DOPAC Research Articles

3H]Dopamine Uptake through the Dopamine and Norepinephrine Transporters is Decreased in the Prefrontal Cortex of Transgenic Mice Expressing HIV-1 Transactivator of Transcription Protein.

Dysregulation of dopamine neurotransmission has been linked to the development of human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND). To investigate the mechanisms underlying this phenomenon, this study used an inducible HIV-1 transactivator of transcription (Tat) transgenic (iTat-tg) mouse model, which demonstrates brain-specific Tat expression induced by administration of doxycycline. We found that induction of Tat expression in the iTat-tg mice for either 7 or 14 days resulted in a decrease (∼30%) in the V max of [3H]dopamine uptake via both the dopamine transporter (DAT) and norepinephrine transporter (NET) in the prefrontal cortex (PFC), which was comparable to the magnitude (∼35%) of the decrease in B max for [3H]WIN 35,428 and [3H]nisoxetine binding to DAT and NET, respectively. The decreased V max was not accompanied by a reduction of total or plasma membrane expression of DAT and NET. Consistent with the decreased V max for DAT and NET in the PFC, the current study also found an increase in the tissue content of DA and dihydroxyphenylacetic acid in the PFC of iTat-tg mice after 7 days' administration of doxycycline. Electrophysiological recordings in layer V pyramidal neurons of the prelimbic cortex from iTat-tg mice found a significant reduction in action potential firing, which was not sensitive to selective inhibitors for DAT and NET, respectively. These findings provide a molecular basis for using the iTat-tg mouse model in the studies of NeuroHIV. Determining the mechanistic basis underlying the interaction between Tat and DAT/NET may reveal novel therapeutic possibilities for preventing the increase in comorbid conditions as well as HAND. SIGNIFICANCE STATEMENT: Human immunodeficiency virus (HIV)-1 infection disrupts dopaminergic neurotransmission, leading to HIV-associated neurocognitive disorders (HANDs). Based on our in vitro and in vivo studies, dopamine uptake via both dopamine and norepinephrine transporters is decreased in the prefrontal cortex of HIV-1 Tat transgenic mice, which is consistent with the increased dopamine and dihydroxyphenylacetic acid contents in this brain region. Thus, these plasma membrane transporters are an important potential target for therapeutic intervention for patients with HAND.

Anti-neuroinflammatory effects of Eucommia ulmoides Oliv. In a Parkinson's mouse model through the regulation of p38/JNK-Fosl2 gene expression

Ethnopharmacological relevanceEucommia ulmoides Oliv., a Chinese medicinal herb called “Duzhong” from the bark of Eucommia ulmoides Oliv., has been shown to possess significant protective effects in Parkinson's disease (PD). However, the molecular mechanism remains unclear. Aim of the studyIn this study, we explored the anti-neuroinflammatory mechanisms of Duzhong on the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model to elucidate the traditional medical theories with modern pharmacological methods and to provide a reference for further clarifying its mechanisms of action. Materials and methodsThe representative components in Duzhong extract were identified by UPLC-Q-TOF/MS. Male C57BL/6J mice were intraperitoneally injected with MPTP to establish an in vivo PD model. The pole, rotarod, and grip strength tests were performed to evaluate the motor coordination ability of the PD mice. HPLC-ECD was used to detect the striatal levels of dopamine (DA), 3,4- dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). The expression of tyrosine hydroxylase (TH) was studied by immunohistochemistry (IHC) and Western blot assays. ELISA and Q-PCR were used examined the levels of proinflammatory cytokines in the serum and midbrain, respectively. Whole-transcriptome analysis of the midbrain was performed to explore the therapeutic effect of Duzhong on PD mice, and Q-PCR was then used to validate the differential gene expression changes in the PD mice treated with Duzhong. ResultsTen compounds were identified from Duzhong extract. Duzhong significantly alleviated the behavioral impairments and dopaminergic neuron degeneration of PD mice, and inhibited the expression of proinflammatory cytokines. Whole-transcriptome analysis revealed nine oppositely regulated genes, and the Fosl2 gene was consistent with the trend of observed by RNA-seq. Furthermore, Duzhong downregulated mRNA expression of p38 and JNK, which are key upstream genes of Fosl2. ConclusionsDuzhong has promising therapeutic potential in PD mice, and its molecular mechanism is mediated by downregulating p38/JNK-Fosl2 gene expression to alleviate neuroinflammation.

