Role of Levo-tetrahydropalmatine and its metabolites for management of chronic pain and opioid use disorders.

BACKGROUND: Opioids have been prescribed to reduce suffering from pain and to enhance quality of life. Due to the addictive potential and the lack of other effective alternatives to treat severe acute and chronic pains, opioids remain a serious public health issue. While, opioids directly influence the drug-seeking behavior, tolerance and withdrawal processes, through neuroadaptation, the brain's endogenous opioid system also adapts in the presence of chronic pain and could contribute to the difficulty of treatment. Despite the seemingly obvious interaction between the presence of pain and opioid-abuse, little is known about the underlying mechanisms in the brain. PURPOSE: To review the current understanding of the interaction mechanisms of neurotransmitter circuitries in pain modulation and reward in the brain and the effects of L-tetrahydropalmatine (L-THP) and its metabolites in pain management and opioid use disorder and gain a better insight on the pharmacological profile and in vivo effects of L-THP and its metabolites. METHOD: A detailed literature search on available (preclinical and clinical) studies about the effects of L-THP and its metabolites against drug addiction and chronic pain has been performed. The data was collected using various search engines such as PubMed, ScienceDirect, Google scholar and articles in English up to December 2020 were included in this review. RESULTS: L-THP and its metabolites demonstrated analgesic and anti-addiction effects. Due to their dual pharmacological properties (D1 partial agonist and D2 antagonist) these compounds could be used as molecular tools to provide a better understanding of the interactions between pain and addiction. CONCLUSION: The available data confirms the potential of L-THP and its metabolites to treat both chronic pain and drug addiction. However, further clinical trials are needed to establish safety and efficacy.

Effects of Yuanhu- Zhitong tablets on alcohol-induced conditioned place preference in mice.

OBJECTIVES: This study aimed at determining the synergistic effects of Yuanhu Zhitong tablets (YHZTP) on alcohol-induced conditioned place preference (CPP) in mice, in addition, the intervention mechanism was preliminarily explored based on traditional Chinese Medicine (TCM) network pharmacology on alcohol addiction. METHODS: Alcohol-induced CPP mice were used to evaluate the effects of either YHZTP or levo-tetrahydropalmatine (l-THP) plus imperatorin (IMP) administration on animal behavior. The network pharmacological strategy was used to establish the "compound-target" and "disease-drug-target" network. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed on the shared targets between the compound and the disease. Twelve algorithms on CytoHubba were used to find the hub genes that were verified by qPCR. RESULTS: Systemic administration (2 g/kg, i.p.) of ethanol (EtOH) to mice was used to induce CPP. YHZTP On its own did not induce CPP or conditioned place aversion (CPA) at the doses of 0.3 g/kg or 0.6 g/kg (i.g.), but attenuated the acquisition and expression of EtOH-induce CPP in mice. In addition, YHZTP (0.3 or 0.6 g/kg) did not exhibit any effect on the motor activity of mice. Acquisition of alcohol-induced CPP was blocked by a combination of l-THP (5 mg/kg, i.g.) + IMP (2.5 mg/kg, i.g.) or l-THP (10 mg/kg, i.g.) + IMP (5 mg/kg, i.g.). However, the combination of l-THP (2.5 mg/kg, i.g.) + IMP (1.25 mg/kg, i.g.) or mono-administration of l-THP and IMP did not exhibit any effect on alcohol-induced CPP. YHZTP was also shown to reverse the up-regulation of Gabra1, Ptgs2, Mapk1, Mapk8, Mapk14, Nr3c, Prkca and Sirt1 genes and the down-regulation of Hhtr2a and Drd2 genes in the prefrontal cortex of EtOH induced CPP mice. These genes were associated with neuroactive ligand-receptor interactions, activation of the sphingolipid, calcium, cAMP, ErbB, NF-kappa B and MAPK signaling pathways. CONCLUSION: YHZTP inhibits EtOH-induced CPP behavior in mice while a combination of l-THP and IMP exerts a synergistic effect on the reduction of EtOH-induced CPP. Possible pharmacological mechanisms include inhibition of the expression of inflammatory factors and regulation of neurotransmitter receptor levels. Therefore, YHZTP is a novel candidate for the treatment of alcohol addiction.

