Muscarinic Cholinergic System Research Articles

ICV orexin-a ameliorates long-lasting effects of early postnatal dysfunction of brain muscarinic cholinergic system on sleep-wakefulness cycle

ICV orexin-a ameliorates long-lasting effects of early postnatal dysfunction of brain muscarinic cholinergic system on sleep-wakefulness cycle

Chronic escalating-dose and acute binge cocaine treatments change the hippocampal cholinergic muscarinic system on drug presence and after withdrawal

Cocaine addiction is a relapsing disorder with loss of control in limiting drug intake. Considering the involvement of acetylcholine in the neurobiology of the disease, our aim was to evaluate whether cocaine induces plastic changes in the hippocampal cholinergic muscarinic system. Male Swiss-Webster mice received saline or cocaine (ip) three times daily (60-min intervals) either acutely or in an escalating-dose binge paradigm for 14 days. Locomotor activity was measured in all treatment days. Dopaminergic and cholinergic muscarinic receptors (D1R, D2R, M1-M5, mAChRs), choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT) and acetylcholinesterase (AChE) were quantified in the hippocampus by immunoblotting one hour after the last injection (on drug) or after 14 days of abstinence (withdrawal). Escalating-dose group showed cocaine-induced locomotor sensitization from day 2. M3 mAChR and ChAT significantly increased after the on-drug acute binge treatment. Escalating-dose on-drug group showed increased ChAT, M1, M5 mAChR and D2R; and decreased D1R. Acute-binge withdrawal group showed increased VAChT, M2 mAChR, D1R, and D2R; and decreased M1 mAChR. Escalating-dose withdrawal group presented increased D1R and VAChT and decreased M1 mAChR and D2R. Locomotor activity was negatively correlated with M1 mAChR and AChE in on-drug group and positively correlated with VAChT in withdrawal group. M1 mAChR was positively correlated with M2 mAChR and ChAT in on-drug group, whereas ChAT was positively correlated with M5 mAChR in withdrawal group. The results indicate that cocaine induced an increase in the hippocampal cholinergic tone in the presence of the drug, whereas withdrawal causes a resetting in the system.

Xanomeline and Trospium: Potential substitute for conventional antipsychotics.

Dear Madam, Schizophrenia is a chronic mental illness with a global prevalence of 24 million people (1). With paucity of researches mounting the exact prevalence of schizophrenia in Pakistan, the treatment of this illness becomes even harder to combat. This condition is typically managed with antipsychotics, which work by blocking the D2 dopamine receptors but recent advances in research also suggest that the muscarinic cholinergic system is also involved in its pathophysiology (2). The drug Xanomeline is an oral muscarinic cholinergic receptor agonist that activates M1 and M4 receptors. Xanomeline however causes side effects like vomiting, nausea, diarrhoea, sweating and hypersalivation. To bypass these effects, Trospium was added, which acts by blocking peripheral muscarinic cholinergic receptors. (3, 4). To observe the reduction of psychosis in schizophrenics, a double-blinded clinical trial was done with promising results: reduction of both, positive and negative symptoms of Schizophrenia, good tolerance and no evidence of weight gain (4). Side effects included constipation, nausea, dry mouth, dyspepsia, and vomiting although the incidence of these effects reduced over the course of the trial. However, there is a dearth of research when it comes to comparison of this combination drug (called KARXT) with the usual antipsychotics. Therefore, further research regarding the safety of KARXT, and its efficacy needs to be explored for potential amelioration of symptoms. Moreover, studies comparing the efficacy of this drug with the commonly used antipsychotics need to be explored in order to effectively assess the advantage and potential replacement benefits of this drug.

Relationship between plasma clozapine/N-desmethylclozapine and changes in basal forebrain-dorsolateral prefrontal cortex coupling in treatment-resistant schizophrenia

Clozapine (CLZ) demonstrates a unique clinical efficacy relative to other antipsychotic drugs. Previous work has linked the plasma ratio of CLZ and its major metabolite, N-desmethylclozapine (NDMC), to an inverse relationship with cognition via putative action on the cholinergic system. However, neuroimaging correlates of CLZ/NDMC remain unknown. Here, we examined changes in basal forebrain functional connectivity with the dorsolateral prefrontal cortex, and secondly, cognition in relation to the CLZ/NDMC ratio. A cohort of nineteen chronically ill participants with treatment-resistant schizophrenia (TRS) undergoing 12 weeks of CLZ treatment were included. Measures of cognition and plasma CLZ/NDMC ratios were obtained in addition to resting-state functional neuroimaging scans, captured at baseline and after 12 weeks of CLZ treatment. We observed a significant correlation between basal forebrain-DLPFC connectivity and CLZ/NDMC ratios across CLZ treatment (p = 0.02). Consistent with previous findings, we also demonstrate a positive relationship between CLZ/NDMC ratio and working memory (p = 0.03). These findings may reflect the action of CLZ and NDMC on the muscarinic cholinergic system, highlighting a possible neural correlate of cognition across treatment.

