Zhilong Huoxue Tongyu Capsule regulates the macrophage polarization and inflammatory response via the let-7i/TLR9/MyD88 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zhilong Huoxue Tongyu Capsule (ZL) is clinically prescribed for acute ischemic stroke (AIS). However, only a few studies have addressed the mechanisms of ZL in treating AIS.

AIM OF THE STUDY

To explore the underlying mechanism of macrophage polarization and inflammation mediated by ZL, and to provide a reference for AIS treatment.

MATERIALS AND METHODS

Sixteen SD rats were fed with different dose of ZL (0, 0.4, 0.8, and 1.6 g/kg/d) for 4 days to prepare ZL serum. After 500 ng/mL lipopolysaccharide (LPS) stimulation, RAW264.7 cells were administrated with ZL serum. Then, experiments including ELISA, flow cytometry, real-time quantitative PCR and Western blot were performed to verify the effects of ZL on macrophage polarization and inflammation. Next, let-7i inhibitor was transfected in RAW264.7 cells when treated with LPS and ZL serum to verify the regulation of ZL on the let-7i/TLR9/MyD88 signaling pathway. Moreover, the interaction between let-7i and TLR9 was confirmed by the dual-luciferase assay.

RESULTS

ZL serum significantly decreased the expression of interleukin (IL)-6 and tumor necrosis factor-α (TNF-α), and increased the expression of IL-10 and transforming growth factor β1 (TGF-β1) of LPS stimulated-macrophages. Furthermore, ZL serum polarized macrophages toward M2, decreased the expressions of TLR9, MyD88, and iNOS, as well as increased the expressions of let-7i, CHIL3, and Arginase-1. It is worth mentioning that the effect of ZL serum is dose-dependent. However, let-7i inhibitor restored all the above effects in LPS stimulated-macrophages. In addition, TLR9 was the target of let-7i.

CONCLUSIONS

ZL targeted let-7i to inhibit TLR9 expression, thereby inhibiting the activation of the TLR9/MyD88 pathway, promoting the M2 polarization, and inhibiting the development of inflammation in AIS.

Zhilong Huoxue Tongyu Capsule attenuates hemorrhagic transformation through the let-7f/TLR4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Hemorrhagic transformation after acute ischemic stroke is a life-threatening disease that currently has no effective chemotherapy. Zhilong Huoxue Tongyu Capsule (ZL) is an empirical prescription of traditional Chinese medicine that is used to prevent and treat cardiovascular and cerebrovascular diseases in China. However, only a few studies have addressed the mechanisms of ZL in treating hemorrhagic transformation.

AIM OF THE STUDY

To evaluate the anti-inflammatory effects of ZL on hemorrhagic transformation model rats and lipopolysaccharide (LPS)-induced RAW264.7 macrophages and to explore the underlying molecular mechanisms.

MATERIALS AND METHODS

Murine RAW264.7 cells were treated with ZL and LPS (1 μg/mL), and cell viability was detected by cell counting kit-8 assay. RT-qPCR was used to detect the expression of inflammatory chemokines, microRNA let-7a/e/i/f, toll like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor kappa-B (NF-κB) p65. The protein expression levels of TLR4, MyD88, NF-κB p65, and apoptosis related molecules were determined by Western blotting. The apoptosis rate of RAW264.7 macrophages was detected by Annexin V-FITC/PI double staining. A hemorrhagic transformation model in rats was established by intraperitoneal injection of high glucose solution combined with thread embolization. Then, the model rats were observed behaviourally, pathologically, and molecularly. The gene expression of TLR4, MyD88, and NF-κB p65 was measured by RT-qPCR and used to evaluate the protective effect of ZL against hemorrhagic transformation in rats.

