Milk metabolome reveals pyrimidine and its degradation products as the discriminant markers of different corn silage-based nutritional strategies.

The purpose of this study was to evaluate the effect of 6 different feeding systems (based on corn silage as the main ingredient) on the chemical composition of milk and to highlight the potential of untargeted metabolomics to find discriminant marker compounds of different nutritional strategies. Interestingly, the multivariate statistical analysis discriminated milk samples mainly according to the high-moisture ear corn (HMC) included in the diet formulation. Overall, the most discriminant compounds, identified as a function of the HMC, belonged to AA (10 compounds), peptides (71 compounds), pyrimidines (38 compounds), purines (15 compounds), and pyridines (14 compounds). The discriminant milk metabolites were found to significantly explain the metabolic pathways of pyrimidines and vitamin B6. Interestingly, pathway analyses revealed that the inclusion of HMC in the diet formulation strongly affected the pyrimidine metabolism in milk, determining a significant up-accumulation of pyrimidine degradation products, such as 3-ureidopropionic acid, 3-ureidoisobutyric acid, and 3-aminoisobutyric acid. Also, some pyrimidine intermediates (such as l-aspartic acid, N-carbamoyl-l-aspartic acid, and orotic acid) were found to possess a high discrimination degree. Additionally, our findings suggested that the inclusion of alfalfa silage in the diet formulation was potentially correlated with the vitamin B6 metabolism in milk, being 4-pyridoxic acid (a pyridoxal phosphate degradation product) the most significant and up-accumulated compound. Taken together, the accumulation trends of different marker compounds revealed that both pyrimidine intermediates and degradation products are potential marker compounds of HMC-based diets, likely involving a complex metabolism of microbial nitrogen based on total splanchnic fluxes from the rumen to mammary gland in dairy cows. Also, our findings highlight the potential of untargeted metabolomics in both foodomics and foodomics-based studies involving dairy products.

Dilated cardiomyopathy in mucolipidosis type 2.

Mucolipidosis II and III are lysosomal storage diseases caused by pathogenetic mutations in GNPTAB and GNPTG genes which cause an impaired activity of the lysosomal hydrolase N-acetylglucosamine- 1-phosphotransferase, a key enzyme in the synthesis of the mannose-6-phosphate targeting signals on lysosomal enzymes. Patients with MLII alpha/beta present coarse facial features, cessation of statural growth, important skeletal manifestations, impaired neuromotor development and cardiorespiratory involvement. All children appear to have cardiac involvement, but severe dilated cardiomyopathy is uncommon. In this report we describe the case of an 11-month-old girl who is affected by a MLII. Analysis of the GNPTAB gene identified at a heterozygous level the previously described gene variants c. 2693delA p(Lys898Serfs*13) and c. 2956C>T p(Arg986Cys). Her main clinical features were coarse face with gingival hypertrophy, dysostosis multiplex, recurrent respiratory infection and an early onset of dilated cardiomyopathy, an uncommon feature for MLII. To our knowledge, dilated cardiomyopathy has been previously described in literature in only two cases of MLII and in one patient affected by MLIII.

Immunization with DISC1 protein in an animal model of ADHD influences behavior and excitatory amino acids in prefrontal cortex and striatum.