Targeting ERα degradation by L-Tetrahydropalmatine provides a novel strategy for breast cancer treatment.

The incidence and mortality of breast cancer (BCa) are the highest among female cancers. There are approximate 70% BCa that are classified as estrogen receptor alpha (ERα) positive. Therefore, targeting ERα is the most significantly therapeutic schedule. However, patients with breast cancer develop resistance to ERα or estrogen (E2) antagonists such as fulvestrant and tamoxifen. In the present study, we found that L-Tetrahydropalmatine (L-THP) significantly suppressed cell proliferation in ERα+ BCa cells via inducing cell cycle arrest rather than apoptosis. Additionally, L-THP enhanced the sensitivity of ERα+ BCa cells to tamoxifen and fulvestrant. Mechanically, the application of L-THP promotes ERα degradation through accumulating ubiquitin chains on ERα. Overexpressing ERα abrogates L-THP induced-antiproliferation in ERα+ BCa cells. Collectively, our work indicates that L-THP may represent a potentially novel therapeutic medicine for ERα+ breast cancer patient.

Levo-tetrahydropalmatine Attenuates Neuron Apoptosis Induced by Cerebral Ischemia-Reperfusion Injury: Involvement of c-Abl Activation.

Ischemic stroke is one of the most dangerous acute diseases which causes death or deformity. Apoptosis has been shown to play an important role in the development and pathogenesis of cerebral ischemia-reperfusion injury (I/R injury), but the related mechanism is unclear. Levo-tetrahydropalmatine (L-THP), a bioactive ingredient extracted from the Chinese herb Corydalis, can penetrate the blood-brain barrier and exert various pharmacological effects on neural tissues. The present study examined the neuroprotective effect of L-THP on neuronal apoptosis induced by cerebral I/R injury. Results showed that pretreatment with L-THP (12.5, 25, and 50 mg/kg) improved neurological outcomes and reduced infarct volume and cerebral edema in comparison with the brains of the middle cerebral artery occlusion (MCAO) group. These findings provided evidence for the neuroprotective effects of L-THP against cerebral I/R injury. Furthermore, administration of L-THP enhanced the expression of Bcl-2 and attenuated the content of Bax, cleaved caspase-3, and PARP. L-THP could improve the reduction of NeuN-positive cells induced by I/R injury. These results suggested that L-THP could inhibit neuroapoptosis in cerebral ischemic rats. c-Abl was discovered as the critical protein responsible for neurocyte apoptosis; however, few data have been published on the relation between ischemic stroke and the expression of c-Abl. We found that both c-Abl expression and neuronal apoptosis were significantly increased in the MCAO group, while pretreatment with L-THP could ameliorate this effect. Therefore, we deduced that reduced c-Abl overexpression may play a role in the anti-apoptosis effect of L-THP after cerebral I/R injury. Thus, L-THP may provide a potential therapeutic approach for the treatment of ischemic stroke. Graphical Abstract ᅟ.

The inhibitory effects of levo-tetrahydropalmatine on rat Kv1.5 channels expressed in HEK293 cells.

Levo-tetrahydropalmatine (l-THP) exerts various pharmacological effects on neural and cardiac tissues and K+ channel can be one of its multiple targets. The rapidly activating Kv1.5 channel is expressed in a variety of tissues including atrial cells and hippocampal neurons, and has an essential role in tuning the action potential and excitability in those cells. The aim of current study is to explore whether there are the possible effects of l-THP on Kv1.5 channels expressed in HEK293 cells. Superfusion of l-THP led to a dose-dependent blockage of Kv1.5 currents with an IC50 value of 53.2µM. This blocking effect was substantially attenuated in mutant H452G rather than R476V and R476Y, suggesting a specific binding site in the outer mouth region. In addition, the properties of Kv1.5 channel kinetics were markedly altered by l-THP. Treatment with l-THP resulted in a potential left shift of the inactivation curve, with the half-maximum inactivation potential (V1/2) of 4.5mV in control and -12.8mV in 50µM l-THP. Our data reveal that l-THP can exert an inhibitory effect on the delayed rectifier Kv1.5 channels expressed in HEK293 cells. These lines of evidence provided an insight to understand the possible effects exerted by l-THP on relative tissues.

