Pharmacokinetics of Gastrodin in rat plasma and CSF after i.n. and i.v

Effects of Three Kinds of Carbohydrate Pharmaceutical Excipients-Fructose, Lactose and Arabic Gum on Intestinal Absorption of Gastrodin through Glucose Transport Pathway in Rats

BACKGROUND

Some glucoside drugs can be transported via intestinal glucose transporters (IGTs), and the presence of carbohydrate excipients in pharmaceutical formulations may influence the absorption of them. This study, using gastrodin as probe drug, aimed to explore the effects of fructose, lactose, and arabic gum on intestinal drug absorption mediated by the glucose transport pathway.

METHODS

The influence of fructose, lactose, and arabic gum on gastrodin absorption was assessed via pharmacokinetic experiments and single-pass intestinal perfusion. The expression of sodium-dependent glucose transporter 1 (SGLT1) and sodium-independent glucose transporter 2 (GLUT2) was quantified via RT‒qPCR and western blotting. Alterations in rat intestinal permeability were evaluated through H&E staining, RT‒qPCR, and immunohistochemistry.

RESULTS

Fructose reduced the area under the curve (AUC) and peak concentration (Cmax) of gastrodin by 42.7% and 63.71%, respectively (P < 0.05), and decreased the effective permeability coefficient (Peff) in the duodenum and jejunum by 58.1% and 49.2%, respectively (P < 0.05). SGLT1 and GLUT2 expression and intestinal permeability remained unchanged. Lactose enhanced the AUC and Cmax of gastrodin by 31.5% and 65.8%, respectively (P < 0.05), and increased the Peff in the duodenum and jejunum by 33.7% and 26.1%, respectively (P < 0.05). SGLT1 and GLUT2 levels did not significantly differ, intestinal permeability increased. Arabic gum had no notable effect on pharmacokinetic parameters, SGLT1 or GLUT2 expression, or intestinal permeability.

CONCLUSION

Fructose, lactose, and arabic gum differentially affect intestinal drug absorption through the glucose transport pathway. Fructose competitively inhibited drug absorption, while lactose may enhance absorption by increasing intestinal permeability. Arabic gum had no significant influence.

Effects of Nutraceutical Compositions Containing Rhizoma Gastrodiae or Lipoic Acid in an In Vitro Induced Neuropathic Pain Model

BACKGROUND

Peripheral neuropathy is caused by a malfunction in the axons and myelin sheaths of peripheral nerves and motor and sensory neurons. In this context, nonpharmacological treatments with antioxidant potential have attracted much attention due to the issues that some conventional pharmaceutical therapy can generate. Most of these treatments contain lipoic acid, but issues have emerged regarding its use. Considering this, the present study evaluated the beneficial effects of nutraceuticals based on Gastrodiae elata dry extract 10:1 or lipoic acid in combination with other substances (such as citicholine, B vitamins, and acetyl L-carnitine).

METHOD

To assess the combination's absorption and biodistribution and exclude cytotoxicity, its bioavailability was first examined in a 3D intestinal barrier model that replicated oral ingestion. Subsequently, a 3D model of nerve tissue was constructed to investigate the impacts of the new combination on the significant pathways dysregulated in peripheral neuropathy.

RESULTS

Our findings show that the novel combination outperformed in initial pain relief response and in recovering the mechanism of nerve healing following Schwann cell injury by successfully crossing the gut barrier and reaching the target site.

CONCLUSION

This article describes a potential alternative nutraceutical approach supporting the effectiveness of combinations with Gastrodiae elata extract in decreasing neuropathy and regulating pain pathways.

Intranasal nanoparticulate delivery systems for neurodegenerative disorders: a review

Neurodegenerative diseases are a significant cause of mortality worldwide, and the blood-brain barrier (BBB) poses a significant challenge for drug delivery. An intranasal route is a prominent approach among the various methods to bypass the BBB. There are different pathways involved in intranasal drug delivery. The drawbacks of this method include mucociliary clearance, enzymatic degradation and poor drug permeation. Novel nanoformulations and intranasal drug-delivery devices offer promising solutions to overcome these challenges. Nanoformulations include polymeric nanoparticles, lipid-based nanoparticles, microspheres, liposomes and noisomes. Additionally, intranasal devices could be utilized to enhance drug-delivery efficacy. Therefore, intranasal drug-delivery systems show potential for treating neurodegenerative diseases through trigeminal or olfactory pathways, which can significantly improve patient outcomes.

Strain differences in the drug transport capacity of intestinal glucose transporters in Sprague-Dawley versus Wistar rats, C57BL/6J versus Kunming mice