RESULTS

ZL (5, 20, 40 μg/mL) was beneficial in cell proliferation. LPS (1 μg/mL) stimulated the production of inflammatory chemokines and inhibited the production of let-7a/e/i/f, with let-7f being influenced most strongly. Moreover, overexpression of let-7f decreased the gene and protein levels of TLR4, MyD88, and NF-κB p65, downregulated TLR4, and inhibited its transcriptional activity. ZL (5, 20, and 40 μg·mL-1) inhibited the production of TLR4, MyD88, and NF-κB p65 and promoted the production of let-7f in a concentration-dependent manner. Furthermore, the blockade of TLR4 antagonized the promoting effects of TLR4 pathway activation in cell inflammation and apoptosis by downregulating let-7f. Critically, it was confirmed in vivo and in vitro that ZL upregulated the expression of let-7f and inhibited the gene expression of TLR4, MyD88, and NF-κB p65 to reduce inflammatory cell infiltration, which determined the occurrence of hemorrhagic transformation.

CONCLUSIONS

ZL can reduce inflammatory response by upregulating let-7f and subsequently inhibiting the TLR4 signaling pathway, thereby decreasing the occurrence of hemorrhagic transformation.

Surface-Based Falff: A Potential Novel Biomarker for Prediction of Radiation Encephalopathy in Patients With Nasopharyngeal Carcinoma

Radiation encephalopathy (RE) is an important potential complication in patients with nasopharyngeal carcinoma (NPC) who undergo radiotherapy (RT) that can affect the quality of life. However, a functional imaging biomarker of pre-symptomatic RE has not yet been established. This study aimed to assess radiation-induced gray matter functional alterations and explore fractional amplitude of low-frequency fluctuation (fALFF) as an imaging biomarker for predicting or diagnosing RE in patients with NPC. A total of 60 patients with NPC were examined, 21 in the pre-RT cohort and 39 in the post-RT cohort. Patients in the post-RT cohort were further divided into two subgroups according to the occurrence of RE in follow-up: post-RT _non-RE (n = 21) and post-RT _{REproved infollow-up} (n = 18). Surface-based and volume-based fALFF were used to detect radiation-induced functional alterations. Functional derived features were then adopted to construct a predictive model for the diagnosis of RE. We observed that surface-based fALFF could sensitively detect radiation-induced functional alterations in the intratemporal brain regions (such as the hippocampus and superior temporal gyrus), as well as the extratemporal regions (such as the insula and prefrontal lobe); however, no significant intergroup differences were observed using volume-based fALFF. No significant correlation between fALFF and radiation dose to the ipsilateral temporal lobe was observed. Support vector machine (SVM) analysis revealed that surface-based fALFF in the bilateral superior temporal gyri and left insula exhibited impressive performance (accuracy = 80.49%) in identifying patients likely to develop RE. We conclude that surface-based fALFF may serve as a sensitive imaging biomarker in the prediction of RE.

Functional Connectivity Density for Radiation Encephalopathy Prediction in Nasopharyngeal Carcinoma

The diagnostic efficiency of radiation encephalopathy (RE) remains heterogeneous, and prediction of RE is difficult at the pre-symptomatic stage. We aimed to analyze the whole-brain resting-state functional connectivity density (FCD) of individuals with pre-symptomatic RE using multivariate pattern analysis (MVPA) and explore its prediction efficiency. Resting data from NPC patients with nasopharyngeal carcinoma (NPC; consisting of 20 pre-symptomatic RE subjects and 26 non-RE controls) were collected in this study. We used MVPA to classify pre-symptomatic RE subjects from non-RE controls based on FCD maps. Classifier performances were evaluated by accuracy, sensitivity, specificity, and area under the characteristic operator curve. Permutation tests and leave-one-out cross-validation were applied for assessing classifier performance. MVPA was able to differentiate pre-symptomatic RE subjects from non-RE controls using global FCD as a feature, with a total accuracy of 89.13%. The temporal lobe as well as regions involved in the visual processing system, the somatosensory system, and the default mode network (DMN) revealed robust discrimination during classification. Our findings suggest a good classification efficiency of global FCD for the individual prediction of RE at a pre-symptomatic stage. Moreover, the discriminating regions may contribute to the underlying mechanisms of sensory and cognitive disturbances in RE.