Normalization of impaired emotion inhibition in bipolar disorder mediated by cholinergic neurotransmission in the cingulate cortex

The muscarinic-cholinergic system is involved in the pathophysiology of bipolar disorder (BD), and contributes to attention and the top-down and bottom-up cognitive and affective mechanisms of emotional processing, functionally altered in BD. Emotion processing can be assessed by the ability to inhibit a response when the content of the image is emotional. Impaired regulatory capacity of cholinergic neurotransmission conferred by reduced M2-autoreceptor availability is hypothesized to play a role in elevated salience of negative emotional distractors in euthymic BD relative to individuals with no history of mood instability. Thirty-three euthymic BD type-I (DSM-V-TR) and 50 psychiatrically-healthy controls underwent functional magnetic resonance imaging (fMRI) and an emotion-inhibition paradigm before and after intravenous cholinergic challenge using the acetylcholinesterase inhibitor, physostigmine (1 mg), or placebo. Mood, accuracy, and reaction time on either recognizing or inhibiting a response associated with an image involving emotion and regional functional activation were examined for effects of cholinergic challenge physostigmine relative to placebo, prioritizing any interaction with the diagnostic group. Analyses revealed that (1) at baseline, impaired behavioral performance was associated with lower activation in the anterior cingulate cortex in BD relative to controls during emotion processing; (2) physostigmine (vs. placebo) affected behavioral performance during the inhibition of negative emotions, without altering mood, and increased activation in the posterior cingulate cortex in BD (vs. controls); (3) In BD, lower accuracy observed during emotion inhibition of negative emotions was remediated by physostigmine and was associated with cingulate cortex overactivation. Our findings implicate abnormal regulation of cholinergic neurotransmission in the cingulate cortices in BD, which may mediate exaggerated emotional salience processing, a core feature of BD.

Lasting changes of sleep-wakefulness produced by early postnatal antagonizing of muscarinic cholinergic system are ameliorated by elevation of CSF orexin-A

Lasting changes of sleep-wakefulness produced by early postnatal antagonizing of muscarinic cholinergic system are ameliorated by elevation of CSF orexin-A

The muscarinic-cholinergic system as a target in the treatment of depressive or manic episodes in bipolar disorder: A systematic review and meta-analysis

• Meta-analysis suggests a significant antidepressant effect of scopolamine. • No significant antidepressant effect of biperiden found on meta-analysis. • Physostigmine lacks an obvious antimanic effect on systematic review. Increasing evidence has implicated the cholinergic system as a modulator of mood episodes, with possible involvement of nicotinic and/or muscarinic receptors. A number of randomized controlled trials (RCTs) have demonstrated a putative rapid antidepressant effect of the muscarinic antagonist scopolamine. Here, we review the clinical evidence regarding the three principal muscarinic-modulating agents administered in studies involving mood disorders: scopolamine, biperiden and physostigmine. We conduct a meta-analysis on RCTs where these agents were administered to participants experiencing a depressive episode. A systematic bibliographic search of Medline, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) for studies utilizing the above agents was conducted between January 1970 and December 2020. A meta-analysis was subsequently performed on 9 studies which satisfied inclusion criteria, including 322 participants. Administration of scopolamine significantly reduced depressive symptoms compared to placebo, as measured by objective mood rating scales with SMD of -0.95 (95% CI -1.49, -0.42, p = 0.0005). This effect increased to -1.13 (95% CI -1.61, -0.66, p < 0.00001) when scopolamine was administered intravenously. Biperiden displayed no significant antidepressant effect. A systematic review noted anergia and an exacerbation of depressive symptomatology following physostigmine administration, but no obvious anti-manic effect. There were a relatively small number of RCTs suitable for meta-analysis. 2 studies included patients enrolled in previous trials. Heterogeneity in study design examining physostigmine prevented meta-analysis for this agent. This study suggests that scopolamine may be a potential rapid-acting and efficacious antidepressant agent. Further adequately statistically powered RCTs should be conducted in participants experiencing depressive episodes in the context of major depressive and bipolar disorder to further elucidate any potential treatment and side effects.