Designing oral drug delivery systems using intestinal glucose transporters (IGTs) may be one of the strategies for improving oral bioavailability of drugs. However, little is known about the biological factors affecting the drug transport capacity of IGTs. Gastrodin is a sedative drug with a structure very similar to glucose. It is a highly water-soluble phenolic glucoside. It can hardly enter the intestine through simple diffusion but exhibits good oral bioavailability of over 80%. We confirmed that gastrodin is absorbed via the intestinal glucose transport pathway. It has the highest oral bioavailability among the reported glycosides' active ingredients through this pathway. Thus, gastrodin is the most selective drug substrate of IGTs and can be used to evaluate the drug transport capacity of IGTs. Obviously, strain is one of the main biological factors affecting drug absorption. This study firstly compared the drug transport capacity of IGTs between SD rats and Wistar rats and between C57 mice and KM mice by pharmacokinetic experiments and single-pass intestinal perfusion experiments of gastrodin. Then, the sodium-dependent glucose transporter type 1 (SGLT1) and sodium-independent glucose transporters type 2 (GLUT2) in the duodenum, jejunum, ileum and colon of these animals were quantified using RT-qPCR and Western blot. The results showed that the oral bioavailability of gastrodin in Wistar rats was significantly higher than in SD rats and significantly higher in KM mice than in C57 mice. Gastrodin absorption significantly differed among different intestinal segments in SD rats, C57 mice and KM mice, except Wistar rats. RT-qPCR and Western blot demonstrated that the intestinal expression distribution of SGLT1 and GLUT2 in SD rats and C57 mice was duodenum ≈ jejunum > ileum > colon. SGLT1 expression did not differ among different intestinal segments in KM mice, whereas the intestinal expression distribution of GLUT2 was duodenum ≈ jejunum ≈ ileum > colon. However, the expression of SGLT1 and GLUT2 did not differ among different intestinal segments in Wistar rats. It was reported that the intestinal expression distribution of SGLT1 and GLUT2 in humans is duodenum > jejunum > ileum > colon. Hence, the intestinal expression distribution of SGLT1 and GLUT2 of SD rats and C57 mice was more similar to that in humans. In conclusion, the drug transport capacity of IGTs differs in different strains of rats and mice. SD rats and C57 mice are more suitable for evaluating the pharmacokinetics of glycosides' active ingredients absorbed via the intestinal glucose transport pathway.

Enzymatic Biosynthesis of Simple Phenolic Glycosides as Potential Anti-Melanogenic Antioxidants

Simple phenolics (SPs) and their glycosides have recently gained much attention as functional skin-care resources for their anti-melanogenic and antioxidant activities. Enzymatic glycosylation of SP aglycone make it feasible to create SP glycosides with updated bioactive potentials. Herein, a glycosyltransferase (GT)-encoding gene was cloned from the fosmid libraries of Streptomyces tenjimariensis ATCC 31603 using GT-specific degenerate PCR followed by in silico analyses. The recombinant StSPGT was able to flexibly catalyze the transfer of two glycosyl moieties towards two SP acceptors, (hydroxyphenyl-2-propanol [HPP2] and hydroxyphenyl-3-propanol [HPP3]), generating stereospecific α-anomeric glycosides as follows: HPP2-O-α-glucoside, HPP2-O-α-2″-deoxyglucoside, HPP3-O-α-glucoside and HPP3-O-α-2″-deoxyglucoside. This enzyme seems not only to prefer UDP-glucose and HPP2 as a favorable glycosyl donor and acceptor, respectively but also differentiates the positional difference of the hydroxyl function as acceptor catalytic sites. Paired in vitro and in vivo antioxidant assays represented SPs and their corresponding glycosides as convincing antioxidants in a time- and concentration-dependent manner by scavenging DPPH radicals and intracellular ROS. Even compared to the conventional agents, HPP2 and glycoside analogs displayed improved tyrosinase inhibitory activity in vitro and still suppressed in vivo melanogenesis. Both HPP2 glycosides are further likely to exert the best inhibitory activity against elastase, eventually highlighting these glycosides with enhanced anti-melanogenic and antioxidant activities as promising anti-wrinkle hits.

Efficacy and tolerability of oral gastrodin for medication overuse headache (EASTERN): Study protocol for a multicenter randomized double-blind placebo-controlled trial

Background

Prophylactic medication in clinical detoxification programs for the treatment of medication overuse headache is still debated. Gastrodin, a main bioactive constituent of Rhizoma Gastrodiae, has been applied clinically to treat primary headache for more than 30 years in China due to its potential analgesic and anti-migraine mechanisms. However, clinical evidence supporting its routing use in MOH is insufficient. The present study aims to investigate the efficacy and tolerability of oral gastrodin in medication overuse headache.

Methods

A multicenter, randomized, double-blind, parallel, placebo-controlled trial will be performed. A target sample size of 186 patients who fulfill the International Classification of Headache Disorders 3rd version (ICHD-3) criteria for MOH will be recruited and screened during a baseline screening period of 28 days before being randomly assigned to either the gastrodin or placebo group at a ratio of 1:1. Enrolled patients will be assessed for each 4 weeks during the 12-weeks double-blind phase and followed up at week 24. The primary endpoint is mean change in monthly headache day frequency. Secondary endpoints will be the proportion of remitted MOH, change in headache pain intensity, headache impact test (HIT-6) score, 50% responder rate, treatment failure, monthly acute medication intake days, and Short Form 36-Item Health Survey (SF-36) score. Tolerability will be assessed by drop-out rates though safety monitoring during treatment.

Discussion

The findings of the present study may help to provide new evidence on gastrodin as a prophylaxis treatment with both efficacy and high tolerability for the treatment of MOH.

Clinical trail registration

Chinese Clinical Trail Registry (ChiCTR2200063719), Protocol Version 1.1, May, 09, 2022.

