Assessing Striatal Dopamine in Schizophrenia

Secondary metal doped cuprous-cyanoimidazole frameworks for triple-mode detection of dopamine

BACKGROUNDS

Metal-organic framework-based nanozymes enable several opportunities for designing novel analysis methods for the detection of pesticides, heavy metal ions, and biomolecules; however, practical applications are still limited by a complicated synthesis route, lower catalytic activity, and single detection mode. Dopamine (DA) is a crucial catecholamine substance in the human body that acts as a neurotransmitter regulating a variety of physiological functions of the central nervous system. Therefore, it is highly significant to explore simple nanozymes synthesis methods for constructing a multiple analysis system to detection DA.

RESULTS

Herein, we elaborately selected cobalt ions as the secondary metal doping in cuprous-cyanoimidazole frameworks (CuCo-CIFs) with a mass-production strategy. CuCo-CIFs possess intrinsic peroxidase-like activity that can convert hydrogen peroxide into various reactive oxygen species (i.e., 1O2, OH·, O2·-) and thereby oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) and DA to blue oxTMB and orange polydopamine (PDA), respectively. The absorption of the detection system increases at 460 nm while decreases at 652 nm as the concentration of DA increases under near-neutral pH (6.1), resulting in a color transition from blue to orange. Consequently, an unprecedented triple-mode analysis system of DA monitored by naked eyes, ratiometric-absorption, and scanometric was constructed. The limit of detection for the ratiometric-absorption and scanometric mode can reach 20 nM and 28 nM, respectively. CuCo-CIFs were successfully used for the rapid and accurate detection of DA in practical samples.

SIGNIFICANCE

As a simple, low-cost, multi-mode colorimetric platform, this kind of nanozyme detection with peroxidase-like activity exhibits significant potential for the detection of DA. Our work not only expands the applications of MOFs in analytical fields but also addresses the general challenges faced by nanozyme-based colorimetric detection systems of DA. This work provides valuable insights for the rational application of nanozyme and the design of new analysis systems.

Dopamine Synthesis Capacity and GABA and Glutamate Levels Separate Antipsychotic-Naïve Patients With First-Episode Psychosis From Healthy Control Subjects in a Multimodal Prediction Model

Background

Disturbances in presynaptic dopamine activity and levels of GABA (gamma-aminobutyric acid) and glutamate plus glutamine collectively may have a role in the pathophysiology of psychosis, although separately they are poor diagnostic markers. We tested whether these neurotransmitters in combination improve the distinction of antipsychotic-naïve patients with first-episode psychosis from healthy control subjects.

Methods

We included 23 patients (mean age 22.3 years, 9 male) and 20 control subjects (mean age 22.4 years, 8 male). We determined dopamine metabolism in the nucleus accumbens and striatum from 18F-fluorodopa (18F-FDOPA) positron emission tomography. We measured GABA levels in the anterior cingulate cortex (ACC) and glutamate plus glutamine levels in the ACC and left thalamus with 3T proton magnetic resonance spectroscopy. We used binominal logistic regression for unimodal prediction when we modeled neurotransmitters individually and for multimodal prediction when we combined the 3 neurotransmitters. We selected the best combination based on Akaike information criterion.

Results

Individual neurotransmitters failed to predict group. Three triple neurotransmitter combinations significantly predicted group after Benjamini-Hochberg correction. The best model (Akaike information criterion 48.5) carried 93.5% of the cumulative model weight. It reached a classification accuracy of 83.7% (p = .003) and included dopamine synthesis capacity (Ki4p) in the nucleus accumbens (p = .664), GABA levels in the ACC (p = .019), glutamate plus glutamine levels in the thalamus (p = .678), and the interaction term Ki4p × GABA (p = .016).

Conclusions

Our multimodal approach proved superior classification accuracy, implying that the pathophysiology of patients represents a combination of neurotransmitter disturbances rather than aberrations in a single neurotransmitter. Particularly aberrant interrelations between Ki4p in the nucleus accumbens and GABA values in the ACC appeared to contribute diagnostic information.

