Open-label study with the monoamine stabilizer (-)-OSU6162 in myalgic encephalomyelitis/chronic fatigue syndrome.

OBJECTIVES: The purpose of the present study was to investigate the safety and tolerability of the monoaminergic stabilizer (-)-OSU6162 in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In addition, a potential therapeutic effect of (-)-OSU6162 in ME/CFS was evaluated by means of observer-rated scales and self-assessment rating scales. MATERIALS AND METHODS: In the current study using an open-label single-arm design ME/CFS patient received treatment with (-)-OSU6162 during 12 weeks. The patients received the following doses of (-)-OSU6162: 15 mg b.i.d. during the first 4-week period, up to 30 mg b.i.d. during the second 4-week period and up to 45 mg b.i.d. during the third 4-week period, with follow-up visits after 16 and 20 weeks. RESULTS: Out of 33 included patients, 28 completed the 12 weeks treatment period. (-)-OSU6162 was well tolerated; only one patient discontinued due to an adverse event. Vital signs and physical examinations showed no abnormal changes. Blood analyses showed an increase in serum prolactin. Therapeutically, improvements were seen on the Clinical Global Impression of Change scale, the FibroFatigue scale, the Mental Fatigue Scale, the Fatigue Severity Scale, Beck Depression Inventory, and the Short Form 36 Health Survey Questionnaire. CONCLUSIONS: (-)-OSU6162 is well tolerated in ME/CFS patients and shows promise as a novel treatment to mitigate fatigue and improve mood and health-related quality of life in ME/CFS. Obviously, the present results need to be confirmed in future placebo-controlled double-blind trials.

Effect of the monoaminergic stabiliser (-)-OSU6162 on mental fatigue following stroke or traumatic brain injury.

OBJECTIVE: The purpose of the present study was to evaluate the efficacy and safety of (-)-OSU6162 in doses up to 30 mg b.i.d. in patients suffering from mental fatigue following stroke or traumatic brain injury (TBI). METHODS: This 4 + 4 weeks double-blind randomised cross-over study included 30 patients afflicted with mental fatigue following a stroke or head trauma occurring at least 12 months earlier. Efficacy was assessed using the Mental Fatigue Scale (MFS), the Self-rating Scale for Affective Syndromes [Comprehensive Psychopathological Rating Scale (CPRS)], the Frenchay Activity Index (FAI), and a battery of neuropsychological tests. Safety was evaluated by recording spontaneously reported adverse events (AEs). RESULTS: There were significant differences on the patients' total FAI scores (p = 0.0097), the subscale FAI outdoor scores (p = 0.0243), and on the trail making test (TMT-B) (p = 0.0325) in favour of (-)-OSU6162 treatment. Principal component analysis showed a clear overall positive treatment effect in 10 of 28 patients; those who responded best to treatment had their greatest improvements on the MFS. Reported AEs were mild or moderate in severity and did not differ between the (-)-OSU6162 and the placebo period. CONCLUSION: The most obvious beneficial effects of (-)-OSU6162 were on the patients' activity level, illustrated by the improvement on the FAI scale. Moreover, a subgroup of patients showed substantial improvements on the MFS. Based on these observed therapeutic effects, in conjunction with the good tolerability of (-)-OSU6162, this compound may offer promise for treating at least part of the symptomatology in patients suffering from stroke- or TBI-induced mental fatigue.

Open study with (-)-OSU6162 in multiple sclerosis-related fatigue.

