Blocking FSH inhibits hepatic cholesterol biosynthesis and reduces serum cholesterol.

Menopause is associated with dyslipidemia and an increased risk of cardio-cerebrovascular disease. The classic view assumes that the underlying mechanism of dyslipidemia is attributed to an insufficiency of estrogen. In addition to a decrease in estrogen, circulating follicle-stimulating hormone (FSH) levels become elevated at menopause. In this study, we find that blocking FSH reduces serum cholesterol via inhibiting hepatic cholesterol biosynthesis. First, epidemiological results show that the serum FSH levels are positively correlated with the serum total cholesterol levels, even after adjustment by considering the effects of serum estrogen. In addition, the prevalence of hypercholesterolemia is significantly higher in peri-menopausal women than that in pre-menopausal women. Furthermore, we generated a mouse model of FSH elevation by intraperitoneally injecting exogenous FSH into ovariectomized (OVX) mice, in which a normal level of estrogen (E2) was maintained by exogenous supplementation. Consistently, the results indicate that FSH, independent of estrogen, increases the serum cholesterol level in this mouse model. Moreover, blocking FSH signaling by anti-FSHß antibody or ablating the FSH receptor (FSHR) gene could effectively prevent hypercholesterolemia induced by FSH injection or high-cholesterol diet feeding. Mechanistically, FSH, via binding to hepatic FSHRs, activates the Gi2α/ß-arrestin-2/Akt pathway and subsequently inhibits the binding of FoxO1 with the SREBP-2 promoter, thus preventing FoxO1 from repressing SREBP-2 gene transcription. This effect, in turn, results in the upregulation of SREBP-2, which drives HMGCR nascent transcription and de novo cholesterol biosynthesis, leading to the increase of cholesterol accumulation. This study uncovers that blocking FSH signaling might be a new strategy for treating hypercholesterolemia during menopause, particularly for women in peri-menopause characterized by FSH elevation only.

[Inhibitory effects of curcumin on inflammatory cytokines in rats with paraquat poisoning].

OBJECTIVE: To explore the mechanism of paraquat (PQ) poisoning and to observe the changes in inflammatory cytokines in PQ-exposed rats treated in different ways. METHODS: Fifty 8-week-old clean male Wistar rats were randomly divided into high-dose curcumin plus conventional treatment group, low-dose curcumin plus conventional treatment group, high-dose curcumin group, PQ poisoning group, and blank control group. On days 1, 3, 5, 7, 14, and 21 after PQ exposure, serum levels of transforming growth factor-ß1(TGF-ß1) , tumor necrosis factor-α (TNF-α) , and interleukin-6 (IL-6) were measured. The pathological changes in lung tissue were evaluated by HE staining. RESULTS: Compared with the blank control group, the high-dose curcumin plus conventional treatment group, low-dose curcumin plus conventional treatment group, high-dose curcumin group, and PQ poisoning group had significantly increased serum levels of TGF-ß1, TNF-α, and IL-6 (P<0.05) , and the three cytokines in each group reached peak levels on day 14 after exposure. Compared with the PQ poisoning group, the high-dose curcumin group had significantly reduced serum levels of TGF-ß1, TNF-α, and IL-6 (P<0.05). On day 21 after exposure, there were no significant differences in serum levels of TGF-ß1, TNF-α, and IL-6 between the high-dose curcumin plus conventional treatment group and the low-dose curcumin plus conventional treatment group (P>0.05). The HE staining revealed alveolar inflammatory changes on days 1~7 and massive pulmonary fibrosis on days 14~21 in the high-dose curcumin plus conventional treatment group, low-dose curcumin plus conventional treatment group, high-dose curcumin group, and PQ poisoning group, but the above changes were milder in the high-dose curcumin group than in the PQ poisoning group. CONCLUSION: For rats with PQ poisoning, curcumin can significantly reduce inflammatory response and pathological changes in lung tissue and inhibit and delay the development and progression of body injury.

Dietary high-fat lard intake induces thyroid dysfunction and abnormal morphology in rats.

AIM: Excess dietary fat intake can induce lipotoxicity in non-adipose tissues. The aim of this study was to observe the effects of dietary high-fat lard intake on thyroid in rats. METHODS: Male Sprague-Dawley rats were fed a high-fat lard diet for 24 weeks, and then the rats were fed a normal control diet (acute dietary modification) or the high-fat lard diet for another 6 weeks. The serum lipid profile, total thyroxine (TT4), free thyroxine (FT4) and thyrotropin (TSH) levels were determined at the 12, 18, 24 and 30 weeks. High-frequency ultrasound scanning of the thyroid glands was performed at the 24 or 30 weeks. After the rats were sacrificed, the thyroid glands were collected for histological and immunohistochemical analyses. RESULTS: The high-fat lard diet significantly increased triglyceride levels in both the serum and thyroid, and decreased serum TT4 and FT4 levels in parallel with elevated serum TSH levels. Ultrasonic imaging revealed enlarged thyroid glands with lowered echotexture and relatively heterogeneous features in the high-fat lard fed rats. The thyroid glands from the high-fat lard fed rats exhibited enlarged follicle cavities and flattened follicular epithelial cells under light microscopy, and dilated endoplasmic reticulum cisternae, twisted nuclei, fewer microvilli and secretory vesicles under transmission electron microscopy. Furthermore, the thyroid glands from the high-fat lard fed rats showed markedly low levels of thyroid hormone synthesis-related proteins TTF-1 and NIS. Acute dietary modification by withdrawal of the high-fat lard diet for 6 weeks failed to ameliorate the high-fat lard diet-induced thyroid changes. CONCLUSION: Dietary high-fat lard intake induces significant thyroid dysfunction and abnormal morphology in rats, which can not be corrected by short-term dietary modification.