OBJECTIVETo investigate the changes and mechanism of angiopoietin1 (Ang1) in murine bone marrow during G-CSF induced mobilization of hematopoietic stem/progenitor cell.

METHODSThe proportion of Lin-Sca1⁺cKit⁺ (LSK) cells in peripheral blood of C57BL/6 mice before and after G-CSF mobilization was detected by flow cytometry. Expression changes of Ang1 and osteocalcin (OCN) during HSC mobilization were determined by immunohistochemistry, enzyme linked immunosorbent assay (ELISA) and real-time fluorescence quantitative PCR. The number of osteoblasts in the bone marrow was counted under the microscope.

RESULTSAfter treated with G-CSF, the proportion of LSK cells in peripheral blood significantly increased from the controls (0.04 ± 0.01)% to (0.61 ± 0.05)% at day 5 (P<0.05). Before G-CSF mobilization, the endosteum cells expressed higher level of OCN and Ang1 than that of bone marrow nucleated cells. The mRNA expression level of OCN was significantly reduced from 28.64 ± 8.61 in the controls to 12.55 ± 7.06 on day 3 and 4.75 ± 1.62 on day 5, and the expression level of Ang1 also declined from 2.84 ± 0.95 in the controls to 0.93 ± 0.30 on day 3 and to 0.92 ± 0.22 on day 5 after G-CSF mobilization. The number of endosteum osteoblasts was significantly decreased after mobilization (P<0.05). The Ang1 expression was decreased in the BM after mobilization. The serum OCN was significantly reduced from (24.11 ± 3.17) ng/ml in the controls to (9.96 ± 2.16) ng/ml on day 3 and (8.43 ± 2.62) ng/ml on day 5, and the Ang1 also declined from (2.24 ± 0.52) ng/ml in the controls to (1.21±0.38) ng/ml on day 3 and (0.90±0.24) ng/ml on day 5.

CONCLUSIONIn G-CSFinduced HSPC mobilization, the bone marrow osteoblasts retraction causes reduction of Ang1, and the reduction of Ang1 may contribute to HSPC mobilization.

Animals ; Bone Marrow ; Bone Marrow Cells ; Granulocyte Colony-Stimulating Factor ; Hematopoietic Stem Cell Mobilization ; Hematopoietic Stem Cells ; Mice ; Mice, Inbred C57BL ; Osteoblasts ; RNA, Messenger

The nucleus tractus solitarii (NTS) is one of the morphologically and functionally defined centers that engage in the autonomic regulation of cardiovascular activity. Phenotypically-characterized NTS neurons have been implicated in the differential regulation of blood pressure (BP). Here, we investigated whether phenylethanolamine N-methyltransferase (PNMT)-expressing NTS (NTS^PNMT) neurons contribute to the control of BP. We demonstrate that photostimulation of NTS^PNMT neurons has variable effects on BP. A depressor response was produced during optogenetic stimulation of NTS^PNMT neurons projecting to the paraventricular nucleus of the hypothalamus, lateral parabrachial nucleus, and caudal ventrolateral medulla. Conversely, photostimulation of NTS^PNMT neurons projecting to the rostral ventrolateral medulla produced a robust pressor response and bradycardia. In addition, genetic ablation of both NTS^PNMT neurons and those projecting to the rostral ventrolateral medulla impaired the arterial baroreflex. Overall, we revealed the neuronal phenotype- and circuit-specific mechanisms underlying the contribution of NTS^PNMT neurons to the regulation of BP.
Solitary Nucleus/metabolism* ; Blood Pressure/physiology* ; Phenylethanolamine N-Methyltransferase/metabolism* ; Neurons/metabolism* ; Paraventricular Hypothalamic Nucleus/metabolism*