Jun Kaneko

Involvement of metabotropic glutamate receptor 5 signaling in activity-related proliferation of adult hippocampal neural stem cells.

Adult hippocampal neural stem cells can be activated by hippocampal neural activities. When focal cerebral ischemia, known as middle cerebral artery occlusion (MCAO), occurs, neural stem cells are activated to promote their proliferation. However, the mechanism by which these cells are activated is still unclear. Here, we indicate the involvement of metabotropic glutamate receptor 5 (mGluR5) signaling in neural stem cells in their activity‐related proliferation after MCAO. We found mGluR5 molecules on neural stem cells by using calcium imaging. We detected the activation of neural stem cells by adding the mGluR5 agonist (RS)‐2‐chloro‐5‐hydroxyphenylglycine. On a hippocampal slice, the activation of neural stem cells to promote their proliferation was initiated by theta‐burst electrical stimulation at the perforant pathway, and this activation was significantly blocked by an mGluR5 antagonist, 2‐methyl‐6‐(phenylethynyl)pyridine (MPEP). In addition to this, the injection of the blood–brain barrier‐permeable mGluR5 agonist 3‐cyano‐N‐(1,3‐diphenyl‐1H‐pyrazol‐5‐yl)benzamide into live mice promoted the proliferation of neural stem cells. Moreover, in vivo theta‐burst electrical stimulation induced proliferation of neural stem cells. A chronic field recording study showed that the activity of the hippocampal formation was elevated after MCAO. Finally, we observed that the mGluR5 antagonist MPEP significantly blocked the stimulated proliferation of neural stem cells induced by MCAO, by blocking mGluR5 signaling. Our results suggest that glutamates released by the elevated neural activities after MCAO may trigger mGluR5 signaling in neural stem cells to promote their proliferation.

Effect of Anserine/Carnosine Supplementation on Verbal Episodic Memory in Elderly People

Our goal in this study was to determine whether or not anserine/carnosine supplementation (ACS) is capable of preserving cognitive function of elderly people. In a double-blind randomized controlled trial, volunteers were randomly assigned to an ACS or placebo group at a 1:1 ratio. The ACS group took 1.0 g of an anserine/carnosine (3:1) formula daily for 3 months. Participants were evaluated by psychological tests before and after the 3-month supplementation period. Thirty-nine healthy elderly volunteers (60–78 years old) completed the follow-up tests. Among the tests, delayed recall verbal memory assessed by the Wechsler Memory Scale-Logical Memory showed significant preservation in the ACS group, compared to the placebo group (p = 0.0128). Blood analysis revealed a decreased secretion of inflammatory cytokines, including CCL-2 and IL-8, in the ACS group. MRI analysis using arterial spin labeling showed a suppression in the age-related decline in brain blood flow in the posterior cingulate cortex area in the ACS group, compared to the placebo group (p = 0.0248). In another randomized controlled trial, delayed recall verbal memory showed significant preservation in the ACS group, compared to the placebo group (p = 0.0202). These results collectively suggest that ACS may preserve verbal episodic memory and brain perfusion in elderly people, although further study is needed.

Daily Carnosine and Anserine Supplementation Alters Verbal Episodic Memory and Resting State Network Connectivity in Healthy Elderly Adults

Carnosine and anserine are strong antioxidants, previously demonstrated to reduce cognitive decline in animal studies. We aimed to investigate their cognitive and neurophysiological effects, using functional MRI, on humans. Thirty-one healthy participants (age 40–78, 10 male/21 female) were recruited to a double-blind placebo-controlled study. Participants were assigned to twice-daily doses of imidazole dipeptide formula (n = 14), containing 500 mg (carnosine/anserine, ratio 1/3) or an identical placebo (n = 17). Functional MRI and neuropsychological assessments were carried out at baseline and after 3 months of supplementation. We analyzed resting state functional connectivity with the FSL fMRI analysis package. There were no differences in neuropsychological scores between the groups at baseline. After 3 months of supplementation, the carnosine/anserine group had better verbal episodic memory performance and decreased connectivity in the default mode network, the posterior cingulate cortex and the right fronto parietal network, as compared with the placebo group. Furthermore, there was a correlation between the extents of cognitive and neuroimaging changes. These results suggest that daily carnosine/anserine supplementation can impact cognitive function and that network connectivity changes are associated with its effects.

Anserine (beta-alanyl-3-methyl-L-histidine) improves neurovascular-unit dysfunction and spatial memory in aged AβPPswe/PSEN1dE9 Alzheimer’s-model mice

Anserine/carnosine supplementation improves cerebral blood flow and verbal episodic memory in elderly people, as we previously reported. Anserine’s buffering activity is superior to that of carnosine at neutral pH. In human sera, carnosine but not anserine is rapidly cleaved by carnosinase, limiting its effectiveness. This study examined the effects of anserine on AβPPswe/PSEN1dE9 Alzheimer’s disease (AD) model mice over 18-months old, an age at which these mice exhibit detectable memory deficits. We found that 8 weeks of anserine treatment completely recovered the memory deficits, improved pericyte coverage on endothelial cells in the brain, and diminished chronic glial neuroinflammatory reactions in these mice. These results suggest that anserine (beta-alanyl-3-methyl-L-histidine) supplementation improved memory functions in AD-model mice by exerting a protective effect on the neurovascular units, which are composed of endothelial cells, pericytes, and supporting glial cells.