The Disrupted-in-schizophrenia 1 (DISC1) gene is involved in vulnerability to neuropsychiatric disorders. Naples high-excitability (NHE) rat model neuropsychiatric problems characterized by an unbalanced mesocortical dopamine system. Here, we assessed behavioral and neurochemical effects of immunization against multimeric rat DISC1 protein in adult NHE rats, an animal model of attention-deficit hyperactivity disorder and their Random-Bred (NRB) controls. Males of both lines received subcutaneous injections of vehicle (PB), adjuvant only (AD) or recombinant rat DISC1 protein purified from E. coli, suspended in AD (anti-DISC1) at age of 30, 45 and 60 postnatal days (pnd). At 75 pnd, the rats were exposed to a Làt maze and 2 days later to an Olton eight-arm radial maze, and horizontal (HA) and vertical activities (VA) were monitored. Non-selective (NSA) and selective spatial attention (SSA) were monitored in the Làt and in the Olton maze by duration of rearings and working memory, respectively. Post mortem neurochemistry in the prefrontal cortex (PFc), dorsal (DS) and ventral (VS) striatum of L-Glutamate, L-Aspartate and L-Leucine was performed. All immunized rats showed a clear humoral IgM (but not IgG) immune response against the immunogen, indicating that immunological self-tolerance to DISC1 can be overcome by immunization. NHE rats exhibited a higher unspecific IgM response to adjuvant, indicating an immunological abnormality. The sole anti-DISC1 immunization-specific behavioral in the NHE rats was an increased horizontal activity in the Làt maze. Adjuvant treatment increased vertical activity in both lines, but in the NRB controls it increased rearing and decreased horizontal activity. Liquid chromatography/tandem mass spectrometry analysis of soluble or membrane-trapped neurotransmitters aspartate, glutamate and leucine revealed increased soluble aspartate levels in the ventral striatum of NRB controls after anti-DISC1 immunization. Immune activation by adjuvant independent of simultaneous DISC1 immunization led to other specific changes in NHE and control NRB rats. In DISC1-immunized NHE rats, horizontal activity in Lat maze correlated with membrane-trapped glutamate in PFc and in the NRB rats, duration of rearing in Olton maze correlated with membrane-trapped glutamate in PFc and aspartate in dorsal striatum. In addition to non-specific immune activation (by AD), the postnatal anti-DISC1 immune treatment led to behavioral changes related to mechanisms of activity and attention and had influenced amino acids and synaptic markers in striatum and neocortex in the adult NHE as well as control animals.

Results from a large multinational clinical trial (guardian™3) using prophylactic treatment with turoctocog alfa in paediatric patients with severe haemophilia A: safety, efficacy and pharmacokinetics.

Recombinant factor VIII (rFVIII) products provide a safe and efficacious replacement therapy for prophylaxis and treatment of bleeding episodes in patients with severe haemophilia A. This multinational, open-label, non-controlled trial investigated the safety, efficacy and pharmacokinetics (PK) of turoctocog alfa, a new rFVIII product, in a paediatric population. The primary objective was to evaluate safety. A total of 31 younger children (0-5 years) and 32 older children (6-11 years), with ≥ 50 exposure days to any factor VIII (FVIII) product and no history of inhibitors, received prophylaxis with turoctocog alfa (25-50 IU kg(-1) every second day or 25-60 IU kg(-1) three times weekly). PK assessments of turoctocog alfa and the patients' previous FVIII product were performed in 28 patients. Mean exposure to turoctocog alfa was 60 exposure days per patient. This corresponds to approximately 4.5 months in the trial. None of the patients developed inhibitors (≥ 0.6 BU) and no safety concerns were raised. A total of 120 bleeding episodes (95%) were controlled with 1-2 infusions of turoctocog alfa. Based on patient reports, the success rate (defined as 'excellent' or 'good' haemostatic response) for treatment of bleeding episodes was 92%. Overall, the median annualized bleeding rate was 3.0 (interquartile range: 8.5) bleeds patient(-1) year(-1) . PK parameters were comparable between the two age groups. In conclusion, the present large global clinical trial showed that turoctocog alfa was safe, effective in treatment of bleeding episodes and had a prophylactic effect in paediatric patients.

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties.

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer-ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical-chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.

Advances in modelling alpha-synuclein-induced Parkinson's diseases in rodents: Virus-based models versus inoculation of exogenous preformed toxic species.

