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Hypoxia induces alterations of central monoaminergic transmission and of behavior. We studied the effect of hypoxia on adult and newborn rats to obtain more information about long-lasting changes of dopamine (DA) transmission caused by neonatal hypoxia. One single exposure of adult rats to hypoxia leads to short-term alterations of DA uptake: decreased affinity of the uptake carrier to DA (Km, 269.5% versus control) and a sharp increase of Vmax up to 301.4% resulting in an increase of total uptake of DA into the striatum synaptosomes. The K+-evoked DA release decreased to 69.5%. After 1 week of recovery all parameters are normalized. Chronic postnatal hypoxia (postnatal day 2-11) caused long-lasting changes of DA release and uptake opposite to those observed in adult rats. Three months after hypoxia, the K+-stimulated DA release was enhanced (132% of control), and the uptake was reduced due to decreased affinity of the uptake carrier system for the substrate (Km, 187% of control value). In conclusion, the alterations observed after chronic postnatal hypoxia reflect special adaptive processes that are related to the high plasticity of the immature neonatal brain and contribute to an increased DA function in the nigrostriatal system.

In the present study mast cell differentiation/maturation was studied in vivo after depletion of mature mast cells from the peritoneal cavity by injection of distilled water. The reconstituting cell population was characterized by use of different staining methods. Additionally, the monoclonal antibody (MAb) IWF F2, which recognizes a membrane antigen of rat mast cells, was used to follow up mast cell differentiation/maturation in the course of the experiment. The antigen expression was studied both by immunofluorescence of antigen-bearing cells and by MAb inhibition of compound 48/80-stimulated histamine release from mast cells. In the course of the experiment the amount of antigen-positive cells increased continuously from less than 5% to control level (1st and 22nd days, respectively). The expression of the membrane antigen detectable by the MAb precedes the appearance of cytochemically identifiable mast cells for several days. The mast cells mature morphologically and functionally as indicated by increasing size, histamine content and MAb inhibition of compound 48/80-stimulated histamine release. The results obtained suggest the MAb IWF F2 to be a useful methodical tool for additional characterization of mast cell differentiation/maturation processes.