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P2X receptors are extracellular ATP-gated ion channels that form homo- or heterotrimers and consist of seven subtypes. They are expressed in various tissues, including neuronal and nonneuronal cells, and play critical roles in physiological processes such as neurotransmission, inflammation, pain, and cancer. As a result, P2X receptors have attracted considerable interest as drug targets, and various competitive inhibitors have been developed. However, although several P2X receptor structures from different subtypes have been reported, the limited structural information of P2X receptors in complex with competitive antagonists hampers the understanding of orthosteric inhibition, hindering the further design and optimization of those antagonists for drug discovery. We determined the cryogenic electron microscopy (cryo-EM) structures of the mammalian P2X7 receptor in complex with two classical competitive antagonists of pyridoxal-5'-phosphate derivatives, pyridoxal-5'-phosphate-6-(2'-naphthylazo-6'-nitro-4',8'-disulfonate) (PPNDS) and pyridoxal phosphate-6-azophenyl-2',5'-disulfonic acid (PPADS), and performed structure-based mutational analysis by patch-clamp recording as well as molecular dynamics (MD) simulations. Our structures revealed the orthosteric site for PPADS/PPNDS, and structural comparison with the previously reported apo- and ATP-bound structures showed how PPADS/PPNDS binding inhibits the conformational changes associated with channel activation. In addition, structure-based mutational analysis identified key residues involved in the PPNDS sensitivity of P2X1 and P2X3, which are known to have higher affinity for PPADS/PPNDS than other P2X subtypes.

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P2X receptors (P2X1-7) are non-selective cation channels involved in many physiological activities such as synaptic transmission, immunological modulation, and cardiovascular function. These receptors share a conserved mechanism to sense extracellular ATP. TNP-ATP is an ATP derivative acting as a nonselective competitive P2X antagonist. Understanding how it occupies the orthosteric site in the absence of agonism may help reveal the key allostery during P2X gating. However, TNP-ATP/P2X complexes (TNP-ATP/human P2X3 (hP2X3) and TNP-ATP/chicken P2X7 (ckP2X7)) with distinct conformations and different mechanisms of action have been proposed. Whether these represent species and subtype variations or experimental differences remains unclear. Here, we show that a common mechanism of TNP-ATP recognition exists for the P2X family members by combining enhanced conformation sampling, engineered disulfide bond analysis, and covalent occupancy. In this model, the polar triphosphate moiety of TNP-ATP interacts with the orthosteric site, while its TNP-moiety is deeply embedded in the head and dorsal fin (DF) interface, creating a restrictive allostery in these two domains that results in a partly enlarged yet ion-impermeable pore. Similar results were obtained from multiple P2X subtypes of different species, including ckP2X7, hP2X3, rat P2X2 (rP2X2), and human P2X1 (hP2X1). Thus, TNP-ATP uses a common mechanism for P2X recognition and modulation by restricting the movements of the head and DF domains which are essential for P2X activation. This knowledge is applicable to the development of new P2X inhibitors.

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P2X receptors are cation channels that sense extracellular ATP. Many therapeutic candidates targeting P2X receptors have begun clinical trials or acquired approval for the treatment of refractory chronic cough (RCC) and other disorders. However, the present negative allosteric modulation of P2X receptors is primarily limited to the central pocket or the site below the left flipper domain. Here, we uncover a mechanism of allosteric regulation of P2X3 in the inner pocket of the head domain (IP-HD), and show that the antitussive effects of quercetin and PSFL2915 (our nM-affinity P2X3 inhibitor optimized based on quercetin) on male mice and guinea pigs were achieved by preventing allosteric changes of IP-HD in P2X3. While being therapeutically comparable to the newly licensed P2X3 RCC drug gefapixant, quercetin and PSFL2915 do not have an adverse effect on taste as gefapixant does. Thus, allosteric modulation of P2X3 via IP-HD may be a druggable strategy to alleviate RCC.