OBJECTIVES: The main objective of this study was to investigate the tolerability and safety of the monoaminergic stabilizer (-)-OSU6162 in patients with multiple sclerosis (MS). In addition, a potential therapeutic effect of (-)-OSU6162 with focus on MS-related fatigue was estimated by means of various self-assessment rating scales as well as a clinical investigator-rated scale. MATERIALS AND METHODS: In this open-label, single-arm study, 30 MS patients received treatment with the monoaminergic stabilizer (-)-OSU6162 during 12 weeks. The dose of (-)-OSU6162 was 15 mg twice daily during the first 4-week period, up to 30 mg twice daily during the second 4-week period and up to 45 mg twice daily during the third 4-week period, with follow-up visits after 16 and 20 weeks. MS-related fatigue was rated by the clinical investigator or by self-assessments, using mainly established rating scales. Twenty-five patients completed the study. RESULTS: (-)-OSU6162 was well tolerated by all patients, and no serious adverse events were observed. Therapeutically, improvements were observed with respect to fatigue and mood, as judged by ratings on the Mental Fatigue Scale (MFS), Short Form-36 (SF-36) scale and Beck Depression Inventory (BDI). Furthermore, the large majority of patients were rated as globally improved in the medical observers' rating scale Clinical Global Impression of Change (CGI-C). CONCLUSIONS: In view of its good tolerability, (-)-OSU6162 may offer a new treatment option for alleviating mental fatigue, as well as depression, in MS. Larger, randomized double-blind controlled trials are warranted to confirm the present preliminary observations.

I see you're in pain - The effects of partner validation on emotions in people with chronic pain.

Background and aims Chronic pain not only affects the person in pain, but can also have a negative impact on relationships with loved ones. Research shows that chronic pain is associated with difficulties in marital relationships, which in turn is related to a variety of negative outcomes such as psychological distress and conflict within the family. This suggests that couples where chronic physical pain is present also struggle with emotional pain and relationship problems, and thus targeting relationship skills and interpersonal functioning might be helpful for these couples. Although studies in this area are promising, their numbers are few. In the present study, validation as a way of communicating is suggested for handling emotional expression in interpersonal interactions. Validation communicates understanding and acceptance of the other person's experience, and it has been shown to have a down-regulating effect on negative emotions. It has previously been demonstrated to be important for these couples. However, the feasibility and effects of increasing partner validation in these couples are unknown. Therefore, the aim of the present study was to investigate if a brief training session in validation for spouses would result in more validating and fewer invalidating responses towards their partners with pain, and to investigate if changes in these behavioural responses were associated with changes in emotion and pain level in the partner with pain. Methods Participants were 20 couples where at least one partner reported chronic pain. The study employed a within-groups design in which spouses of people with pain received validation training (without their partner's knowledge), and their validating and invalidating responses were rated pre- and post-intervention using a reliable observational scale. Also, positive and negative affect and subjective pain level in the persons with pain were rated pre- and post-intervention. Results Results showed that the validation training was associated with increased validating and decreased invalidating responses in the partners. Their spouses with chronic pain reported a decrease in negative affect from pre- to post-training. Conclusions Our results indicate that the partner or closest family member, after brief validation training, increased validating responses and decreased invalidating responses towards the person with pain, which had an immediate positive impact on emotions in the other person. Implications This study suggests that using validation in interpersonal interactions is a promising tool for couples where chronic pain is present.

The dopamine stabilizer (-)-OSU6162 occupies a subpopulation of striatal dopamine D2/D3 receptors: an [(11)C]raclopride PET study in healthy human subjects.

(-)-OSU6162 is a dopamine stabilizer that can counteract both hyperdopaminergic and hypodopaminergic states. In this study, D2/D3 receptor occupancy of (-)-OSU6162 in the human brain was investigated using positron emission tomography (PET). Twelve male healthy volunteers underwent [(11)C]raclopride PET scanning before and 1 h after a single oral dose of (-)-OSU6162 (15-90 mg). Blood samples for determination of (-)-OSU6162 and prolactin plasma levels were collected at Tmax. Parametric images of [(11)C]raclopride binding potential relative to nondisplaceable tissue (cerebellar grey matter) uptake (BPND) at baseline and after (-)-OSU6162 administration were generated using the simplified reference tissue model. MRI-based regions of interest were defined for the striatum, composed of caudate nucleus and putamen, and projected onto the co-registered parametric [(11)C]raclopride BPND image. Furthermore, three striatal subregions, ie, anterior dorsal caudate, anterior dorsal putamen, and ventral striatum, were defined manually and additionally analyzed. Plasma concentrations of (-)-OSU6162, ranging from 0.01 to 0.9 µM, showed a linear relationship with prolactin levels, reflecting blockade of pituitary D2 receptors. A concentration-dependent increase in striatal D2/D3 receptor occupancy was observed, reaching a value of about 20% at an (-)-OSU6162 plasma level of 0.2 µM, and which for higher concentrations leveled off to a maximal occupancy of about 40%. Findings were similar in the striatal subregions. The present data corroborate the notion that (-)-OSU6162 binds preferentially to a subpopulation of D2/D3 receptors, possibly predominantly extrasynaptic, and this may form the basis for the dopamine-stabilizing properties of (-)-OSU6162.

