Evidence for the involvement of Na+/Ca2+ exchange in the stimulation of inositol phospholipid hydrolysis by sodium channel activation and depolarization.

Amiloride, an inhibitor of the Na+/Ca2+ exchanger, blocked the hydrolysis of inositol phospholipids in mouse cerebrocortical slices induced by the sodium channel activator veratridine, by KCl, or by the sodium ionophore monensin; there was no inhibition by A 23187, a Ca2+ ionophore, or by serotonin. It is concluded that agents that increase intracellular Na2+ stimulate inositide hydrolysis by an indirect effect via Na+/Ca2+ exchange.

Regional distribution of brain calpastatin and of calpain II. Activity with casein and with endogenous brain protein substrates.

We examined the regional distribution in rat brain of calpain II, the calcium-activated neutral proteinase maximally active in the presence of 2mM Ca(2+), and of calpastatin, the endogenous inhibitor of the enzyme. A single-step chromatographic procedure was used to separate the constituents before determination. With [methyl-(14)C]?-casein as substrate, specific activity of calpain II was lowest in the cortex.

Developing concepts of cerebral amino acid uptake 1950-1970.

This issue of the journal honors Professor Henry McIlwain for his contributions to our knowledge of neurochemistry, as a pioneer (an important contributor already in the 1950s), as a scientist, and as a teacher of great influence and help to the next generation of neurochemists. It is fitting that in his semi-retirement he turns his interest to the history and background of our discipline and demonstrates to us that there is a great deal to learn from the past. In today's explosion of knowledge and new approaches, and the consequent rush to do the work, we tend to forget not only the important past accomplishments but also the past mistakes not to be repeated.

Effects of caffeine on amino acid transport in the brain.

Chronic administration of caffeine to mice did not alter cellular (low-affinity) transport as measured in brain slices of the amino acids ?-aminobutyric acid, glutamic acid, and glycine. Chronic caffeine administration did, however, increase the long-term (60-min) uptake of ?-aminoisobutyric acid and valine into brain slices. A similar tendency, although not statistically significant, towards increased amino acid uptake was also seen in the transport of phenylalanine and lysine across the blood-brain barrier in chronically treated rats.

Oxidative metabolism of cocaine: comparison of brain and liver.

Norcocaine (NC) and N-hydroxynorcocaine (NHNC), products of the oxidative metabolism of cocaine, were examined in plasma, brain, and liver of mice injected intraperitoneally with cocaine. Plasma levels of NHNC were altered in vivo by inhibiting esterase activity with diazinon and chloral hydrate or activating esterase activity with phenobarbital, and activating the microsomal P-450 system with phenobarbital. Changes in plasma concentrations of NHNC resulted in similar changes in brain, which were often different from those in liver.

Long-term blockade of the dopamine uptake complex by metaphit, an isothiocyanate derivative of phencyclidine.

[3H]Mazindol was used to label the dopamine uptake complex in mouse striatum in vitro in the presence and absence of metaphit, an isothiocyanate derivative of phencyclidine. In some experiments, metaphit was present in the incubation fluid throughout the procedure; in other experiments it was eliminated by several washings and centrifugations. It was found that after removal of the metaphit by washing and centrifugation, the mazindol binding was not restored.

Ascorbic acid inhibits [3H]SCH-23390 binding to striatal dopamine D1 receptors.

The present study describes the inhibition of [3H]SCH-23390 binding to striatal dopamine D1 receptors in the presence of ascorbic acid. Specific [3H]SCH-23390 binding was maximally inhibited by 0.1 mM ascorbic acid.

Diversity of rat brain cysteine proteinase inhibitors: isolation of low-molecular-weight cystatins and a higher-molecular weight T-kininogen-like glycoprotein.

Conditions for extraction of rat brain soluble and particulate cysteine proteinase inhibitors (CPIs) were compared and an optimal one was selected to isolate low- and high-molecular-weight forms active toward papain or brain cathepsins B/L. The different forms were purified by affinity chromatography on alkylated papain, and identified on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels by use of Schiff's reagent, or by immunoblots using antisera to monomer or polymeric forms of human urinary cystatin c, to a human plasma histidine-rich glycoprotein (HRG), or to rat plasma T-kininogen. In particulates containing nuclei (P1) or synaptosomes (P2) the predominant CPI was an 80-kDa glycoprotein cross-reacting to anti-HRG and shown to be a T-kininogen by treatment with TPCK-trypsin, and subsequent bioassay of the released kinins.

Effect of chronic oral nicotine on dopaminergic function in the MPTP-treated mouse.

Although epidemiological studies have suggested a lower incidence of Parkinson's disease in cigarette smokers, repeated exposure to cigarette smoke or nicotine does not protect against neurotoxicity induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Since there is some evidence that nicotinic antagonists, nicotine, and neurotransmitters may have tropic effects on neurite outgrowth, the present study examined the effects of chronic nicotine administration for 16 weeks (in drinking water; 5 mg/kg consumed per day) on the rate of terminal recovery after striatal lesioning with MPTP (2 x 30 mg/kg, s.c.

Evidence that there is no direct correlation between alpha 2-adrenoceptor antagonism and inhibition of voltage-dependent sodium channels.

Electrophysiological and biochemical evidence suggests that the voltage-dependent sodium channel is the site of local anesthetic action, and that there is pharmacological similarity between alpha-adrenoceptors and Na+-channels. Yohimbine, a non-selective alpha 2-adrenoceptor antagonist, with a structure similar to that of cocaine affects the sodium channel by a mechanism different from that of other local anesthetics including cocaine. Some structural analogues of yohimbine -berbane compounds- were found to be potent and selective alpha 2-adrenoceptor antagonists.

Aminothiols: synthesis and effect on chicken brain aminopeptidases.