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Morphine, the most widely used analgesic, relieves severe pain by activating the µ-opioid receptor (MOR), whereas naloxone, with only slight structural changes compared to morphine, exhibits inhibitory effect, and is used to treat opioid abuse. The mechanism by which the MOR distinguishes between the two is unclear. Molecular dynamics (MD) simulations on a 1-µs time scale and metadynamics-enhanced conformational sampling are used here to determine the different interactions of these two ligands with MOR: morphine adjusted its pose by continuously flipping deeper into the pocket, whereas naloxone failed to penetrate deeper because its allyl group conflicts with several residues of MOR. The endogenous peptide ligand endomorphin-1 (EM-1) underwent almost no significant conformational changes during the MD simulations. To validate these processes, we employed GIRK4S143T, a MOR-activated Gßγ-protein effector, in combination with mutagenesis and electrophysiological recordings. We verified the role of some key residues in the dynamic recognition of naloxone and morphine and identified the key residue I322, which leads to differential recognition of morphine and naloxone while assisting EM-1 in activating MOR. Reducing the side chain size of I322 (MORI322A) transformed naloxone from an inhibitor directly into an agonist of MOR, and I322A also significantly attenuated the potency of MOR on EM-1, confirming that binding deep in the pocket is critical for the agonistic effect of MOR. This finding reveals a dynamic mechanism for the response of MOR to different ligands and provides a basis for the discovery of new ligands for MOR at the atomic level.

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P2X receptors are a class of nonselective cation channels widely distributed in the immune and nervous systems, and their dysfunction is a significant cause of tumors, inflammation, leukemia, and immune diseases. P2X7 is a unique member of the P2X receptor family with many properties that differ from other subtypes in terms of primary sequence, the architecture of N- and C-terminals, and channel function. Here, we suggest that the observed lengthened ß2- and ß3-sheets and their linker (loop ß2,3), encoded by redundant sequences, play an indispensable role in the activation of the P2X7 receptor. We show that deletion of this longer structural element leads to the loss of P2X7 function. Furthermore, by combining mutagenesis, chimera construction, surface expression, and protein stability analysis, we found that the deletion of the longer ß2,3-loop affects P2X7 surface expression but, more importantly, that this loop affects channel gating of P2X7. We propose that the longer ß2,3-sheets may have a negative regulatory effect on a loop on the head domain and on the structural element formed by E171 and its surrounding regions. Understanding the role of the unique structure of the P2X7 receptor in the gating process will aid in the development of selective drugs targeting this subtype.

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Gefapixant/AF-219, a selective inhibitor of the P2X3 receptor, is the first new drug other than dextromethorphan to be approved for the treatment of refractory chronic cough (RCC) in nearly 60 years. To date, seven P2X subtypes (P2X1-7) activated by extracellular ATP have been cloned, and subtype selectivity of P2X inhibitors is a prerequisite for reducing side effects. We previously identified the site and mechanism of action of Gefapixant/AF-219 on the P2X3 receptor, which occupies a pocket consisting of the left flipper (LF) and lower body (LB) domains. However, the mechanism by which AF-219 selectively acts on the P2X3 receptor is unknown. Here, we combined mutagenesis, chimera construction, molecular simulations, covalent occupation and chemical synthesis, and find that the negative allosteric site of AF-219 at P2X3 is also present in other P2X subtypes, at least for P2X1, P2X2 and P2X4. By constructing each chimera of AF-219 sensitive P2X3 and insensitive P2X2 subtypes, the insensitive P2X2 subtype was made to acquire the inhibitory properties of AF-219 and AF-353, an analog of AF-219 with higher affinity. Our results suggest that the selectivity of AF-219/AF-353 for P2X3 over the other P2X subtypes is determined by a combination of the accessibility of P2X3 binding site and the internal shape of this pocket, a finding that could provide new perspectives for drug design against P2X3-mediated diseases such as RCC, idiopathic pulmonary fibrosis, hypertension and overactive bladder disorder.

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Thymopentin (TP5) is an immunomodulatory pentapeptide that has been widely used in malignancy patients with immunodeficiency due to radiotherapy and chemotherapy. Here, we propose that TP5 directly inhibits the stemness of colon cancer cells HCT116 and therefore enhances the cytotoxicity of oxaliplatin (OXA) in HCT116 cells. In the absence of serum, TP5 was able to induce cancer stemness reduction in cultured HCT116 cells and significantly reduced stemness-related signals, such as the expression of surface molecular markers (CD133, CD44 and CD24) and stemness-related genes (ALDH1, SOX2, Oct-4 and Nanog), and resulted in altered Wnt/ß-catenin signaling. Acetylcholine receptors (AchRs) are implicated in this process. OXA is a common chemotherapeutic agent with therapeutic effects in various cancers. Although TP5 had no direct effect on the proliferation of HCT116, this pentapeptide significantly increased the sensitivity of HCT116 to OXA, where the effect of TP5 on the stemness of colon cancer cells through stimulation of AchRs may contribute to this process. Our results provide a promising strategy for increasing the sensitivity of colon cancer cells to chemotherapeutic agents by incorporating immunomodulatory peptides.

