Dopamine-mediated actions of ephedrine in the rat substantia nigra

Ephedrine and cocaine cause developmental neurotoxicity and abnormal behavior in zebrafish

Ephedrine (EPH) and cocaine (COC) are illegal stimulant drugs, and have been frequently detected in aquatic environments. EPH and COC have negative effects on the nervous system and cause abnormal behaviors in mammals and fish at high concentrations, but their mechanisms of neurotoxicity remain unclear in larvae fish at low concentrations. To address this issue, zebrafish embryos were exposed to EPH and COC for 14 days post-fertilization (dpf) at 10, 100, and 1000 ng L-1. The bioaccumulation, development, behavior, cell neurotransmitter levels and apoptosis were detected to investigate the developmental neurotoxicity (DNT) of EPH and COC. The results showed that EPH decreased heart rate, while COC increased heart rate. EPH caused cell apoptosis in the brain by AO staining. In addition, behavior analysis indicated that EPH and COC affected spontaneous movement, touch-response, swimming activity and anxiety-like behaviors. EPH and COC altered the levels of the neurotransmitters dopamine (DA) and γ-aminobutyric acid (GABA) with changes of the transcription of genes related to the DA and GABA pathways. These findings indicated that EPH and COC had noticeable DNT in the early stage of zebrafish at environmentally relevant concentrations.

Natural Sympathomimetic Drugs: From Pharmacology to Toxicology

Sympathomimetic agents are a group of chemical compounds that are able to activate the sympathetic nervous system either directly via adrenergic receptors or indirectly by increasing endogenous catecholamine levels or mimicking their intracellular signaling pathways. Compounds from this group, both used therapeutically or abused, comprise endogenous catecholamines (such as adrenaline and noradrenaline), synthetic amines (e.g., isoproterenol and dobutamine), trace amines (e.g., tyramine, tryptamine, histamine and octopamine), illicit drugs (e.g., ephedrine, cathinone, and cocaine), or even caffeine and synephrine. In addition to the effects triggered by stimulation of the sympathetic system, the discovery of trace amine associated receptors (TAARs) in humans brought new insights about their sympathomimetic pharmacology and toxicology. Although synthetic sympathomimetic agents are mostly seen as toxic, natural sympathomimetic agents are considered more complacently in the terms of safety in the vision of the lay public. Here, we aim to discuss the pharmacological and mainly toxicological aspects related to sympathomimetic natural agents, in particular of trace amines, compounds derived from plants like ephedra and khat, and finally cocaine. The main purpose of this review is to give a scientific and updated view of those agents and serve as a reminder on the safety issues of natural sympathomimetic agents most used in the community.

Comprehensive review on the interaction between natural compounds and brain receptors: Benefits and toxicity

Given their therapeutic activity, natural products have been used in traditional medicines throughout the centuries. The growing interest of the scientific community in phytopharmaceuticals, and more recently in marine products, has resulted in a significant number of research efforts towards understanding their effect in the treatment of neurodegenerative diseases, such as Alzheimer's (AD), Parkinson (PD) and Huntington (HD). Several studies have shown that many of the primary and secondary metabolites of plants, marine organisms and others, have high affinities for various brain receptors and may play a crucial role in the treatment of diseases affecting the central nervous system (CNS) in mammalians. Actually, such compounds may act on the brain receptors either by agonism, antagonism, allosteric modulation or other type of activity aimed at enhancing a certain effect. The current manuscript comprehensively reviews the state of the art on the interactions between natural compounds and brain receptors. This information is of foremost importance when it is intended to investigate and develop cutting-edge drugs, more effective and with alternative mechanisms of action to the conventional drugs presently used for the treatment of neurodegenerative diseases. Thus, we reviewed the effect of 173 natural products on neurotransmitter receptors, diabetes related receptors, neurotrophic factor related receptors, immune system related receptors, oxidative stress related receptors, transcription factors regulating gene expression related receptors and blood-brain barrier receptors.