Aggregates of alpha-synuclein (αSyn) have been described in Parkinson's disease (PD) patients, and recent evidence has suggested that the most toxic αSyn species in PD are small soluble aggregates including oligomers, prefibrils, protofibrils. The physiological function of αSyn is still highly debated, with a possible role in synaptic vesicle trafficking and release at the presynaptic compartment, and in the regulation of gene expression in the nucleus. Emerging evidence indicate that most of αSyn functions are related with the crucial ability to bind biological membranes, which is associated with structural conversion from a disordered monomer to an α-helical enriched structure. Conformational properties of αSyn can be modulated by a number of factors including post-translational modifications, gene duplication and triplication-driven overexpression, single point mutations, environmental changes, which affect membrane binding and the protein propensity to aggregate in toxic species. The recognized toxic role of αSyn in PD has laid the rational for purposing of αSyn-based, neuropathologically relevant preclinical models of PD. Different approaches have led to the establishment of transgenic models, viral vector-based models, and more recently models based on the intracerebral inoculation of exogenous αSyn preformed fibrils/oligomers. Here, we overview and compare viral vector-based models of αSyn overexpression and models obtained by direct intracerebral infusion of in vitro preformed αSyn species. The advantages and pitfalls associated with these different approaches are discussed.

Galactosylated dopamine enters into the brain, blocks the mesocorticolimbic system and modulates activity and scanning time in Naples high excitability rats.

Pathological conditions, such as Parkinson's disease and attention deficit hyperactivity disorder, have been linked to alterations of specific dopamine (DA) pathways. However, since exogenous DA does not cross the blood-brain barrier, DA levels can be modulated e.g. by DA precursors or DA reuptake blockers. Hereby histochemical, analytical and behavioral evidence shows that a galactosylated form of DA (GAL-DA) carries DA into the brain, thus modulating activity and nonselective attention in rats. To this aim adult male rats of the Naples high-excitability (NHE) and random bred controls (NRB) lines were given a single i.p. injection of GAL-DA (10 or 100 mg/kg). Three hours later the behavior was videotaped and analyzed for horizontal activity, orienting frequency and scanning duration. The dose of 100 mglkg of GAL-DA reduced by 25% the horizontal activity in NHE rats, mainly in the first part of the testing period. No effect was observed on orienting frequency or on scanning duration. However, GAL-DA 100 mg/kg was associated with longer rearing episodes in the second part of the testing period in NHE rats. In parallel experiments histochemistry with a galactose-specific lectin showed 10% increase in galactose residues into the striatum between 0.5 and 3.0 h. To quantify the level of GAL-DA, its metabolite DA-succinate and DA in the prefrontal cortex, neostriatum, and cerebellum, rats were killed 2.0 h after the injection of prodrug. Mass high performance liquid chromatography (HPLC) was used for analysis of GAL-DA and DA succinate whereas electrochemical HPLC for DA. Both HPLC techniques demonstrate that GAL-DA carries and releases DA into the brain. Specifically 100 mg/kg of GAL-DA increased DA level in the striatum in the NHE rats only. Moreover, DA in the mesencephalon (MES) was correlated positively with striatal and prefrontal cortex DA in NHE rats. In contrast DA in the MES was negatively correlated with striatal DA in NRB. GAL-DA disrupted these correlations in both rat lines. Thus, this new DA prodrug may modify DA neurotransmission and might have a potential clinical application.

Galactosilated dopamine increases attention without reducing activity in C57BL/6 mice.

Different strategies can be used to carry dopamine into the brain such as L-Dopa precursors or galactosilated form of DA (GAL-DA). The aim of this study was to investigate whether GAL-DA would reduce hyperactivity and increase non-selective attention (NSA) in a mouse model of attention deficit hyperactivity disorder (ADHD), as, i.e. C57BL/6 as did in NHE rats. Here we report that GAL-DA increases NSA in a spatial novelty in C57BL/6 mice. They received a single i.p. injection of GAL-DA (10 mg/kg or 100 mg/kg) or equimolar galactose vehicle. Another mouse strain the Swiss albino was introduced as inbred control group. Three hours after last injection mice were tested in a Làt-maze for 30-min. Behaviour was analyzed for horizontal (traveled distance) and vertical activity (orienting frequency and scanning durations) which shares cognitive and non-cognitive nature, respectively. Ten milligram per kilograms of GAL-DA, increases scanning duration in C57BL/6 mice. Thus a low dose of GAL-DA increases NSA without reducing hyperactivity in this mouse model of ADHD.