Epigenetic Targets in Schizophrenia Development and Therapy

Schizophrenia is regarded as a neurodevelopmental disorder with its course progressing throughout life. However, the aetiology and development of schizophrenia are still under investigation. Several data suggest that the dysfunction of epigenetic mechanisms is known to be involved in the pathomechanism of this mental disorder. The present article revised the epigenetic background of schizophrenia based on the data available in online databases (PubMed, Scopus). This paper focused on the role of epigenetic regulation, such as DNA methylation, histone modifications, and interference of non-coding RNAs, in schizophrenia development. The article also reviewed the available data related to epigenetic regulation that may modify the severity of the disease as a possible target for schizophrenia pharmacotherapy. Moreover, the effects of antipsychotics on epigenetic malfunction in schizophrenia are discussed based on preclinical and clinical results. The obtainable data suggest alterations of epigenetic regulation in schizophrenia. Moreover, they also showed the important role of epigenetic modifications in antipsychotic action. There is a need for more data to establish the role of epigenetic mechanisms in schizophrenia therapy. It would be of special interest to find and develop new targets for schizophrenia therapy because patients with schizophrenia could show little or no response to current pharmacotherapy and have treatment-resistant schizophrenia.

The Effect of Menopause on Antipsychotic Response

Background: It has been hypothesized that, whenever estrogen levels decline, psychosis symptoms in women increase. At menopause, this can happen in two main ways: (a) the loss of estrogen (mainly estradiol) can directly affect central neurotransmission, leading to increase in schizophrenia-related symptoms, and (b) the loss of estrogen can decrease the synthesis of enzymes that metabolize antipsychotic drugs, thus weakening their efficacy. Aims and Methods: The aim of this narrative review was to investigate the second possibility by searching PubMed and ClinicalTrials.gov for studies over the last two decades that investigated the metabolism of antipsychotics and their efficacy before and after menopause in women or that studied systemic and local estrogen level effects on the pharmacokinetics and pharmacodynamics of individual antipsychotic drugs. Results: The evidence suggests that symptom level in women with schizophrenia rises after menopause for many reasons beyond hormones but, importantly, there is an estrogen-dependent loss of efficacy related to antipsychotic treatment. Conclusion: Effective clinical intervention is challenging; nevertheless, several promising routes forward are suggested.

Dopamine, Psychosis, and Symptom Fluctuation: A Narrative Review

It has been hypothesized since the 1960s that the etiology of schizophrenia is linked to dopamine. In the intervening 60 years, sophisticated brain imaging techniques, genetic/epigenetic advances, and new experimental animal models of schizophrenia have transformed schizophrenia research. The disease is now conceptualized as a heterogeneous neurodevelopmental disorder expressed phenotypically in four symptom domains: positive, negative, cognitive, and affective. The aim of this paper is threefold: (a) to review recent research into schizophrenia etiology, (b) to review papers that elicited subjective evidence from patients as to triggers and repressors of symptoms such as auditory hallucinations or paranoid thoughts, and (c) to address the potential role of dopamine in schizophrenia in general and, in particular, in the fluctuations in schizophrenia symptoms. The review also includes new discoveries in schizophrenia research, pointing to the involvement of both striatal neurons and glia, signaling pathway convergence, and the role of stress. It also addresses potential therapeutic implications. We conclude with the hope that this paper opens up novel avenues of research and new possibilities for treatment.

Schizophrenia: A Narrative Review of Etiopathogenetic, Diagnostic and Treatment Aspects

Although schizophrenia is currently conceptualized as being characterized as a syndrome that includes a collection of signs and symptoms, there is strong evidence of heterogeneous and complex underpinned etiological, etiopathogenetic, and psychopathological mechanisms, which are still under investigation. Therefore, the present viewpoint review is aimed at providing some insights into the recently investigated schizophrenia research fields in order to discuss the potential future research directions in schizophrenia research. The traditional schizophrenia construct and diagnosis were progressively revised and revisited, based on the recently emerging neurobiological, genetic, and epidemiological research. Moreover, innovative diagnostic and therapeutic approaches are pointed to build a new construct, allowing the development of better clinical and treatment outcomes and characterization for schizophrenic individuals, considering a more patient-centered, personalized, and tailored-based dimensional approach. Further translational studies are needed in order to integrate neurobiological, genetic, and environmental studies into clinical practice and to help clinicians and researchers to understand how to redesign a new schizophrenia construct.