The monoaminergic stabilizer (-)-OSU6162 reverses delay-dependent natural forgetting and improves memory impairment induced by scopolamine in mice.

The aim of the present study was to evaluate the effect of the monoaminergic stabilizer (-)-OSU6162 on spatial recognition memory. Male NMRI mice were tested in the object location model which is based on the animals' inherent interest to examine changes in their environment: The animals' propensity to explore relocated objects in relation to unaltered objects, presented in two different sessions (sample and trial), was studied. In a first series of experiments the effect of (-)-OSU6162 on natural forgetting was evaluated. With an inter-session interval (ISI) of 30 min or an hour, untreated mice spent longer time exploring the displaced object, but when the time between sessions was as long as 6 h, the mice did not identify the displaced object. However, using the 6 h ISI design we found that (-)-OSU6162 in doses up to 30 µmol/kg, given directly after the sample session, caused an increased interest for the displaced object. Twenty-four hours after administration, (-)-OSU6162 was still effective in facilitating identification of the displaced object. We also evaluated the effect of (-)-OSU6162 on scopolamine-induced memory deficits in this model - the two agents were given 30 min before the sample session and the ISI was one hour. Under these conditions scopolamine induced a deficit in object location memory and this effect was counteracted by (-)-OSU6162. The data from the present study suggest that (-)-OSU6162 prolongs object location memory in normal mice and reverses scopolamine-induced memory deficits. (-)-OSU6162 might be a valuable drug candidate for memory deficits and other cognitive impairments.

I. In vivo evidence for partial agonist effects of (-)-OSU6162 and (+)-OSU6162 on 5-HT2A serotonin receptors.

The locomotor effects of (-)- and (+)-OSU6162 were evaluated in 'low activity' animals (reserpinized mice and habituated rats) and 'high activity' animals (drug-naive mice and non-habituated rats). Both enantiomers of OSU6162 had dual effects on behavior, stimulating locomotor activity in 'low activity' animals and inhibiting locomotor activity in 'high activity' animals. There were also certain differences between the two enantiomers in their behavioral profiles. The stimulatory effects of both enantiomers in reserpinized mice were blocked by the 5-HT2A selective antagonist M100907, but not by the D2-selective antagonists haloperidol or raclopride, or by the D1-selective antagonists SCH23390 or SCH39166. The stimulatory effect in mice was more pronounced for (+)- than for (-)-OSU6162. In drug-naive mice, both enantiomers of OSU6162 produced head twitches, albeit to a much lesser extent than DOI, and both enantiomers inhibited DOI-induced head twitches, the (-)-form more effectively so than the (+)-form. These results suggest that (-)- and (+)-OSU6162 are partial agonists on 5-HT2A receptors and that the (+)-form has a higher intrinsic activity than the (-)-form. At high doses, both enantiomers inhibited locomotor activity in drug-naive mice, with (-)-OSU6162 being more potent than (+)-OSU6162. Similarly, in high-active rats, both enantiomers inhibited locomotor activity, with the (-)-enantiomer being more potent than the (+)-enantiomer. Conversely, in habituated rats, both enantiomers stimulated locomotor activity, and here, as opposed to the case in low-active mice, (-)-OSU6162 was more effective than (+)-OSU6162. The stimulatory effects in habituated rats of both enantiomers could be antagonized with either haloperidol or M100907. Overall, these results indicate that the dual effects on behavior of (-)- and (+)-OSU6162 are mediated through D2 and 5-HT2A receptors, consistent with their in vitro functional selectivity profiles (see Burstein et al., accompanying paper). Thus, both enantiomers of OSU6162 seem to act as stabilizers not only on dopaminergic, but also on serotonergic brain signaling. These discoveries have important implications for the potential clinical utility of both compounds, as well as for several of their congeners.