Multiplexing Neurochemical Detection Using Carbon Electrodes and Fast Scan Cyclic Voltammetry

Fast scan cyclic voltammetry (FSCV) and carbon-fiber microelectrodes (CFMEs) have been utilized used to detect several important neurochemicals in vivo. However, this method is limited due to the ability to discriminate dopamine from several of its metabolites. PEDOT, Nafion, and Polyethyleneimine modified microelectrodes will be utilized to detect physiologically low levels of neurotransmitters that also resist surface fouling and have high temporal resolution to detect fast changes of neurotransmitters. Furthermore, novel electrode coatings and waveforms will also be utilized to detect several neurotransmitter metabolites such as dopamine, norepinephrine, normetanephrine, 3-methoxytyramine (3-MT), homovanillic acid (HVA), 3,4 dihydroxyphenylacetic acid (DOPAC), and other metabolites. Currently, dopamine is thought to be an important neurotransmitter concerning several disease states such Parkinson’s disease, drug abuse (amphetamine, cocaine, etc.), and even for gambling and sex-disorders. However, dopamine is metabolized on a subsecond timescale, and studies have pointed to the importance of neurotransmitter metabolites in these disease states apart from dopamine. Presently, there is no method to selectively co-detect these neurotransmitter metabolites of dopamine utilizing FSCV. Through several waveform modifications and polymer electrode coatings, we develop a novel method to tune the detection of dopamine and said metabolites, which will help differentiate dopamine and respective metabolites through the shapes and positions of their respective cyclic voltammograms. Preliminary measurements have also been made in zebrafish retina showing the application of this technique in biological tissue. The co-detection and differentiation of dopamine metabolites and dopamine will have many implications in better understanding complex disease, behavioral, and pharmacological states.Moreover, within the greater neuroscience community, there has long been a critical need for the development of versatile and affordable multichannel sensors for the detection of neurotransmitters. Little success has been achieved in developing and commercializing these multielectrode arrays used specifically for the detection of neurotransmitters with voltammetry in multiple brain regions.The brain is by far the most heterogeneous organ, and it is critically important to monitor various brain regions simultaneously in order to understand complex pharmacological, drug, and behavioral states. For example, several studies have shown significant differences in electrical activity and neurotransmitter concentrations in disparate brain regions such as the striatum, hippocampus, and prefrontal cortex among others. Therefore, it is critically important to make high temporal resolution neurochemical measurements to study the phasic firing of neurons in several brain regions concurrently. FSCV allows for high temporal measurements (< 100 msec) of neurotransmitter levels. Some of the many applications of this technique could be measuring neurochemical changes during epileptic seizures with simultaneous EEG measurements in rodents, drug abuse studies, measuring robust dopamine increases during deep brain stimulation in Parkinsonian models, and possibly many others.This work will also discuss the development of multielectrode arrays (MEAs) for neurotransmitter detection with fast scan cyclic voltammetry in multiple brain regions simultaneously. Parylene and silicon insulated carbon fiber microelectrode arrays were shown to be able to measure neurochemicals in multiple brain regions simultaneously when coupled with multichannel potentiostats. Moreover, we have utilized techniques such as plasma enhanced chemical vapor deposition (PECVD) to deposit conductive carbon nanospikes onto the surface of existing metal multielectrode arrays to give them dual functionality as neurotransmitter sensors with FSCV in addition to being used primarily for electrical stimulation and recording. Other assays have shown the utility of electrodepositing carbon nanotubes and polymers such as PEDOT to coat metal arrays with carbon to give them dual sensing capabilities. This BRAIN Initiative funded work will allow us to further understand complex brain heterogeneity by making measurements in multiple brain regions simultaneously.

The Time-Course of Changes in the State of Brain Monoaminergic Systems of Mice Under the Acute Hypoxia with Hypercapnia