Update on PET Tracer Development for Muscarinic Acetylcholine Receptors.

The muscarinic cholinergic system regulates peripheral and central nervous system functions, and, thus, their potential as a therapeutic target for several neurodegenerative diseases is undoubted. A clinically applicable positron emission tomography (PET) tracer would facilitate the monitoring of disease progression, elucidate the role of muscarinic acetylcholine receptors (mAChR) in disease development and would aid to clarify the diverse natural functions of mAChR regulation throughout the nervous system, which still are largely unresolved. Still, no mAChR PET tracer has yet found broad clinical application, which demands mAChR tracers with improved imaging properties. This paper reviews strategies of mAChR PET tracer design and summarizes the binding properties and preclinical evaluation of recent mAChR tracer candidates. Furthermore, this work identifies the current major challenges in mAChR PET tracer development and provides a perspective on future developments in this area of research.

Some Aspects of Investigation of the Central Mechanism of Antinociceptive Effect of a New Analgetic from the Hexaazaisowurtzitane Group.

Possible involvement of μ1- and κ-opioid receptors and cannabinoid type 1 receptors (CB1) into the mechanism of analgesic activity of the experimental drug product "Thiowurtzine, (capsule 120 mg)" synthesized on the basis of active pharmaceutical substance 4-(3,4-dibromthiophencarbonyl)-2,6,8,12-tetraacethyl-2,4,6,8,10,12hexaazatetracyclo [5,5,0,03,11,05,9]dodecane was studied in vivo using the hot plate test and acetic acid writhing test. The involvement of κ-opioid receptors and noninvolvement of μ1-receptors and CB1 receptors in the mechanism of thiowurtzine analgesia were demonstrated. The mechanism of interaction of the test analgesic with opioid receptors differs from that of the reference drug tramadol. The interaction of thiowurtzine with serotonergic, GABAergic, and muscarinic cholinergic neurotransmitter systems was studied in vivo using pharmacological analyzers. The absence of muscarinic cholinolytic effect of thiowurtzine was demonstrated in the model of arecoline-induced tremor. The central serotonin-blocking activity of the analgesic was revealed in the model of 5-hydroxytryptophan hyperkinesis in mice. Anticonvulsant activity was demonstrated in the corazol convulsions test, which attested to the presence of a GABAergic component. The mechanism of central analgesia caused by the drug product "Thiowurtzine, capsule 120 mg" appeared to be polymodal. The antinociceptive activity of the analgesic was comparable to that of tramadol.

Caffeic acid attenuates gastric mucosal damage induced by ethanol in rats via nitric oxide modulation

Anti-oxidant and anti-inflammatory properties of caffeic acid (CA) have been reported recently. In this study, the therapeutic effects of CA on ethanol-induced ulcer and the roles of nitric oxide and cholinergic pathways in these effects were investigated. Ulcer was induced by ethanol via oral gavage. Ulcer induced rats were treated with either vehicle (ulcer group) or CA (100, 250 or 500 mg/kg, per oral gavage). Macroscopic evaluation showed that 250 mg/kg CA was the effective dose. To elucidate the action mechanism of CA, 10 mg/kg l-NAME or 1 mg/kg atropine sulfate was administered to 250 mg/kg CA treated groups. All rats were decapitated 1 h after ulcer induction and gastric samples were scored macroscopically and microscopically, and analyzed for myeloperoxidase (MPO), malondialdehyde (MDA), and glutathione (GSH) levels. ANOVA test was used for statistical analyses. Macroscopic and microscopic damage scores, MDA levels and MPO activity were increased while GSH levels were decreased in ulcer group. Treatment with 250 mg/kg and 500 mg/kg CA reduced macroscopic and microscopic damage scores, decreased MPO activity and MDA levels, and preserved the depleted glutathione significantly. l-NAME administration before CA treatment elevated MDA levels, MPO activity and depleted glutathione. However, atropine sulfate had no effect on biochemical parameters.We conclude that CA ameliorates ethanol-induced gastric mucosal damage, and NO pathway contributes to this effect. On the other hand, there is a lack of evidence for the contribution of the muscarinic cholinergic system.