Nitric oxide and peroxynitrite platelet levels in women with small-for-gestational-age fetuses.

OBJECTIVE: The placenta produces reactive oxygen species (ROS) including nitric oxide (NO) and peroxynitrite (ONOO(-)) that have pronounced effects on placental function. Excessive ROS production may occur in pathological pregnancies, such as those complicated by small-for-gestational-age (SGA) fetuses. DESIGN: The aim of the present work was to study NO and ONOO(-) levels in platelets of pregnant women with SGA fetuses compared with a control group. SETTING AND POPULATION: The study was performed on 30 pregnant women with SGA fetuses (SGA group) and on 30 healthy pregnant women (appropriate-for-gestational-age [AGA] group) matched for maternal and gestational age. All women included in this study were in the third trimester of pregnancy. METHODS: Platelets were isolated by differential centrifugation. NO metabolites, after enzymatic conversion followed by the Griess reaction, were measured as nitrite by spectrophotometric detection. Peroxynitrite (ONOO(-)) levels were evaluated using the fluorescence probe 2,7-dichlorofluorescein diacetate (DCFDA). MAIN OUTCOME MEASURES: The following determinations were made: platelet nitric oxide and peroxynitrite levels in the SGA group and controls; inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS) and nitrotyrosine (N-Tyr) expression in the same groups. RESULTS: Our results show that both platelet NO and ONOO(-) levels were significantly higher in the SGA group than in the controls. CONCLUSION: Increased platelets levels of nitric oxide and peroxynitrite might play a role in the pathophysiology of intrauterine growth restriction. Further investigations are in progress to clarify if these molecules are pathogenetic factors, an epiphenomenon or a pathophysiological marker.

Enhanced limbic/impaired cortical-loop connection onto the hippocampus of NHE rats: Application of resting-state functional connectivity in a preclinical ADHD model.

Due to a hyperfunctioning mesocorticolimbic system, Naples-High-Excitability (NHE) rats have been proposed to model for the meso-cortical variant of attention deficit/hyperactivity disorder (ADHD). Compared to Naples Random-Bred (NRB) controls, NHE rats show hyperactivity, impaired non-selective attention (Aspide et al., 1998), and impaired selective spatial attention (Ruocco et al., 2009a, 2014). Alteration in limbic functions has been proposed; however, resulting unbalance among forebrain areas has not been assessed yet. By resting-state functional Magnetic-Resonance Imaging (fMRI) in vivo, we investigated the connectivity of neuronal networks belonging to limbic vs. cortical loops in NHE and NRB rats (n=10 each). Notably, resting-state fMRI was applied using a multi-slice sagittal, gradient-echo sequence. Voxel-wise connectivity maps at rest, based on temporal correlation among fMRI time-series, were computed by seeding the hippocampus (Hip), nucleus accumbens (NAcc), dorsal striatum (dStr), amygdala (Amy) and dorsal/medial prefrontal cortex (PFC), both hemispheres. To summarize patterns of altered connection, clearly directional connectivity was evident within the cortical loop: bilaterally and specularly, from orbital and dorsal PFCs through dStr and hence towards Hip. Such network communication was reduced in NHE rats (also, with less mesencephalic/pontine innervation). Conversely, enhanced network activity emerged within the limbic loop of NHE rats: from left PFC, both through the NAcc and directly, to the Hip (all of which received greater ventral tegmental innervation, likely dopamine). Together with tuned-down cortical loop, this potentiated limbic loop may serve a major role in controlling ADHD-like behavioral symptoms in NHE rats.

Stimulation of in vivo dopamine transmission in the bed nucleus of stria terminalis by reinforcing drugs.