Stimuli-responsive In situ gelling system for nose-to-brain drug delivery

The diagnosis and treatment of neurological ailments always remain an utmost challenge for research fraternity due to the presence of BBB. The intranasal route appeared as an attractive and alternative route for brain targeting of therapeutics without the intrusion of BBB and GI exposure. This route directly and effectively delivers the therapeutics to different regions of the brain via olfactory and trigeminal nerve pathways. However, shorter drug retention time and mucociliary clearance curtail the efficiency of the intranasal route. The in situ mucoadhesive gel overthrow the limitations of direct nose-to-brain delivery by not only enhancing nasal residence time but also minimizing the mucociliary clearance and enzymatic degradation. This delivery system further improves the nasal absorption as well as bioavailability of drugs in the brain. The in situ mucoadhesive gel is a controlled and sustained release system that facilitates the absorption of various proteins, peptides and other larger lipophilic and hydrophilic moieties. Owing to multiple benefits, in situ gelling system has been widely explored to target the brain via nasal route. However, very few review works are reported which explains the application of in situ nasal gel for brain delivery of CNS acting moieties. Hence, in this piece of work, we have initially discussed the global statistics of neurological disorders reported by WHO and other reputed organizations, nasal anatomy, mechanism and challenges of nose-to-brain drug delivery. The work mainly focused on the use of different stimuli-responsive polymers, specifically thermoresponsive, pH-responsive, and ion triggered systems for the development of an effective and controlled dosage form, i.e., in situ nasal gel for brain targeting of bioactives. We have also highlighted the origin, structure, nature and phase transition behavior of the smart polymers found suitable for nasal administration, including poloxamer, chitosan, EHEC, xyloglucan, Carbopol, gellan gum and DGG along with their application in the treatment of neurological disorders. The article is aimed to gather all the information of the past 10 years related to the development and application of stimuli-responsive in situ nasal gel for brain drug delivery.

The Potential Role of PKA/CREB Signaling Pathway Concerned with Gastrodin Administration on Methamphetamine-Induced Conditioned Place Preference Rats and SH-SY5Y Cell Line

To investigate the effects of gastrodin (GAS) on methamphetamine (MA)-induced conditioned place preference (CPP) in rats and explore its potential mechanisms. MA (10 mg/kg) was initially injected intraperitoneally (i.p.) in rats, after which they were administered either MA or saline alternately from day 4 to 13 (D4-13) for 10 days, followed by treatment with GAS (10 or 20 mg/kg, i.p.) on D15-21 for 7 days. The rats underwent CPP testing after MA and GAS treatment. In vitro, SH-SY5Y cells were exposed to MA (2.0 mM) for 24 h, followed by treatment with GAS (2.0 or 4.0 mM) for 24 h. The expression levels of PKA, P-PKA, CREB, and P-CREB proteins in the prefrontal cortex, nucleus accumbens, and ventral tegmental area of MA-induced CPP rats and in SH-SY5Y cells were detected by Western blot analysis. The MA-induced CPP rat model was successfully established. The administration of MA stimulated a significant alteration in behavior, as measured by the CPP protocol. After treatment with GAS, the amount of time rats spent in the MA-paired chamber was significantly reduced. Results also showed that MA increased the expression levels of PKA, P-PKA, CREB, and p-CREB proteins in the prefrontal cortex, nucleus accumbens, and ventral tegmental area of CPP rats and in SH-SY5Y cells (p < 0.05). GAS attenuated the effect of MA-induced CPP in rats and decreased the expression levels of proteins in vivo and in vitro. Our study suggests that GAS can attenuate the effects of MA-induced CPP in rats by regulating the PKA/CREB signaling pathway.

Metabolite Profiling and Distribution of Militarine in Rats Using UPLC-Q-TOF-MS/MS

Militarine, a natural glucosyloxybenzyl 2-isobutylmalate, isolated from Bletilla striata, was reported with a prominent neuroprotective effect recently. The limited information on the metabolism of militarine impedes comprehension of its biological actions and pharmacology. This study aimed to investigate the metabolite profile and the distribution of militarine in vivo, which help to clarify the action mechanism further. A total of 71 metabolites (57 new metabolites) in rats were identified with a systematic method by ultra-high-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). The proposed metabolic pathways of militarine include hydrolyzation, oxidation, glycosylation, esterification, sulfation, glucuronidation and glycine conjugation. Militarine and its metabolites were distributed extensively in the treated rats. Notably, six metabolites of militarine were identified in cerebrospinal fluid (CSF), which were highly consistent with the metabolites after oral administration of gastrodin in rats. Among the metabolites in CSF, five of them were not reported before. It is the first systematic metabolic study of militarine in vivo, which is very helpful for better comprehension of the functions and the central nervous system (CNS) bioactivities of militarine. The findings will also provide an essential reference for the metabolism of other glucosylated benzyl esters of succinic, malic, tartaric and citric acids.

Gastrodin Ameliorates Acute Rejection via IRE1α/TRAF2/NF-κB in Rats Receiving Liver Allografts

Background

Liver transplantation (LT) is currently an effective treatment for end-stage liver disease, but the occurrence of acute rejection (AR) is still the main problem to be solved. The present study aimed to evaluate the effect of gastrodin (GAS) on LT.

Methods

Rat transplant models were established and divided into SHAM, LT, GAS-L (50 mg/kg GAS), and GAS-H (100 mg/kg GAS) groups. The liver function, inflammatory factors, liver histopathology, survival of rats, number of M2-type macrophages, liver cell apoptosis, and pathway proteins were assayed at 7 days and 14 days after the operations.

Results

With increasing GAS concentrations, liver function, expression of proinflammatory factors in the liver, and expression of M2-type molecules in macrophages were significantly improved, and the survival time of rats was significantly prolonged (P < 0.05). All rats treated with low or high doses of GAS were judged to have nondeterministic acute rejection. Flow cytometry showed that liver cell apoptosis was decreased significantly in the GAS-L and GAS-H groups after GAS administration compared with apoptosis and differentiation in the LT group (P < 0.05). Expression levels of Caspase-3, Bad, and Bax proteins were decreased, and the expression of the antiapoptotic protein Bcl-2 was increased in the GAS-L and GAS-H groups (P < 0.05). Mechanistically, the ERS-related IRE1α/TRAF2/NF-κB pathway was suppressed by GAS, and GAS acted mainly on intrahepatic macrophages to affect AR and reduce ROS production (P < 0.05).

