Chronic nicotine treatment enhances vascular smooth muscle relaxation in rats.

AIM: To investigate the effect of chronic nicotine treatment on vascular function and to identify the underlying mechanisms. METHODS: Adult rats were treated with nicotine (3 mg·kg(-1)·d(-1), sc) for 6 weeks. After the rats were sacrificed, aortic rings were prepared for detecting vascular reactivity, and thoracic aorta and periaortic fat samples were collected for histological and molecular biology studies. RESULTS: Chronic nicotine treatment significantly reduced periaortic fat, and specifically enhanced smooth muscle relaxation without altering the aortic adventitial fat and endothelium function. Pretreatment with the soluble guanylyl cyclase inhibitor ODQ (3 µmol/L) or PKG inhibitor Rp-8-Br-PET-cGMP (30 µmol/L) abolished the nicotine-induced enhancement of smooth muscle relaxation, whereas the cGMP analogue 8-Br-cGMP could mimic the nicotine-induced enhancement of smooth muscle relaxation. However, the chronic nicotine treatment did not alter PKG protein expression and activity in aortic media. CONCLUSION: Chronic nicotine treatment enhances vascular smooth muscle relaxation of rats via activation of PKG pathway.

[Study of screening nephroprotective bioactive substances based on triple-color fluorescence probes in Carthami flos].

In this study, an approach based on triple-color fluorescence probes was developed for screening potential nephro-protective bioactive substances. Three fluorescent probes (i. e. FDA, MTR and Hoechst 33342) were used to label HK-2 cells injured by doxorubicin hydrochloride, and cellular fluorescence images were subsequently acquired and analyzed by a cellular-fluorescence image microscopy platform. The established method was applied to screening 53 components of Carthami Flos, and three components C17, C18 and C19 were found to exhibit nephroprotective effects against doxorubicin hydrochloride induced injury on HK-2 cells. Eight compounds (i. e. hydroxysafflor yellow A, 6-hydroxykaempferol-3-O-rutinoside-6-O-glucoside, 6-hydroxykaempferol-3,6-di-O-gluco-side or 6-hydroxykaempferol-6, 7-di-O-glucoside, 6-hydroxykaempferol-3-O-rutinoside, 6-hydroxykaempferol-3-O-glucoside or 6-hydroxykaempferol-7-O-glucoside, rutin, isoquercetin, and kaempferol-3-O-rutinoside) in components C17, C18 and C19 were preliminarily identified by liquid chromatography-mass spectrometry (LC-MS). Isoquercetin, rutin, kaempferol-3-O-rutinoside, and hydroxysafflor yellow A were confirmed by comparing with reference substances, Further study indicated that these four compounds had moderate nephroprotective effects, while isoquercetin showed a significant nephroprotective effect in a dose-dependent manner. These results suggest that isoquercetin, rutin, kaempferol-3-O-rutinoside and hydroxysafflor yellow A might be the nephroprotective bioactive substances in Carthami Flos.

Vascular smooth muscle cell apoptosis is an early trigger for hypothyroid atherosclerosis.

AIMS: Endothelial dysfunction is an initial and vascular smooth muscle cell (VSMC) apoptosis, a later step of atherosclerosis. Hypothyroidism accelerates atherosclerosis. However, the early events responsible for this pro-atherosclerotic effect are unclear. METHODS AND RESULTS: Rats were resistant to induction of atherosclerosis by high cholesterol diet alone, but became susceptible in hypothyroid state achieved by administration of propylthiouracil (PTU) for 6 weeks. VSMC dysfunction and apoptosis were obvious within 1 week after PTU treatment, without signs of endothelial dysfunction. This early VSMC damage was caused by hypothyroidism but not the high cholesterol diet. In ApoE knockout mice, PTU-induced hypothyroidism triggered early VSMC apoptosis, increased oxidative stress, and accelerated atherosclerosis development. Thyroid hormone supplementation (T4, 10, or 50 µg/kg) prevented atherogenic phenotypes in hypothyroid rats and mice. In rats, thyroidectomy caused severe hypothyroidism 5 days after operation, which also led to rapid VSMC dysfunction and apoptosis. In vitro studies did not show a direct toxic effect of PTU on VSMCs. In contrast, thyroid hormone (T3, 0.75 µg/L plus T4, 50 nmol/L) exerted a direct protection against VSMC apoptosis, which was reduced by knockdown of TRα1, rather than TRß1 and TRß2 receptors. TRα1-mediated inhibition of apoptotic signalling of JNKs and caspase-3 contributed to the anti-apoptotic action of thyroid hormone. CONCLUSION: These findings provide an in vivo example for VSMC apoptosis as an early trigger of hypothyroidism-associated atherosclerosis, and reveal activation of TRα1 receptors to prevent VSMC apoptosis as a therapeutic strategy in this disease.

[Study on rapid screening and identifying hepatotoxic compounds in toosendan fructus].

Fluorescein diacetate-labeled HepG2 cells model and flouresence automatic microscopy screening assay were used for fast screening 23 components from Toosendan Fructus, in which 5 components showed significant toxicity on HepG2 cells. The 10 compounds in the 2 components were tentatively identified with LC-MS(n), and 3 of them (meliasenin B, trichilinin D and 1-O-tigloy-1-O-debenzoylohchinal) were prepared and identified. Further experiments showed that the 3 compounds displayed dose-dependent toxicity on HepG2 cells, suggesting that these compounds in Toosendan Fructus may cause hepatotoxicity.

[Effects of three different treatments on atherosclerosis and adipose in rats].

OBJECTIVE: To explore the effects of three different treatments, including probucol plus aspirin (PS), lovastatin plus aspirin (AS) and probucol, lovastatin plus aspirin (PAS) on atherosclerotic plaque and adipose. METHODS: A total of 31 SD rats with established atherosclerosis were randomly divided into control group (n = 7), high-fat group (n = 4), PS group (n = 8), AS group (n = 5) and PAS group (n = 7). The PS group rats were lavaged with probucol (104.4 mg×kg(-1)×d(-1)) and aspirin 10.4 mg×kg(-1)×d(-1)), AS group ones aspirin (10.4 mg×kg(-1)×d(-1)) and lovastatin (2.1 mg×kg(-1)×d(-1)) and PAS group ones probucol (104.4 mg×kg(-1)×d(-1)), aspirin (10.4 mg×kg(-1)×d(-1)) and lovastatin (2.1 mg×kg(-1)×d(-1)) for 8 weeks. At the same time, the control group received an equal volume of saline. Finally the plaque stability and adipose function of treatment groups were evaluated by the changes of body weight, serum parameters, adipose weights and pathological specimens. RESULTS: Body weights in PS and PAS groups significantly increased than those in AS group (251 g ± 5 g and 247 g ± 7 g vs 220 g ± 6 g, P < 0.01). The serum levels of low density lipoprotein cholesterol (LDL), glucose (Glu), total cholesterol (TC) and high density lipoprotein cholesterol (HDL) were significantly better in PS and PAS groups than those in AS group (P < 0.01). The level of tumor necrosis factor-alpha (TNF-α) was lower in PAS group than that in high-fat group (27 ± 21 vs 100 ± 34 pg/ml, P < 0.05). The stability level of atherosclerotic plaque was more in PAS group than those in PS and AS groups by oil red staining in aorta, oil red staining in different organs and hematoxylin and eosin staining in different aortal parts. CONCLUSION: Atherosclerosis improves more pronouncedly in PS and PAS groups than that in AS group. Through an analysis of the changes of fat-related indicators, adipose factor may play an important role in atherosclerotic treatment.