Drugs of abuse preferentially increase dopamine transmission in the shell of the nucleus accumbens. This area is considered as a transition between the striatum and the extended amygdala a complex neural system that includes the central amygdala and the bed nucleus of stria terminalis, areas that, like the nucleus accumbens shell, are heavily innervated by mesolimbic dopamine neurons originating in the ventral tegmental area. Given the anatomical and neurochemical relationships and similarities with the nucleus accumbens shell it was of interest to investigate whether the dopamine transmission of the bed nucleus of stria terminalis shares with the accumbens shell the peculiar responsiveness to drugs of abuse. To this end we studied by microdialysis with concentric probes, the effect of drugs of abuse on extracellular dopamine in the bed nucleus of stria terminalis. We report that morphine, nicotine, cocaine, ethanol, and the selective dopamine uptake inhibitor GBR 12909 increase effectively and dose dependently extracellular dopamine in the bed nucleus of stria terminalis. These results indicate that the bed nucleus of stria terminalis shares with the nucleus accumbens shell a peculiar sensitivity to the dopamine stimulant actions of drugs of abuse.

Cocaine and amphetamine increase extracellular dopamine in the nucleus accumbens of mice lacking the dopamine transporter gene.

Behavioral and biochemical studies suggest that dopamine (DA) plays a role in the reinforcing and addictive properties of drugs of abuse. Recently, this hypothesis has been challenged on the basis of the observation that, in mice genetically lacking the plasma membrane dopamine transporter [DAT-knock out (DAT-KO)], cocaine maintained its reinforcing properties of being self-administered and inducing place preference, despite the failure to increase extracellular dopamine in the dorsal striatum. Here we report that, in DAT-KO mice, cocaine and amphetamine increase dialysate dopamine in the medial part of the nucleus accumbens. Moreover, reboxetine, a specific blocker of the noradrenaline transporter, increased DA in the nucleus accumbens of DAT-KO but not of wild-type mice; in contrast, GBR 12909, a specific blocker of the dopamine transporter, increased dialysate dopamine in the nucleus accumbens of wild-type but not of DAT-KO mice. These observations provide an explanation for the persistence of cocaine reinforcement in DAT-KO mice and support the hypothesis of a primary role of nucleus accumbens dopamine in drug reinforcement.

Increase of dialysate dopamine in the bed nucleus of stria terminalis by clozapine and related neuroleptics.

Neuroleptics are known to stimulate dopamine release in neostriatal terminal areas. In the present study, we have investigated by brain microdialysis in freely moving rats the effect of typical and atypical neuroleptics on dopamine transmission in the bed nucleus of stria terminalis, a dopamine terminal area belonging to the limbic system and recently assigned the so-called extended amygdala. Mean basal dialysate dopamine values were 14.3 f moles/20 microliters sample. Dopamine output in dialysates was increased dose-dependently by clozapine (max + 158%, 298%, and 461% of basal at 5, 10, and 20 mg/kg i.p., respectively), risperidone (max + 115% and 221% of basal at 1 and 3 mg/kg i.p., respectively), olanzapine (max + 138% and 235% of basal at 3 and 6 mg/kg i.p., respectively), BIMG 80 (max + 64% and 164% of basal at 3 and 5 mg/kg i.p., respectively), amperozide (max + 110% and 194% of basal at 3 and 6 mg/kg i.p., respectively). The selective dopamine D4 antagonist L-745,870 increased dialysate dopamine but at rather high doses and not as effectively as clozapine (max + 32%, 89%, and 130% of basal at 2.7, 5.4, and 10.8 mg/kg i.p., respectively). The typical neuroleptic haloperidol (0.1 and 0.5 mg/kg s.c.) and the selective D2 antagonist raclopride (0.14, 0.56, and 2.1 mg/kg s.c.), the serotonergic 5-HT2 antagonist ritanserin (0.5 and 1.5 mg/kg i.p.), and the adrenergic alpha 1 antagonist prazosin (0.91 and 2.73 mg/kg i.p.) did not affect dialysate dopamine in the bed nucleus of stria terminalis. Saline (1 ml/kg s.c. or 3 ml/kg i.p.) did not modify dialysate dopamine. Therefore, atypical neuroleptics share the ability of stimulating dopamine transmission in the bed nucleus of stria terminalis, but this property is not mimicked by any of the drug tested that selectively act on individual receptors among those that are affected by atypical neuroleptics. These observations raise the possibility that the property of increasing dopamine transmission in the bed nucleus of stria terminalis is the result of combined blockade of dopamine, serotonin, and noradrenaline receptors and that might be predictive of an atypical neuroleptic profile.

Dihydropyridines change the uptake of calcium induced by depolarization into primary cultures of cerebellar granule cells.

The uptake of calcium (Ca++) into cerebellar granule cells in primary culture was increased by depolarizing the cells with either 60 mM KC1 or veratridine. Nitrendipine, at concentrations of 100 nM or greater, antagonized approximately 40 percent of the depolarization induced Ca++ uptake. The half maximal concentration of nitrendipine was 7nM. Furthermore, another dihydropyridine derivative, BAY K 8644 enhanced the uptake of Ca++ and in the presence of nitrendipine, this facilitation of Ca++ uptake was reduced. Thus, these data indicate the existence of voltage dependent Ca++ channels which are sensitive to dihydropyridines in primary cultures of cerebellar granule cells.

Serotonin release estimated by transcortical dialysis in freely-moving rats.

The transcerebral dialysis method has been utilized for measuring extracellular brain concentrations of serotonin and 5-hydroxyindolacetic acid. Dialysis fibres were implanted transversally in the rat frontal cortex and perfused by Ringer. Serotonin and 5-hydroxyindolacetic acid were quantified by reverse phase high performance liquid chromatography with electrochemical detection. Experiments were performed in freely-moving rats 20-24 h after the implant of the fibre. Basal output of serotonin and 5-hydroxyindolacetic acid was 0.12 and 22.8 pmol in 20 min, respectively. The output of serotonin was calcium-dependent and tetrodotoxin-sensitive (1 micron in the Ringer) while was stimulated by veratridine (50 microns) and by high concentrations of K+ (60 and 100 mM). Serotonin output was increased in a concentration-dependent manner by chlorimipramine (1-10 microM) in the Ringer; this drug stimulated serotonin release also when administered s.c. (20 mg/kg) in a tetrodotoxin-sensitive manner. The irreversible monoamine-oxidase inhibitor pargyline (75 mg/kg, i.p.) strongly stimulated serotonin output while reduced 5-hydroxyindolacetic acid output. A proposed serotonin releaser, fenfluramine (25 mg/kg, s.c.), stimulated serotonin release and this effect was strongly potentiated by local application of tetrodotoxin (1 microM). Agonists of serotonin receptors such as lisuride (0.03 mg/kg, s.c.), 8-hydroxy-2-(di-n-propilamino)tetraline (0.25 mg/kg, s.c.) and 5-methoxy 3(1,2,3,6-tetrahydro-4-pyridinil)-1H indole succinate (1 mg/kg, s.c.) reduced serotonin release. It appears that brain dialysis is a suitable method for the study of serotonin release in the cortex of freely-moving rats.

Amphetamine, cocaine, phencyclidine and nomifensine increase extracellular dopamine concentrations preferentially in the nucleus accumbens of freely moving rats.

The effect of systemically administered amphetamine, cocaine, phencyclidine and nomifensine on the extracellular concentrations of dopamine in freely moving rats was estimated by microdialysis in the nucleus accumbens and in the dorsal caudate. All the drugs tested stimulated dopamine output in both areas but more effectively in the accumbens as compared to the caudate. Low doses of cocaine (1.0 mg/kg s.c.) stimulated dopamine output only in the nucleus accumbens. Nomifensine (1.25-5.0 mg/kg s.c.) increased by a similar extent peak dopamine output in the two dopaminergic areas but the duration of the effect was longer in the accumbens as compared to the caudate. The effect of cocaine, phencyclidine and nomifensine was prevented by systemic gamma-butyrolactone (700 mg/kg i.p.) and by omitting Ca2+ from the Ringer used for dialysis, the effect of amphetamine was insensitive to these manipulations. Thus, in contrast with amphetamine, cocaine, phencyclidine and nomifensine increase synaptic dopamine concentrations in vivo by a mechanism which depends on intact activity of dopaminergic neurons and by an exocytotic process.