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Transient receptor potential canonical (TRPC) channels, as important membrane proteins regulating intracellular calcium (Ca2+i) signaling, are involved in a variety of physiological and pathological processes. Activation and regulation of TRPC are more dependent on membrane or intracellular signals. However, how extracellular signals regulate TRPC6 function remains to be further investigated. Here, we suggest that two distinct small molecules, M085 and GSK1702934A, directly activate TRPC6, both through a mechanism of stimulation of extracellular sites formed by the pore helix (PH) and transmembrane (TM) helix S6. In silico docking scanning of TRPC6 identified three extracellular sites that can bind small molecules, of which only mutations on residues of PH and S6 helix significantly reduced the apparent affinity of M085 and GSK1702934A and attenuated the maximal response of TRPC6 to these two chemicals by altering channel gating of TRPC6. Combing metadynamics, molecular dynamics simulations, and mutagenesis, we revealed that W679, E671, E672, and K675 in the PH and N701 and Y704 in the S6 helix constitute an orthosteric site for the recognition of these two agonists. The importance of this site was further confirmed by covalent modification of amino acid residing at the interface of the PH and S6 helix. Given that three structurally distinct agonists M085, GSK1702934A, and AM-0883, act at this site, as well as the occupancy of lipid molecules at this position found in other TRP subfamilies, it is suggested that the cavity formed by the PH and S6 has an important role in the regulation of TRP channel function by extracellular signals.

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Highly conserved amino acids are generally anticipated to have similar functions across a protein superfamily, including that of the P2X ion channels, which are gated by extracellular ATP. However, whether and how these functions are conserved becomes less clear when neighboring amino acids are not conserved. Here, we investigate one such case, focused on the highly conserved residue from P2X4, E118 (rat P2X4 numbering, rP2X4), a P2X subtype associated with human neuropathic pain. When we compared the crystal structures of P2X4 with those of other P2X subtypes, including P2X3, P2X7, and AmP2X, we observed a slightly altered side-chain orientation of E118. We used protein chimeras, double-mutant cycle analysis, and molecular modeling to reveal that E118 forms specific contacts with amino acids in the "beak" region, which facilitates ATP binding to rP2X4. These contacts are not present in other subtypes because of sequence variance in the beak region, resulting in decoupling of this conserved residue from ATP recognition and/or channel gating of P2X receptors. Our study provides an example of a conserved residue with a specific role in functional proteins enabled by adjacent nonconserved residues. The unique role established by the E118-beak region contact provides a blueprint for the development of subtype-specific inhibitors of P2X4.

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Although the extracellular ATP-gated cation channel purinergic receptor P2X5 is widely expressed in heart, skeletal muscle, and immune and nervous systems in mammals, little is known about its functions and channel-gating activities. This lack of knowledge is due to P2X5's weak ATP responses in several mammalian species, such as humans, rats, and mice. WT human P2X5 (hP2X5Δ328-349) does not respond to ATP, whereas a full-length variant, hP2X5 (hP2X5-FL), containing exon 10 encoding the second hP2X5 transmembrane domain (TM2), does. However, although rat P2X5 (rP2X5) has a full-length TM2, ATP induces only weak currents in rP2X5, which prompted us to investigate the mechanism underlying this small ATP response. Here, we show that single replacements of specific rP2X5 residues with the corresponding residues in hP2X5 (S191F or F195H) significantly enhance the current amplitude of rP2X5. Using a combination of engineered disulfide cross-linking, single-channel recording, and molecular modeling, we interrogated the effects of S191F and F195H substitutions on the allostery of the left flipper (LF) domain. On the basis of our findings, we propose that the bound ATP-induced distinct allostery of the LF domain with that of other functional subtypes has caused the weak ATP response of rP2X5 receptors. The findings of our study provide the prerequisite for future transgenic studies on the physiological and pathological functions of P2X5 receptors.

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Four new indole alkaloids (1-4) and twenty known compounds (5-24) were isolated from the leaves and stems, and fruits of Kopsia officinalis. Their structures were confirmed by means of spectroscopic methods. All these isolates were evaluated for their antagonizing high glucose-evoked podocyte injury activity for the first time, and compounds 5-8 showed potent activity with EC50 values of 3.0-12.0 µM.