Simultaneous determination of l-tetrahydropalmatine and its active metabolites in rat plasma by a sensitive ultra-high-performance liquid chromatography with tandem mass spectrometry method and its application in a pharmacokinetic study.

A sensitive and reliable ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for simultaneous determination of l-tetrahydropalmatine (l-THP) and its active metabolites l-isocorypalmine (l-ICP) and L-corydalmine (l-CD) in rat plasma. The analytes were extracted by liquid-liquid extraction and separated on a Bonshell ASB C18 column (2.1 × 100 mm; 2.7 µm; Agela) using acetonitrile-formic acid aqueous as mobile phase at a flow rate of 0.2 mL/min in gradient mode. The method was validated over the concentration range of 4.00-2500 ng/mL for l-THP, 0.400-250 ng/mL for l-ICP and 1.00-625 ng/mL for l-CD. Intra- and inter-day accuracy and precision were within the acceptable limits of <15% at all concentrations. Correlation coefficients (r) for the calibration curves were >0.99 for all analytes. The quantitative method was successfully applied for simultaneous determination of l-THP and its active metabolites in a pharmacokinetic study after oral administration with l-THP at a dose of 15 mg/kg to rats.

Development and validation of a high performance liquid chromatography quantification method of levo-tetrahydropalmatine and its metabolites in plasma and brain tissues: application to a pharmacokinetic study.

Levo-tetrahydropalmatine (l-THP) is an alkaloid isolated from Chinese medicinal herbs of the Corydalis and Stephania genera. It has been used in China for more than 40 years mainly as an analgesic with sedative/hypnotic effects. Despite its extensive use, its metabolism has not been quantitatively studied, nor there a sensitive reliable bioanalytical method for its quantification simultaneously with its metabolites. As such, the objective of this study was to develop and validate a sensitive and selective HPLC method for simultaneous quantification of l-THP and its desmethyl metabolites l-corydalmine (l-CD) and l-corypalmine (l-CP) in rat plasma and brain tissues. Rat plasma and brain samples were processed by liquid-liquid extraction using ethyl acetate. Chromatographic separation was achieved on a reversed-phase Symmetry® C18 column (4.6 × 150 mm, 5 µm) at 25°C. The mobile phase consisted of acetonitrile-methanol-10 mm ammonium phosphate (pH 3) (10:30:60, v/v) and was used at a flow rate of 0.8 mL/min. The column eluent was monitored at excitation and emission wavelengths of 230 and 315 nm, respectively. The calibration curves were linear over the concentration range of 1-10,000 ng/mL. The intra- and interday reproducibility studies demonstrated accuracy and precision within the acceptance criteria of bioanalytical guidelines. The validated HPLC method was successfully applied to analyze samples from a pharmacokinetic study of l-THP in rats. Taken together, the developed method can be applied for bioanalysis of l-THP and its metabolites in rodents and potentially can be transferred for bioanalysis of human samples.

Pharmacokinetic analysis of levo-tetrahydropalmatine in rabbit plasma by rapid sample preparation and liquid chromatography-tandem mass spectrometry.

A rapid extraction method was developed and validated for levo-tetrahydropalmatine (l-THP) determination in rabbit plasma by liquid chromatography tandem-mass spectrometry (LC-MS/MS). The sample preparation included a single-step acetonitrile extraction and salting out liquid-liquid partitioning from the water in plasma with MgSO4. Berberine was used as internal standard. The mass spectrometry source was negative electrospray ionization. The method showed good performance in the concentration range from 5 to 200ngmL(-1). The limit of quantification (LOQ) was 1ngmL(-1). The method was successfully applied to a pharmacokinetic study in rabbit comparing the two drug formulation of l-THP including the raw material and the self-microemulsifying drug delivery system pellet.

