Publisher Correction: No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations.

The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata', authors Ehouarn Millour and Roland Young were missing from the ACS and NOMAD Science Teams list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.

No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations.

The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere, which-given methane's lifetime of several centuries-predicts an even, well mixed distribution of methane.

Diminished synaptosomal dopamine (DA) release and DA autoreceptor supersensitivity in schizophrenia.

Post-mortem brain regions of schizophrenics were investigated in comparison to matched controls regarding synaptosomal K(+)-stimulated [3H]DA release and its modulation by DA autoreceptors. Brain specimens were cryopreserved in liquid nitrogen until release experiments; synaptosomes from brain pieces preincubated with dimethylsulfoxide have unchanged ability for [3H]DA release and its autoreceptor-mediated inhibition after cryo-preservation. Release data were individually corrected for post-mortem delay back to the zero-time state based on [3H]DA release alterations after in situ preservation of rat heads.

Characterization of synaptosomal dopamine release in rat and human brain after post-mortem storage and cryopreservation.

In preparing pathobiochemical studies on [(3)H]dopamine (DA) release in post-mortem human brain, freezing methods were tested regarding their applicability for cryopreservation of brain tissue. An optimal method was to incubate pieces of the nucleus accumbens of rats or humans in 0.32 M sucrose containing 5% dimethylsulfoxide before freezing the brain material.

Putative interaction of presynaptic dopamine and serotonin receptors modulating synaptosomal tyrosine hydroxylase activity in the nucleus accumbens of rats.

Inhibition of synaptosomal tyrosine hydroxylase activity by dopamine (DA) autoreceptors and serotonin (5-HT) heteroreceptors was used as a functional measure for the receptor activity in the nucleus accumbens of rats. Kinetic analysis of the concentration dependence of inhibition with and without antagonists indicates that the sensitivity of the autoreceptor to DA is significantly increased by blockade of the 5-HT heteroreceptor and vice versa. The results provide evidence for autoreceptor-heteroreceptor interactions at the presynaptic membrane level on dopaminergic nerve terminals.

Influence of antipsychotics and serotonin antagonists on presynaptic receptors modulating the release of serotonin in synaptosomes of the nucleus accumbens of rats.

In the nucleus accumbens of rats the release of [3H]serotonin (5-HT) from superfused synaptosomes stimulated by 30 mM K+ was investigated. In the presence of 40 microM of the uptake inhibitor cocaine the release of [3H]5-HT was inhibited by 5-HT in a concentration-dependent manner (IC50 = 0.45 microM).

Characterization of synaptosomal dopamine uptake in post-mortem brain regions of schizophrenics.

The drug sensitivity of synaptosomal high-affinity dopamine (DA) uptake was investigated in post-mortem brain regions of schizophrenics, in comparison to controls matched for age, sex, and post-mortem delay, and in model experiments in rats. DA uptake was inhibited by nomifensine in the investigated regions of rat brain in a concentration-dependent manner; the regional rank order of inhibitory potency was: nucleus (n) caudatus greater than n. accumbens greater than frontal cortex.

Synaptosomal uptake and release of dopamine in rat striatum after hypoxia.

Hypoxia induces alterations of central monoaminergic transmission and of behavior. We studied the effect of hypoxia on adult and newborn rats to obtain more information about long-lasting changes of dopamine (DA) transmission caused by neonatal hypoxia. One single exposure of adult rats to hypoxia leads to short-term alterations of DA uptake: decreased affinity of the uptake carrier to DA (Km, 269.

[Effect of the atypical neuroleptics carbidine and sulpiride on dopamine biosynthesis in the synaptosomes of the nucleus accumbens septi in rats].

Neurochemical mechanisms of actions of atypical neuroleptics carbidine (a derivative of gamma-carboline) and sulpiride on dopamine (DA) biosynthesis in synaptosomes of the nucleus accumbens septi of the rat brain were studied. Carbidine caused a dose-dependent decrease of the animals' locomotor hyperactivity induced by apomorphine (1 mg/kg). Both carbidine and sulpiride administered in a dose of 5 mg/kg increased the activity of tyrosine hydroxylase in synaptosomes of the nucleus accumbens septi.

Influence of cholecystokinin on the synaptosomal dopamine uptake in the nucleus accumbens of rats.

The influence of the sulfated cholecystokinin octapeptide (CCK-8S) on the synaptosomal high-affinity [(3)H]dopamine (DA) uptake was investigated in the medial and lateral part of nucleus accumbens in rats. CCK-8S induced a concentration-dependent biphasic inhibition of [(3)H]-DA uptake in both subregions. After preincubation of CCK-8S with the synaptosomes the inhibitory effect was completely abolished.

Studies in postmortem dopamine uptake. II. Alterations of the synaptosomal catecholamine uptake in postmortem brain regions in schizophrenia.