Conclusion

GAS ameliorated AR by inhibiting the IRE1α/TRAF2/NF-κB pathway in LT.

A Review on Central Nervous System Effects of Gastrodin

Rhizoma Gastrodiae (also known as Tian ma), the dried rhizome of Gastrodia elata Blume, is a famous Chinese herb that has been traditionally used for the treatment of headache, dizziness, spasm, epilepsy, stoke, amnesia and other disorders for centuries. Gastrodin, a phenolic glycoside, is the main bioactive constituent of Rhizoma Gastrodiae. Since identified in 1978, gastrodin has been extensively investigated on its pharmacological properties. In this article, we reviewed the central nervous system (CNS) effects of gastrodin in preclinical models of CNS disorders including epilepsy, Alzheimer's disease, Parkinson's disease, affective disorders, cerebral ischemia/reperfusion, cognitive impairment as well as the underlying mechanisms involved and, where possible, clinical data that support the pharmacological activities. The sources and pharmacokinetics of gastrodin were also reviewed here. As a result, gastrodin possesses a broad range of beneficial effects on the above-mentioned CNS diseases, and the mechanisms of actions include modulating neurotransmitters, antioxidative, anti-inflammatory, suppressing microglial activation, regulating mitochondrial cascades, up-regulating neurotrophins, etc. However, more detailed clinical trials are still in need for positioning it in the treatment of neurological disorders.

Comparative effects of traditional Chinese and Western migraine medicines in an animal model of nociceptive trigeminovascular activation

Background

Migraine is a highly prevalent and disabling disorder of the brain with limited therapeutic options, particularly for preventive treatment. There is a need to identify novel targets and test their potential efficacy in relevant preclinical migraine models. Traditional Chinese medicines have been used for millennia and may offer avenues for exploration.

Methods

We evaluated two traditional Chinese medicines, gastrodin and ligustrazine, and compared them to two Western approaches with propranolol and levetiracetam, one effective and one ineffective, in an established in vivo rodent model of nociceptive durovascular trigeminal activation.

Results

Intravenous gastrodin (30 and 100 mg/kg) significantly inhibited nociceptive dural-evoked neuronal firing in the trigeminocervical complex. Ligustrazine (10 mg/kg) and propranolol (3 mg/kg) also significantly inhibited dural-evoked trigeminocervical complex responses, although the timing of responses of ligustrazine does not match its pharmacokinetic profile. Levetiracetam had no effects on trigeminovascular responses.

Conclusion

Our data suggest gastrodin has potential as an anti-migraine treatment, whereas ligustrazine seems less promising. Interestingly, in line with clinical trial data, propranolol was effective and levetiracetam not. Exploration of the mechanisms and modelling effects of Chinese traditional therapies offers novel route for drug discovery in migraine.

Analytical Techniques and Pharmacokinetics of Gastrodia elata Blume and Its Constituents

Gastrodia elata Blume (G. elata), commonly called Tianma in Chinese, is an important and notable traditional Chinese medicine (TCM), which has been used in China as an anticonvulsant, analgesic, sedative, anti-asthma, anti-immune drug since ancient times. The aim of this review is to provide an overview of the abundant efforts of scientists in developing analytical techniques and performing pharmacokinetic studies of G. elata and its constituents, including sample pretreatment methods, analytical techniques, absorption, distribution, metabolism, excretion (ADME) and influence factors to its pharmacokinetics. Based on the reported pharmacokinetic property data of G. elata and its constituents, it is hoped that more studies will focus on the development of rapid and sensitive analytical techniques, discovering new therapeutic uses and understanding the specific in vivo mechanisms of action of G. elata and its constituents from the pharmacokinetic viewpoint in the near future. The present review discusses analytical techniques and pharmacokinetics of G. elata and its constituents reported from 1985 onwards.

Cytotoxic effects of gastrodin extracted from the rhizome of Gastrodia elata Blume in glioblastoma cells, but not in normal astrocytes, via the induction of oxidative stress-associated apoptosis that involved cell cycle arrest and p53 activation

Researches have been conducted to explore the biological effect of gastrodin, a natural compound extracted from the rhizome of Gastrodia elata Blume, in different models. However, the effects of gastrodin on cytotoxicity, cell cycle distribution and oxidative stress in glia cells have not been explored. The aim of this study was to investigate the cytotoxic effect of gastrodin and its mechanisms in DBTRG-05MG human glioblastoma cells and CTX TNA2 rat astrocytes. In DBTRG-05MG cells but not in CTX TNA2 cells, gastrodin (20-30 μM) induced cytotoxicity, G2/M phase cell cycle arrest and apoptosis. Regarding oxidative stress, gastrodin (20-30 μM) elevated intracellular ROS levels but reduced GSH levels. Treatment with the antioxidant NAC (10 μM) partially reversed gastrodin-altered antioxidant enzymes levels. Furthermore, gastrodin induced mitochondria-associated apoptosis. The apoptotic effects evoked by gastrodin were partially inhibited by the antioxidant NAC and the pancaspase inhibitor Z-VAD-FMK. Together, in DBTRG-05MG cells, but not in CTX TNA2 cells, gastrodin activated ROS-associated mitochondrial apoptotic pathways that involved cell cycle arrest. These data provide insight into the molecular mechanisms governing the ability of gastrodin to induce cytotoxicity in human glioblastoma cells and further suggest that gastrodin is a new potential agent for the treatment of human gliblasoma.