P.591 Orexin-A ameliorates lasting effects of postnatal dysfunctioning of muscarinic cholinergic system on sleep-wakefulness

Needle domains are thin, lamellar domains that can appear as fine lines or stripes in a ferroelectric crystal. They affect the poling, switching, and other properties of ferroelectrics. A model is established to study the stress and electric fields caused by needle domains and their interaction. Considering the electrical and mechanical compatibility conditions at the tip of a needle domain, the fields are represented using equivalent edge dislocations and line charges. Accordingly, the dislocation fields derived by Barnett and Lothe for anisotropic piezoelectric media are employed. A modified Peach–Koehler force and calculations of the total energy due to the needle domains are used to study the formation, interaction and stability of needle patterns, taking full account of the strong anisotropy and electromechanical coupling present.The interaction of pairs of needle domains in an infinite piezoelectric with properties of barium titanate is found to be dominated by the electrostatic terms. This makes comb-like arrays of needle domains unstable if perfectly insulating properties are assumed. By considering redistribution of charge, stable equilibrium states for arrays of needle domains are found; these agree well with experimental observations. The model explains the stability of various observed needle patterns and also how unstable patterns evolve.

Некоторые аспекты исследования центрального механизма антиноцицептивного действия нового анальгетика из класса гексаазаизовюрцитанов

Possible involvement of μ1- and κ-opioid receptors and cannabinoid type 1 receptors (CB1) into the mechanism of analgesic activity of the experimental drug product "Thiowurtzine, (capsule 120 mg)" synthesized on the basis of active pharmaceutical substance 4-(3,4-dibromthiophencarbonyl)-2,6,8,12-tetraacethyl-2,4,6,8,10,12hexaazatetracyclo [5,5,0,03,11,05,9]dodecane was studied in vivo using the hot plate test and acetic acid writhing test. The involvement of κ-opioid receptors and noninvolvement of μ1-receptors and CB1 receptors in the mechanism of thiowurtzine analgesia were demonstrated. The mechanism of interaction of the test analgesic with opioid receptors differs from that of the reference drug tramadol. The interaction of thiowurtzine with serotonergic, GABAergic, and muscarinic cholinergic neurotransmitter systems was studied in vivo using pharmacological analyzers. The absence of muscarinic cholinolytic effect of thiowurtzine was demonstrated in the model of arecoline-induced tremor. The central serotonin-blocking activity of the analgesic was revealed in the model of 5-hydroxytryptophan hyperkinesis in mice. Anticonvulsant activity was demonstrated in the corazol convulsions test, which attested to the presence of a GABAergic component. The mechanism of central analgesia caused by the drug product "Thiowurtzine, capsule 120 mg" appeared to be polymodal. The antinociceptive activity of the analgesic was comparable to that of tramadol.

P.556 Orexin-A ameliorates lasting behavioral and sleep disturbances produced by early postnatal dysfunctioning of brain muscarinic cholinergic system

A goal of the paper is to present a method and measuring system that enables determination of the composite error of voltage transformers and dividers for transformation of sinusoidal and distorted voltages. Moreover, the cost-effective procedure for evaluation of transformation accuracy of the designed wideband, high impedance, symmetrical differential voltage to single-ended voltage converter is presented. Essential for its resultant accuracy of transformation for sinusoidal differential voltage in frequencies range from 50 Hz to 20 kHz equal to ±5% is proper technique of converter's application. It requires equal voltages for its both input channels in relation to the output voltage of additional adjustable reference voltage divider. Application of the converter enables a possibility for utilization of a measured rms values of the voltage composite error or its harmonics spectrum to determine more precisely accuracy of voltage transformers and dividers for transformation of sinusoidal or distorted primary voltages. Moreover, developed converter may be also used to assess accuracy of measuring systems designed for evaluation of voltage ratio error and phase displacement of voltage transformers and dividers. Both, instrumentation concepts will improve control of modern distribution systems.

Orexin-A ameliorates lasting behavioral and sleep disturbances produced by early postnatal dysfunctioning of brain muscarinic cholinergic system

Orexin-A ameliorates lasting behavioral and sleep disturbances produced by early postnatal dysfunctioning of brain muscarinic cholinergic system

Effects of obesity induced by high-calorie diet and its treatment with exenatide on muscarinic acetylcholine receptors in rat hippocampus

Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO + E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO + E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO + E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO + E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO + E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO + E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO + E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.