Exploring the neuromechanism of chronic ephedrine addiction in rhesus monkeys: A behavioural and brain resting-state fMRI study

Ephedrine is thought to exert behavioural effects primarily through actions on the central nervous system. However, the neuromechanism underlying the effects of ephedrine addiction still remains unclear. Our study aimed to establish chronic ephedrine addiction models in rhesus monkeys and to investigate the neuromechanism of chronic ephedrine addiction using the behavioural methods combined with resting-state blood oxygenation level dependent-functional magnetic resonance imaging (BOLD-fMRI). Monkeys in the ephedrine addiction group (n = 6) received intramuscular injections of ephedrine using a dose escalation method, with a chronic model established in 8 weeks, while in the control group (n = 4), monkeys received a pure 0.9% saline injection. The weight and behaviors of the monkeys were observed throughout the treatment. All monkeys underwent the brain MR scans for two times (before treatment and after treatment had been discontinued). After molding, the weight of the ephedrine group was significantly reduced, while the weight of the control group increased significantly. Compared with the control group, the ephedrine addicted monkeys showed more abnormal behaviors related to addiction. In fMRI study, the ephedrine addicted monkeys showed more increased brain activation than that of the control group, mainly including the prefrontal cortex(PFC) and anterior cingulate cortex (ACC), the left ventral tegmental area(VTA), right insula, right amygdala, hippocampus, left thalamus, and left cerebellum.We hypothesize that the principal neuromechanism underlying chronic ephedrine addiction involves multiple abnormal brain neuron circuits, mainly in the PFC and the limbic system, and is closely related to addictive behaviors.

The genus Sida L. - A traditional medicine: Its ethnopharmacological, phytochemical and pharmacological data for commercial exploitation in herbal drugs industry

ETHNOPHARMACOLOGICAL RELEVANCE

Sida L. (Malvaceae) has been used for centuries in traditional medicines in different countries for the prevention and treatment of different diseases such as diarrhea, dysentery, gastrointestinal and urinary infections, malarial and other fevers, childbirth and miscarriage problems, skin ailments, cardiac and neural problems, asthma, bronchitis and other respiratory problems, weight loss aid, rheumatic and other inflammations, tuberculosis, etc.

AIMS OF THIS REVIEW

To assess the scientific evidence for therapeutic potential of Sida L. and to identify the gaps of future research needs.

METHODS

The available information on the ethnomedicinal uses, phytochemistry, pharmacology and toxicology of Sida species was collected via a library and electronic searches in SciFinder, PubMed, ScienceDirect, Google Scholar for the period, 1933-2015.

RESULTS

A variety of ethnomedicinal uses of Sida species have been found in India, China, Afrian and American countries. Phytochemical investigation of this genus has resulted in identification of about 142 chemical constituents, among which alkaloids, flavonoids and ecdysteroids are the predominant groups. The crude extracts and isolates have exhibited a wide spectrum of in vitro and in vivo pharmacological effects involving antimicrobial, analgesic, anti-inflammatory, abortifacient, neuroprotective, cardiovascular and cardioprotective, antimalarial, antitubercular, antidiabetic and antiobesity, antioxidant and nephroprotective activities among others. Ethnopharmacological preparations containing Sida species as an ingredient in India, African and American countries possess good efficacy in health disorders. From the toxicity perspective, only three Sida species have been assessed and found safe for oral use in rats.

CONCLUSIONS

Pharmacological results supported some of the uses of Sida species in the traditional medicine. Alkaloids, flavonoids, other phenolics and ecdysteroids were perhaps responsible for the activities of extracts of the plants of this genus. No clinical study was reported. The detailed study on mechanism of action of isolates and extracts and their clinical study are needed for their use in modern medicine. More attention should be paid to Sida acuta, Sida cordifolia, Sida spinosa, Sida rhombifolia and Sida veronicaefolia in the domain of diarrhea, dysentery, gastrointestinal and urinary infections, skin ailments, asthma, bronchitis and other respiratory problems, malaria, childbirth and miscarriage problems, cardiac and neural problems, weight loss aid, and rheumatic and other inflammations, etc. Furthermore, detailed study on quality and safety assurance data on available ethnopharmacological preparations is needed for their commercial exploitation in local and global markets.

Soma, food of the immortals according to the Bower Manuscript (Kashmir, 6th century A.D.)

