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Sympathoexcitatory neurons in the C1 adrenergic area of the rostral ventrolateral medulla (RVL) are tonically inhibited by gamma-aminobutyric acid (GABA). To identify the source of this GABAergic input, the distribution of neurons containing glutamate decarboxylase (GAD) was determined immunocytochemically in rats treated with colchicine. Numerous(More)
We sought to identify amino acid neurotransmitter candidates within the nucleus of the solitary tract in rats. Twenty endogenous amino acids were quantified by reverse-phase HPLC with fluorescence detection (30-fmol limit). Micropunches (1 mm) of the intermediate area of the solitary nucleus were prepared, and the amino acid content determined. Of all the(More)
In previous experiments we implicated projections from the medial geniculate body (MG) to a subcortical field, involving portions of the posterior caudate-putamen and amygdala, in the classical conditioning of emotional responses to acoustic stimuli in the rat. In the present series of experiments we examined whether intrinsic neurons in the subcortical(More)
Glutamic acid decarboxylase (GAD), the enzyme which synthesizes the inhibitory transmitter gamma-aminobutyric acid (GABA), was localized immunocytochemically within cells and processes distributed throughout the ventrolateral medulla. In caudal regions, GAD-stained cells were adjacent to the 'precerebellar' lateral reticular nucleus and partially overlapped(More)
Intraventricular injection of colchicine in rat results in the appearance within hypothalamus of numerous neurons containing the adrenaline-synthesizing enzyme, phenylethanolamine N-methyltransferase, but not the other catecholamine biosynthetic enzymes. Increased PNMT staining in hypothalamus was paralleled by an increase in PNMT activity measured in(More)
The substrate-promoted inactivation of glutamate decarboxylase from hog brain was studied. Inactivation was a slow process that was dependent on the concentration of glutamate. Glutamate-dependent inactivation was not first order but was best described as the sum of two exponential decay processes. At 10 mM glutamate, the half-lives at 30 degrees C were(More)
The effects of ATP and inorganic phosphate (Pi) on the reactivation of glutamate apodecarboxylase by its cofactor pyridoxal-5'-phosphate (pyridoxal-P) was studied. Apoenzyme was prepared by preincubation with glutamate. Apoenzyme prepared with glutamate alone was reactivated slowly and incompletely by adding a saturating concentration of pyridoxal-P (20(More)
Binding sites labeled by [3H]p-aminoclonidine ([3H]PAC) were characterized in bovine brain membranes prepared from the ventrolateral medulla, the probable site of the antihypertensive action of clonidine and analogs. Comparison was made with [3H]PAC binding to membranes prepared from frontal cortex, which has been studied extensively. Saturation binding(More)
We sought to determine in rat, whether interruption of the major extrathalamic projections to the cerebral cortex originating in and projecting through the basal forebrain (BF), will impair the increase in regional cerebral blood flow (rCBF), but not metabolism, elicited in the cerebral cortex by electrical stimulation of the cerebellar fastigial nucleus(More)
We sought to characterize the interactions of an endogenous clonidine-displacing substance (CDS) with the specific receptor sites to which clonidine and its analogs bind: (a) the non-adrenergic imidazole binding site, which is present in the ventrolateral medulla (VLM) but not the frontal cortex, (b) high-affinity and (c) low-affinity states of the alpha(More)