II. In vitro evidence that (-)-OSU6162 and (+)-OSU6162 produce their behavioral effects through 5-HT2A serotonin and D2 dopamine receptors.

(-)-OSU6162 has promise for treating Parkinson's disease, Huntington's disease and schizophrenia. Behavioral tests evaluating the locomotor effects of (-) and (+)-OSU6162 on 'low activity' animals (reserpinized mice and habituated rats) and 'high activity' animals (drug naive mice and non-habituated rats) revealed that both enantiomers of OSU6162 had dual effects on behavior, stimulating locomotor activity in 'low activity' animals and inhibiting locomotor activity in 'high activity' animals. To elucidate a plausible mechanism of action for their behavioral effects, we evaluated the intrinsic actions of (-)- and (+)-OSU6162, and a collection of other antipsychotic and antiparkinsonian agents at 5-HT2A and D2 receptors in functional assays with various degrees of receptor reserve, including cellular proliferation, phosphatidyl inositol hydrolysis, GTPγS and beta-arrestin recruitment assays. We also tested for possible allosteric actions of (-)-OSU6162 at D2 receptors. Both enantiomers of OSU6162 were medium intrinsic activity partial agonists at 5-HT2A receptors and low intrinsic activity partial agonists at D2 receptors. (+)-OSU6162 had higher efficacy at 5-HT2A receptors, which correlated with its greater stimulatory activity in vivo, but (-)-OSU6162 had higher potency at D2 receptors, which correlated with its greater inhibitory activity in vivo. (-)-OSU6162 did not display any convincing allosteric properties. Both (+)- and (-)-OSU6162 were significantly less active at 27 other monoaminergic receptors and reuptake transporters tested suggesting that D2 and 5-HT2A receptors play crucial roles in mediating their behavioral effects. Compounds with balanced effects on these two receptor systems may offer promise for treating neuropsychiatric diseases.

Effects of the dopamine stabilizers (S)-(-)-OSU6162 and ACR16 on prolactin secretion in drug-naive and monoamine-depleted rats.

Dopaminergic stabilizers may be conceptualized as drugs with normalizing effects on dopamine-mediated behaviours and neurochemical events. (S)-(-)-OSU6162 (OSU6162) and ACR16 are two structurally related compounds ascribed such properties, principally because of their stabilizing effects on motor activity in rodents. Reports in the literature indicate possible partial D2 receptor agonist effects using various in vitro systems. This study aimed to measure D2 receptor antagonist and agonist effects of OSU6162 and ACR16 in vivo. To address this, we have studied the effects of both compounds on prolactin secretion in drug-naive and dopamine-depleted rats; dopamine depletion was induced by pretreatment with reserpine plus α-methyl-DL: -p-tyrosine. We find that OSU6162 and ACR16 both stimulate prolactin secretion in drug-naive rats with OSU6162 being considerably more potent and efficacious. Both compounds show a non-significant trend towards reversal of the increased secretion caused by dopamine depletion, whereas the D2 receptor antagonist haloperidol further increased prolactin secretion. Thus, this study suggests that OSU6162 and ACR16 act as D2 receptor antagonists under normal conditions in vivo, possibly with minor agonist effects in a state of dopamine depletion.

A 1H magnetic resonance spectroscopy study in adults with obsessive compulsive disorder: relationship between metabolite concentrations and symptom severity.