Gastrodia elata and epilepsy: Rationale and therapeutic potential

BACKGROUND

Gastrodia elata Blume (G. elata) is a traditional Chinese herb used for centuries in folk medicine. Due to the claimed anticonvulsant properties of G. elata, it is expected that this herb continues to be a target of research, aiming to deepen the available knowledge on its biological activity and safety.

PURPOSE

The current review aims to discuss the most recent advances on the elucidation of the phytochemical composition and anticonvulsant potential of G. elata.

METHODS

Available literature was reviewed from PubMed, ISI Web of Knowledge and Science Direct, using combinations of the following keywords: Gastrodia elata, tianma, epilepsy, anticonvulsant and pharmacokinetics. Abstracts and full texts were evaluated for their clarity and scientific merit.

RESULTS

G. elata rhizome, as well as specific phenolic compounds isolated from this herb, have demonstrated anticonvulsant potential in a variety of in vitro and in vivo models. The pharmacological mechanisms potentially involved in the anticonvulsant activity have been extensively studied, being similar to the known mechanisms claimed for the available antiepileptic drugs. In addition, the pharmacokinetics of the main bioactive component of G. elata (gastrodin) has also been studied.

CONCLUSION

Due to its recognised therapeutic properties, G. elata has gained an increasing interest within the scientific community and, therefore, new medicinal preparations containing G. elata rhizome itself or its bioactive components are expected to be developed in the coming years. Moreover, specific phytochemical constituents isolated from G. elata may also be considered to integrate programs of discovery and development of new anticonvulsant drug candidates.

Antidepressant-like effects of water extract of Gastrodia elata Blume in rats exposed to unpredictable chronic mild stress via modulation of monoamine regulatory pathways

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional herbal medicine belonging to the Orchidaceae family, and has been used to manage neurological disorders for centuries. We have previously reported that its water extract (WGE) could improve the depressive-like behaviours in the forced swimming test (FST), an animal model of depression.

AIM OF THE STUDY

To investigate the antidepressant-like effects of WGE in rats exposed to unpredictable chronic mild stress (UCMS) model, and to explore its possible molecular mechanisms.

MATERIALS AND METHODS

UCMS rats were orally administered with WGE (0.5g/kg body weight) daily within the 4 weeks UCMS procedure. The sucrose preference test and the open field test were conducted to assess anhedonia and spontaneous behaviours, respectively. The cerebral turnover rates of monoamine neurotransmitters and the serum corticosterone levels were measured. In vitro direct and indirect monoamine oxidase A (MAO-A) inhibitory assays were employed to assess the possible antidepressant-like mechanisms of WGE (0.5mg/mL) and its major component, gastrodin (GAS, 15, 30 and 60μg/mL). Western blot was used to examine the expression of protein related to monoamine regulation, such as MAO-A and tyrosine hydroxylase (TH).

RESULTS

WGE significantly reversed the sucrose preference and other abnormal behaviours induced by 4 weeks of UCMS. WGE significantly restored the cerebral turnover rates of serotonin and dopamine and decreased serum corticosterone levels. WGE and gastrodin inhibited the activity and protein expression of MAO-A, and increased TH levels in PC12 cells.

CONCLUSION

The antidepressant-like effects of WGE and gastrodin might be mediated by the regulation of monoamine neurotransmitters, and therefore were beneficial in depression treatment as a complementary approach.

Pharmacokinetic study of Gastrodia elata in rats

The pharmacokinetics of parishin, gastrodin, Gastrodia elata extract and Rhizoma Gastrodiae capsule was investigated by intragastric and/or intravenous administration to rats. Parishin was metabolized into nine metabolites after intravenous administration, and the area under the curve (AUC0-∞) of parishin and its metabolites (except parishin G and parishin E) increased nonlinearly from 72.5 to 220 mg/kg. When combining regression equation with the AUC0-∞ and dose of gastrodin injection, the percent conversion of parishin to gastrodin was obtained as 50 %. Based on multi-active metabolites of parishin in vivo, integrated pharmacokinetic mode was established. It is notable that each metabolite from parishin shares the similar metabolic process at three dosages of parishin and the bioavailability of parishin was approximately 14 %. The integrated pharmacokinetic mode was successfully applied to evaluate the holistic pharmacokinetics of gastrodin injection, G. elata extract and Rhizoma Gastrodiae capsule. The results showed that the holistic pharmacokinetics of gastrodin injection and G. elata extract was closed to that of gastrodin, but for parishin and Rhizoma Gastrodiae capsule, integrated pharmacokinetic parameters were more suitable to evaluate its holistic pharmacokinetics. Graphical abstract Pharmacokinetic study of Gastrodia elata in rats.