Hispidulin Inhibits Neuroinflammation in Lipopolysaccharide-Activated BV2 Microglia and Attenuates the Activation of Akt, NF-κB, and STAT3 Pathway

Microglia, resident innate immune cells in central nervous system, regulates neuroinflammation and is associated with a variety of neuropathologies. The present study investigated the antineuroinflammatory effects of hispidulin (HPD), a naturally flavone compound, in lipopolysaccharide- (LPS-) stimulated BV2 microglia cells. The expression levels of nitric oxide (NO), reactive oxygen species (ROS), and pro-inflammatory factors were determined by the Griess method, flow cytometry, and enzyme-linked immunosorbent assay (ELISA). Western blotting was used to measure various transcription factors such as Akt, nuclear factor-kappa B (NF-κB), and signal transducer and activator of transcription 3 (STAT3) activities. Our experimental results demonstrated that HPD increased cell viability and reduced apoptosis in LPS-treated BV2 microglia cells. Moreover, HPD significantly reduced the levels of NO, ROS, inducible nitric oxide synthase (iNOS), cyclooxygenase- (COX-) 2, tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and prostaglandin E2 (PGE2) in a dose-dependent manner. Phosphorylation of NF-κB/IκB, Akt, and STAT3 proteins expression by HPD was suppressed in LPS-induced BV2 microglial cells. We concluded that HPD may inhibit neuroinflammatory responses by inhibiting NF-κB pathway activation and ROS formation. These results propose that HPD has potential as anti-inflammatory agents against microglia-mediated neuroinflammatory disorders.

ADP-mimicking Platelet Aggregation Caused by Rugosin E, an Ellagitannin Isolated from Rosa rugosa Thunb

Among the nine ellagitannins, rugosin E was the most potent platelet aggregating agent with an EC50 of 1.5 ± 0.1 µM in rabbit platelets and 3.2 ±0.1 µM in human platelets. The aggregations caused by rugosin E and ADP were inhibited by EGTA, PGE1, mepacrine, sodium nitroprusside and neomycin, but not by indomethacin, verapamil, TMB-8, BN52021 and GR32191B. Rugosin E-induced thromboxane formation was suppressed by indomethacin, EGTA, PGE,, verapamil, mepacrine, TMB-8 and neomycin. ADP-scavenging agents, such as CP/CPK and apyrase inhibited concentration-dependently ADP (20 εM)-, but not rugosin E (5 εM)-induced platelet aggregation. In thrombin (0.1 U/ml)-treated and degranulated platelets, rugosin E and ADP still caused 63.5 ± 3.0% and 61.2 ± 3.5% of platelet aggregation, respectively. Selective ADP receptor antagonists, ATP and FSBA inhibited rugosin E- and ADP-induced platelet aggregations in a concentration-dependent manner. Both rugosin E and ADP did not induce platelet aggregation in ADP (1 mM)-desensitized platelets. In contrast to ADP, rugosin E did not decrease cAMP formation in washed rabbit platelets. Both rugosin E and ADP did not cause phosphoinositide breakdown in [3H]myo-inositol-labeled rabbit platelets. In fura-2/AM- load platelets, both rugosin E and ADP induced increase in intracellular calcium concentration and these responses were inhibited by ATP and PGEj. All these data suggest that rugosin E may be an ADP receptor agonist in rabbit platelets.