The changes of monoaminergic systems under acute hypoxia with hypercapnia have been studied in male albino mice kept for a long time under the conditions of social isolation. Concentrations of noradrenaline, dopamine, serotonin, and their metabolites (dihydroxyphenylacetic, homovanillic and 5-hydroxyindoleacetic acids) have been measured using the HPLC method in cerebral cortex, hippocampus, and striatum of the right and left sides of the brain. In mice kept under the conditions of social isolation, which were not subjected to hypoxia with hypercapnia, higher levels of dopamine and serotonin in the left cortex were found. There was no asymmetry in monoamines and their metabolites in other studied brain structures. Ten min after the onset of exposure, acute hypoxia with hypercapnia resulted in a right-sided increase in the noradrenaline level and a decrease in the dopamine level in the striatum and serotonin levels in the hippocampus. In the cerebral cortex, 10 min after the beginning of the hypoxic treatment, there was a left-sided decrease in the dopamine content, while the initial asymmetry, found in the cortex of intact animals, disappeared. In mice kept under social isolation and died of hypoxia with hypercapnia, almost all parameters returned to the control level. The only exception was the ratio in the level of the serotonin metabolite (5-hydroxyindoleacetic acid) to the serotonin level: in the right cortex this parameter became lower than that of the control animals. It is suggested that in albino mice the brain monoaminergic systems are relatively resistant to the negative consequences of hypoxia and hypercapnia, and the changes in their parameters are obviously associated with the reflex brain response to changes in the gas composition of the respiratory air.

Extraction and preconcentration of compounds from the l-tyrosine metabolic pathway prior to their micellar electrokinetic chromatography separation

The prominent biological effects of adrenaline (A), noradrenaline (NA) and dopamine (DA) as well as the clinical importance of their metabolites (such as dihydroxyphenylacetic acid (DOPAC), methoxy‑4-hydroxyphenyl glycol (MHPG), dihydroxyphenylglycol (DHPG), metanephrine (M), normetanephrine (NM), vanillylmandelic acid (VMA), homovanillic acid (HVA)) have forced researchers to evaluate new analytical methodologies for their isolation and preconcentration from biological samples. For this reason, the three most popular extraction techniques (dispersive liquid-liquid microextraction (DLLME), solid-phase extraction (SPE), solid-phase microextraction (SPME)) were tested. Micellar electrokinetic chromatography (MEKC) – a mode of capillary electrophoresis – with a diode array detector (DAD) was applied to assess the extraction efficiency. Next, the enrichment factor (EF) of each applied method was calculated in respect to standard mixtures of the analytes at the same concentration levels. The EF results of seven selected metabolites of biogenic amines (BAs) from urine after sample preparation procedures based on twenty-five different protocols (one DLLME, thirteen SPE and eleven SPME) were calculated and compared using hierarchical cluster analysis (HCA). The SPE as well as SPME procedures were proved to be the most effective approaches for the simultaneous extraction of the chosen compounds. Moreover, an ionic liquid (IL) – 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide – added to methanol in SPME additionally could successfully improve the extraction efficiency. It was also confirmed that the HCA approach could be considered a supportive tool in the selection of a suitable sample preparation procedure for that group of endogenous substances.

Research progress on mechanism of gastrodin and p-hydroxybenzyl alcohol on central nervous system

Gastrodin(GAS) and p-hydroxybenzyl alcohol(HBA) are extracts of dried tubers of Gastrodia elata, which is the material basis for its efficacy and belongs to phenolic compounds. Modern pharmacology studies have shown that they have significant effects on central nervous system diseases, such as insomnia, convulsions, depression, ischemic stroke, anxiety, and cognitive impairment, and these diseases are closely related to neurotransmitters and cytokines. This paper described various mechanisms of GAS and HBA monomer components on the central nervous system. They alleviate hippocampal neuronal toxicity mainly by regulating a variety of neurotransmitters, such as acetylcholine, glutamic acid(GLU), γ-aminobutyric acid(GABA), serotonin(5-HT), dopamine(DA), norepinephrine(NE), 5-indoleacetic acid(5-HIAA), high vanillic acid(HVA) and dihydroxyphenylacetic acid(DOPAC), pro-inflammatory cell growth factors, such as IL-1β, IL-6 and TNF-α and relevant receptor functions, and exert neuropharmacological effects by effectively increasing mRNA expressions of brain neurotrophic factors, such as BDNF and GDNF, and further inhibiting the apoptosis of damaged neurons. This paper summarized various mechanisms on the central nervous system, which provides a scientific basis for the further research of the neuropharmacological mechanism of GAS and HBA and the development of new drugs and functional food.