Stimulation of dopamine transmission in the dorsal caudate nucleus by pargyline as demonstrated by dopamine and acetylcholine microdialysis and Fos immunohistochemistry.

The effect of pargyline on dopamine neurotransmission was investigated by trans-striatal microdialysis combined with Fos immunohistochemistry. Pargyline, 75 mg/kg i.p., increased dopamine and acetylcholine output while drastically decreased dopamine deaminated metabolites. Administration of pargyline resulted in the appearance of Fos-positive nuclei distributed along a gradient around the dialysis probe. Pretreatment with the D1 antagonist SCH 23390 potentiated the effect of pargyline on dopamine output while preventing that on acetylcholine output and on Fos formation. Similarly, lack of calcium in the perfusion medium abolished the effect of pargyline on dopamine and acetylcholine output and on Fos formation. In rats not implanted with dialysis probes pargyline administration resulted in only rare Fos-positive nuclei in the dorsal caudate. The present study indicates that pargyline stimulates dopamine transmission in the dorsal caudate in the area around the dialysis probe but not distant from the fibre or in unimplanted rats. This effect appears to reflect an interaction between the drug-induced changes and those locally elicited by the probe.

On the preferential release of dopamine in the nucleus accumbens by amphetamine: further evidence obtained by vertically implanted concentric dialysis probes.

Concentric dialysis probes were vertically implanted in rats in the nucleus accumbens (Acc) of one side and in the dorsal caudate-putamen (CPu) of the other side. On the day after the implant the output of dopamine was monitored and the changes elicited by d-amphetamine sulphate were compared in the two areas. Amphetamine preferentially stimulated dopamine release in the Acc in a wide range of doses (0.25, 0.5, 1.0, 2.0 mg/kg SC) when Acc probes were located in the medial aspect of the Acc. In contrast, no significant differences between the Acc and the dorsal CPu were obtained in response to amphetamine (0.5 mg/kg SC) when Acc probes were located about 0.7 mm lateral to the previous site. It is concluded that the preferential effect of amphetamine in the Acc is related to precise topographical boundaries. This in turn might be related to the existence of a sharp anatomical and functional heterogeneity within the Acc.

SCH 23390 blocks drug-conditioned place-preference and place-aversion: anhedonia (lack of reward) or apathy (lack of motivation) after dopamine-receptor blockade?

The influence of the D1 antagonist SCH 23390 on the motivational properties of rewarding (morphine, nicotine and diazepam) and aversive (naloxone, phencyclidine and picrotoxin) drugs was studied in the rat in a two-compartment place-conditioning paradigm, which included a pre-conditioning test for spontaneous place-preference. The specific D1 dopamine-receptor antagonist SCH 23390 (0.05 mg/kg SC), paired with both compartments or, separately, with the preferred or with the non-preferred compartment, failed to affect the spontaneous unconditioned preference of the animal. Pairing of morphine (1.0 mg/kg SC), nicotine (0.6 mg/kg SC) or diazepam (1.0 mg/kg IP) with the less preferred compartment induced significant preference for that compartment. Pairing of SCH 23390 (0.05 mg/kg SC) with both compartments completely blocked the place-preference induced by morphine, nicotine and diazepam. Naloxone (0.8 mg/kg SC), phencyclidine (2.5 mg/kg SC) or picrotoxin (2.0 mg/kg IP) paired with the preferred compartment elicited place-aversion. Pairing of SCH 23390 (0.05 mg/kg SC) with both compartments abolished also the place-aversion induced by naloxone, phencyclidine and picrotoxin. The results indicate that blockade of dopamine transmission blocks the motivational properties of rewarding as well as aversive stimuli. It is suggested that neuroleptics rather than simply blocking the rewarding impact of positive reinforcers (anhedonia, lack of pleasure) exert a more general influence on conditioned behaviour by blocking the affective impact of negative as well as positive reinforcers (apathy, lack of motivation).