Molecular Changes Involving MEK3-p38 MAPK Activation in Chronic Masticatory Myalgia

The exact mechanism underlying chronic masticatory myalgia (CMM), a conspicuous symptom in temporomandibular disorders, remains unclear. This investigation compared gene expression profiles between CMM patients and healthy subjects. Peripheral blood leukocytes were collected in 8 cases and 8 controls and subjected to whole genome microarray analyses. Data were analyzed with Gene Ontology and interactive pathways analyses. According to Gene Ontology analysis, categories such as ion transport, response to stimuli, and metabolic process were upregulated. The pathway analysis suggested overexpression of the mitogen-activated protein kinase (MAPK) pathway in CMM patients and to a higher degree in a pathway network. Overexpression of representative members of the MAPK pathway-including MAPK kinase 3 (MEK3), calcium voltage-gated channel auxiliary subunit gamma 2 (CACNG2), and growth arrest and DNA damage-inducible gamma (GADD45G)-was validated with real-time polymerase chain reaction. The upregulation of MEK3 was negatively correlated with the age of the CMM group. In the next step, the authors focused on MEK3, the gene that exhibited the greatest degree of differential expression, and its downstream target protein p38 MAPK. The results revealed upregulation of MEK3, as well as phosphorylated MEK3 and phosphorylated p38 MAPK, in CMM patients. These results provide a "fingerprint" for mechanistic studies of CMM in the future and highlight the importance of MEK3-p38 MAPK activation in CMM.

[Radiographic and masticatory physiologic evaluation after conservative treatment of condylar fractures in children and adolescents]

OBJECTIVE

To evaluate the developmental and functional outcome of condylar fractures in children and adolescents after conservative treatment.

METHODS

Eight children and adolescents with unilateral condylar fracture, aged 5-13 were included. A removable occlusal splint, the thickness of which was determined according to the age, the developmental stage of the dentition, the level of the fracture and the degree of dislocation, worn for 1-3 months, and the patients were asked to perform functional exercises. The patients were followed up by clinical observation, panoramic radiograph, temporomandibular joint(TMJ ) cone beam computed tomography(CBCT), and surface electromyography(sEMG) of masticatory muscles (superficial masseter, anterior temporalis, and anterior digastric muscles). Ramus height and body length of mandible were measured on panoramic radiograph. The patients were asked to return for follow-up visits at 1, 3, and 6 months after treatment, and then once a year. The patients underwent clinical examination at each follow-up visit, and radiological examinations at 6 months and then annually.

RESULTS

All the patients showed clinically satisfactory results. CBCT showed smooth and continuous cortex. Panoramic X-ray revealed that the ramus height was shorter in the fractured side than in the contralateral side, while body length was longer. The mean asymmetry index(AI,x±s) for ramus height and body length were (3.29±2.68)% and (4.01 ± 2.54)%. sEMG showed either hypertension or hypotension in the masticatory muscles of the fractured side and asymmetries were obvious. The mean AI for sEMG activity of the anterior temporalis, masseter, and anterior digastric muscle were masseter: (15.0 ± 16.9)%; anterior temporalis: (21.5 ± 15.9)%; anterior digastric muscles: (11.9 ± 10.7)%.

CONCLUSIONS

Conservative treatment of condylar fracture in children and adolescents had clinically satisfactory results, while mandibular development was slightly interrupted. Asymmetries of EMG activities of masticatory muscles were obvious. EMG could objectively reveal the functional recovery of condylar fracture in children.

A new benzodioxocinone from the leaves of Cinnamomum tenuifolium

Investigation of the leaves' extract of Cinnamomum tenuifolium (Lauraceae) led to the isolation of one novel benzodioxocinone, 2,3-dihydro-6,6-dimethylbenzo-[b][1,5]dioxocin-4(6 H)-one (1). The structure was determined through in-depth spectroscopic and mass-spectrometric analyses. The antioxidant potential was evaluated using the following in vitro method: scavenging of 1,1-diphenyl-2-picrylhydrazyl radical. We also detected the anti-proliferative effect of 1 on human oral cancer cells and its IC(50) is 107.7 µM.