Prolonged oral administration of Gastrodia elata extract improves spatial learning and memory of scopolamine-treated rats

Gastrodia elata (GE) is traditionally used for treatment of various disorders including neurodegenerative diseases such as Alzheimer's disease. To investigate the neuroprotective effect of GE, amyloid-β peptide (Aβ)-treated PC12 cells were cultured with GE aqueous extract. In vitro assay demonstrated that 50 µM of pre-aggregated Aβ was lethal to about a half portion of PC12 cells and that Aβ aggregate-induced cell death was significantly decreased with GE treatment at ≤10 mg/mL in a dose-dependent manner. To further examine in vivo cognitive-improving effects, an artificial amnesic animal model, scopolamine-injected Sprague-Dawley rats, were orally administered the extract for 6 weeks followed by behavioral tests (the passive avoidance test and Morris water maze test). The results showed that an acute treatment with scopolamine (1 mg/kg of body weight) effectively induced memory impairment in normal rats and that the learning and memory capability of scopolamine-treated rats improved after prolonged administration of GE extract (50, 250 and 500 mg/kg of body weight for 6 weeks). These findings suggest that a GE regimen may potentially ameliorate learning and memory deficits and/or cognitive impairments caused by neuronal cell death.

Nanotechnology for CNS delivery of bio-therapeutic agents

The current therapeutic strategies are not efficient in treating disorders related to the central nervous system (CNS) and have only shown partial alleviation of symptoms, as opposed to, disease modifying effects. With change in population demographics, the incidence of CNS disorders, especially neurodegenerative diseases, is expected to rise dramatically. Current treatment regimens are associated with severe side-effects, especially given that most of these are chronic therapies and involve elderly population. In this review, we highlight the challenges and opportunities in delivering newer and more effective bio-therapeutic agents for the treatment of CNS disorders. Bio-therapeutics like proteins, peptides, monoclonal antibodies, growth factors, and nucleic acids are thought to have a profound effect on halting the progression of neurodegenerative disorders and also provide a unique function of restoring damaged cells. We provide a review of the nano-sized formulation-based drug delivery systems and alternate modes of delivery, like the intranasal route, to carry bio-therapeutics effectively to the brain.

Identification and analysis of gastrodin and its five metabolites using ultra fast liquid chromatography electrospray ionization tandem mass spectrometry to investigate influence of multiple-dose and food

A reliable and highly sensitive ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) analytical method was developed for identification and quantification of gastrodin (GAS) and its metabolites in rat plasma. Five metabolites were identified: p-formylphenyl-β-d-glucopyranoside (M1), p-hydroxybenzonic acid (M2), p-hydroxybenzyl alcohol (M3), p-formaldehydephenyl-β-d-glucopyranoside (M4), p-hydroxybenzaldehyde (M5). The molecular structures of metabolites were proposed based on the characters of their precursor ions, product ions and chromatographic retention time. Four of them were reported firstly in rat plasma. This method involved the addition of bergeninum as the internal standard (IS), UFLC separation, and quantification by MS/MS system using negative electrospray ionization in the multiple reaction monitoring (MRM) mode. The lower limit of quantification of gastrodin and five metabolites were all 1ng/mL. The method was linear in the concentration range of 0.001-10μg/mL. The intra- and inter-day precisions (R.S.D %) were within 15.0% for all analytes. No interference was noted due to endogenous substances. All analytes were stable in rat plasma stored at room temperature and 4°C for at least 4h, -20°C combined with three freeze-thaw cycles for at least 1 month. By this method, the influence of multiple-dose and food on the pharmacokinetics behaviors of GAS and its metabolites were studied for the first time. We hope pharmacokinetic data of present study may inspire rational clinical usage of GAS.

The Aqueous Extract of Rhizome of Gastrodia elata Protected Drosophila and PC12 Cells against Beta-Amyloid-Induced Neurotoxicity

This study aims to investigate the neuroprotective effect of the rhizome of Gastrodia elata (GE) aqueous extract on beta-amyloid(Aβ)-induced toxicity in vivo and in vitro. Transgenic Drosophila mutants with Aβ-induced neurodegeneration in pan-neuron and ommatidia were used to determine the efficacy of GE. The antiapoptotic and antioxidative mechanisms of GE were also studied in Aβ-treated pheochromocytoma (PC12) cells. In vivo studies demonstrated that GE (5 mg/g Drosophila media)-treated Drosophila possessed a longer lifespan, better locomotor function, and less-degenerated ommatidia when compared with the Aβ-expressing control (all P < 0.05). In vitro studies illustrated that GE increased the cell viability of Aβ-treated PC12 cells in dose-dependent manner, probably through attenuation of Aβ-induced oxidative and apoptotic stress. GE also significantly upregulated the enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase, leading to the decrease of reactive oxidation species production and apoptotic marker caspase-3 activity. In conclusion, our current data presented the first evidence that the aqueous extract of GE was capable of reducing the Aβ-induced neurodegeneration in Drosophila, possibly through inhibition of apoptosis and reduction of oxidative stress. GE aqueous extract could be developed as a promising herbal agent for neuroprotection and novel adjuvant therapies for Alzheimer's disease.

Intranasal administration of oxytocin: behavioral and clinical effects, a review

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The mechanisms behind the effects of IN-applied substances need more attention.

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The mechanisms involved in the brain-distribution of IN-OT are completely unexplored.

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The possibly cascading effects of IN-OT on the intrinsic OT-system require serious investigation.

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IN-OT induces clear and specific changes in neural activation.

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IN-OT is a promising approach to treat certain clinical symptoms.

The intranasal (IN-) administration of substances is attracting attention from scientists as well as pharmaceutical companies. The effects are surprisingly fast and specific. The present review explores our current knowledge about the routes of access to the cranial cavity. ‘Direct-access-pathways’ from the nasal cavity have been described but many additional experiments are needed to answer a variety of open questions regarding anatomy and physiology.