Content of Monoamines in the Pons Varolii in Experimental Post-Traumatic Stress Disorder

Abstract—In posttraumatic stress disorder (PTSD), the development of anxiety symptoms correlates with an increase in the content of noradrenaline and dopamine and a decrease in the content of serotonin in the limbic structures of the brain. Unfortunately, the character of changes in the level of monoamines in the brain stem structures such as the pons Varolii is not known, although it is damaged in patients with PTSD. The aim of the study was to determine the content of monoamine-neurotransmitters and their metabolites in the pons Varolii under the conditions of experimental PTSD. To reproduce the symptoms of PTSD, a predator stress model was used by exposing rats to the smell of a cat. The level of anxiety was determined using an elevated plus maze. High performance liquid chromatography was used to determine the concentrations of noradrenaline, dopamine, and the metabolite of dopamine, dihydroxyphenylacetic acid. It was found that under experimental PTSD, the content of noradrenaline in the pons Varolii decreased. At the same time, the content of dopamine and serotonin did not undergo significant changes. The content of noradrenaline negatively correlated with the anxiety index. In the pons Varolii, there were no changes in the level of monoamines typical of PTSD. In contrast to limbic structures, we observed a decrease in the level of noradrenaline with a constant level of other monoamines and their metabolites.

Hypothalamic Monoaminergic Pathology in a Neurodevelopmental Rat Model Showing Prenatal 5-Bromo-2′-Deoxyuridine Treatment-Induced Hyperactivity and Hyporeproductivity

Objective: Prenatal treatment of rats with 5-bromo-2′-deoxyuridine (BrdU) is a neurodevelopmental model showing hyperactivity and impaired sexual activity. Human neurodevelopmental disorders, such as autism, exhibit sex-related pathology, but sex-related neurodevelopment has not been fully investigated in this model. We conducted this study to facilitate the understanding of the pathophysiology of neurodevelopmental disorders. Methods: Pregnant rats received 50 mg/kg BrdU on gestational days 9–15. The tissue content of dopamine (DA), serotonin (5-HT), and their metabolites dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid were measured in male and female offspring at 3 weeks (juveniles) and 10 weeks (adults) of age. Results: Prenatally BrdU-treated rats had reduced DA metabolism or DA content in the hypothalamus from the juvenile through the adult period without sex differences, but sex-specific striatal DA abnormalities emerged after maturation. A reduction in 5-HT metabolism was measured in the hypothalamus without sex differences throughout development. Developmental alterations in the striatal 5-HT states were sex-dependent. Temporal changes in DA or 5-HT metabolism were found in the frontal cortex and midbrain. Conclusion: The sex-specific influence of a genotoxic factor on the development of the DA and 5-HT systems was clarified in the hypothalamus and striatum. The results suggest that the observed sex dependence and region specificity are related to the pathology of social dysfunction in neurodevelopmental disorders.

The acute toxic and neurotoxic effects of 3,4-methylenedioxymethamphetamine are more pronounced in adolescent than adult mice

3,4-methylenedioxymethamphetamine (MDMA) recently achieved breakthrough status from the Food and Drug Administration (FDA) for post-traumatic stress disorder (PTSD). However, evidence indicates that exposure to toxic doses of MDMA can lead to long-lasting dysregulation of brain monoaminergic neurotransmitters, primarily from studies conducted in young adult rodents. To date, there is a paucity of data on whether toxic doses of MDMA can differentially affect neurotransmitter systems in adolescents and mature adults, which is an important question as adolescents and adults may be differentially vulnerable to MDMA abuse.In the current study, adolescent (6–7 weeks of age) and mature adult (16–18 weeks of age) male, Swiss-Webster mice were exposed to MDMA (20 mg/kg) using a binge-like dosing regimen (4 administrations spaced every 2 h). Acute lethality, acute hyperthermia, and acute decreases in body weight following MDMA administration were more pronounced in adolescent than adult mice. Likewise, acute loss of striatal dopamine neurochemistry was also exacerbated in adolescents, as determined by high-pressure liquid chromatography coupled to electrochemical detection. Exposure to MDMA induced greater turnover of dopamine into its major metabolite dihydroxyphenylacetic acid (DOPAC) in adolescents, but not in adults, suggesting a novel mechanism through which adolescents may show increased vulnerability to the acute toxic and neurotoxic effects of MDMA, or conversely that mature adults show greater protection. These data caution that MDMA exposure in adolescence may be particularly dangerous and that the therapeutic window for MDMA may differ between adolescents and mature adults.

