ИСТИНА

Chronic high-fat Western diet (WD) produces weight gain and obesity. How it affects the brain function remains elusive. We performed the study in hippocampal slices of 4 months old mice after one month of WD. No significant changes in the astrocyte density were observed in CA1 str. radiatum after WD. Astrocytes were recorded in whole-cell voltage-clamp mode for electrophysiological analysis and simultaneously loaded with Alexa Fluor 594 for two-photon microscopy morphological study. WD induced significant remodeling in astrocytic distal branches as well as an increase in volume fraction of perisynaptic astrocytic leaflets unresolved with diffraction limited optical microscopy. The number of cells coupled through the gap-junctions in the astrocytic syncytium was not significantly different after WD, and no significant difference in the length constant of coupling was detected. The activity-dependent facilitation of glutamate transporter current and facilitation of synaptically-induced K + current were not different in astrocytes after WD. However, the activity-dependent increase in transporter current decay time was abolished after WD. These findings suggest that enhanced astrocytic coverage of synapses may prevent glutamate spillover after WD. Next, we performed confocal Ca 2+ imaging in astrocytes stained with Oregon Green BAPTA-AM in CA1 str. radiatum. Spontaneous Ca 2+ event size decreased in the astrocytic network after WD. However, the event duration was increased, as well as Ca 2+ event integral. The long-term potentiation was significantly enhanced in CA3-CA1 synapses after WD. Thus, along with astrocyte remodeling and enhanced Ca 2+ signaling, temporary WD promotes synaptic plasticity in young mice. Our results are consistent with the beneficial effects of high fat intake in young age.