An amino acid derivative, leucinethiol, was reported to be a strong inhibitor of aminopeptidase activity. In order to obtain selective inhibitors of various brain aminopeptidases, we tested the inhibition by amino acid analogs of brain aminopeptidase activity. In particular, we synthesized the trifluoroacetyl derivatives of phenylalaninol, tyrosinol, and leucinol; leucinethiol; and phenylalaninethiol and measured their effect on soluble puromycin-sensitive aminopeptidase S1 and SII purified in our laboratory.

Uptake of [3H]serotonin into plasma membrane vesicles from mouse cerebral cortex.

Preparations of plasma membrane vesicles were used as a tool to study the properties of the serotonin transporter in the central nervous system. The vesicles were obtained after hypotonic shock of synaptosomes purified from mouse cerebral cortex. Uptake of [3H]serotonin had a Na+-dependent and Na+-independent component.

3-Mercaptopropionic acid administration into the caudate-putamen of the rat provokes dyskinesia.

The unilateral administration of 3-mercaptopropionic acid (MPA) through an implanted guide cannula into the caudate-putamen produced dyskinesia in the rat. Striatal GABA and dopamine were decreased and the dopamine metabolites 3,4-dihydroxyphenylacetic and homovanillic acid were increased on the MPA-injected side at 2-10 min after the onset of dyskinesia. The dyskinetic movements were blocked by GABA or alpha-aminooxaloacetic acid but not by glycine or haloperidol.

Interaction of yohimbine with batrachotoxinin binding to mouse brain sodium channels.

To study the local anesthetic properties of yohimbine in more detail, its effect was examined in vitro on the scorpion toxin-enhanced specific binding of [3H]batrachotoxinin A 20-alpha-benzoate [( 3H]BTX-B) to the gating complex in sodium channel preparations from mouse brain cortex. Both equilibrium and kinetic experiments were carried out. Yohimbine inhibited the specific binding of [3H]BTX-B in the vesicular preparation with an IC50 value of 2.

The mode of action of ethanol on batrachotoxinin-A benzoate binding to sodium channels in mouse brain cortex.

Since ethanol has local anesthetic activity its effect was examined in vitro on the scorpion toxin-enhanced specific binding of [3H]batrachotoxinin A 20-alpha-benzoate ([3H]BTX-B) to the gating complex in sodium channel preparations from mouse brain cortex by equilibrium and kinetic experiments. Ethanol inhibited the specific binding of [3H]BTX-B in a vesicular preparation with an IC50 value of 310 mM and a Hill number of 1.0.

Metaphit prevents locomotor activation induced by various psychostimulants and interferes with the dopaminergic system in mice.

Metaphit, an isothiocyanate analog of phencyclidine and a proposed phencyclidine receptor acylator, inactivated the carrier involved in the neuronal uptake of dopamine in in vitro experiments with preparations of the striatum in the mouse. In ex vivo experiments 2 and 24 hr after the intravenous administration of metaphit, no changes were observed either in the binding of [3H]cocaine to striatal membranes or in the uptake of [3H]dopamine into synaptosomes or slices. In in vivo experiments 24 hr after pretreatment with metaphit, selective labelling of uptake sites for dopamine in the striatum of the mouse with [3H]GBR 12935 was unaffected.

Ascorbic acid and striatal transport of [3H] 1-methyl-4-phenylpyridine (MPP+) and [3H] dopamine.

The inhibition of uptake of [3H] dopamine and [3H] 1-methyl-4-phenylpyridine (MPP+) was examined in mouse striatal synaptosomal preparations. Kinetic analysis indicated that ascorbic acid is a noncompetitive inhibitor of [3H] MPP+ uptake. No inhibition of [3H] dopamine uptake is observed.

Rat brain cathepsin L: characterization and differentiation from cathepsin B utilizing opioid peptides.

The specificity of purified rat brain cathepsin L (EC 3.4.22.

Binding sites for [3H]tetracaine in synaptosomal sodium channel preparations from mouse brain.

The present study was an attempt to answer the question whether the local anesthetic [3H]tetracaine labels sodium channels in mouse brain synaptosomes. Binding of [3H]tetracaine had a Kd of 0.19 microM and a Bmax ranging from 3.

Cocaine disposition in the brain after continuous or intermittent treatment and locomotor stimulation in mice.

Intermittent s.c. and i.

Pharmacokinetics of systemically administered cocaine and locomotor stimulation in mice.

Cocaine and its metabolites were measured in plasma and brain from mice injected i.p. with cocaine and monitored for spontaneous locomotor behavior.

Behavioral and biochemical effects of nicotine in an MPTP-induced mouse model of Parkinson's disease.

This study examined the effects of nicotine on locomotor activity and on the level of dopamine (DA) and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum and olfactory tubercle of mice that had been treated with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP significantly lowered the spontaneous locomotor activity 1-2 weeks and 2 months after 2 injections of MPTP (30 mg/kg SC, 24 hr apart) in young adult (3 months) and old mice (22-24 months old). The effect of nicotine on locomotion was biphasic; an initial stimulation of locomotor (0-5 min after nicotine) followed by a depressant period lasting from 5 to 20 min after injection.

Effect of several amino acid phosphonates and related compounds on rat brain aminopeptidases.

N-Terminal sodium phosphonate derivatives Na3O3PCH2CONHR (R-Leu, Phe, or Tyr) and Na3O3PCH2CONHR-R (R-R = Leu-Phe, Phe-Leu, Phe-Phe, and Phe-Tyr) were synthesized. All showed no activity toward a soluble rat brain aminopeptidase. We could not prepare the corresponding N-2-phosphono-2,2-diphenylacetyl compounds (Na3O3PC(C6H5)2CONHR) by the same Arbusov reaction.