Among the IN-applied substances oxytocin (OT) has an extensive history. Originally applied in women for its physiological effects related to lactation and parturition, over the last decade most studies focused on their behavioral ‘prosocial’ effects: from social relations and ‘trust’ to treatment of ‘autism’.

Only very recently in a microdialysis study in rats and mice, the ‘direct-nose-brain-pathways’ of IN-OT have been investigated directly, implying that we are strongly dependent on results obtained from other IN-applied substances. Especially the possibility that IN-OT activates the ‘intrinsic’ OT-system in the hypothalamus as well needs further clarification.

We conclude that IN-OT administration may be a promising approach to influence human communication but that the existing lack of information about the neural and physiological mechanisms involved is a serious problem for the proper understanding and interpretation of the observed effects.

Nose-to-brain transport pathways of wheat germ agglutinin conjugated PEG-PLA nanoparticles

PURPOSE

To investigate the possible pathways for transport of wheat germ agglutinin conjugated PEG-PLA nanoparticles (WGA-NP) into the brain after nasal administration.

METHODS

The nose-to-brain pathways were investigated using WGA-NP containing 6-coumarin (as a fluorescent marker) and (125)I-labeled WGA-NP. Ex vivo imaging analysis was also employed to visualize the transport process.

RESULTS

Nasal administration of WGA-NP to rats resulted in transcellular absorption across the olfactory epithelium and transfer to the olfactory bulb within 5 min. After entering the lamina propria, a proportion of WGA-NP were transferred from the olfactory nerve bundles and their surrounding connective tissue to the olfactory bulb. The trigeminal nerves also contributed to WGA-NP brain transfer, especially to WGA-NP distribution in the caudal brain areas. However, cerebrospinal fluid pathway may have little contribution to the process of transferring WGA-NP into the central nervous system (CNS) after intranasal administration.

CONCLUSIONS

These results demonstrated that intranasally administered WGA-NP reach the CNS via olfactory pathway and trigeminal nerve pathway, and extracellular transport along these nerves is the most possible mechanism.

Formulation and evaluation of in situ gelling systems for intranasal administration of gastrodin

Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

Formulation of intranasal mucoadhesive temperature-mediated in situ gel containing ropinirole and evaluation of brain targeting efficiency in rats

Mucoadhesive temperature-mediated in situ gel formulations using chitosan and hydroxyl propyl methyl cellulose were used to enhance intranasal (i.n.) delivery of the dopamine D2 agonist ropinirole to the brain. Formulations were tested for gelation time, thermosensitivity, mucoadhesion, in vitro release and permeation, in vitro cytotoxicity, nasal clearance, in vivo bioavailability and brain uptake. In vivo bioavailability and brain uptake of ropinirole were assessed in albino rats following intranasal administration of 99mTc-ropinirole in situ gel, intranasal ropinirole solution and intravenous (i.v.) ropinirole solution. Radiolabeled ropinirole uptake was calculated as a fraction of administered dose. The absolute bioavailabilty of ropinirole from the temperature-mediated in situ gelling nasal formulation was 82%. The AUC (0-480 min) in brain after nasal administration of ropinirole in situ gel was 8.5 times (869 +/- 250% x min/g versus 102 +/- 20% x min/g) that obtained following i.v. administration, this value was also considerably higher (869 +/- 250% x min/g versus 281 +/- 52% x min/g) than that achieved with intranasal ropinirole solution. High brain direct drug transport percentage (DTP; 90.36%) and drug targeting index (DTI) > 1 confirms direct nose to brain transport of the intranasal in situ gel formulation of ropinirole.

Determination and pharmacokinetics of gastrodin in human plasma by HPLC coupled with photodiode array detector

In present study, an HPLC method coupled with photodiode array detector (HPLC-PDA) was established for determination and pharmacokinetics of gastrodin (GAS) in human plasma after an oral administration of GAS capsule. In the method, ethanol and dichloromethane were respectively used for deproteinization and purification during the sample preparation procedure. Separation of GAS was achieved on an AichromBond-AQ C18 column (5 microm, 150 mm x 4.6 mm) with the mobile phase of methanol-0.1% phosphoric acid solution (2:98, v/v) at a flow rate of 0.8 ml/min. The wavelength was set at 220 nm and the injection volume was 20 microl. Under the conditions, the calibration curve was linear within the concentration range of 50-4000 ng/ml with the correlation coefficient (r) of 0.99554 (weight=1/X(2)) and the lower limit of quantification (LLOQ) was 50 ng/ml. The inter- and intra-day precisions were less than 11% and the accuracies (%) were within the range of 95.55-103.78%. The extraction recoveries were over 65% with RSDs less than 5.50%. The GAS was proved to be stable under tested conditions. Thus, the method was valid enough to be applied for pharmacokinetic study of GAS in human plasma. The pharmacokinetic parameters of GAS in human plasma after an oral administration of 200 mg GAS capsule were described as: C(max), 1484.55+/-285.05 ng/ml; T(max), 0.81+/-0.16 h; t(1/2alpha), 3.78+/-2.33 h; t(1/2beta), 6.06+/-3.20 h; t(1/2Ka), 0.18+/-0.53 h; K(12), 0.18+/-0.41/h; K(21), 0.20+/-0.16/h; K(10), 4.11+/-15.81/h; V1/F, 180.35+/-89.44 L; CL/F, 62.50+/-140.03 l/h; AUC(0-->t), 5619.41+/-1972.88 (ng/ml) h; and AUC(0-->infinity), 7210.26+/-3472.74 (ng/ml) h, respectively. These will be useful for the clinical application of GAS.

