Retinoid X receptor agonists alleviate fibroblast activation and post-infarction cardiac remodeling via inhibition of TGF-ß1/Smad pathway.

Retinoid X receptor (RXR), particularly RXRα, has been implicated in cardiovascular diseases. However, the functional role of RXR activation in myocardial infarction (MI) remains unclear. This study aimed to determine the effects of RXR agonists on MI and to dissect the underlying mechanisms. Sprague-Dawley (SD) rats were subjected to MI and then treated (once daily for 4 weeks) with either RXR agonist bexarotene (10 or 30 mg/kg body weight) or vehicle. Heart function was determined using echocardiography and cardiac hemodynamic measurements. Four weeks post MI, myocardial tissues were collected to evaluate cardiac remodeling. Primary cardiac fibroblasts (CFs) were treated with or without RXR ligand 9-cis-RA followed by stimulation with TGF-ß1. Immunoblot, immunofluorescence, and co-immunoprecipitation were performed to elucidate the regulatory role of RXR agonists in TGF-ß1/Smad signaling. In vivo treatment with Bexarotene moderately affects systemic inflammation and apoptosis and ameliorated left ventricular dysfunction after MI in rat model. In contrast, bexarotene significantly inhibited post-MI myocardial fibrosis. Immunoblot analysis of heart tissue homogenates from MI rats revealed that bexarotene regulated the activation of the TGF-ß1/Smad signaling pathway. In vitro, 9-cis-RA inhibited the TGF-ß1-induced proliferation and collagen production of CFs. Importantly, upon activation by 9-cis-RA, RXRα interacted with p-Smad2 in cytoplasm, inhibiting the TGF-ß1-induced nuclear translocation of p-Smad2, thereby negatively regulating TGF-ß1/Smad signaling and attenuating the fibrotic response of CFs. These findings suggest that RXR agonists ameliorate post-infarction myocardial fibrosis, maladaptive remodeling, and heart dysfunction via attenuation of fibrotic response in CFs through inhibition of the TGF-ß1/Smad pathway activation.

Streptozotocin-Induced Hyperglycemia Affects the Pharmacokinetics of Koumine and its Anti-Allodynic Action in a Rat Model of Diabetic Neuropathic Pain.

Koumine (KM), the most abundant alkaloid in Gelsemium elegans, has anti-neuropathic, anti-inflammatory, and analgesic activities; thus, it has the potential to be developed as a broad-spectrum analgesic drug. However, factors determining the relationship between analgesic efficacy and the corresponding plasma KM concentration are largely unclear. The pharmacokinetics and pharmacodynamics of KM and their optimization in the context of neuropathic pain have not been reported. We investigated the pharmacokinetics and pharmacodynamics of KM after oral administration in a streptozotocin-induced rat model of diabetic neuropathic pain (DNP) using a population approach. A first-order absorption and elimination pharmacokinetics model best described the plasma KM concentration. This pharmacokinetic model was then linked to a linear pharmacodynamic model with an effect compartment based on the measurement of the mechanical withdrawal threshold. KM was rapidly absorbed (time to maximum plasma concentration: 0.14-0.36 h) with similar values in both DNP and naïve rats, suggesting that DNP did not influence the KM absorption rate. However, the area under the curve (AUC0-∞) of KM in DNP rats was over 3-fold higher than that in naïve rats. The systemic clearance rate and volume of KM distribution were significantly lower in DNP rats than in naïve rats. Blood glucose value prior to KM treatment was a significant covariate for the systemic clearance rate of KM and baseline value of the threshold. Our results suggest that streptozotocin-induced hyperglycemia is an independent factor for decreased KM elimination and its anti-allodynic effects in a DNP rat model. To the best of our knowledge, this is the first study to investigate the role of DNP in the pharmacokinetics and pharmacokinetics-pharmacodynamics of KM in streptozotocin-induced diabetic rats.

Anti-allodynic and neuroprotective effects of koumine, a Benth alkaloid, in a rat model of diabetic neuropathy.

Diabetic neuropathy is characterized by progressive degeneration of nerve fibers associated with diabetes mellitus. Antidepressants and anticonvulsants are the mainstay of pharmacological treatment, but are often limited in effectiveness against the core clinical feature of pain. In the current study, we examined the potential effects of koumine, a Gelsemium elegans Benth alkaloid, using a rat model of diabetic neuropathy. Rats were administered intraperitoneally a single dose of streptozocin (60 mg/kg) to induce type 1 diabetes. Koumine was given at a dose range of 0.056-7 mg/kg subcutaneously for one week starting 3 weeks after streptozocin adminstration. Behavioral responses to mechanical stimuli were evaluated every day after streptozocin injection. At 4 weeks after streptozocin injection, sensory nerve conduction velocity (SNCV) and morphological alternation of sciatic nerves were assessed by electron microscopy. Diabetic rats developed mechanical hyperalgesia within 3 weeks after streptozocin injection and exhibited reduced SNCV and impaired myelin/axonal structure. Koumine treatment of diabetic rats decreased neuropathic pain behavior as early as after the first administration. At a dose of 7 mg/kg, koumine was more effective than gabapentin (100 mg/kg), and decreased mechanical sensitivity threshold to a level comparable to healthy control. Repeated treatment of koumine significantly reduced the damage to axon and myelin sheath of the sciatic nerve and increased SNCV, without affecting body weight and blood glucose. These findings encourage the use of koumine in the treatment of diabetic neuropathy.

[Morphology and microRNA expression profiles of drug-resistant cells in hepatocellular carcinoma].