Inhibitory action of methadone and its metabolites on erg-mediated K+ current in GH₃ pituitary tumor cells

Methadone (Mtd) is a widely used opioid drug associated with the side effect of hyperprolactinemia. The mechanism of how Mtd induces prolactin secretion remains unclear. The effects of Mtd and its two main metabolites (EDDP: (±)-2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium percholarate and EMDP: 2-ethyl-5-methyl-3,3-dipnehyl-1-pyrroline) on ion currents were investigated in GH₃ pituitary tumor cells. Hyperpolarization-elicited K+ currents in GH₃ cells bathed in a high-K(+), Ca(2+)-free solution were studied to evaluate the effects of Mtd and other related compounds on the ether-à-go-go-related-gene (erg) K(+) current (I(K(erg))). Mtd suppressed the amplitude of I(K(erg)) in a concentration-dependent manner with an IC(50) value of 10.4 μM. With the aid of a minimal binding scheme, the inhibitory action of Mtd on I(K(erg)) was estimated with a dissociation constant of 8.2 μM. Mtd tended to increase the rate of I(K(erg)) deactivation in a voltage-dependent fashion. EDDP (10 μM) had no effect on I(K(erg)), while EMDP (10μM) slightly suppressed it. In GH₃ cells incubated with naloxone (30 μM), the Mtd-induced inhibition of I(K(erg)) remained unaltered. Under cell-attached voltage-clamp recordings, Mtd increased the frequency of spontaneous action currents with no change in current amplitude. Similarly, Mtd can suppress I(K(erg)) in differentiated NG108-15 cells; dynorphin A(1-13) did not reverse Mtd-induced inhibition of I(K(erg)). This study shows that Mtd has a depressant effect on I(K(erg)), and suggests its ability to affect membrane excitability and prolactin secretion. The cyclization of Mtd, in which EDDP and EMDP are formed, tends to be critical in removal of the Mtd binding to erg K+ channel.

Thymol-evoked Ca2+ Mobilization and Ion Currents in Pituitary GH3 Cells

In this study, an attempt was made to elucidate the effects of thymol, a monocyclic phenolic compound, on Ca2+ mobilization and ion currents in pituitary GH3 cells with the aid of fura-2 fluorimetry and the whole-cell voltage-clamp technique. Thymol increased intracellular Ca2+ concentrations ([Ca2+]i) in GH3 cells loaded with Ca2+-sensitive dye fura-2. Removing extracellular Ca2+ reduced the thymol-induced [Ca2+]i rise. In Ca2+-free solution, thymol-evoked [Ca2+]i rise was unchanged by depleting the Ca2+ store with thapsigargin (1 μM), while the thapsigargin-induced [Ca2+]i rise was reduced by pretreatment with thymol. These results imply that the Ca2+ stores depleted by thymol comprise thapsigargin-sensitive and thapsigargin-insensitive pools. In addition, after depletion of the internal Ca2+ store with 100 μM thymol in Ca2+-free solution, a subsequent application of Ca2+ greatly induced a [Ca2+]i increase. The results indicate that, similar to thapsigargin, 100 μM thymol may activate the capacitative calcium entry (CCE) channel. However, thymol (100 μM) had a slight depressant action in L-type calcium current ( ICaL). The stimulatory actions of thymol on Ca2+ signaling may partly be responsible for the underlying cellular mechanisms through which it affects neuroendocrine functions.

Thymol-evoked Ca+ mobilization and ion currents in pituitary GH3 cells

In this study, an attempt was made to elucidate the effects of thymol, a monocyclic phenolic compound, on Ca2+ mobilization and ion currents in pituitary GH3 cells with the aid of fura-2 fluorimetry and the whole-cell voltage-clamp technique. Thymol increased intracellular Ca2+ concentrations ([Ca2+]i) in GH3 cells loaded with Ca2+-sensitive dye fura-2. Removing extracellular Ca2+ reduced the thymol-induced [Ca2+]i rise. In Ca2+ -free solution, thymol-evoked [Ca2+]i rise was unchanged by depleting the Ca2+ store with thapsigargin (1 microM), while the thapsigargin-induced [Ca2+]i rise was reduced by pretreatment with thymol. These results imply that the Ca2+ stores depleted by thymol comprise thapsigargin-sensitive and thapsigargin-insensitive pools. In addition, after depletion of the internal Ca2+ store with 100 microM thymol in Ca2+ -free solution, a subsequent application of Ca2+ greatly induced a [Ca2+]i increase. The results indicate that, similar to thapsigargin, 100 microM thymol may activate the capacitative calcium entry (CCE) channel. However, thymol (100 microM) had a slight depressant action in L-type calcium current (I(CaL)). The stimulatory actions of thymol on Ca2+ signaling may partly be responsible for the underlying cellular mechanisms through which it affects neuroendocrine functions.

