Whole-cell recordings of spontaneous synaptic currents in medial preoptic neurons from rat hypothalamic slices: mediation by amino acid neurotransmitters.

Whole-cell recordings in hypothalamic slices from immature rats were used to test the hypothesis that inhibitory and excitatory amino acid neurotransmitters mediate fast synaptic currents in the medial preoptic area (MPOA). Bicuculline methiodide reversibly blocked spontaneous inhibitory postsynaptic currents (IPSCs), and 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX) blocked spontaneous excitatory postsynaptic currents (EPSCs). These competitive antagonists act at gamma-aminobutyric acid (GABA)A and non-N-methyl-D-aspartate (NMDA) glutamate receptors, respectively, thus supporting the hypothesis that these amino acid receptors activate most if not all fast synaptic currents in the MPOA.

Homogeneity of intracellular electrophysiological properties in different neuronal subtypes in medial preoptic slices containing the sexually dimorphic nucleus of the rat.

The sexually dimorphic nucleus of the preoptic area (SDN-POA) is larger in male than in female rats, the male phenotype requiring the presence of circulating androgens perinatally. These experiments investigated the intracellular electrophysiology and morphology of SDN-POA neurons and compared these properties with those of other medial preoptic area (MPOA) neurons. Biocytin-injected cells in the SDN-POA either had one or two primary dendrites, or they had multipolar dendritic arrays; dendrites were aspiny or sparsely spiny and displayed limited branching.

Subcellular location and differential antibody specificity of arginase in tissue culture and whole animals.

Studies in man and other mammals have demonstrated the existence of two forms of arginase, a cytoplasmic form located primarily in liver and a mitochondrial form expressed in lesser amounts in a larger number of organs, but especially kidney. They appear to be encoded in different gene loci. Using a colloidal silica gradient separation technique, we have now located arginase in H4 cells, a rat hepatoma-derived line, to the cytoplasm and the arginase in human embryonic kidney-derived line, to the mitochondrion.