Direct visualization of glucocorticoid receptor positive cells in the hippocampal regions using green fluorescent protein transgenic mice.

The hippocampal formation is a plastic brain structure important for certain types of learning and memory, and also vulnerable to the effects of stress and trauma. Since hippocampal neurons express high levels of corticosteroid receptor, the morphological changes, including alterations in the size of soma, and the length and number of neurites and spines, in response to glucocorticoids released as a result of stress are intriguing. In order to highlight the morphology of neurons that express glucocorticoid receptor (GR), we have generated a transgenic mouse line expressing green fluorescent protein (GFP) under the control of the GR promoter. We found strong green fluorescence in the pyramidal cell layer of the CA1 and CA2 regions and the granule cell layer of the dentate gyrus of the hippocampus in brain sections of the transgenic mice. GFP fluorescence was observed not only in somas, but also in neurites including both dendrites and axons. In dissociated culture, we also observed GFP fluorescence in the soma, neurites including both dendrites and axons, and dendritic spines. Microtubule-associated protein 2 immunopositive pyramidal-shaped neurons clearly showed two different populations, GFP positive and GFP negative neurons. These results indicate that this transgenic mouse line should be useful for live imaging of neuronal structure in animals as well as GR-positive cultured cells using GFP as a specific indicator.

Pharmacokinetic modelling of [2-13C]uracil metabolism in normal and DPD-deficient dogs.

A physiologically based pharmacokinetic (PBPK) model to simulate the plasma concentration and 13CO2 exhalation after [2-13C]uracil administration to DPD-suppressed dogs was developed. Simulation using this PBPK model should be useful in clinical situations where DPD-deficient patients at risk are to be detected with [2-13C]uracil as an in vivo probe.

Light and electron microscopic studies on capillaries of the goat cardiac muscle with special reference to the topographical relationship between the vessels and Purkinje fibers.

The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.