1H magnetic resonance spectroscopy (1H MRS) studies exploring brain metabolites, especially glutamine + glutamate (Glx), in obsessive compulsive disorder (OCD) are of vital interest for trying to understand more about the pathophysiology of OCD. Therefore, we conducted the present 1H MRS study with the aims of (1) comparing MRS metabolites in a group of adult patients with OCD and a group of healthy controls, and (2) examining the relationship between MRS metabolite concentrations and symptom severity in the patient group. Three brain regions were studied, the right caudate nucleus, the anterior gyrus cinguli and the occipital cortex bilaterally. Since multivariate analysis is a highly useful tool for extraction of 1H MRS data, we applied principal component analysis (PCA) and partial least square projection to latent structures (PLS) to the MRS data. PLS disclosed a strong relationship between several of the metabolites and OCD symptom severity, as measured with Yale-Brown obsessive-compulsive scale (YBOCS): the YBOCS score was found to be positively correlated to caudate creatine, Glx, glutamate, and choline compounds as well as occipital cortex myoinositol, and negatively correlated to occipital cortex Glx. The negative correlation between occipital cortex Glx and YBOCS was the most impressive. PCA did not reveal any tendency for a separation between the patients with OCD and controls with respect to MRS metabolites. The results are discussed in relation to corticostriatothalamocortical feedback and previous observations of poor visuospatial ability in OCD.

Adaptive properties and heterogeneity of dopamine D(2) receptors - pharmacological implications.

In this review, we focus on the marked adaptability of dopamine D(2) receptors to varying agonist levels and we discuss the extent to which this phenomenon can account for the heterogeneity of these receptors in regard to function and pharmacological responsiveness. We emphasize the significance of a distinction between synaptic and extrasynaptic receptors in this context. For example, the application of this dichotomy appears to shed new light on the various subgroups of antipsychotic drugs and the mechanisms underlying their different profiles.

Effects of (-)-OSU6162 and ACR16 on motor activity in rats, indicating a unique mechanism of dopaminergic stabilization.

Dopaminergic stabilizers can be defined as drugs that stimulate or inhibit dopaminergic signalling depending on the dopaminergic tone. (-)-OSU6162 and ACR16 appear to possess such a profile. They have been proposed to act as partial dopamine receptor agonists or as antagonists with preferential action on dopaminergic autoreceptors. Previous studies have shown either stimulation or inhibition of behaviour in response to (-)-OSU6162 and ACR16, which has been suggested to reflect their dual effects on dopaminergic signalling. The aims of the present work are to (1) examine the relation between behavioural response to these drugs and activity baseline, and (2) test the suggested mechanisms of action by means of close comparisons with the known partial D2-receptor agonists (-)-3-PPP and aripiprazole, and the D2 autoreceptor preferring antagonist amisulpride with respect to effects on behaviour. From the results of these experiments it can be concluded that: (1) The direction of the response to (-)-OSU6162 and ACR16 is dependent on activity baseline, which in turn, under physiological conditions, is determined primarily by test arena size of and degree of habituation to the environment. (2) The effects of (-)-OSU6162 and ACR16 cannot be explained on the basis of either partial dopamine receptor agonism or preferential dopamine autoreceptor antagonism. Nevertheless, the current data suggest at least two different D2-receptor-associated targets which mediate opposite effects on activity. This result fits in with a mechanism proposed from a recent in vitro study, according to which (-)-OSU6162 has a dual action on dopamine D2 receptors, (a) an allosteric effect causing an enhanced response to dopamine, and (b) the previously proposed orthosteric effect antagonizing the action of dopamine.

A dopaminergic deficit hypothesis of schizophrenia: the path to discovery.

In contrast to the conventional view of dopamine involvement in schizophrenia, which posits hyperactive dopaminergic transmission, we propose that for unknown developmental and/or biochemical reasons, a primary defect occurs in efficient, tight dopaminergic synaptic transmission, triggering feedback activation and receptor upregulation, and resulting in the well-characterized increase in dopaminergic tone. This hypothesis is driven by suggestive evidence for subpopulations of dopamine D2 receptors delivering contrasting forms of dopaminergic transmission: synaptic receptors, responsible for basic dopaminergic function and subject to effective feedback control, and poorly controlled extrasynaptic receptors partly responsible for the positive symptoms of psychosis. Since the primary defect is dopamine deficiency, we term this theory the dopaminergic deficit hypothesis of schizophrenia. It is currently informing clinical studies with novel partial dopamine antagonists (dopamine stabilizers) such as ACR16, which preferentially target extrasynaptic receptors while leaving synaptic transmission and basic dopamine function intact.