ADP-mimicking platelet aggregation caused by rugosin E, an ellagitannin isolated from Rosa rugosa Thunb

Among the nine ellagitannins, rugosin E was the most potent platelet aggregating agent with an EC50 of 1.5 +/- 0.1 microM in rabbit platelets and 3.2 +/- 0.1 microM in human platelets. The aggregations caused by rugosin E and ADP were inhibited by EGTA, PGE1, mepacrine, sodium nitroprusside and neomycin, but not by indomethacin, verapamil, TMB-8, BN52021 and GR32191B. Rugosin E-induced thromboxane formation was suppressed by indomethacin, EGTA, PGE1, verapamil, mepacrine, TMB-8 and neomycin. ADP-scavenging agents, such as CP/CPK and apyrase inhibited concentration-dependently ADP (20 microM)-, but not rugosin E (5 microM)-induced platelet aggregation. In thrombin (0.1 U/ml)-treated and degranulated platelets, rugosin E and ADP still caused 63.5 +/- 3.0% and 61.2 +/- 3.5% of platelet aggregation, respectively. Selective ADP receptor antagonists, ATP and FSBA inhibited rugosin E- and ADP-induced platelet aggregations in a concentration-dependent manner. Both rugosin E and ADP did not induce platelet aggregation in ADP (1 mM)-desensitized platelets. In contrast to ADP, rugosin E did not decrease cAMP formation in washed rabbit platelets. Both rugosin E and ADP did not cause phosphoinositide breakdown in [3H]myo-inositol-labeled rabbit platelets. In fura-2/AM-load platelets, both rugosin E and ADP induced increase in intracellular calcium concentration and these responses were inhibited by ATP and PGE1. All these data suggest that rugosin E may be an ADP receptor agonist in rabbit platelets.

Characterization of the thromboxane (TP-) receptor subtype involved in proliferation in cultured vascular smooth muscle cells of rat

1. The effects of the thromboxane A2 (TxA2)-mimetic, U-46619, on the proliferation of vascular smooth muscle cells (VSMCs) were examined in a clonal smooth muscle cell line, A10, which was derived from foetal rat aorta. 2. [3H]-U-46619 bound to A10 cells of passages 18-20 (p18-20) with two classes of sites. The high affinity site showed a Bmax of 3.0 +/- 1.8 fmol mg-1 protein with a KD value 1.0 +/- 0.1 nM, while the low affinity site showed a Bmax of 43.0 +/- 6.0 fmol mg-1 protein and KD value of 129.0 +/- 7.9 nM. However, [3H]-U-46619 bound to A10 cells from passages 28-30 (p28-30) at a single class of site with a Bmax 111.0 +/- 9.0 fmol mg-1 protein and a KD value of 175.4 +/- 22.0 nM. 3. Cinnamophilin and SQ29548 inhibited specific [3H]-U-46619 binding to p18-20 A10 cells in a concentration-dependent manner with Ki values of 390.0 +/- 3.2 and 4.6 +/- 1.0 nM, respectively at a high affinity site, and 2.6 +/- 0.2 microM and 310.0 +/- 6.4 nM, respectively at the low affinity site. 4. U-46619 produced isometric contractions of rat aorta in a concentration-dependent manner with an EC50 7.0 +/- 1.2 nM. Cinnamophilin and SQ29548 antagonized U-46619-induced aortic contractions with pA2 values 6.3 +/- 0.1 and 8.2 +/- 0.2, respectively. 5. U-46619 increased [3H]-thymidine incorporation into DNA of p18-20 and p28-30 A10 cells in aconcentration-dependent manner with EC50 values 362.7 +/- 27.0 and 302.5 +/- 20.1 nm, respectively. The U-46619-induced increase of [3H]-thymidine incorporation into DNA of p28 -30 AO0 cells was potentiatedby PDGF (1 ng ml-1) and FCS (1%) and was inhibited by cinnamophilin (10 microM) and SQ29548 (1 microM)with estimated pKB values 5.4 +/- 1.2 and 6.3 +/- 0.9, respectively.6. Cell cycle analysis revealed that U-46619-increased cell cycle progression was primarily due to a rapidtransition from the DNA synthetic (S) to the G2/mitotic (M) phase. Moreover, U-46619 also increasedprotein synthesis and cell numbers in VSMC. All these effects of U-46619 were inhibited bycinnamophilin and SQ29548.7. U-46619 caused phosphoinositide breakdown and increased the intracellular Ca2+ concentration inVSMC, effects which were blocked by cinnamophilin and SQ29548.8 These data indicate there are two U-46619 binding sites in AlO VSMC. The high affinity site is correlated to U-46619-induced vasoconstriction while the low affinity site is correlated to U-46619-mediated VSMC proliferation. These data also reveal that U-46619 stimulates the cell cycle progression in VSMC primarily through a rapid transition from S to G2/M. Since cinnamophilin inhibits TPreceptor-mediated VSMC proliferation, it may thus hold promising potential for the prevention of atherosclerosis or vascular diseases.