Diazepam treatment blocks the elevation of hippocampal activity and the accelerated proliferation of hippocampal neural stem cells after focal cerebral ischemia in mice.

Hippocampal neurogenesis is accelerated during the elevation of hippocampal neural activities under both physiological and pathophysiological conditions. One of these conditions, middle cerebral artery occlusion (MCAO), induces both the hyperactivities of hippocampal network and the elevation of neural stem cell (NSC) proliferation. However, the causal relationship between the elevated activity and the elevation of NSC proliferation is still unclear. In this study, to block the elevation of hippocampal activity after MCAO in mice, we utilized a typical γ‐aminobutyric acid type A (GABAA) receptor active modulator, diazepam. With MCAO mice treated with diazepam, we observed complete disappearance of the elevation of hippocampal activity. Additionally, the diazepam treatment blocked the elevation of NSC proliferation after MCAO. From this result, it is speculated that the increased NSC proliferation is blocked by the suppression of elevated neural activity. However, diazepam might have effects other than the suppression of hippocampal activity, so we performed additional experiment and found that diazepam did not affect the number of bromodeoxyuridine‐positive cells under the normal condition, whereas the GABA agonist pentobarbital stimulated NSC/neural progenitor cell proliferation and differentiation. Next, we evaluated the expression of the diazepam‐binding inhibitor (DBI) protein and found that the cells expressed DBI in soma and on the surface of cell membrane. From these observations, we can propose that diazepam blocks the elevation of hippocampal activity and also NSC proliferation after MCAO.

Anserine/Carnosine Supplementation Preserves Blood Flow in the Prefrontal Brain of Elderly People Carrying APOE e4

In a previously reported double-blind, randomized controlled trial (RCT), we demonstrated that daily supplementation with anserine (750 mg) and carnosine (250 mg) improves brain blood flow and memory function in elderly people. Here, we conducted a sub-analysis of MRI data and test scores from the same RCT to determine whether anserine/carnosine supplementation specifically benefits elderly people carrying the APOE e4 allele, which is a risk gene for accelerated brain aging and for the onset of Alzheimer’s Disease. We collected data from 68 participants aged 65 years or older who received anserine/carnosine supplementation (ACS) or placebo for 12 months. Subjects were assessed at the start and end of the trial using several neuropsychological tests, including the Wechsler Memory Scale-Logical Memory (WMS-LM). We also collected two types of MRI data, arterial spin labeling (ASL) and diffusion tensor imaging (DTI) at the start and end of the trial. We found that ACS significantly preserved verbal memory (WMS-LM, F[1,65] = 4.2003, p = 0.0445) and blood flow at frontal areas of the brain (FWEcluster level, p < 0.001). Sub-analysis based on the APOE4 genotype showed a significant preservation of blood flow (p = 0.002, by ASL analysis) and white-matter microstructure (p = 0.003, by DTI analysis) at prefrontal areas in APOE4+ subjects in the active group, while there was no significant difference between APOE4- subjects in the active and placebo groups. The effect of ACS in preserving brain structure and function in elderly people carrying APOE4 should be verified by further studies.

β-ALANYL-3-METHYL-L-HISTIDINE, ANSERINE, AMELIORATES COGNITIVE DEFICITS IN AGED APPSWE/PSEN1DE9 ALZHEIMER’S DISEASE MODEL MOUSE THROUGH THE IMPROVEMENT OF BLOOD VESSEL DYSFUNCTION AS WELL AS GLIAL NEUROINFLAMMATORY REACTIONS

CK2 phosphorylating SET mediates the neurofibrillary pathology in AD remains unknown. Methods:The level of CK2 and its substrates weretested in different AD mice by Western blotting.CK2 activity was measured by using a CK2 activity assay kit. An adeno-associated virus serotype 2 (AAV2) was employed to induce expression of CK2in mice brain. Fear conditioning and Morris water maze were used to detect animal behavior. Synaptic function was measured by LTP and Golgi-Cox staining. Immunofluorescence was used to detect the location of phosphorylated SET.HEK293-Tauwere transfected with SET/wt, SET S9A and SET S9E plasmids for 48 hours. Cell lysates were collected for PP2A activity assay and Western blotting. Results: CK2 overexpression induced tau pathology associated with cognitive defect and synaptic impairment. Meanwhile, CK2 phosphorylated SET at Ser9 and regulated SET nuclear import. However, mutation of SET Ser 9 to Ala abolished CK2-induced tau pathology in Alzheimer’s disease. Conclusions:CK2-mediated phosphorylation of SETat Ser9 play an essential role in inducing tau pathology in Alzheimer’s disease.

Cell-cycle analysis of neural stem cells in the adult mouse dentate gyrus

P3-e07 Expression of tryptophan 2,3-dioxygenase in mature granule cells of the adult mouse dentate gyrus Koji Ohira 1 , Hideo Hagihara 1,2, Keiko Toyama 1,2, Keizo Takao 2,3, Masaaki Kanai 4, Hiroshi Funakoshi 4, Toshikazu Nakamura 4, Tsuyoshi Miyakawa 1,2,3 1 Division of Systems Medical Science, Fujita Health University 2 CREST, Saitama 3 Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Aichi 4 Division of Molecular Regenerative Medicine, Osaka University Graduate School of Medicine, Osaka