The selective electrochemical sensing of dopamine at a polypyrrole film doped with an anionic β−cyclodextrin

Pyrrole was electropolymerised in a 0.01 M sulfonated β−cyclodextrin solution to generate an adherent polypyrrole film doped with the anionic sulfonated β−cyclodextrin, PPy−SβCD. This polymeric material was used as an electrochemical sensor for the detection of dopamine (DA), and compared with the sensing abilities of polypyrrole doped with several more common anionic dopants. The sensing performance of the PPy−SβCD film was significantly better, with a linear calibration curve extending to 50 μM, with a sensitivity of 0.90 μA μM−1 cm−2 and a detection limit of 1.0 × 10−6 M. Excellent selectivity was achieved and no interference was observed from a range of interference compounds, including ascorbic acid, uric acid, aspartic acid, acetylcholine, aminobutyric acid, glutamic acid, glycine, histamine, acetaminophenol 5−hydroxytryptamine and 5−hydroxyindole acetic acid. However, interference was seen with the structurally−related epinephrine (Ep) and 3,4−dihydroxyphenylacetic acid (DOPAC), with the oxidation of DA, Ep and DOPAC occurring at similar potentials. The good selectivity in the presence of the other interference species was attributed to an interaction between the cyclodextrin dopant and the protonated DA molecule which was evident when data were fitted to Michaelis−Menten and Lineweaver−Burk kinetics.

Fabrication of solid lipid nanoparticles containing vitexin protects dopaminergic neurons against 6-hydroxydopamine induced Parkinson's disease model via altered the genetic backgrounds

Vitexin is a flavonoid which obtained from Crataegus pinnatifida Bunge. Further, its neuroprotective effects are examined in PD model. The motive of the current study was to fabricate vitexin loaded solid lipid nanoparticles and evaluate the effect against 6- hidroxidopamine (6-OHDA) induced parkinson's disease animal model. Intracerebroventricular injection of 6-OHDA was used for induction the PD and mice were treated with the said drug loaded nanocarrier for 28 days. In our study, hot melt emulsification and ultrasonication method was employed for the preparation of Vitexin loaded nanolipoidal carrier. Further, the enzymatic activities incudes Catalase (CAT), superoxide dismutase (SOD), glutathione (GSH) glutathione peroxidase (GPx), glutathione S-transferase (GST), level of reactive oxygen species, total reactive antioxidant dopamine and its metabolite homovanilic and 3, 4-dihydroxyphenylacetic acid, were determined in the striatum. Furthermore, the behavioural parameters including locomotor, memory and depressive were estimated. The Vitexin loaded solid lipid nanoparticles therapeutics in 6-OHDA induced Parkinson's, results clearly showed improvement in total reactive antioxidant, CAT, GPx, Dopamine and its metabolite level in striatum of mice. We also observed that reactive oxygen species in the striatum were diminished by solid lipid nanoparticles of Vitexin. Furthermore, the said formulation is well efficient in averting the memory destruction in Morris water maze test as well as depressive like behaviour in tail suspension test. Vitexin loaded solid lipid nanoparticles founds protective effects in neurodegeneration on 6-OHDA induced neurotoxicity in mice. In features, this could be alternative effective therapeutic approach for the management of PD.

Effects of 7-Methylxanthine on Deprivation Myopia and Retinal Dopamine Release in Chickens

Introduction: Intake of 7-methylxanthine (7-MX), an adenosine receptor (AR) antagonist, has been shown to inhibit school myopia in children and deprivation myopia in rhesus monkeys, but the underlying mechanisms are not known. Also retinal dopamine seems to be involved in the control of eye growth, and in the brain, ARs and dopamine receptors interact widely by heteromerization. We have studied whether 7-MX can inhibit deprivation myopia also in chickens and whether inhibition may involve the retinal dopamine system. Methods: 7-MX was applied by either tube-feeding (100 µg/g body weight, twice a day) or intravitreal injection (12.5 µg, every other day). Forty-eight 2-week-old chicks wore unilateral diffusers and were randomly assigned to either the tube-feeding group (involving 7-MX, vehicle [xanthan gum], or no feeding, for 13 days) or the intravitreal injection group (involving 7-MX, vehicle, or DMSO, for 8 days). Refractions (REs), ocular biometry (AL, VCD), and scleral and choroidal thickness (ChT) were measured before and after treatment. Dopamine and dihydroxyphenylacetic acid (DOPAC) content were determined in retina and vitreous by HPLC at the end of the experiments. Results: No matter how 7-MX was applied, it did not inhibit deprivation myopia in chicks. No significant differences were observed in RE, VCD, AL, and scleral fibrous layer thickness. Feeding 7-MX produced more choroidal thinning in the open contralateral eye compared to control eyes in the vehicle-fed group (–40 ± 14 vs. –1 ± 7 µm, unpaired t test, p < 0.05). DOPAC and dopamine concentration in vitreous and DOPAC concentration in retina did not change with 7-MX. Vitreal dopamine content was significantly decreased in deprived eyes in the groups fed with the vehicle xanthan gum (paired t test, p < 0.01) but not in 7-MX-treated eyes, perhaps indicating a small effect of 7-MX on dopamine. Conclusions: In our study, 7-MX had no effect on DM in chicks and only minor effects on ChT and retinal dopamine. It remains unclear whether 7-MX inhibits myopia through a retinal mechanism or whether it acts directly on choroid and sclera. In the latter case, the finding that myopia is suppressed in mammals but not birds might be explained by differences in scleral structure.

