| First Author | Ozawa K | Year | 2023 |
| Journal | Int J Mol Sci | Volume | 24 |
| Issue | 17 | PubMed ID | 37686396 |
| Mgi Jnum | J:340319 | Mgi Id | MGI:7527596 |
| Doi | 10.3390/ijms241713590 | Citation | Ozawa K, et al. (2023) Astrocytic GPCR-Induced Ca(2+) Signaling Is Not Causally Related to Local Cerebral Blood Flow Changes. Int J Mol Sci 24(17) |
| abstractText | Activation of Gq-type G protein-coupled receptors (GPCRs) gives rise to large cytosolic Ca(2+) elevations in astrocytes. Previous in vitro and in vivo studies have indicated that astrocytic Ca(2+) elevations are closely associated with diameter changes in the nearby blood vessels, which astrocytes enwrap with their endfeet. However, the causal relationship between astrocytic Ca(2+) elevations and blood vessel diameter changes has been questioned, as mice with diminished astrocytic Ca(2+) signaling show normal sensory hyperemia. We addressed this controversy by imaging cortical vasculature while optogenetically elevating astrocyte Ca(2+) in a novel transgenic mouse line, expressing Opto-Gq-type GPCR Optoalpha1AR (Astro-Optoalpha1AR) in astrocytes. Blue light illumination on the surface of the somatosensory cortex induced Ca(2+) elevations in cortical astrocytes and their endfeet in mice under anesthesia. Blood vessel diameter did not change significantly with Optoalpha1AR-induced Ca(2+) elevations in astrocytes, while it was increased by forelimb stimulation. Next, we labeled blood plasma with red fluorescence using AAV8-P3-Alb-mScarlet in Astro-Optoalpha1AR mice. We were able to identify arterioles that display diameter changes in superficial areas of the somatosensory cortex through the thinned skull. Photo-stimulation of astrocytes in the cortical area did not result in noticeable changes in the arteriole diameters compared with their background strain C57BL/6. Together, compelling evidence for astrocytic Gq pathway-induced vasodiameter changes was not observed. Our results support the notion that short-term (<10 s) hyperemia is not mediated by GPCR-induced astrocytic Ca(2+) signaling. |
