Background Perturbed functional coupling between the metabotropic glutamate receptor-5 (mGluR5) and N-methyl-d-aspartate (NMDA) receptor-mediated excitatory glutamatergic neurotransmission may contribute to the pathophysiology of psychiatric disorders such as schizophrenia. We aimed to establish the functional interaction between mGluR5 and NMDA receptors in brain of mice with genetic ablation of the mGluR5. Methods We first measured the brain glutamate levels with magnetic resonance spectroscopy (MRS) in mGluR5 knockout (KO) and wild-type (WT) mice. Then, we assessed brain glucose metabolism with [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography before and after the acute administration of an NMDA antagonist, MK-801 (0.5 mg/kg), in the same mGluR5 KO and WT mice. Results Between-group comparisons showed no significant differences in [18F]FDG standardized uptake values (SUVs) in brain of mGluR5 KO and WT mice at baseline, but widespread reductions in mGluR5 KO mice compared to WT mice after MK-801 administration (p < 0.05). The baseline glutamate levels did not differ significantly between the two groups. However, there were significant negative correlations between baseline prefrontal glutamate levels and regional [18F]FDG SUVs in mGluR5 KO mice (p < 0.05), but no such correlations in WT mice. Fisher’s Z-transformation analysis revealed significant between-group differences in these correlations (p < 0.05). Conclusions This is the first multimodal neuroimaging study in mGluR5 KO mice and the first report on the association between cerebral glucose metabolism and glutamate levels in living rodents. The results indicate that mGluR5 KO mice respond to NMDA antagonism with reduced cerebral glucose metabolism, suggesting that mGluR5 transmission normally moderates the net effects of NMDA receptor antagonism on neuronal activity. The negative correlation between glutamate levels and glucose metabolism in mGluR5 KO mice at baseline may suggest an unmasking of an inhibitory component of the glutamatergic regulation of neuronal energy metabolism.
Most embankment of the reservoirs (99.1 %) have been constructed in the earth filled type in Korea because the construction of this type is less expensive and simpler than others such as concrete one. However, it has to be reinforced the slope to prevent the breach due to overtopping or piping under unexpected flood conditions. This study has been analyzed the retardation effect using three types (L, T, L * shape) of stiffener in order to reinforce embankment when they are collapsed by overtopping flow. Experimental results showed that L-type stiffener is the most effective in delaying the breaching of embankment and reducing the soil erosion when compared with others. The reinforced embankment breaching showed that time delay was occurred about 1.73 to 2.29 times and the peak flowrate was reduced compared to non-stiffener embankments due to energy dissipation by collision and less soil erosion. The embankment breaching mostly leads to major damages because of the lack of repair time. Thus, since these stiffeners can resist the rapid breach, it would be possible to earn the time to emergency repair and lifesaving, as well as reduction of damages of embankment in downward region with decreasing peak flowrate. Results from this study would be used for the basis when establishing the emergency action plan for the reservoirs on the verge of hazard.
Genetic research has implicated dopamine neurotransmission in the expression of the self‐transcendence trait in humans. However, molecular imaging of dopaminergic markers is undocumented in relation to this personality trait. In this multimodal imaging study, we first investigated the relationship between the self‐transcendence trait and in vivo dopamine D2/3 receptor availability using [18F]fallypride positron emission tomography (PET). We next conducted seed‐based functional connectivity analyses using resting‐state functional magnetic resonance imaging (rs‐fMRI) data with regions derived from the PET analysis as seeds to explore the functional significance of D2/3 receptor availability foci associated with the self‐transcendence trait. Twenty‐one healthy subjects underwent high‐resolution PET with [18F]fallypride and a subset of 18 subjects also completed 3‐Tesla rs‐fMRI. The Temperament and Character Inventory was used to measure the self‐transcendence trait. A voxel‐based whole brain analysis revealed that the [18F]fallypride binding potential (BPND) within the cluster of the left insula was significantly positively correlated with self‐transcendence trait scores. A region‐of‐interest analysis also showed a significant positive correlation between self‐transcendence and [18F]fallypride BPND in the left insula. The exploratory [18F]fallypride BPND seed‐based rs‐fMRI analysis showed that the functional connectivity from the left insula seed to the prefrontal cortices (including the inferior frontal region) was negatively associated with self‐transcendence trait scores. The results of the present study suggest that D2/3 receptor‐mediated neurotransmission in the left insula may constitute a significant neurobiological factor in the self‐transcendence trait. The negative associations between BPND seed‐based functional connectivity and self‐transcendence trait scores may suggest reduced prefrontal control in this personality trait.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.