(Invited) Co-Detection of Dopamine and Metabolites Using Fast Scan Cyclic Voltammetry and Modified Carbon Fiber-Microelectrodes

Fast scan cyclic voltammetry (FSCV) and carbon-fiber microelectrodes (CFMEs) have been utilized used to detect several important neurochemicals in vivo. However, this method is limited due to the ability to discriminate dopamine from several of its metabolites. Carbon nanotube and polymer modified microelectrodes will be utilized to detect physiologically low levels of neurotransmitters that also resist surface fouling and have high temporal resolution to detect fast changes of neurotransmitters. Furthermore, novel electrode coatings and waveforms will also be utilized to detect several neurotransmitter metabolites such as dopamine, norepinephrine, normetanephrine, 3-methoxytyramine (3-MT), homovanillic acid (HVA), 3,4 dihydroxyphenylacetic acid (DOPAC), and other metabolites. Currently, dopamine is thought to be an important neurotransmitter concerning several disease states such Parkinson’s disease, drug abuse (amphetamine, cocaine, etc.), and even for gambling and sex-disorders. However, dopamine is metabolized on a subsecond timescale, and studies have pointed to the importance of neurotransmitter metabolites in these disease states apart from dopamine. Presently, there is no method to selectively co-detect these neurotransmitter metabolites of dopamine utilizing FSCV. Through several waveform modifications and polymer electrode coatings, we develop a novel method to tune the detection of dopamine and said metabolites, which will help differentiate dopamine and respective metabolites through the shapes and positions of their respective cyclic voltammograms. Preliminary measurements have also been made in zebrafish whole brain ex vivo showing the application of this technique in biological tissue. Discriminating the detection of dopamine from its metabolites will have many implications in better understanding complex disease, behavioral, and pharmacological states.

Lactoferrin Coupled Lower Generation PAMAM Dendrimers for Brain Targeted Delivery of Memantine in Aluminum-Chloride-Induced Alzheimer's Disease in Mice.

Lower generation PAMAM dendrimers have an immense potential for drug delivery with lower toxicity, but these dendrimers yet need certain basic ameliorations. In this study, the brain delivery potential of the synthesized PAMAM-Lf (lower generation PAMAM and lactoferrin conjugate) loaded with memantine (MEM) was explored and evaluated in vitro and in vivo in the disease-induced mouse model. The developed nanoscaffolds were characterized for size, zeta potential and in vitro release. Increase in the average size from 11.54 ± 0.91 to 131.72 ± 4.73 nm, respectively, was observed for drug-loaded PAMAM (i.e., PAMAM-MEM) and PAMAM-Lf (i.e., MEM-PAMAM-Lf).Releaseprofile of MEMfrom MEM-PAMAM-Lf was slow and sustained up to 48 h. In vivo biodistribution in the Sprague-Dawley rat model revealed that the brain uptake of MEM-PAMAM-Lf was significantly higher than that of MEM alone. The behavioral response study in the healthy ratsdid not result in any significant changes. The in vivo study in an AlCl3-induced Alzheimer's (AD) mice model showed a significant improvement in behavioral responses. Optical density, which reflects the acetylcholinesterase (AChE) activity, was highest in the AL group 0.16 ± 0.01 (higher than the CON group, 0.09 ± 0.02; p < 0.05). No significant suppression of AChE activity was recorded in all the other treated groups. Similarly, the DOPAmine and 3,4 dihydroxyphenylacetic acid (DOPAC) levels were unaffected by the developed formulations. The study reported improved brain bioavailability of MEM in AlCl3-induced Alzheimer's mice leading to improved memory, with the resultant mechanism behind in a descriptive manner. This study is among the preliminary studies reporting the memory improvement aspect ofPAMAM-Lf conjugates for MEM in AlCl3-AD induced mice. The formulation developed was beneficial in AD-induced mice and had a significant impact on the memory aspects.