Kinetic parameters KM and Vmax of the synaptosomal high-affinity dopamine (DA) and noradrenaline (NA) uptake were measured in the nucleus (n.) accumbens, n. caudatus and frontal cortex from post-mortem brains of schizophrenic patients and matched controls.

Studies in postmortem dopamine uptake. I. Kinetic characterization of the synaptosomal dopamine uptake in rat and human brain after postmortem storage and cryopreservation. Comparison with noradrenaline and serotonin uptake.

The effect of various post-mortem storage times and temperatures on the kinetic parameters of synaptosomal high-affinity dopamine (DA) uptake was studied in rat nucleus accumbens. After post-mortem storage up to 48 hours of rat heads in situ at 22 degrees C the KM data increase moderately in contrast to the Vmax data decreasing rapidly (t1/2 = 30 hours); at 2 degrees C similar changes were observed. The post-mortem changes of the kinetic parameters of noradrenaline (NA) and serotonin (5 HT) uptake were shown in this model to be similar.

[Regulation of 3H-dopamine release by presynaptic GABA and glutamate heteroreceptors in the synaptosomes of the rat nucleus accumbens].

The influence of GABA, muscimol, delta-aminolevulinic acid (DALA), baclofen and L-glutamate on K+-evoked release of 3H-dopamine (3H-DA) from the rat brain n. accumbens crude synaptosomal fraction was studied in superfusion experimental conditions. Both GABA-receptor agonists--GABA and muscimol (50 microM) depressed the 3H-DA release by bicuculline- and picrotoxin-sensitive manner.

Influence of antipsychotics on presynaptic receptors modulating the release of dopamine in synaptosomes of the nucleus accumbens of rats.

The release of preloaded [3H]dopamine (DA) from superfused synaptosomes stimulated by 30 mM K+ was investigated in the nucleus accumbens of rats. Under conditions preventing the uptake of DA (presence of 40 microM cocaine) release of [3H]DA was inhibited by DA and apomorphine in a concentration-dependent manner (IC50s 0.65 and 0.

Characterization of the synaptosomal high-affinity uptake of noradrenaline in the nucleus accumbens of rats.

In the nucleus (n.) accumbens, a predominantly dopaminergic innervated brain region, a high-affinity noradrenaline (NA) uptake exists indicating NA termination in this area. The affinity of the uptake carrier (Km) is in the range of that given for other regions.

Presynaptic dopamine and serotonin receptors modulating tyrosine hydroxylase activity in synaptosomes of the nucleus accumbens of rats.

Tyrosine hydroxylase (TH) activity was determined by measuring the formation of [3H]DOPA from [3,5-3H]tyrosine in the crude synaptosomal fraction of the nucleus accumbens under conditions preventing dopamine reuptake in 30 mM K+-containing medium. TH seems to be allosterically activated under depolarizing conditions: a 4.4 fold decrease of the Km value for tyrosine of the synaptosomal TH was observed.

Influence of psychotomimetics and lisuride on synaptosomal dopamine release in the nucleus accumbens of rats.

In superfusion experiments with a crude synaptosomal fraction from the nucleus accumbens of rats, lysergic acid diethylamide, mescaline and N,N-dimethyltryptamine (representing different chemical classes of psychotomimetics) produced a concentration-related inhibition of K+-evoked [3H]dopamine release whereas spontaneous release remained unchanged. The nonpsychotomimetic ergoline lisuride tested at the same concentration range did not modulate spontaneous or K+-evoked [3H]dopamine release. The inhibitory effects of the psychotomimetics tested were antagonized by equal concentrations of haloperidol or methiothepine.

Synaptosomal uptake and release of dopamine and 5-hydroxy-tryptamine in the nucleus accumbens in vitro following in vivo administration of lysergic acid diethylamide in rats.

The uptake and the depolarisation-induced release of dopamine (DA) and serotonin (5-HT) were investigated after systemic application of LSD on synaptosomes of the nucleus accumbens of rats. For the release experiments synaptosomes were prelabelled with [14C]-DA and [3H]-5-HT, respectively, and superfused with physiological and potassium-enriched (50 mM) solutions. Low doses of LSD (0.

Carbon dioxide fixation in the brain: its relation to glucose synthesis.

The incorporation in vivo of radiocarbon from 14C-bicarbonate in blood into relevant metabolites in rat brain is described. The animals, partially hepatectomized and nephrectomized, received the tracer bicarbonate via the intravenous route. The time course of label was followed in CO2 of blood and brain, in the anionic and cationic fractions of brain extract, in aspartate, glutamate, glutamine and in free glucose and in glycogen.

[Effect of increased plasma levels of glucose, adrenaline, and angiotensin upon glucose metabolism of totally ischemic and normally perfused rat brain].

Tracer kinetic studies on the effect of i.v. infused adrenaline and angiotensin, and a hyperglycemia induced by glucose application, upon glucose metabolism of the rat brain under ischemic and normoxic conditions are reported.