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PURPOSE: Fatalities due to heart and cerebrovascular diseases caused by uncontrolled hyperlipidaemia increase every year; on the other hand, lipid-lowering drugs are known to cause side effects. The gut microbiota has been thoroughly investigated by researchers and consumers, because they have unique functional properties and littler side effects. However, the effects of the gut microbiota remain controversial. We conducted a meta-analysis to assess the effects of products designed to modulate the gut microbiota on various hyperlipidaemias. METHODS: We systematically searched PubMed, Embase, Cochrane Library (Central), and Web of Science for randomized controlled trials (published before June 2017, and those only in English) to compare treatment (products designed to modulate the gut microbiota) versus placebo. Our main endpoints were total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in serum. We assessed pooled data using a fixed effects model. RESULTS: Of 1337 identified studies, 21 were eligible and included in our analysis (n = 1436 participants). The combined estimate of effect size for the impact of products designed to modulate the gut microbiota on serum TC (WMD - 11.07 mg/dL, 95% CI - 13.72 to - 8.43, p < 0.001), LDL-C (WMD - 10.96 mg/dL, 95% CI - 13.37 to - 8.56, p < 0.001), and HDL-C (WMD 0.72 mg/dL, 95% CI 0.06-1.38, p = 0.032) were statistically significant, while no significant effect was found on TG concentrations (WMD - 0.56 mg/dL, 95% CI - 5.59 to 4.47, p = 0.828). Subgroup analysis showed parallel trials, probiotics, and long-term intervention had better effects on lowering blood lipid levels. CONCLUSION: Products designed to modulate the gut microbiota results in changes of the plasma lipid concentrations and these changes may protect against cardiovascular disease.

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BACKGROUND: Diabetic nephropathy is one of the most common and serious complications of diabetes mellitus. HYPOTHESIS/PURPOSE: The present study aimed to investigate the effects of protodioscin on renal damage in high-fat diet-fed and streptozotocin-induced diabetic rats. METHODS: After 4 weeks of feeding a high-fat diet, male Sprague-Dawley rats were injected 35 mg/kg streptozotocin intraperitoneally. The diabetic rats were divided into 4 groups, and treated orally with carboxymethylcellulose sodium, metformin, or protodioscin (20 or 40 mg/kg). After 12 weeks of treatment, blood, urine, and renal tissue were collected for biochemical and histological examination. RESULTS: Protodioscin significantly reduced the levels of blood glucose, serum creatinine, and blood urea nitrogen, and also the excretion of urinary protein and albumin in diabetic rats. Histological examinations showed that protodioscin ameliorated the diabetes-induced glomerular and tubular pathological changes. Furthermore, protodioscin significantly reduced the renal concentrations of total cholesterol, triglycerides, free fatty acids, phospholipids, and TNF-α. CONCLUSION: These results indicate that protodioscin has ameliorative effects on diabetic nephropathy.

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P2X receptors are a family of extracellular ATP-gated trimeric cation channels that is widely distributed in human tissues. Quite some drug candidates targeting P2X receptors have entered into preclinical or main phases of clinical trials, but many of them failed due to low subtype-selectivity or species differences in pharmacological activities between human and experimental animals. Here, we identified the distinct inhibitory efficacies of NF110, a competitive inhibitor, between the rat (rP2X3) and human (hP2X3) P2X3 receptors. We demonstrated that this difference is determined by two amino acids located in the dorsal fin (DF) domain of P2X3 receptors. As revealed by mutagenesis, metadynamics, and covalent modification, NF110-mediated rP2X3 inhibition may be through a filling in the cavity formed by the DF, left flipper (LF) and lower body (LB) to partially, rather than fully, occupy the ATP-binding pocket. Moreover, substitution of residues located in the DF and/or LF domains of the rP2X2 receptor, a NF110-insensitive subtype, with the equivalent amino acids of rP2X3, bestowed the sensitivity of rP2X2 to NF110. The critical roles of the DF and LF domains in channel gating of P2X and low conservativity in residue sequences of those two domains raise the possibility that small molecules differentially interacting with the residues of the DF and LF domains of different P2X receptors may modulate channel's activity in a subtype-selective manner. However, the possible species-specificity of P2X inhibitors/modulators makes it more complex when interpreting the preclinical data into clinical researches. Nevertheless, our data provide new insights into the subtype-selectivity of competitive inhibitors and their distinct potencies in the human and experimental animals, both of which are extremely important in the drug discovery of P2X receptors.