Effects of dicentrine on haemodynamic, plasma lipid, lipoprotein level and vascular reactivity in hyperlipidaemic rats

1. The effects of dicentrine on haemodynamic, plasma lipid, lipoprotein level and vascular reactivity were investigated in Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats, fed a high fat-high cholesterol diet. 2. In high fat-high cholesterol (HF-HC) diet fed WKY and SH rats, oral administration of dicentrine (5 and 10 mg kg-1, twice a day) for 4 weeks caused significant reductions in total plasma cholesterol (CE) by reducing the low density lipoprotein (LDL) fraction, and reductions in total plasma triglyceride (TG) by reducing the very low density lipoprotein (VLDL) fraction. 3. Dicentrine therapy was associated with increased high density lipoprotein (HDL)-cholesterol levels; thus the ratio of total plasma cholesterol to HDL-cholesterol was improved. 4. In HF-HC diet fed conscious WKY and SH rats, oral administration of dicentrine (5 and 10 mg kg-1, twice a day) also evoked dose-related decreases in mean arterial pressure (MAP) which were of greater magnitude in SH rats. Neither dose of dicentrine caused a significant change in heart rate (HR). 5. The aortic arches from SH rats fed the HF-HC diet for 8 weeks were significantly more affected by the atherosclerotic lesions than the abdominal aortae and renal arteries of WKY and SH rats. Oral administration of dicentrine (5 and 10 mg kg-1) for 4 weeks did not diminish the atherosclerotic lesion areas in WKY and SH rats. 6. In aortae of the hyperlipidaemic rats, significantly attenuated EC50 values and augmented maximal responses for phenylephrine-induced contraction were obtained. Endothelium-dependent relaxation to acetylcholine was abolished, while endothelium-independent relaxation to nitroprusside was well preserved. Dicentrine therapy caused significantly augmented EC50 values and attenuated maximal responses for phenylephrine-induced contraction in hyperlipidaemic rats. However, dicentrine neither prevented the impaired relaxation to acetylcholine, nor affected the relaxation to nitroprusside during atherosclerosis progression.7. It is concluded that dicentrine decreases MAP, plasma CE, LDL-CE, plasma TG, VLDL-TG,vascular hyperreactivity to phenylephrine and increases HDL-CE levels. Dicentrine may thus hold potential for the reduction of two of the major risk factors, hypertension and hyperlipidaemia, for cardiovascular disease.