ETHNOPHARMACOLOGICAL RELEVANCE

Food is medicine and vice versa. In Hindu and Ayurvedic medicine, and among human cultures of the Indian subcontinent in general, the perception of the food-medicine continuum is especially well established. The preparation of the exhilarating, gold-coloured Soma, Amrita or Ambrosia, the elixir and food of the 'immortals'-the Hindu pantheon-by the ancient Indo-Aryans, is described in the Rigveda in poetic hymns. Different theories regarding the botanical identity of Soma circulate, but no pharmacologically and historically convincing theory exists to date. We intend to contribute to the botanical, chemical and pharmacological characterisation of Soma through an analysis of two historical Amrita recipes recorded in the Bower Manuscript. The recipes are referred therein as panaceas (clarified butter) and also as a medicine to treat nervous diseases (oil), while no exhilarating properties are mentioned. Notwithstanding this, we hypothesise, that these recipes are related to the ca. 1800 years older Rigvedic Soma. We suppose that the psychoactive Soma ingredient(s) are among the components, possibly in smaller proportions, of the Amrita recipes preserved in the Bower Manuscript.

MATERIALS AND METHODS

The Bower Manuscript is a medical treatise recorded in the 6th century A.D. in Sanskrit on birch bark leaves, probably by Buddhist monks, and unearthed towards the end of the 19th century in Chinese Turkestan. We analysed two Amrita recipes from the Bower Manuscript, which was translated by Rudolf Hoernle into English during the early 20th century. A database search with the updated Latin binomials of the herbal ingredients was used to gather quantitative phytochemical and pharmacological information.

RESULTS

Together, both Amrita recipes contain around 100 herbal ingredients. Psychoactive alkaloid containing species still important in Ayurvedic, Chinese and Thai medicine and mentioned in the recipe for 'Amrita-Prâsa clarified butter' and 'Amrita Oil' are: Tinospora cordifolia (Amrita, Guduchi), three Sida spp., Mucuna pruriens, Nelumbo nucifera, Desmodium gangeticum, and Tabernaemontana divaricata. These species contain several notorious and potential psychoactive and psychedelic alkaloids, namely: tryptamines, 2-phenylethylamine, ephedrine, aporphines, ibogaine, and L-DOPA. Furthermore, protoberberine alkaloids, tetrahydro-β-carbolines, and tetrahydroisoquinolines with monoamine oxidase inhibitor (MAO-I) activity but also neurotoxic properties are reported.

CONCLUSIONS

We propose that Soma was a combination of a protoberberine alkaloids containing Tinospora cordifolia juice with MAO-I properties mixed together with a tryptamine rich Desmodium gangeticum extract or a blending of Tinospora cordifolia with an ephedrine and phenylethylamine-rich Sida spp. extract. Tinospora cordifolia combined with Desmodium gangeticum might provide a psychedelic experience with visual effects, while a combination of Tinospora cordifolia with Sida spp. might lead to more euphoric and amphetamine-like experiences.

Ameliorative effect of Sida cordifolia in rotenone induced oxidative stress model of Parkinson's disease

Present study focused on the evaluation of aqueous extract of Sida cordifolia (AESC), and its different fractions; hexane (HFSC), chloroform (CFSC) and aqueous (AFSC), against rotenone induced biochemical, neurochemical, histopathological and behavioral alterations in a rat model of Parkinson's disease (PD). An estimation of the level of thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and catalase (CAT) along with superoxide anion generation (SAG) in different brain regions (cortex, midbrain and cerebellum) was carried out to assess biochemical changes. Behavioral evaluation tests (catalepsy, rearing behavior and posture instability) and neurochemical estimations (norepinephrine, dopamine and serotonin level) along with histopathological evaluations of different brain regions were also performed. The varying doses (50, 100, 250mg/kg; p.o.) of different test treatments (AESC, HFSC, CFSC and AFSC) were co-administered along with rotenone (2mg/kg; s.c.), for a period of 35 days to rats of various groups and compared with rotenone per se (negative control) and l-deprenyl (positive control; 10mg/kg; p.o.) treated groups for the above mentioned parameters. The increase in catalepsy and posture instability along with decrease in rearing behavior observed due to rotenone treatment was significantly attenuated by co-treatment with varying doses of AESC and AFSC. Results of the histopathological studies of different brain regions of rats showed eosinophilic lesions in the mid brain region due to rotenone treatment. The eosinophilic lesions were significantly attenuated in co-treated groups of AESC-100mg/kg and AFSC-100mg/kg. Rotenone induced oxidative damage, revealed by increased level of TBARS, SAG and decreased level of GSH and CAT in mid brain region of rats, was attenuated by the co-treatment of AESC and AFSC. The rotenone induced decrease of dopamine level in the midbrain region of rats was also attenuated by co-treatment of AESC-100mg/kg and AFSC-100mg/kg. The maximum effect in all the above activities was observed in AFSC (100mg/kg) treated group, which was comparable to l-deprenyl treated group. The HFSC and CFSC co-treatment failed to show significant attenuation of rotenone induced damage. These results indicate the possible therapeutic potential of most polar fraction of AESC i.e. AFSC in PD by virtue of its antioxidative actions.