Total glucosides of paeony (TGP) extracted from Radix Paeoniae Alba exerts neuroprotective effects in MPTP-induced experimental parkinsonism by regulating the cAMP/PKA/CREB signaling pathway

Ethnopharmacological relevanceThe totally-amounted glucosides of paeony (TGP), which are made up of paeoniflorin, albiflorin, oxypaeoniflorin as well as benzoylpaeoniflorin, constitute the Baishao’ actively-working component extracted from Radix Paeonia alba employed in conventional oriental medicine aiming to treat cerebrovascular disorders, such as Parkinson's disease. However, its pharmacologic mechanism is not clear. Aim of the studyThe initial investigation was made on TGP's neuroprotective effects on PD of the mouse model based on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) as well as the identification of potential involvement of a molecular signaling pathway. Materials and methodsThe evaluation of the behavioral damage as well as neurotoxicity in mice was made through MPTP. Spontaneous motor activity test, as well as a test of Rota-rod on mice was employed for the measurement of bradykinesia symptom. Additionally, liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) works as the determiner of the main monoamine neurotransmitters dopamine (DA) along with its metabolites 3, 4-dihydroxyphenylacetic acid (DOPAC) as well as homovanillic acid (HVA) based on mouse hippocampus connected with the anti-Parkinson's disease like effect of TGP. Besides, the measurement of the effects of TGP treatment on the expressions level of TH, DAT, a-synuclein, p-CREBS133 as well as apoptosis influence was made with the help of western-blot assay with apoptosis-related markers such as Bax and Bcl-2. ResultsThe results showed that TGP treatment lessened the behavior-based loss shown “in the spontaneous motor activity as well as the potential of falling to rotarod test”. In addition, we found that pretreatment with TGP markedly improved motor coordination, striatal dopamine and its metabolite levels. Furthermore, pretreatment of TGP conducted the protection for dopaminergic neurons with the prevented MPTP-induced reductions within the tyrosine hydroxylase (TH), substantia nigra dopaminergic transporter (DAT), as well as increasing α-synuclein protein levels with transformed dopamine catabolism as well as inhibited dopamine turnover. Besides, TGP treatment helped reversed apoptosis signaling molecules Bcl-2/Bax’ reduction; meanwhile improving p-CREBS133 the factor of growth signaling in the substantia nigra’ decrease. ConclusionThese results suggested that TGP can enhance dopaminergic neuron's cell survival in the SNpc in virtue of the activated cAMP/PKA/CREB factor of growth on inhibiting the pathway of second messenger apoptosis as well. In conclusion, the current findings indicate TGP is expected to be a new cure for PD.

Determination of endogenous substance change in PM2.5-induced rat plasma and lung samples by UPLC-MS/MS method to identify potential markers for lung impairment.

Exposure to fine particulate matter (PM2.5) could induce lung impairment aggravation. Moreover, endogenous substances are known to play a significant role in lung impairment. Therefore, the research objectives was to investigate the influence of PM2.5-induced lung impairment on the levels of the eight endogenous substances, γ-aminobutyric acid (GABA), acetylcholine (ACh), glutamate (Glu), serotonin (5-HT), 5-hydroxyindole-3-acetic acid (5-HIAA), noradrenaline (NE), dopamine (DA), and 3, 4-dihydroxyphenylacetic acid (DOPAC). A sensitive UPLC-MS/MS method for the simultaneous determination of these endogenous substances in rat plasma and lung tissues was developed. The validated method was successfully applied for comparing profiles of analytes in rat plasma and lung tissues. The results indicated that five endogenous substances, namely, GABA, Ach, Glu, DA, and DOPAC, had a significant change in the rats with PM2.5-induced lung impairment.

Anxiolytic effect of a novel 9,10-dihydrophenanthrene, juncuenin H, is associated with metabolic changes in cortical serotonin/dopamine levels in mice