Influence of muscarinic M1 receptor antagonism on brain choline levels and functional connectivity in medication-free subjects with psychosis: A placebo controlled, cross-over study

An increasing number of studies implicate the muscarinic cholinergic system in cognitive dysfunction associated with psychosis. This study examined the effect of muscarinic M1 receptor modulation on anterior cingulate cortex (ACC) and striatal choline concentrations and the relation with cognitive performance, as well as functional connectivity of cognitive networks. Thirty medication-free subjects with a psychosis spectrum disorder and 30 gender, age and IQ-matched healthy control subjects underwent 1H-proton magnetic resonance spectroscopy (1H-MRS) twice, once after placebo and once after a single dose of biperiden (M1 receptor antagonist, 4 mg). A subset of 19 psychotic subjects and 28 controls underwent resting-state functional magnetic resonance imaging (rs-fMRI) as well. No significant differences were found in ACC and striatal choline levels, nor in functional connectivity, between the two groups after placebo. Moreover, M1 antagonism did not significantly affect choline levels or functional connectivity. No correlations were found between choline levels and cognition as well as psychotic symptoms. Our findings do not support an association between the cholinergic system and cognition and psychotic symptoms. However, the lack of group differences in choline concentrations and functional connectivity, both after biperiden and placebo, may indicate that there were no severe cholinergic abnormalities present in our sample.

Anti-inflammatory, anti-nociceptive and antipyretic activity of young and old leaves of Vernonia amygdalina

BackgroundBoth young and old leaves of Vernonia amygdalina (VA) are traditionally used to treat inflammation, pain and fever. However, the efficacy of young and old leaves for treating these ailments have not been compared till date. AimTo ascertain the effect of young and old leaves of VA in managing inflammation, pain and fever. MethodsBoth quantitative and qualitative phytochemical screening of ethanol extracts of young (EthYL) and old (EthOL) leaves of VA were performed. The anti-inflammatory activity of orally administered EthYL and EthOL (50–200 mg/kg) and Diclofenac (10 mg/kg) were evaluated in carrageenan-induced inflammation model in rats. Antipyretic activity of EthYL, EthOL and Aspirin (25 mg/kg) were assessed in the Baker’s yeast-induced pyrexia model. Anti-allodynic effect of both extracts were evaluated by inserting inflamed paws of rats in cold water. Antinociceptive property of the extracts were assessed using tail withdrawal and formalin-induced nociception test. Histopathological examination of the paws was performed, in addition to formalin test to understand the possible mechanism of action of the extracts. Negative control rats received 2 ml/kg normal saline in all tests. ResultsThe amount of flavonoids, alkaloids, tannins, and phenolics were significantly (p < 0.05) higher in EthOL than EthYL, while saponins were significantly higher (p < 0.05) in EthYL than EthOL. The antioxidant ability and total antioxidant capacity were significantly (p < 0.05) higher in EthYL than EthOL. However, this was significantly (p < 0.05) lower than the anti-oxidant activity of Ascorbic acid. A dose-dependent increase in anti-inflammatory, antipyretic and antinociceptive properties were observed in both EthYL and EthOL, similar to the standard drugs. Mast cell degranulation accompanied by vasodilatation and high leukocytosis were observed in the negative control, but were markedly low in extract treated groups. Both extracts mediated their analgesic effect through opioidergic and nitric oxide pathways with EthYL additionally implicating the muscarinic cholinergic system. ConclusionAlthough both EthYL and EthOL alleviate inflammation, pyrexia and nociception, EthYL of VA was found to be more potent than EthOL.

Cholinergic Agonists and Antagonists Have an Effect on the Metabolism of the Beetle Tenebrio Molitor.