Ephedrine induced thioredoxin-1 expression through β-adrenergic receptor/cyclic AMP/protein kinase A/dopamine- and cyclic AMP-regulated phosphoprotein signaling pathway

Ephedrine (Eph) is one of alkaloids that has been isolated from the ancient herb ephedra (ma huang) and is used as the treatment of asthma, hypotension and fatigue. However, its molecular mechanism remains unknown. Thioredoxin-1 (Trx-1) is a redox regulating protein, which has various biological activities, including regulating transcription factor DNA binding activity and neuroprotection. In this study, we found that Eph induced Trx-1 expression, which was inhibited by propranolol (β-adrenergic receptor inhibitor), but not by phenoxybenzamine (α-adrenergic receptor inhibitor) in rat pheochromocytoma PC12 cells. Moreover, the increase of Trx-1 expression was inhibited by SQ22536 (adenylyl cyclase inhibitor) and H-89 (protein kinase A inhibitor). Interestingly, the effect of Eph on dopamine- and cyclic AMP-regulated phosphoprotein (DARPP-32) was similar to Trx-1. Thus, the relationship between Trx-1 and DARPP-32 was further studied. The DARPP-32 siRNA significantly reduced Trx-1 expression, but Trx-1 siRNA did not exchange DARPP-32. These results suggested that Eph induced the Trx-1 expression through β-adrenergic receptor/cyclic AMP/PKA/DARPP-32 signaling pathway. Furthermore, Eph induced PKA-mediated cyclic AMP response element-binding protein (CREB) phosphorylation. Down-regulation of DARPP-32 expression decreased phosphorylated CREB. In addition, Eph had a significant effect on the viability of the rat pheochromocytoma PC12 cells through β-adrenergic receptors. Trx-1 may play an important role in the actions of Eph.

Common responses in gene expression by Ephedra herba in brain and heart of mouse

The physiological activities of Ephedra herba have been investigated extensively, particularly in the cardiovascular and cerebrovascular systems. However, the molecular mechanisms underlying the effects of Ephedra herba on the brain and heart have yet to be thoroughly elucidated at the whole genome level. Therefore, the present study focused on the identification of the regulatory pattern of gene expression occurring in response to Ephedra herba, using microarray assays in three mouse organs - namely, the brain, heart and liver. Interestingly, the brain and heart exhibited a similar reciprocal pattern of gene expression during the early stages after the administration of Ephedra herba, whereas the liver evidenced a different gene expression profile. Moreover, pathways analysis showed that genes regulated reciprocally by Ephedra herba were associated with neural disease-related functions, such as the Parkinson's disease pathway, in both the brain and the heart. Promoter sequence analysis demonstrated that reciprocally regulated genes could be classified into subgroups on the basis of the similarity of their transcription factor binding sequences, in which temporally up-regulated genes were clustered as distinctive subgroups. In conclusion, the brain and heart responded commonly to Ephedra herba with a temporally reciprocal pattern of gene expression.

Neurotoxicity following chronic intravenous use of "Russian cocktail"

INTRODUCTION

Recently, neurological abnormalities in methcathinone users have been attributed to manganese. We report similar toxicity in three patients following the use of a mixture similar to methcathinone: potassium permanganate, ephedrine, and aspirin.

