Increased expression of the N-methyl-D-aspartate receptor subunit, NR1, in immunohistochemically identified magnocellular hypothalamic neurons during dehydration.

N-Methyl-D-aspartate receptors are thought to be involved in synaptic signaling within the hypothalamo-neurohypophysial system, but the extent and nature of their involvement has not been determined. In this study, in the rat, we evaluated the effect of hyperosmotic stimulation on the N-methyl-D-aspartate receptor subunit, NR1, which confers function to N-methyl-D-aspartate receptor heteromers. Co-localization of immunoreactivity for NR1 and vasopressin- or oxytocin-associated neurophysin in magnocellular neurons of the supraoptic and paraventricular hypothalamic nuclei was accomplished using double-label immunohistochemistry.

Calbindin-D28k: role in determining intrinsically generated firing patterns in rat supraoptic neurones.

1. Physiological activation of rat supraoptic nucleus (SON) neurones leads to phasic firing in vasopressin neurones and fast, continuous firing in oxytocin neurones. Using whole-cell patch clamp methods in brain slices, we investigated the role of endogenous calbindin-D28k (calbindin) in determining these intrinsically generated patterns of firing.

Taurine immunoreactivity in the rat supraoptic nucleus: prominent localization in glial cells.

Taurine is an inhibitory amino acid that hyperpolarizes magnocellular neurosecretory neurons. To determine which cell types in the rat supraoptic nucleus contain taurine, we used a monoclonal antibody raised against a taurine conjugate. Preembedding immunocytochemistry was carried out at the light and electron microscopic levels using diaminobenzidine and gold-substituted silver-intensified peroxidase as markers.

VGF expression in the brain.

VGF is a neuronal polypeptide first identified as a cDNA clone in a gene library from nerve growth factor-stimulated PC12 cells. In the present paper, the expression of VGF is examined for the first time throughout the adult rat central nervous system with immunocytochemistry and Northern blot analysis. VGF RNA was found in all brain regions studied, including hypothalamus, hippocampus, cerebellum, olfactory bulb, and cortex.

Converging GABA- and glutamate-immunoreactive axons make synaptic contact with identified hypothalamic neurosecretory neurons.

To study the neurochemical identity of axons in synaptic contact with identified hypothalamic neurosecretory neurons in rats, we combined retrograde axonal transport of a marker molecule with postembedding immunogold staining for amino acid neurotransmitters. After intravenous injections of horseradish peroxidase, neurosecretory neurons with axons in the median eminence or neurohypophysis transported the peroxidase retrogradely back to the cell body of origin. Serial ultrathin sections from the paraventricular and arcuate nuclei were immunostained with glutamate or GABA antisera.