Two novel phenanthrenoids, juncuenin H (1) and dijuncuenin B (2), together with eight known phenanthrenoids, effusol (3), dehydroeffusol (4), juncusol (5), dehydrojuncusol (6), juncuenin B (7), dehydrojuncuenin B (8), juncuenin A (9), and dehydrojuncuenin A (10), were isolated from the underground parts of Juncus setchuenensis. The structures of the compounds were determined by 1D and 2D NMR and mass spectroscopy. The anxiolytic activities of compounds 1, 6, 9, and 10 were evaluated. In order to explore the mechanisms underlying their anxiolytic activities, the levels of serotonin (5-HT), dopamine (DA), and their metabolites in the cerebral cortex and hippocampus of mice treated with compound 1 were determined by quantitative mass spectrometry. The mice treated with compound 1 had significantly lower levels of 5-HT, 3-methoxytyramine (3-MT), 5-hydroxyindole-3-acetic acid (5-HIAA), homovanillic acid (HVA), and 3, 4-dihydroxyphenylacetic acid (DOPAC) in the cerebral cortex than those of the vehicle control-treated mice. The levels of HVA and 5-HIAA in the hippocampus were also significantly lower in the mice treated with compound 1 than in the control group mice. These results suggest that the metabolic changes, reflected in the levels of DA and/or 5-HT, may contribute to the anxiolytic activity of the phenanthrenoids studied herein.

Role of glucocorticoids on noradrenergic and dopaminergic neurotransmission within the basolateral amygdala and dentate gyrus during morphine withdrawal place aversion.

Aversive memories related to drug withdrawal can generate a motivational state leading to compulsive drug taking. However, the mechanisms underlying the generation of these withdrawal memories remain unclear. Limbic structures, such as the basolateral amygdala (BLA) and the dentate gyrus (DG) of the hippocampus, play a crucial role in the negative affective component of morphine withdrawal. Given the prominent role of glucocorticoids (GCs), noradrenaline (NA), and dopamine (DA) in memory-related processes, in the present study, we employed the conditioned place aversion (CPA) paradigm to uncover the role of GCs on NA and DA neurotransmission within the BLA and NA neurotransmission within the DG during opiate-withdrawal conditioning (memory formation consolidation), and after reexposure to the conditioned environment (memory retrieval). We observed that adrenalectomy impaired naloxone-induced CPA. Memory retrieval was associated with an increase in dihydroxyphenylacetic acid (DOPAC) levels in the BLA in morphine-addicted animals in a GC-independent manner. Importantly, NA turnover was related with the expression of withdrawal physical signs during the conditioning phase and with locomotor activity during the test phase. On the other hand, reduced DA concentration in the BLA was correlated with the CPA score. Our results indicate that while noradrenergic system is more associated with the somatic consequences of withdrawal, dopaminergic neurotransmission modulates the affective state. Nevertheless, it seems necessary that both systems work together with GCs to enable aversive-memory formation and recall.

Efficient biosynthesis of 3, 4-dihydroxyphenylacetic acid in Escherichia coli

3, 4-Dihydroxyphenylacetic acid (3, 4-DHPA) is a phenolic acid with strong anti-oxidative activity, showing potential applications in food and pharmaceutical industries. In this study, a 3, 4-DHPA biosynthetic pathway was designed by connecting 4-hydroxyphenylacetic acid (4-HPA) biosynthesis with its hydroxylation. The starting strain produced only 46 mg/L of 4-HPA in 48 h. Enhancing the shikimate pathway increased the titer by 19-fold to 923 ± 57 mg/L. Furthermore, pykA and pykF were disrupted to conserve phosphoenolpyruvate for 4-HPA production. With this effort, 4-HPA titer was increased to 1817 ± 55 mg/L. Introducing the hydroxylase HpaBC into the 4-HPA overproducing strain resulted in 3, 4-DHPA production and the best strain produced 1856 ± 67 mg/L of 3, 4-DHPA in shake flask cultures. This work reports de novo biosynthesis of 3, 4-DHPA for the first time and provides a promising alternative for sustainable production of this valuable compound.

Phospholipid-modified carbon fiber brush electrode for the detection of dopamine and 3,4-dihydroxyphenylacetic acid

Different procedures for modification of carbon fiber brush electrode (CFBE) with phospholipids were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. Simple immersion of the preanodized electrode into hexane solution of asolectin (a mixture of soybean phospholipids) followed by formation of the phospholipid layer in NaCl solution was the most effective procedure. Phospholipid layer-modified electrode (PL-CFBE) was applied to detect dopamine and its metabolite, 3,4 dihydroxyphenylacetic acid, using differential pulse and square-wave voltammetry in phosphate buffer solution of pH 6.5. Accumulation of dopamine, supported by electrostatic interactions between positively charged amino group and negatively charged phosphate moiety of the layer, enhanced sensitivity of PL-CFBE compared to bare CFBE. On the contrary, repulsive interaction between 3,4 dihydroxyphenylacetate anion and negatively charged phosphate moiety of the layer suppressed PL-CFBE sensitivity, measured as a slope of calibration dependence.