CASE REPORTS

Three teenagers (15 to 19 years old) presented with extrapyramidal abnormalities and movement disorders following chronic intravenous use of a mixture known as "Russian Cocktail". All three patients had multiple movement disorders. One patient had normal blood manganese concentration (<19 microg/L) and MRI. The other two had elevated blood manganese (2100 microg/L and 3176 microg/L) and MRIs showing bilateral symmetric hyper-intensities on T1-weighted-images in the dentate nucleus, subcortical white substance of cerebellar hemisphere, globus pallidus, and putamen. Abstinence and treatment with EDTA, levodopa, and para-aminosalicylic acid was associated with decreasing blood manganese concentrations and subjective improvement, but no change in objective findings.

DISCUSSION

The "Russian Cocktail" likely contains manganese as a result of the oxidation of ephedrine by potassium permanganate in water acidified by acetylsalicylic acid. We believe that manganese with the possible contribution of methcathinone caused the neurological impairments.

CONCLUSIONS

Three toxic substances have been made into a mixture administered intravenously, similar to methcathinone. Our patients learned of this mixture, called "Russian Cocktail", from their friends. The toxicity from repeated use of this mixture is one of extrapyramidal abnormalities and movement disorders. Standard therapies were unsuccessful in reversing the clinical toxicity.

D1- and D2-like dopamine receptors regulate signaling properties of group I metabotropic glutamate receptors in the rat globus pallidus

Dopamine is essential to the proper functioning of basal ganglia (BG) because loss of dopaminergic input profoundly alters the activity of these nuclei. Experimental evidence suggests that multiple aspects of glutamatergic neurotransmission in the BG are altered with the loss of dopaminergic input. Using whole-cell patch-clamp recording in rat brain slices, we examined whether activity of dopamine receptors is necessary to maintain signaling properties of group I metabotropic glutamate receptor subtypes, mGluR1 and 5, in the rat globus pallidus (GP), one of the nuclei in the BG circuit. Dopaminergic depletion due to systemic treatment with reserpine caused a change in the signaling properties of group I mGluRs, where mGluR1 lost the ability to depolarize GP neurons, while mGluR5 gained such ability. Bath-application of dopamine or D1- and D2-like dopamine receptor agonists to slices from reserpinized rats partly reversed these effects and caused mGluR1 to gain back its ability to depolarize GP neurons. On the other hand, stimulation of either D1-like or D2-like dopamine receptors was sufficient to abolish the activating properties of mGluR5 acquired following reserpine treatment. Interestingly, inhibition of protein kinase A activity alone was sufficient to largely reverse plasticity in function of group I mGluRs that was induced by reserpine treatment. Our data reveal that specific roles of group I mGluRs in the GP depend on the activity of D1-like and D2-like dopamine receptors, further corroborating the importance of dopamine in maintaining proper glutamatergic neurotransmission in the BG.

Tyramine excites rat subthalamic neurons in vitro by a dopamine-dependent mechanism

Tyramine, an endogenous ligand for mammalian trace amine-associated receptors, may act as a neuromodulator that regulates neuronal activity in basal ganglia. Using whole-cell patch recordings of subthalamic nucleus (STN) neurons in rat brain slices, we found that bath application of tyramine evoked an inward current in voltage-clamp in over 60% of all STN neurons. The inward current induced by tyramine was mimicked by the D(2)-like dopamine receptor agonist quinpirole, but was only partially blocked by the D(2)-like receptor antagonist sulpiride. In contrast, the D(1)-like receptor agonist SKF38393 evoked no current in STN neurons. Inward current evoked by tyramine was significantly reduced by the catecholamine uptake inhibitor nomifensine, and by exhausting catecholamines in the brain via pretreatment with reserpine. Tyramine also reduced the amplitude of GABA(A) receptor-mediated IPSCs that were evoked by focal electrical stimulation of the slice. Inhibition of IPSCs by tyramine was mimicked by quinpirole and was blocked by sulpiride but not by SCH23390, a D(1) receptor antagonist. Moreover, tyramine-induced inhibition of IPSCs was reduced in slices pretreated with reserpine, and this inhibition could be restored by briefly superfusing the slice with dopamine. These results suggest that tyramine acts as an indirect dopamine agonist in the STN. Although inhibition of IPSCs is mediated by D(2)-like receptors, the dopamine-dependent inward currents evoked by tyramine do not fit a typical dopamine receptor pharmacological profile.