Glial-neuronal interactions are impaired in the schizophrenia model of repeated MK801 exposure.

Schizophrenia-mimicking compounds such as phencyclidine (PCP) and MK801 are antagonists at the N-methyl-D-aspartate (NMDA) receptor and produce the whole spectrum of positive, negative, and cognitive symptoms. This is one of the most important pillars of the hypoglutamatergic hypothesis of schizophrenia. Since the synthesis of glutamate and GABA in neurons is closely connected to astrocyte metabolism, the study of astrocytic function is essential in this context. Dizocilpine-maleate (MK801) (0.5 mg/kg) was injected into rats every day for 6 days. The last dose was given together with [1-(13)C]glucose and [1,2-(13)C]acetate. Extracts from frontal, retrosplenial, and cingulate cortices (CRFC) and temporal lobes were examined by (13)C nuclear magnetic resonance spectroscopy, high pressure liquid chromatography, and light microscopy. In CRFC, significant increases in the levels of glutamate, glutathione, and taurine were seen, whereas amounts and turnover of noradrenaline, dopamine, and serotonin were unchanged. Glutamate and glutamine, derived from [1,2-(13)C]acetate and thus astrocytes, were significantly decreased in CRFC as compared to controls. Labeling from [1-(13)C]glucose and thus mostly neuronal metabolism was affected in the same brain region with decreased labeling of glutamate and GABA. The present model mimics the increased glutamate/glutamine activity found in drug-naive patients with first episode schizophrenia. Moreover, the decreased labeling indicates the transition to lower glutamatergic function seen in chronic schizophrenia patients. The disturbance in astrocytic function and the glutamine-glutamate-GABA cycle are of significant importance and might add to the malfunction of the cortico-striato-thalamo-cortical loop caused by NDMA receptor blockade.

Differential effects of classical neuroleptics and a newer generation antipsychotics on the MK-801 induced behavioural primitivization in mouse.

Cognitive dysfunction plays an important role in mental disorders like schizophrenia and may involve inadequate glutamatergic signalling in different regions of the brain, mediated by e.g. glutamatergic N-methyl-D-aspartate (NMDA) receptors. In rodents, NMDA receptor antagonists often increase motor activity; in addition they induce a more primitive and undifferentiated behavioural pattern, which we believe may correspond to some of the cognitive defects seen in schizophrenia. In the present study, the movement pattern of mice treated with the uncompetitive NMDA receptor antagonist MK-801 in conjunction with six antipsychotic agents, some with reported clinical effects on cognition, was characterised and quantified. The classical neuroleptic drugs chlorpromazine and trifluoperazine, the atypical antipsychotic agents ziprasidone and olanzapine, the gamma-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-receptor potentiator CX516 and the serotonin (5-HT)2A-antagonist M100907 were tested. In accordance with previous observations, MK-801 was found to induce a primitive and monotonous behavioural pattern dominated by forward locomotion; spatial movements, the number of switches between the states moving and stationary, and rearing frequency were reduced. All test substances counteracted MK-801-induced hyperactivity, but differed in their ability to improve behavioural quality. Chlorpromazine and trifluoperazine were unable to restore behavioural diversity while ziprasidone, olanzapine, CX516 and M100907 restored it to varying degrees. A striking similarity in movement pattern was seen between the hypoglutamatergic mice treated with the AMPA-receptor agonist CX516, and those receiving the 5HT2A-antagonist M100907.

The dopaminergic stabilizers (-)-OSU6162 and ACR16 reverse (+)-MK-801-induced social withdrawal in rats.

Schizophrenia is manifested by positive and negative symptoms, as well as cognitive deficits. Most existing antipsychotic agents have poor effects on the negative symptoms of schizophrenia, thus emphasizing the necessity for developing new antipsychotic treatments. Dopaminergic stabilizers constitute one of the latest novelties in the quest for new antipsychotic drugs. Social withdrawal in rats, in response to treatment with NMDA-receptor antagonists such as (+)-MK-801, may be used to model negative symptoms. In this study we aimed to evaluate the dopaminergic stabilizers (-)-OSU6162 and ACR16, compared to haloperidol and clozapine, in a rat model for schizophrenia, focusing on (+)-MK-801 induced social withdrawal. Social behaviour and motor activity were assessed using a videotracking system, allowing automated analysis of the behaviour. Both (-)-OSU6162 and ACR16 were capable of restoring social behaviour, measured as proximity, to control level. These results indicate that these drugs may be effective in the treatments of negative symptoms.

(+)-MK-801 induced social withdrawal in rats; a model for negative symptoms of schizophrenia.

Dopaminergic agonists and NMDA-receptor antagonists form the basis for the dopamine and glutamate models of schizophrenia, respectively. In human subjects dopaminergic agonists evoke a psychosis resembling positive symptoms of schizophrenia, while NMDA-receptor antagonists produce both positive and negative symptoms. Consequently, the glutamate model may be considered the most complete of the two models. Alterations in animal behaviour, in response to amphetamine or NMDA-receptor antagonists, are widely used to model schizophrenia. NMDA-receptor antagonist induced social withdrawal in rat is an established model for negative symptoms of schizophrenia. In this study we have set up an automated method, based on video tracking, to assess social behaviour, motor activity and movement pattern in rats. This method was then used to evaluate the effects of amphetamine and the NMDA-receptor antagonist (+)-MK-801, administered as single intraperitoneal injections, on rat behaviour. Amphetamine caused significantly increased motor activity and a tendency towards stimulation of social interactions. (+)-MK-801 also stimulated motor activity, but induced a significant inhibition of social interactions. These results indicate that a single injection of (+)-MK-801 to rats models both positive and negative symptoms of schizophrenia. Amphetamine, in contrast, reflects only the positive symptoms of schizophrenia in this model.

Nicotine treatment of obsessive-compulsive disorder.

Following initial observations of marked effects of nicotine self-medication in a patient with obsessive-compulsive disorder (OCD), another four OCD patients were treated with nicotine for eight weeks in an open label fashion. Patients fulfilling DSM-IV criteria for OCD and with initial Yale-Brown Obsessive-Compulsive Scale (YBOCS) score>15 were included in the study. The patients were scored with YBOCS, Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), NIMH Global Obsessive-Compulsive Scale (NIMH) and Global Assessment of Functioning (GAF). Four of five patients receiving nicotine treatment displayed a favourable response with reductions in YBOCS scores. For these four patients, the nicotine chewing gum enabled a more adequate behaviour in stressful, OCD-eliciting, situations. We feel that these results are encouraging enough to warrant a larger, controlled study on nicotine treatment of OCD.

The dopaminergic stabiliser ACR16 counteracts the behavioural primitivization induced by the NMDA receptor antagonist MK-801 in mice: implications for cognition.

The Carlsson research group has developed a series of compounds capable of stabilising the dopamine system without inducing the deleterious hypodopaminergia that encumbers the currently used antipsychotic drugs. In the present study one of these dopaminergic stabilisers, ACR16, was tested in a mouse model for cognitive deficits of schizophrenia and autism. Since we believe that hypoglutamatergia is a key element in both schizophrenia and autism we used mice rendered hypoglutamatergic by treatment with the N-methyl-D-aspartate (NMDA) antagonist MK-801. MK-801 causes both hyperactivity and a behavioural primitivization. ACR16 attenuated the MK-801-induced hyperactivity and, in addition, caused a marked improvement of behavioural quality with a movement pattern approaching that of control animals. Since we believe that the impoverishment of the behavioural repertoire caused by MK-801 may correspond to the cognitive deficits seen in schizophrenia and autism, these results suggest that ACR16 may improve cognitive status in these disorders.