High Fat and Diet Induced Obesity

i-Fect^TM Delivers Again!

Research shows that rats and humans on a high-fat diet (HFD) are less sensitive to satiety signals known to act via vagal afferent pathways. Impaired vagal afferent responsiveness to both gastric satiety hormones (CCK and leptin) and mechanical stimulation raises the possibility that changes in electrophysiological properties may be the underlying mechanism responsible for impaired vagal responsiveness to a wide variety of satiety signals.

Potassium channels play a central role. To demonstrate this researchers used our i-Fect siRNA Transfection Kit to silence TRESK and TASK1 to understand their impact on HFD and vagal responsiveness. Gintautas Grabauskas, Xiaoyin Wu, ShiYi Zhou, JiYao Li, Jun Gao, and Chung Owyang. (2019). High-fat diet–induced vagal afferent dysfunction via upregulation of 2-pore domain potassium TRESK channel. JCI Insight. https://doi.org/10.1172/jci.insight.130402.

Images: (A) Representative recordings of NG neuron responses to intra–superior pancreaticoduodenal artery infusions of CCK-8 (60 pmol/kg) and leptin (60 pmol/kg) in LFD-fed or HFD-fed rats and transfected with control siRNA or TRESK siRNA. Note that CCK-8 generated significantly fewer action potentials in HFD-fed rats compared with those fed an LFD. (B) Summary histograms showing single-unit discharges in response to CCK-8 in rats given an LFD and transfected with control siRNA (n = 11) or TRESK siRNA (n = 6), HFD + control siRNA (n = 12), and HFD treated with TRESK siRNA (n = 10). Data are represented as mean ± SEM. One-way ANOVA with Bonferroni’s test, *P < 0.05 vs. LFD + control siRNA; #P < 0.05 vs. HFD + control siRNA. (C) Summary histogram showing single-unit discharges in response to leptin in rats given an LFD and transfected with control siRNA (n = 11) and TRESK siRNA (n = 5), HFD (n = 12), and HFD treated with TRESK siRNA (n = 10). Data are represented as mean ± SEM. One-way ANOVA with Bonferroni’s test, *P less than 0.05 vs. LFD + control siRNA; #P less than 0.05 vs. HFD + control siRNA. (D) Summary histogram showing CCK-AR and ObR expression in vagal sensory ganglia from LFD- and HFD-fed rats were not significantly different. HPRT was used as a loading control. Data are represented as mean ± SEM. CCK-8, cholecystokinin-8.

Following 2 weeks of high-fat feeding, there was a significant upregulation of TRESK and a modest increase in TASK1 channels in the NG. Silencing studies indicate that the upregulation by TRESK channels is mainly responsible for a global decrease in excitability of vagal sensory neurons, which in turn dampens the response to satiety signals, such as CCK and leptin. 

This make TRESK a potential therapeutic target for treating Obesity.

i-Fect in Action

Knock-down of HIF-1a Attenuates Chemo Induced Pain
i-Fect ^TM is one of our original products. It has enjoyed 14 years of upping transfection percentages both in-vitro and in-vivo.

Here is a new study showing successful use of i-Fect to knock down HIF-1a in-vivo-Taylor Ludman and Ohannes K. Melemedjian. (2019). Bortezomib-induced aerobic glycolysis contributes to chemotherapy-induced painful peripheral neuropathy. Molecular Pain. https://doi.org/10.1177/1744806919837429.

Figure 1. (a) Treatment of mice with bortezomib (Bor) for five days augmented HIF1A expression in L4-6 DRGs (*P ¼ 0.0412, five mice/ group) relative to the vehicle-treated group. (b) A schematic depicting the site of the intrathecal (IT) siRNA injection. The siRNA was administered between the L4 and L5 vertebrae which is around 17 mm rostral to the spinal cord (SC) section innervated by the L4-6 DRGs. (c) IT injection of siRNA (1 mg in 5 ml) that targets HIF1A (siRNA) but not control siRNA (Cont), for two consecutive days, significantly reduced the levels of HIF1A in L4-6 DRGs. (***P=0.0006, five mice/group). (d) IT siRNA did not affect HIF1A levels in L4-6 spinal cord (five mice/group). (e) After determining baseline withdrawal thresholds using von Frey filaments, male ICR mice received IP injection of vehicle or bortezomib (black arrows) and IT siRNA (blue arrows). The withdrawal thresholds were measured on days 7 to 14. IT HIF1A siRNA prevented the development of bortezomib-induced neuropathic pain. (****P less than 0.0001, five mice/group). DRG: dorsal rootganglia; HIF1A: hypoxia-inducible factor 1 alpha; IT: intrathecal; IP: intraperitoneal; siRNA: small interfering RNA.

This study is the first to demonstrate that the stabilization of HIF1A expression underpins the development of bortezomib-induced neuropathic pain. Crucially, these findings reveal that the initiation and maintenance of bortezomib-induced neuropathic pain are regulated by distinct mechanisms.

Looking to up your odds for high percentage siRNA Transfection? Try i-Fect.

i-Fect used to Study Angiogenesis in Brain Injury

Silencing Lactate Dehydrogenase A in vivo

Pathologic CNS is characterized by neuronal damage that leads to the release of intracellular components. However, the effect of damaged cells on angiogenesis has not been clarified. This study revealed that LDHA, which is a known damage marker, promotes CNS-specific angiogenesis. LDHA-mediated angiogenesis depends on vimentin on the surface of vascular endothelial cells. The work described here proposes a novel mechanism by which neurodegeneration drives angiogenesis in the CNS.

A mixture of our i-Fect^TM and LDHA siRNA, in this study, were directly injected into mice cortexes: Hsiaoyun Lin, Rieko Muramatsu, Noriko Maedera, Hiroto Tsunematsu, Machika Hamaguchi, Yoshihisa Koyama, Mariko Kuroda, Kenji Ono, Makoto Sawada, Toshihide Yamashita. Extracellular Lactate Dehydrogenase A Release From Damaged Neurons Drives Central Nervous System Angiogenesis. doi.org/10.1016/j.ebiom.2017.10.033.

Images: LDHA is sufficient to evoke CNS angiogenesis. (a) Representative images of CD105-labeled spinal cord sections obtained 7 days after LDHA administration. (b) Length of CD105+ neovessels around the LDHA administration site as indicated in a, n = 5 each. (c) Representative image of a Nissl-stained brain section after controlled cortical impact (CCI). (d) Representative image of the CD105-immunolabelled cerebral cortex obtained 7 days after CCI. (e) Length of CD105+ neovessels around CCI lesions as indicated in d; n = 5 each, all error bars represent the s.e.m. **P < 0.01, Student's t-tests. Scale bars, 200 μm.

The findings reveal unexpected neurovascular interactions in the injured adult CNS that may be relevant to our understanding of neuronal damage, which is a hallmark of many CNS disorders.