Fluorescent reporters of monoamine transporter distribution and function

Visualization of an Endogenous Mitochondrial Azoreductase Activity under Normoxic Conditions Using a Naphthalimide Azo-Based Fluorogenic Probe

In this paper, we demonstrate the existence of an endogenous mitochondrial azoreductase (AzoR) activity that can induce the cleavage of N═N double bonds of azobenzene compounds under normoxic conditions. To this end, 100% OFF-ON azo-based fluorogenic probes derived from 4-amino-1,8-naphthalimide fluorophores were synthesized and evaluated. The in vitro study conducted with other endogenous reducing agents of the cell, including reductases, demonstrated both the efficacy and the selectivity of the probe for AzoR. Confocal experiments with the probe revealed an AzoR activity in the mitochondria of living cells under normal oxygenation conditions, and we were able to demonstrate that this endogenous AzoR activity appears to be expressed at different levels across different cell lines. This discovery provides crucial information for our understanding of the biochemical processes occurring within the mitochondria. It thus contributes to a better understanding of its function, which is implicated in numerous pathologies.

Illuminating the monoamine transporters: Fluorescently labelled ligands to study dopamine, serotonin and norepinephrine transporters

Fluorescence microscopy has revolutionized the visualization of physiological processes in live-cell systems. With the recent innovations in super resolution microscopy, these events can be examined with high precision and accuracy. The development of fluorescently labelled small molecules has provided a significant advance in understanding the physiological relevance of targeted proteins that can now be visualized at the cellular level. One set of physiologically important target proteins are the monoamine transporters (MATs) that play an instrumental role in maintaining monoamine signalling homeostasis. Understanding the mechanisms underlying their regulation and dysregulation is fundamental to treating several neuropsychiatric conditions such as attention deficit hyperactivity disorder (ADHD), anxiety, depression and substance use disorders. Herein, we describe the rationale behind the small molecule design of fluorescently labelled ligands (FLL) either as MAT substrates or inhibitors as well as their applications to advance our understanding of this class of transporters in health and disease.

Simultaneous Determination of Four Monoamine Neurotransmitters and Seven Effective Components of Zaoren Anshen Prescription in Rat Tissue using UPLC-Ms/Ms

Background:

Zaoren Anshen Prescription (ZAP) is widely used as a classic Chinese Traditional Medicine (TCM) prescription for the treatment of palpitations and insomnia in China. Some studies have identified the main active components for its anti-insomnia effect and observed changes of some endogenous components that are closely related to its anti-insomnia effect. However, simultaneous determination of four monoamine neurotransmitters and seven effective components of ZAP and the investigation of their distribution in tissues by using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) have not been reported.

Methods:

An ultra-performance liquid chromatography with tandem mass spectrometry method was developed and validated for simultaneous quantification of four monoamine neurotransmitters (norepinephrine, dopamine, 5-hydroxy tryptamine and 5-hydroxyindoleacetic acid) and seven prescription components (danshensu, protocatechualdehyde, spinosin, 6´´´-feruylspinosin, salviaolic acid B, schisandrin and deoxyschisandrin) in rats’ tissues. Tissue samples were prepared by protein precipitation with acetonitrile. Chromatographic separation was carried out on a C18 column with a gradient mobile phase consisting of acetonitrile and 0.01% formic acid water. An electrospray ionization triple quadrupole concatenation mass spectrometer was set to switch between positive and negative modes in single run time. All the components were quantitated by multiple-reaction monitoring scanning.

Results:

: The lower limits of quantitation for all analytical components were 0.78 ng/mL-1.99 ng/mL in the heart, liver, spleen, lung, kidney and brain. All the calibration curves displayed good linearity (r > 0.99544). The precision was evaluated by intra-day and inter-day assays, and the relative standard deviation (RSD) values were all within 12.67%. The relative errors of the accuracy were all within ± 19.88%. The recovery ranged from 76.00% to 98.78% and the matrix effects of eleven components were found to be between 85.10% and 96.40%.

Conclusion:

This method was successfully applied to study the distribution of seven components from ZAP and the concentration changes of four monoamine neurotransmitters after oral ZAP in six tissues.

Inherited disorders of brain neurotransmitters: pathogenesis and diagnostic approach

Neurotransmitters (NTs) play a central role in the efficient communication between neurons necessary for normal functioning of the nervous system. NTs can be divided into two groups: small molecule NTs and larger neuropeptide NTs. Inherited disorders of NTs result from a primary disturbance of NTs metabolism or transport. This group of disorders requires sophisticated diagnostic procedures. In this review we discuss disturbances in the metabolism of tetrahydrobiopterin, biogenic amines, γ-aminobutyric acid, foliate, pyridoxine-dependent enzymes, and also the glycine-dependent encephalopathy. We point to pathologic alterations of proteins involved in synaptic neurotransmission that may cause neurological and psychiatric symptoms. We postulate that synaptic receptors and transporter proteins for neurotransmitters should be investigated in unresolved cases. Patients with inherited neurotransmitters disorders present various clinical presentations such as mental retardation, refractory seizures, pyramidal and extrapyramidal syndromes, impaired locomotor patterns, and progressive encephalopathy. Every patient with suspected inherited neurotransmitter disorder should undergo a structured interview and a careful examination including neurological, biochemical, and imaging.

Cyclisation reactions of N-cinnamoyl-9-aminoanthracenes

N-Cinnamoyl-9-aminoanthracenes cyclise with PPA or triflic acid to form novel 2-azahexacyclo[10.6.6.0(1,5).0(6,11).0(13,18).0(19,24)]tetracosa-6(11),7,9,13,15,17,19(24),20,22-nonaen-3-ones. In contrast, both N-cinnamoyl-N-methyl-9-(2-aminomethyl)anthracene and N-cinnamoyl-9-(2-aminoethyl)anthracene undergo an intramolecular Diels-Alder cycloaddition.

Serotonin and blood pressure regulation

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension.