BACKGROUND: Rat mast cells were regarded as a good model for mast cell function in immune response. METHODS: Rat bone marrow mast cells (BMMC) were prepared both by recombinant rat IL-3 (rrIL-3) and by recombinant mouse stem cell factor (rmSCF), and investigated for both proliferation and differentiation in time course. Rat BMMC was induced by culture of rat bone marrow cells (BMCs) in the presence of both rrIL-3 (5 ng/ml) and rmSCF (5 ng/ml). Culture media were changed 2 times per week with the cell number condition of 5x10(4)/ml in 6 well plate. Proliferation was analyzed by cell number and cell counting kit-8 (CCK-8) and differentiation was by rat mast cell protease (RMCP) II and histamine. RESULTS: Cell proliferation rates reached a maximum at 8 or 11 days of culture and decreased thereafter. However, both RMCP II production and histamine synthesis peaked after 11 days of culture. By real time RT-PCR, the level of histidine decarboxylase mRNA was more than 500 times higher on culture day 11 than on culture day 5. By transmission electron microscopy, the cells were heterogeneous in size and contained cytoplasmic granules. Using gated flow cytometry, we showed that cultured BMCs expressed high levels of FcepsilonRI and the mast cell antigen, ganglioside, on culture day 11. CONCLUSION: These results indicate that rat BMMCs were generated by culturing BMCs in the presence of rrIL-3 and rmSCF and that the BMMCs have the characteristics of mucosal mast cells.
Animals ; Bone Marrow ; Bone Marrow Cells ; Cell Count ; Cell Proliferation ; Culture Media ; Cytoplasmic Granules ; Flow Cytometry ; Histamine ; Histidine Decarboxylase ; Interleukin-3 ; Kinetics ; Mast Cells ; Mice ; Microscopy, Electron, Transmission ; Phenotype ; Rats ; RNA, Messenger ; Stem Cell Factor

OBJECTIVETo investigate the modulatory effects of morphine on the susceptibility to pentylenetetrazole-induced seizures, and the involvement of endogenous histamine in this process.

METHODSBoth the wild-type (WT) mice and histidine decarboxylase (a key enzyme for histamine biosynthesis) deficient (HDC-KO) mice were subcutaneously injected with different doses of morphine, and 1 hour later the pentylenetetrazole solution (1.5 %) was infused into the tail vein at a constant rate of 0.3 ml/min. The minimal dose of pentylenetetrazole (mg/kg) needed to induce myoclonic jerks and clonus convulsion was recorded as the thresholds of seizures.

RESULTIn WT mice, morphine dose-dependently decreased the thresholds of both myoclonic jerks and clonus convulsion. In HDC-KO mice, morphine at 10 mg/kg only significantly decreased the threshold of myoclonic jerks from (38.6 +/-2.9)mg/kg to (32.5 +/-0.7)mg/kg, but had no significant effect on the threshold of clonus convulsion [from (51.8 +/-2.1)mg/kg to (47.6 +/-1.2)mg/kg]. In addition, the value of decreased myoclonic jerks (15.8 +/-1.4)% and clonus convulsion (8.3 +/-0.9)% thresholds were much lower in HDC-KO mice than in WT mice [(26.1 +/-2.5)% and (20.8 +/-2.4)%, respectively].

CONCLUSIONMorphine can decrease the thresholds of pentylenetetrazole in induction of seizure, and the endogenous histamine may be involved in this process.

Animals ; Disease Susceptibility ; chemically induced ; metabolism ; physiopathology ; Dose-Response Relationship, Drug ; Histamine ; metabolism ; physiology ; Histidine Decarboxylase ; genetics ; metabolism ; Male ; Mice ; Mice, Knockout ; Morphine ; pharmacology ; Myoclonus ; chemically induced ; metabolism ; physiopathology ; Narcotics ; pharmacology ; Pentylenetetrazole ; Random Allocation ; Seizures ; chemically induced ; genetics ; physiopathology ; Sensory Thresholds ; drug effects