Synthetic insecticides are still widely used in plant protection. The main target for their action is the nervous system, in which the cholinergic system plays a vital role. Currently available insecticides have low selectivity and act on the cholinergic systems of invertebrates and vertebrates. Acetylcholine, a cholinergic system neurotransmitter, acts on cells by two types of receptors: nicotinic and muscarinic. In mammals, the role of muscarinic acetylcholine receptors (mAChRs) is quite well-known but in insects, is still not enough. Based on data indicating that the muscarinic cholinergic system strongly affects mammalian metabolism, we investigated if it similarly occurs in insects. We investigated the influence of agonists (acetylcholine, carbachol, and pilocarpine) and antagonists (tropane alkaloids: atropine and scopolamine) of mAChRs on the level of selected metabolites in Tenebrio molitor beetle trophic tissues. We analyzed the glycogen content in the fat body and midgut, the total free sugar concentration in the hemolymph and the lipid amount in the fat body. Moreover, we analyzed the levels of insulin-like peptides in the hemolymph. The tested compounds significantly influenced the mentioned parameters. They increased the glycogen content in the fat body and midgut but decreased the concentration of free sugars in the hemolymph. The observed effects were tissue-specific, and were also time- and dose-dependent. We used nonligated and neck-ligated larvae (to eliminate the influence of head factors on tissue metabolism) to determine whether the observed changes are the result of direct or indirect impacts on tissues. The obtained data suggest that the cholinergic system affects the fat body and midgut indirectly and directly and a pleiotropic role for mAChRs exists in the regulation of energy metabolism in insects. Moreover, tested compounds significantly affected the level of insulin-like peptides in hemolymph. Our studies for the first time showed that mAChRs are involved in regulation of insect metabolism of trophic tissues, and act on them directly and indirectly. Improved knowledge about insect cholinergic system may help in searching more selective and environment-friendly solutions in pest management.

S172. BRAIN METABOLITES AND THE RELATION WITH COGNITION AND PSYCHOTIC SYMPTOMS IN MEDICATION-FREE PSYCHOSIS AND CONTROLS: A PHARMACOLOGICAL MAGNETIC RESONANCE SPECTROSCOPY STUDY

BackgroundPsychotic disorders are complex neuropsychiatric disorders characterized by positive, negative and cognitive symptoms. Over the recent years, several neurotransmitter systems and neurometabolites have been related to psychotic disorders but the exact underlying neurobiological mechanisms are still not well understood. One neurotransmitter system that has been increasingly related to psychosis is the cholinergic muscarinic system. Increased choline concentrations and reduced muscarinic M1 receptor expression have been reported in schizophrenia. Therefore, the present study investigated brain metabolite concentrations, their responsivity to M1 receptor blockage, and their relation to cognitive, positive and negative symptoms in psychosis.Methods31 medication-free subjects with a psychotic disorder (mean age 27 years) and 31 gender, age and IQ-matched healthy control subjects (mean age 25 years) were enrolled in the study. 1H-proton magnetic resonance spectroscopy (1H-MRS, PRESS) was used to measure brain metabolites in the anterior cingulate cortex (ACC) and striatum. Metabolites measured included choline (Cho), glutamate (Glu), glutamine (Gln), GLX, myoinositol (MI), N-acetylaspartate (NAA) and gluthatione (GSH) (metabolite to creatine ratios were analyzed). All subjects were measured twice: once after placebo and once after a pharmacological challenge (4 mg. biperiden, a M1 receptor antagonist). The order of drug – challenge was counterbalanced. In addition, cognitive function was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and psychotic symptom severity was assessed with the Positive and Negative Syndrome Scale (PANSS) to examine the relation between brain metabolites and cognition and psychosis symptoms.ResultsNo significant differences were found in both ACC and striatal brain metabolite levels between subjects with a psychotic disorder and controls after placebo. Moreover, M1 blockade did not significantly affect brain metabolite levels in these regions and no group x challenge interaction effects were found. In addition, in both groups, no correlation was found between cognitive functioning and any of the brain metabolites. In subjects with a psychotic disorder, a positive correlation was found between striatal choline levels (after placebo) and negative symptom severity (p = 0.024).DiscussionThese results suggest that there are no differences in ACC and striatal brain metabolites between medication-free subjects with a psychotic disorder and healthy controls and that these metabolites are not influences by acute muscarinic M1 receptor antagonism. The significant correlation between striatal choline and negative symptom severity in the psychosis group could indicate that the cholinergic system is involved in negative symptom pathology. This is the first study that examined the influence of M1 receptor blockade on brain metabolites and therefore these results warrant replication.

Lasting effects of early postnatal malfunctioning of brain muscarinic cholinergic system are ameliorated by icv microinjection of Orexin-a (Hypocretin-1) and Orexin-b (Hypocretin-2)

Lasting effects of early postnatal malfunctioning of brain muscarinic cholinergic system are ameliorated by icv microinjection of Orexin-a (Hypocretin-1) and Orexin-b (Hypocretin-2)