No abstract

Itch is a distinct aversive sensation that elicits a strong urge to scratch. Despite recent advances in our understanding of the peripheral basis of itch, we know very little regarding how central neural circuits modulate acute and chronic itch processing. Here we establish the causal contributions of defined periaqueductal gray (PAG) neuronal populations in itch modulation in mice. Chemogenetic manipulations demonstrate bidirectional modulation of scratching by neurons in the PAG. Fiber photometry studies show that activity of GABAergic and glutamatergic neurons in the PAG is modulated in an opposing manner during chloroquine-evoked scratching. Furthermore, activation of PAG GABAergic neurons or inhibition of glutamatergic neurons resulted in attenuation of scratching in both acute and chronic pruritis. Surprisingly, PAG GABAergic neurons, but not glutamatergic neurons, may encode the aversive component of itch. Thus, the PAG represents a neuromodulatory hub that regulates both the sensory and affective aspects of acute and chronic itch.

SummaryThe fetal liver kinase 1 (FLK-1)+ hemangioblast can generate hematopoietic, endothelial, and smooth muscle cells (SMCs). ER71/ETV2, GATA2, and SCL form a core transcriptional network in hemangioblast development. Transient coexpression of these three factors during mesoderm formation stage in mouse embryonic stem cells (ESCs) robustly enhanced hemangioblast generation by activating bone morphogenetic protein (BMP) and FLK-1 signaling while inhibiting phosphatidylinositol 3-kinase, WNT signaling, and cardiac output. Moreover, etsrp, gata2, and scl inhibition converted hematopoietic field of the zebrafish anterior lateral plate mesoderm to cardiac. FLK-1+ hemangioblasts generated by transient coexpression of the three factors (ER71-GATA2-SCL [EGS]-induced FLK-1+) effectively produced hematopoietic, endothelial, and SMCs in culture and in vivo. Importantly, EGS-induced FLK-1+ hemangioblasts, when codelivered with mesenchymal stem cells as spheroids, were protected from apoptosis and generated functional endothelial cells and SMCs in ischemic mouse hindlimbs, resulting in improved blood perfusion and limb salvage. ESC-derived, EGS-induced FLK-1+ hemangioblasts could provide an attractive cell source for future hematopoietic and vascular repair and regeneration.

Supplemental Digital Content is Available in the Text. Gucy2d is expressed by spinal inhibitory neurons but is absent from brain and dorsal root ganglia. Gucy2d knockout mice respond normally to mechanical, heat, cold, and itch stimuli.