Simultaneous determination of L-tetrahydropalmatine and cocaine in human plasma by simple UPLC-FLD method: application in clinical studies.

Currently, there are no FDA approved medications for treatment of cocaine addiction underscoring the dire need to develop such a product. There is an accumulating body of evidence that l-tetrahydropalmatine (l-THP), a non-selective dopamine antagonist, can be used for the treatment of cocaine addiction. Indeed, the FDA recently approved its usage in a Phase I study in cocaine abusers and it was indispensable to develop a simple and sensitive method for the simultaneous determination of l-THP and cocaine in human plasma. We developed a UPLC-FLD method for quantitation of these molecules using an ACQUITY BEH C18 column (2.1 mm × 50mm, 1.7 µm) and a mobile phase that consisted of 10mM ammonium phosphate (pH=4.75), methanol, and acetonitrile (v:v:v, 78:16:6). Venlafaxine was used as the internal standard while hexane was used for the liquid-liquid extraction. The flow rate was 0.4 mL/min with fluorescence detection using an excitation wavelength of 230 nm and emission detection wavelength of 315 nm. This method was selective, linear and sensitive with a lower limit of quantification of 2.5 ng/mL for both cocaine and l-THP. The intra-day precision of cocaine and l-THP was <9.50% while the accuracy was <4.29%. The inter-day precision of cocaine and l-THP was <9.14%, and the accuracy was <12.49%. The recovery for cocaine and l-THP ranged from 43.95 to 50.02% and 54.65 to 58.31%, respectively. In comparison to forty reported cocaine quantitation methods this method is simple, sensitive and cost-effective and can be used for simultaneous quantitation of l-THP and cocaine. This method meets the FDA guidelines and can be used in current and future clinical studies.

Roles of levo-tetrahydropalmatine in modulating methamphetamine reward behavior.

Levo-tetrahydropalmatine (l-THP), as an alkaloid purified from the traditional Chinese herbal medicine Corydalis and Stephania, has been widely used to produce many traditional Chinese herbal preparations. The effect of l-THP on methamphetamine-induced reward learning still remains unclear although it has been proved to be effective on treating allodynia and drug addiction. This experiment has been designed to examine the effect of l-THP on the acquisition, expression, extinction, and reinstatement of methamphetamine-induced conditioned place preference (CPP) in mice. The results show that methamphetamine (METH) could induce CPP in mice at doses of 0.5mg/kg, 1.0mg/kg and 2.0mg/kg respectively, but l-THP alone could not do so. Meanwhile, l-THP could not induce conditioned place aversion at doses of 1.25mg/kg to 20.0mg/kg in mice, but it could attenuate the acquisition and expression of METH-induced CPP and facilitate the extinction of METH-induced CPP in mice. Besides, l-THP could inhibit the reinstatement of METH-induced CPP at the dose of 10.0mg/kg whether it was given in the extinction training phase or 30min before the reinstatement. These results suggest that l-THP can globally suppress the rewarding properties of METH on all phases of the CPP task and it may have potential effects on the treatment of METH abuse.

Influence of l-tetrahydropalmatine on morphine-induced conditioned place preference / 中国药理学通报

Aim To study the effect of different doses of l-Tetrahydropalmatine( l-THP) on morphine-induced conditioned place preference(CPP) and observe whether l-THP itself induces CPP.Methods ①♂SD rats were administered with morphine (5.00 mg?kg -1 ,sc) or saline and trained for 8 days;on d 9,the rats were tested CPP with no treatment or 40 min after they were given different doses of l-THP(1.25～5.00 mg?kg -1,ip) to observe the effect of l-THP on morphine-induced CPP;② With daily injection of l-THP (ip) at different doses,effect on the extinguishment of morphine-induced CPP was tested weekly; ③ Normal saline (NS) or l-THP (1.25～5.00 mg?kg -1 , ip) was used as a training drug to test whether l-THP could induce CPP in the rats. Results 5.00 mg?kg -1 morphine (sc) induced CPP; l-THP of 2.50 mg?kg -1 and 5.00 mg?kg -1 administered prior to the testing reduced the expression of morphine-induced CPP significantly (P