expression was downregulated in the PFC, whereas CNRIP1 expression was not only elevated in the hippocampus, but also significantly increased in pyridoxine- supplemented MAM rats. Meanwhile, pyridoxine supplementation alleviated the reduction of doublecortin (DCX)-positive cells and Ki67-positive cells in MAM rats. These results indicate that prepuberty pyridoxine supplementation has a positive effect on the prevention of cognitive deficits and sensorimotor gating impairment in MAM-induced schizophrenia-like rats, accompanied by changes in the CB1R and CNRIP1 expression in PFC and hippocampus, as well as the regeneration of neurons in the DG region.

The proteomic signature of circulating extracellular vesicles following intracerebral hemorrhage: Novel insights into mechanisms underlying recovery

Circulating extracellular vesicles (EVs) can participate in innate repair processes triggered after intracerebral hemorrhage (ICH). We aimed to describe changes in the proteomic profile of circulating EVs between the acute and subacute phases of ICH and to compare the findings depending on outcomes, as an approach to unraveling such repair mechanisms. This was a prospective observational study including patients with non-traumatic supratentorial ICH. Exclusion criteria were previous disability, signs of herniation on baseline computed tomography, or limited life expectancy. EVs were isolated from blood samples at 24 h and 7 days after symptom onset. After 6-months' follow-up, patients were dichotomized into poor and good outcomes, defining good as an improvement of >10 points or > 50 % on the National Institutes of Health Stroke Scale and a modified Rankin Scale of 0-2. The protein cargo was analyzed by quantitative mass spectrometry and compared according to outcomes. Forty-four patients completed follow-up, 16 (35.5 %) having good outcomes. We identified 1321 proteins in EVs, 37 with differential abundance. In patients with good outcomes, proteins related to stress response (DERA, VNN2, TOMM34) and angiogenesis (RHG01) had increased abundance at 7 days. EVs from patients with poor outcomes showed higher levels of acute-phase reactants (CRP, SAA2) at 7 days compared with 24 h. In conclusion, the protein content of circulating EVs in patients with ICH changes over time, the changes varying depending on the clinical outcome, with greater abundance of proteins potentially involved in the repair processes of patients with good outcomes.

Mutation of the attractin gene impairs working memory in rats

OBJECTIVE

Attractin (ATRN) is a widely expressed member of the cell adhesion and guidance protein family in humans that is closely related to cellular immunity and neurodevelopment. However, while previous studies in our laboratory have confirmed the effect of ATRN mutations on long-term memory, its specific role and the molecular mechanism by which it influences spatial cognition are poorly understood.

METHODS

This study aimed to examine the effect of ATRN mutations on working memory in water maze with a novel ATRN-mutant rat generated by the CRISPR/Cas9 system; the mutation involved the substitution of the 505th amino acid, glycine (G), with cysteine (C), namely, a mutation from GGC to TGC. The changes in myelin basic protein (MBP) expression in rats were also analyzed with the western blot.

RESULTS

The ATRN-G505C(KI/KI) rats exhibited significant increases in the required latency and distance traveled to locate the escape platform in a Morris water maze test of working memory. In addition, the expression of MBP was reduced in ATRN-mutant rats, as shown in the western blot analysis.

CONCLUSION

Our results indicate that ATRN gene mutations may directly lead to the impairment of working memory in the water maze; this impairment may be due to the inhibition of MBP expression, which in turn affects the spatial cognition.

Positional cloning of rat mutant genes reveals new functions of these genes

The laboratory rat (Rattus norvegicus) is a key model organism for biomedical research. Rats can be subjected to strict genetic and environmental controls. The rat's large body size is suitable for both surgical operations and repeated measurements of physiological parameters. These advantages have led to the development of numerous rat models for genetic diseases. Forward genetics is a proven approach for identifying the causative genes of these disease models but requires genome resources including genetic markers and genome sequences. Over the last few decades, rat genome resources have been developed and deposited in bioresource centers, which have enabled us to perform positional cloning in rats. To date, more than 100 disease-related genes have been identified by positional cloning. Since some disease models are more accessible in rats than mice, the identification of causative genes in these models has sometimes led to the discovery of novel functions of genes. As before, various mutant rats are also expected to be discovered and developed as disease models in the future. Thus, the forward genetics continues to be an important approach to find genes involved in disease phenotypes in rats. In this review, I provide an overview the development of rat genome resources and describe examples of positional cloning in rats in which novel gene functions have been identified.

Neural stem cell secretome exerts a protective effect on damaged neuron mitochondria in Parkinson's disease model

Parkinson's disease (PD) is a common neurodegenerative disease. The main pathological changes are the loss of dopaminergic neurons and the formation of Lewy bodies. There is still no effective cure for PD, and cell replacement therapy has entered a bottleneck period due to tumorigenicity and rejection. Therefore, stem cell secretome has received widespread attention. However, the exploration of the secretome components of neural stem cells (NSCs) is still in its infancy. In this study, 6-hydroxydopamine (6-OHDA) was used to establish a PD rat model in vito and the PC12 cell-damaged model in vitro. The results indicated that the injection of neural stem cell-conditioned medium (NSC-CM) into the striatum and substantia nigra could improve the motor and non-motor deficits of PD rats and rescue the loss of dopaminergic neurons. In addition, NSC-CM alleviated 6-OHDA-induced apoptosis of PC12 cells, reduced the level of oxidative stress, and improved mitochondrial dysfunction in vitro. Parkinson disease protein 7 (Park7) was found in NSC-CM by Liquid chromatography-tandem mass spectrometry (LC-MS/MS), and it may be related to the protective effect of NSC-CM on 6-OHDA-injured neurons through Sirt1 pathway. In conclusion, NSC secretome might provide new ideas for the treatment of PD.