Intranasal delivery to the central nervous system: mechanisms and experimental considerations

The blood-brain barrier (BBB) limits the distribution of systemically administered therapeutics to the central nervous system (CNS), posing a significant challenge to drug development efforts to treat neurological and psychiatric diseases and disorders. Intranasal delivery is a noninvasive and convenient method that rapidly targets therapeutics to the CNS, bypassing the BBB and minimizing systemic exposure. This review focuses on the current understanding of the mechanisms underlying intranasal delivery to the CNS, with a discussion of pathways from the nasal cavity to the CNS involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system. In addition to the properties of the therapeutic, deposition of the drug formulation within the nasal passages and composition of the formulation can influence the pathway a therapeutic follows into the CNS after intranasal administration. Experimental factors, such as head position, volume, and method of administration, and formulation parameters, such as pH, osmolarity, or inclusion of permeation enhancers or mucoadhesives, can influence formulation deposition within the nasal passages and pathways followed into the CNS. Significant research will be required to develop and improve current intranasal treatments and careful consideration should be given to the factors discussed in this review.

Pharmacokinetic behavior of huperzine A in plasma and cerebrospinal fluid after intranasal administration in rats

The aim of this study was to investigate the pharmacokinetic behavior of huperzine A (Hup A) in plasma and cerebrospinal fluid (CSF) after intranasal administration (0.5 mg/kg) in male Sprague-Dawley rats. A pharmacokinetic study of intravenous Hup A (0.5 mg/kg) was also performed. The concentrations of Hup A in the biological samples were measured by high performance liquid chromatography-mass spectrometry. Blood samples were taken from the tail vein and CSF was sampled by cisternal puncture using a stereotaxic frame. The contribution of the olfactory pathway to the uptake of Hup A into CSF was determined by comparing the AUC(CSF)/AUC(plasma) ratios after intranasal and intravenous administration. The AUC ratios of intranasal to intravenous administration in CSF and plasma were 104% and 118%, respectively. No significant difference was observed between the AUC(CSF)/AUC(plasma) ratios of Hup A after intranasal administration (20%) and after intravenous infusion (23%). This indicated that approximately 20% of the Hup A level in plasma reached the CSF after both nasal and intravenous administration, and that no direct transport of Hup A from nose to CSF was found in rats.

Brain targeting studies on buspirone hydrochloride after intranasal administration of mucoadhesive formulation in rats

Objectives

The purpose of this study was to find out whether nasal application of buspirone could increase its bioavailability and directly transport the drug from nose to brain.

Methods

A nasal formulation (Bus-chitosan) was prepared by dissolving 15.5 mg buspirone hydrochloride, 1% w/v chitosan hydrochloride and 5% w/v hydroxypropyl β-cyclodextrin (HP-β-CD) in 5 ml of 0.5% sodium chloride solution. The formulation was nasally administered to rats and the plasma and brain concentration compared with that for buspirone hydrochloride solution after intravenous and intranasal (Bus-plain) administration. The brain drug uptake was also confirmed by gamma scintigraphic study.

Key findings

The nasal Bus-chitosan formulation improved the absolute bioavailability to 61% and the plasma concentration peaked at 30 min whereas the peak for nasal Bus-plain formulation was 60 min. The AUC0-480 in brain after nasal administration of Bus-chitosan formulation was 2.5 times that obtained by intravenous administration (711 ± 252 ng/g vs 282 ± 110 ng/g); this was also considerably higher than that obtained with the intranasal Bus-plain formulation (354 ± 80 ng/g). The high percentage of direct drug transport to the brain (75.77%) and high drug targeting index (&gt;1) confirmed the direct nose to brain transport of buspirone following nasal administration of Bus-chitosan formulation.

Conclusions

These results conclusively demonstrate increased access of buspirone to the blood and brain from intranasal solution formulated with chitosan and HP-β-CD.

Distribution and metabolism of gastrodin in rat brain

Gastrodin is the major and bioactive component in Tianma (Gastrodia elata Bl.) and has sedative, anticonvulsive and neuroprotective effects. Since little is known about its neuropharmacokinetics and brain metabolism, this study was undertaken to investigate the kinetic inter-relationship of gastrodin in rat plasma, cerebrospinal fluid (CSF) and brain microdialysate (frontal cortex, hippocampus, thalamus and cerebellum). Gastrodin was administered via the femoral vein at a dose of 200mg/kg, and blood, CSF and brain microdialysate were collected at timed intervals for the measurement of gastrodin concentrations by high-performance liquid chromatography. The samples were analyzed on a Diamonsil C18 column (5 microm, 250 mm x 4.6mm i.d.) with a mobile phase consisting of acetonitrile-water (5% acetonitrile for brain microdialysate, 2.5% acetonitrile for plasma and CSF), and detected with a UV detector at 221 nm. The distribution of gastrodin in rat showed that levels of gastrodin declined rapidly after drug administration, and the entry of gastrodin into the brain was rapid. However, the ratios of AUC(brain)/AUC(plasma) were not high. The individual ratios of the AUC in the CSF, frontal cortex, hippocampus, thalamus and cerebellum to the AUC in the plasma were 4.8+/-2.4%, 3.3+/-1.2%, 3.0+/-0.7%, 3.3+/-1.3% and 6.1+/-1.9%, respectively. The AUC in the cerebellum was significantly higher than that in other brain regions (P<0.05). The concentrations of p-hydroxybenzyl alcohol, the main metabolite of gastrodin, were very low both in the CSF and plasma.