Selective activation of synapses near the tip of drug-ejecting microelectrode, and effects of antagonists of excitatory amino acids in the hippocampus.

A technique was developed to selectively facilitate transmission through synapses near the tip of a drug-ejecting micropipette by increasing Ca2+ concentration in a small space surrounding the tip. By means of this technique, we found that antagonists of excitatory amino acids, cis-2,3-piperidine dicarboxylic acid, gamma-D-glutamylglycine and glutamic acid diethylester, blocked excitation induced in CA3 neurons by glutamate and by mossy fiber stimulation in thin hippocampal sections of the guinea pig.

Suppressing action of 2-amino-4-phosphonobutyric acid on mossy fiber-induced excitation in the guinea pig hippocampus.

The action of 2-amino-4-phosphonobutyric acid (APB) on mossy fiber-induced excitation in CA3 neurons was studied in vitro with thin sections of guinea pig hippocampus. D- and DL-APB suppressed field potentials induced in regio CA3 by granular layer stimulation. Threshold concentration of DL-APB to induce the suppression was 2--5 microM.

Purification and properties of bovine brain dopamine beta-hydroxylase.

Dopamine beta-hydroxylase (DBH) was purified from bovine brain by a series of steps including extraction with 0.5% Triton X-100, ammonium sulfate fractionation, and serial chromatographies with Concanavalin A (Con A)-Sepharose, Biogel A-1.5 m, DEAE-Sephadex, and phenyl-Sepharose.

Black widow spider venom: excitatory action on hippocampal neurons.

Electrical activities of thin hippocampal sections of the guinea pig were studied in vitro during and after administration of black widow spider venom (BSV). In CA3 neurons, BSV induced spontaneous discharges which were suppressed by Co2+ or Mn2+. During BSV administration, trains of potential changes resembling excitatory postsynaptic potentials (EPSPs) were recorded intracellularly.

Excitatory actions of homocysteic acid on hippocampal neurons.

The actions of D- and D,L-homocysteate (DH and DLH) on CA3 neurons were studied in thin sections of the guinea pig hippocampus. DH and DLH administered to the stratum radiatum induced large depolarizations in CA3 neurons. The responses to DH and DLH were accompanied by increases in membrane conductance.

Sensitivity of hippocampal neurons to glutamic acid and its analogues.

In thin slices of the guinea-pig hippocampus, depolarizations induced by glutamate (Glu) and its analogues were studied by intracellular recording. It was found that Glu induced stereospecific responses, that L-Glu was more potent than homocysteate and N-methyl-D-aspartate. It is probable that the high-affinity uptake mechanism played a decisive role in termination of L-Glu excitation.

Quantal analysis of excitatory postsynaptic potentials induced in hippocampal neurons by activation of granule cells.

The values of quantal content (m) and quantal amplitude (q) of excitatory postsynaptic potentials (EPSPs) elicited in CA3 neurons by activation of granule cells were estimated in thin hippocampal sections maintained in vitro. For this purpose, DL-homocysteate was administered to granule cells, and trains of EPSPs that were typical for single granule cell activation were recorded from individual CA3 neurons. The amplitudes of the first and second EPSPs in each train were measured.

Highly sensitive assay for dopamine-beta-hydroxylase activity in human cerebrospinal fluid by high performance liquid chromatography-electrochemical detection: properties of the enzyme.

This paper describes a new, sensitive assay for dopamine-beta-hydroxylase (DBH) activity in human cerebrospinal fluid (CSF), serum and brain tissues by high performance liquid chromatography (HPLC) with electrochemical detection (ED). Dopamine (DA) was used as a substrate and was incubated under optimal conditions. Norepinephrine (NE) formed enzymatically from DA was isolated by a double-column procedure, the first column of Dowex-50-H+ and the second column of aluminum oxide.

The long-lasting inhibition recorded in vitro from the lateral nucleus of the amygdala.

Potentials evoked by stimulation of stria terminalis and a part of the lateral nucleus of the amygdala were recorded in vitro from thin amygdaloid sections. The presence of inhibitory postsynaptic potentials lasting for 0.3-1 sec and mediated by gamma-aminobutyric acid was demonstrated by intracellular and extracellular recordings.

Postsynaptic inhibitory actions of catecholamines and opioid peptides in the bed nucleus of the stria terminalis.

Effects of catecholamines, enkephalins and related compounds on electrical activity of the bed nucleus of stria terminalis (BST) were studied in vitro on thin BST sections prepared from guinea pig brains. Norepinephrine (NE) and epinephrine (E) suppressed field potentials elicited by a single shock to the stria terminalis (ST). The effects of NE and E were mimicked by phenylephrine and blocked by phenoxybenzamine.

Electrical activity recorded from thin sections of the bed nucleus of the stria terminalis, and the effects of neurotensin.

Effects of neurotensin on neurons in the bed nucleus of the stria terminalis (BST) were studied in vitro in thin brain sections of the guinea pig. Electrical stimulation to the stria terminalis (ST) elicited a negative field potential in the BST. The field potential was markedly suppressed in the medium containing Ca2+ at a low concentration of Mg2+ at a high concentration.

Inhibition of dopamine-beta-hydroxylase, A copper enzyme, by bleomycin.

Bleomycin was found to be one of the most potent inhibitors of dopamine-beta-hydroxylase. Bleomycin-A2 at 8 X 10(-8) M inhibited the enzyme activity by 50%. Kinetic studies showed that the inhibition by bleomycin-A2 was of the competitive type with both the substrate and the cofactor, ascorbate, and was not affected by fumarate, a stimulator for the enzyme.

[First marriage tables for Japanese males and females, 1975].

The authors present net nuptiality tables for Japanese males and females in 1975. Data are from official registers and the 1975 census. "According to the tables, 87.

Potentiation of excitatory postsynaptic potentials during and after repetitive stimulation in thin hippocampal sections.

Excitatory postsynaptic potentials (EPSPs) elicited by mossy fiber stimulation were recorded intracellularly from neurons in the CA3 region in thin hippocampal sections in vitro and potentiation of the EPSPs was examined during and after repetitive stimulation. Inhibitory postsynaptic potentials (IPSPs) and seizure discharges were blocked by bicuculline and high concentrations of Mg2+. When two shocks were applied at short intervals, the second EPSP was markedly potentiated.

Dendritic spikes in Purkinje cells of the guinea pig cerebellum studied in vitro.

Extracellular spikes were recorded simultaneously from dendrites and somata of Purkinje cells in thin cerebellar sections. Spontaneously occurring dendritic spikes were biphasic with the initial phase positive. Triphasic dendritic spikes with a large negative phase appeared during electrophoretic application of glutamate.