OBJECTIVE: To compare morphological differences of three drug-resistant hepatocellular carcinoma (HCC) cell subclones (Huh-7/ADM, Huh-7/CBP, Huh-7/MMC) and their parental Huh-7 cell line, to analyze differential microRNA (miRNA) expression profiles in these cells and, finally to screen for the abnormal expressed miRNAs in drug-resistant HCC cells. METHODS: Cellular morphology was observed by histology and transmission electron microscopy. MiRNA microarray was used to analyze the differential miRNA expression profiles in these cells (Huh-7, Huh-7/ADM, Huh-7/CBP, Huh-7/MMC) followed by real time quantitative PCR validation. RESULTS: The drug-resistant cells had more intracytoplasmic organelles and were larger in size along with increased cytological pleomorphism than the parental Huh-7 cells. Compared with the parental Huh-7 cells, 32 simultaneously up-regulated and 22 down-regulated miRNAs were found in three drug-resistant cells. Up-regulation of miR-15a, miR-16, miR-27b, miR-30b, miR-146a, miR-146b-5p, miR-181a, miR-181d and miR-194 was verified by RT-qPCR. CONCLUSION: Drug-resistant HCC cells have abnormal expressed miRNAs, which may be explored to further investigate the association of miRNA expressions with multidrugs resistance in HCC.

[Therapeutic effects of photocatalytic nano-TiO2on human nasopharyngeal carcinoma xenografts in nude mice].

OBJECTIVE: To study the therapeutic effect of photocatalytic nano-TiO2 on nasopharyngeal carcinoma xenograft in nude mice and underlying mechanism. METHODS: Nude mice bearing human nasopharyngeal carcinoma xenograft were randomly divided into six groups: nano-TiO2 + UV irradiation (with gradient concentration of nano-TiO2); nano-TiO2 alone and UV irradiation alone and blank control. The nano-TiO2 suspension was injected into xenografts, and 24 h after UV light with the wave length of 330 - 400 nm, all the xenografts were removed and sectioned for HE staining. Ultrastructure and apoptosis of tumor cells in the xenografts were observed by transmission electron microscope (TEM). The expression of Caspase-3 was examined immunohistochemical staining and the apoptosis was detected with TUNEL. RESULTS: Pathological analysis showed significant inflammatory responses (grade II and III) with local necrosis occurred in tumor tissues after nano-TiO2 photodynamic therapy, but not in the negative control and blank control. TEM showed the nano-TiO2 particles entered into the cytoplasm and the nucleus of tumor cells and many tumor cells had morphological changes for apoptosis. Significant positive expression of Caspase-3 and TUNEL-positive cells were found in the the xenografts with the treatments of nano-TiO2 + UV irradiation compared to control (P < 0.01), which were enhanced with the increases in nano-TiO2 concentration (P < 0.01). CONCLUSION: Photocatalytic nano-TiO2 can inhibit the growth of nasopharyngeal carcinoma xenograft in nude mice by inducing Caspase-3 expression and apoptosis in the tumor cells.

Effect of chronic intermittent hypoxia on the expression of Nip3, cell apoptosis, beta-amyloid protein deposit in mice brain cortex.

BACKGROUND: Chronic intermittent hypoxia (CIH) is the most important pathophysiologic feature of sleep apnea syndrome (SAS). To explore the relationship between SAS and dementia, the effects of CIH on the expression of Nip3, neuron apoptosis and beta-amyloid protein deposit in the brain cortex of the frontal lobe of mice were evaluated in this study. METHODS: Thirty male ICR mice were divided into four groups: control group (A, n = 10, sham hypoxia/reoxygenation), 2 weeks CIH group (B, n = 5), 4 weeks CIH group (C, n = 5), and 8 weeks CIH group (D, n = 10). The ICR mice were placed in a chamber and exposed to intermittent hypoxia (oxygen concentration changed periodically from (21.72 +/- 0.55)% to (6.84 +/- 0.47)% every two minutes, eight hours per day). Neuron apoptosis of the cortex of the frontal lobe was detected by means of terminal deoxy-nucleotidyl transferase-mediated in situ end labeling (TUNEL). Immunohistochemical staining was performed for measuring expression of Nip3 and beta-amyloid protein. The ultrastructure of neurons was observed under a transmission electron microscope. RESULTS: TUNEL positive neurons in each square millimeter in the cortex of the frontal lobe were categorized by median or Ri into group A (1, 5.5), group B (133, 13), group C (252, 21), and group D (318, 24). There were significant differences among the above four groups (P = 0.000). The significance test was performed between the control group and each CIH group respectively: group A and B (P > 0.05); group A and C (P < 0.01); and group A and D (P < 0.005). The number of apoptotic neurons kept increasing in the ICR mice under CIH condition, and reached the peak in the group D, but there was no significant difference between groups B and C, between groups B and D, and between groups C and D. Nip3 positive neurons in each square millimeter in the cortex of the frontal lobe in each group were calculated by median or Ri as follows: group A (2, 5.5), group B (117, 13), group C (227, 26.2), and group D (479, 21.4). There were significant differences among the four groups (P = 0.000). The statistical test was performed between the control group and each CIH group respectively: groups A and B (P > 0.05); groups A and C (P < 0.005); and groups A and D (P < 0.005). There was no significant difference between groups B and C, groups B and D, and groups C and D. The expression of Nip3 was closely correlated with neuron apoptosis in the brain (P < 0.05). The expression of beta-amyloid protein in the brain of mice was negative in all CIH groups and the control group. Ultrastructure observation showed karyopyknosis of nucleus, swelling of chondriosomes, deposit of lipofuscins and degeneration of neural sheath in all CIH groups but not in the control group. CONCLUSION: The results of this study indicate that CIH could up-regulate the expression of Nip3, and result in neuron apoptosis and ultrastructural changes in neurons of the frontal cortex.