Effects of Rapamycin on Clinical Manifestations and Blood Lipid Parameters in Different Preeclampsia-like Mouse Models

Role of mammalian target of rapamycin signaling pathway in regulation of fatty acid oxidation in a preeclampsia-like mouse model treated with pravastatin

Background:

Fatty acid oxidation (FAO) disorder is involved in the pathogenesis of some cases of preeclampsia (PE). Several studies show that mammalian target of rapamycin (mTOR) signaling pathway is related to FAO. Pravastatin (Pra) can promote FAO in Nω-nitro-L-arginine methyl ester (L-NAME) PE-like mouse model in our previous study. This study aimed to investigate the effect of mTOR signaling pathway in PE-like model treated with Pra.

Methods:

Pregnant mice were randomly injected with L-NAME as PE-like model group or saline as control group respectively, from gestational 7th to 18th day. Giving Pra (L-NAME + Pra, Control + Pra, n = 8) or normal saline (NS; L-NAME + NS, Control + NS, n = 8) from gestational 8th to 18th day, the mice were sacrificed on day 18 and their liver and placental tissues were collected. Then the activation of mTOR and its substrates in the liver and placenta were detected. And the association between mTOR activation and serum free fatty acid (FFA) levels and the expression of long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) were evaluated using Pearson correlation test. Differences between groups were analyzed using independent t-test or one-way analysis of variance (ANOVA).

Results:

Both in the maternal liver and placenta, the activation of mTOR protein and its effect on substrates increased significantly in the L-NAME + NS group and decreased significantly in the L-NAME + Pra group. The p-mTOR/mTOR protein ratio decreased in the L-NAME + Pra group significantly than that in the L-NAME + NS group both in liver and placenta (liver: 0.74 ± 0.08 vs. 0.85 ± 0.06, t = 2.95, P < 0.05; placenta: 0.63 ± 0.06 vs. 0.77 ± 0.06, t = 4.64, P < 0.05). The activation of mTOR protein in the liver and placenta negatively correlated with the expression of LCHAD in the L-NAME + NS group (liver: r = −0.745, P < 0.05; placenta: r = −0.833, P < 0.05) and that in the maternal liver negatively correlated with the expression of LCHAD (r = −0.733, P < 0.05) and positively with the serum FFA levels (r = 0.841, P < 0.05) in the L-NAME + Pra group.

Conclusion:

The inhibition of mTOR signaling pathway might be involved in the regulation of FAO in mouse model treated with Pra.

Folic acid delays development of atherosclerosis in low-density lipoprotein receptor-deficient mice

Many studies support the cardioprotective effects of folic acid (FA). We aimed to evaluate the utility of FA supplementation in preventing the development of atherosclerotic in low‐density lipoprotein receptor‐deficient (LDLR−/−) mice and to elucidate the molecular processes underlying this effect. LDLR−/− mice were randomly distributed into four groups: control group, HF group, HF + FA group and the HF + RAPA group. vascular smooth muscle cells (VSMCs) were divided into the following four groups: control group, PDGF group, PDGF + FA group and PDGF + FA + RAPA group. Blood lipid levels, oxidative stress and inflammatory cytokines were measured. Atherosclerosis severity was evaluated with oil red O staining. Haematoxylin and eosin (H&E) staining was used to assess atherosclerosis progression. Immunohistochemical staining was performed with antismooth muscle α‐actin (α‐SMA) antibodies and anti‐osteopontin (OPN) antibodies that demonstrate VSMC dedifferentiation. The protein expression of α‐SMA, OPN and mechanistic target of rapamycin (mTOR)/p70S6K signalling was detected by Western blot analysis. FA and rapamycin reduced serum levels of total cholesterol, triacylglycerol, LDL, inhibiting oxidative stress and the inflammatory response. Oil red O and H&E staining demonstrated that FA and rapamycin inhibited atherosclerosis. FA and rapamycin treatment inhibited VSMC dedifferentiation in vitro and in vivo, and FA and rapamycin attenuated the mTOR/p70S6K signalling pathway. Our findings suggest that FA attenuates atherosclerosis development and inhibits VSMC dedifferentiation in high‐fat‐fed LDLR−/− mice by reduced lipid levels and inhibiting oxidative stress and the inflammatory response through mTOR/p70S6K signalling pathway.