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The viral Bcl-2 homolog (vBcl2) of Kaposi's sarcoma-associated herpesvirus (KSHV) displays efficient antiapoptotic and antiautophagic activity through its central BH3 domain, which functions to prolong the life span of virus-infected cells and ultimately enhances virus replication and latency. Independent of its antiapoptotic and antiautophagic activity, vBcl2 also plays an essential role in KSHV lytic replication through its amino-terminal amino acids (aa) 11 to 20. Here, we report a novel molecular mechanism of vBcl2-mediated regulation of KSHV lytic replication. vBcl2 specifically bound the tegument protein open reading frame 55 (ORF55) through its amino-terminal aa 11 to 20, allowing their association with virions. Consequently, the vBcl2 peptide derived from vBcl2 aa 11 to 20 effectively disrupted the interaction between vBcl2 and ORF55, inhibiting the incorporation of the ORF55 tegument protein into virions. This study provides new insight into vBcl2's function in KSHV virion assembly that is separable from its inhibitory role in host apoptosis and autophagy.IMPORTANCE KSHV, an important human pathogen accounting for a large percentage of virally caused cancers worldwide, has evolved a variety of stratagems for evading host immune responses to establish lifelong persistent infection. Upon viral infection, infected cells can go through programmed cell death, including apoptosis and autophagy, which plays an effective role in antiviral responses. To counter the host response, KSHV vBcl2 efficiently blocks apoptosis and autophagy to persist for the life span of virus-infected cells. Besides its anti-programmed-cell-death activity, vBcl2 also interacts with the ORF55 tegument protein for virion assembly in infected cells. Interestingly, the vBcl2 peptide disrupts the vBcl2-ORF55 interaction and effectively inhibits KSHV virion assembly. This study indicates that KSHV vBcl2 harbors at least three genetically separable functions to modulate both host cell death signaling and virion production and that the vBcl2 peptide can be developed as an anti-KSHV therapeutic application.

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To elucidate the increasing dissolution and enhancement mechanism of wine-processed Radix Scutellaria (RS) by fractal theory in nitroglycerin (NTG)-induced migraine rats. We prepared three RS from the process with 10% (S1), 15% (S2), 20% (S3) (v/m) rice wine. Mercury intrusion porosimetry and scanning electron microscope were employed to explore the internal structure of RS and the components dissolution of RS was analyzed by HPLC. Rats were randomly allocated into following groups and orally given different solutions for 10days: normal group (NOR, normal saline), model group (MOD, normal saline), Tianshu capsule group (TSC, 0.425mg/kg), ibuprofen group (IBU, 0.0821mg/kg), crude RS group (CRU, 1.04mg/kg) and wine-processed RS group (WP, 1.04mg/kg) followed by bolus subcutaneously injection of NTG (10mg/kg) to induce migraine model except NOR. Biochemical indexes (nitric oxide-NO, calcitonin-gene-related peptide-CGRP, and endothelin-ET) and c-fos positive cells were measured with commercial kits and immunohistochemical method, separately. Total surface area significantly increased in wine-processed RS (p<0.05) while fractal dimension markedly decreased (p<0.05) compared with crude RS. Additionally, S3 owned the highest increase of dissolution including the percentage increase of total extract, total flavonoids and main compounds (all p<0.05 vs S1 and S2). Pharmacodynamic data showed c-fos positive cells significantly decreased (p<0.05) in WP compared with MOD and the level of NO, CGRP, ET in WP was better than that of CRU. Wine-processed RS could be a promising candidate medicine for migraine treatment due to its increased component dissolution.

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BACKGROUND: Migraine is a complex nervous system disease characterized by typical throbbing and unilateral headache, which causes severe healthy and social issues worldwide. The purpose of this study was to investigate the effect of baicalein (BAI) on the treatment of migraine. MATERIAL AND METHODS: Twenty-four rats were randomly divided equally into four groups, including a blank group, model group, positive group (ibuprofen tablets 82mg/kg), and BAI group (60mg/kg). All rats were intragastrically treated with the corresponding treatment for 10 consecutive days, and they were subcutaneously injected with NTG (10mg/kg) 1h after the last treatment, except in the blank group. After model establishment, the behaviors of all rats, including scratching head and shaking body were observed continuously for 100min. Four hours after NTG treatment, all rats were anaesthetized and the blood was collected. Thereafter, nitric oxide (NO) in plasma was determined by colorimetric method, the level of calcitonin gene-related peptide (CGRP) and endothelin (ET) were detected by radioimmunoassay method. In addition, immunohistochemistry was applied to detect c-Fos neuronal activity in trigeminal nucleus caudalis (TNC). RESULTS: Behavioral research showed that BAI administration alleviated the hyperalgesia in migraine rats. Compared with the model group, the levels of NO and CGRP in BAI administration groups were markedly decreased (p<0.01), and the levels of ET was significantly increased (p<0.01). Meanwhile, immunohistochemistry results showed that NTG treatment significantly activated c-Fos neurons while BAI treatment inhibited the expression of c-Fos. CONCLUSIONS: BAI could alleviate the migraine-like headache induced by NTG, which is related to the regulation of vasoactive substances. These findings may contribute to the further study of BAI as a potential drug for migraine pharmacotherapy.

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BACKGROUND: Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease, which affects approximately 1% adult population in the worldwide. AIM: The present study was to investigate the anti-arthritic effect of berberine and its involved mechanism in Freund's complete adjuvant (FCA) induced arthritis rats. METHODS AND MATERIALS: Rats were divided randomly into control, FCA, tripterysium glycosides, berberine (75 and 150mg/kg). The apparent indicators, including changes of body weights, paw swelling degrees and arthritis indexes, were analyzed to evaluate anti-arthritic effect of berberine. The levels of IL-6, IL-10, IL-17 and TGF-ß in serum were measured by ELISA. Histopathological changes and immunohistochemical expression of anti-IL-10 and anti-IL-17 antibodies in ankle joint tissues were examined. RESULTS: Berberine obviously suppressed the severity of RA rats by attenuating the apparent indicators as mentioned above. Meanwhile, berberine significantly decreased the levels of IL-6 and IL-17, and increased the levels of IL-10 and TGF-ß. Histopathological examinations indicated that berberine attenuated the synovial hyperplasia and inflammatory cell infiltration in joint tissues. In addition, immunohistochemical results showed that the amount of anti-IL-10 antibody increased, while the amount of anti-IL-17 antibody decreased in ankle tissues of arthritis rats. CONCLUSIONS: Our results showed that berberine exerted a superior anti-arthritic effect and the mechanism maybe involve the balance between Treg and Th17 cells.

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The purpose of this study was to explore the enhancing effects and the mechanism of monocyclic monoterpene penetration enhancers (menthol and menthone) on the transdermal absorption of ligustrazine hydrochloride (LH). Franz-type diffusion cells were used to determine percutaneous parameters of LH in vitro and surface changes of porcine skin were studied by a scanning electron microscope (SEM). The effects of promoters on the biophysical natures of stratum corneum (SC) were researched by Fourier transform-infrared (FT-IR). Penetration parameters of menthol (p < 0.01) and menthone groups (p < 0.05) were greater than those of the control; morphological changes of skin monitored by SEM demonstrated that the menthone group had the most disruption and desquamation of SC flakes, which resulted from extracted lipids. FT-IR measurements showed menthone had the greatest changes in peak shift and peak area, which resulted from C-H stretching vibrations of SC lipids. The results suggest that the penetration mechanism might include disturbing and extracting SC lipids and the hydrogen bond connection.

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The present study aimed to investigate the gastroprotective activity of the total alkaloids from the bark of Phellodendron amurense and identify their possible mechanism. Total alkaloids were obtained through an alcohol extraction method and were analyzed using LC-MS/MS. Chronic gastric ulcers were induced by acetic acid (0.14 mol/L) filter paper on the gastric serosa. The antiulcer effect of total alkaloids was evaluated using the ulcer area, the ulcer inhibition ratio, and epidermal growth factor. The gastroprotective mechanism of total alkaloids was revealed using the levels of serotonin and noradrenaline. The results showed that oral administration of total alkaloids (30 mg/kg/day) obviously decreased the ulcer area (7.67 ± 2.06 mm2; p < 0.01) compared with the model group (15.15 ± 2.34 mm2). The ulcer inhibition ratio of the total alkaloids group (50 %) was higher than the omeprazole-treated group (46 %), which showed that the antiulcer effect of the total alkaloids may be superior to omeprazole. Besides, the total alkaloids significantly increased the epidermal growth factor level and accelerated the healing of ulcers. Histological examination of gastric tissues also supported the same conclusion. In addition, the total alkaloids significantly elevated the levels of serotonin and noradrenaline (both p < 0.01 compared to the model group). Our data indicates that total alkaloids of Cortex Phellodendri exerts a beneficial gastroprotective effect and the involved mechanism is likely neurohumoral regulation. Thus, Cortex Phellodendri may develop into a promising clinical medicinal agent for improving the quality of ulcer healing.

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