A soy glycinin derived octapeptide protects against MCD diet induced non-alcoholic fatty liver disease in mice

Soy glycinin derived octapeptide(SGP8)is a peptide obtained from degradation of the soy glycinin,whose amino acid sequence is IAVPGEVA.To determine the effect of SGP8 on non-alcoholic fatty liver disease(NAFLD),steatosis Hep G2 cells were induced by 1 mmol/L free fatty acid(FFA)and C57 BL/6 J mice were fed with methionine-choline defi cient(MCD)diet for 3 weeks to establish NAFLD model.The results of oil red O staining and total cholesterol(TC)/triglyceride(TG)contents showed that SGP8 could signifi cantly reduce the lipid content of steatosis Hep G2 cells.In vivo,SGP8 lowered plasma alanine aminotransferase(ALT)and low density lipoprotein(LDL)content,normalized hepatic superoxide dismutase(SOD)and malondialdehyde(MDA)production,and reduced the severity of liver infl ammation.The results of Western blotting showed that SGP8 increased expression of Sirtuin-1(SIRT1)and phosphorylation level of AMP activated protein kinase(AMPK)in hepatocytes.Through activation of SIRT1/AMPK pathway,SGP8 downregulated the expression of sterol regulatory element binding protein 1 c(SREBP-1 c)and its target genes ACC and FAS expression levels,and increased the phosphorylation level of acetyl Co A carboxylase(ACC).Furthermore,SGP8 also upregulated the expression of transcription factor peroxisome proliferator activated receptorα(PPARα),which was regulated by SIRT1/AMPK pathway,and its target gene CPT1 level.In conclusion,SGP8 might improve NAFLD by activating the SIRT1/AMPK pathway.Our data suggest that SGP8 may act as a novel and potent therapeutic agent against NAFLD.

Effects of cholecystokinin octapeptide receptor on lung injury in endotoxemia rats

Objective:To investigate the effects of CCK-8 receptor on lung injury in endotoxemia rats. Methods: Male SD rats were randomized into four groups (n=6): control group (LPS+CCK-8 group), CCK-1R antagonist group, CCK-2R antagonist group, DFSO+PF group. The rats were injected by LPS (5 mg.kg-1). CCK-8 (20 μg.kg-1) was administered 30 min after LPS injection. Either a specific CCK-1R antagonist or CCK-2R antagonist (0.5.kg-1) was injected before CCK-8 treatment (after LPS 20min). The tidal volume (TV) was collected by a multi-channel data physiological recorder. The lung injury was observed by light and electron microscopy. The concentrations of TNF-α、IL-1 and IL-6 in lung homogenates were measured by ELISA kits.Rresults: Compared with control group, the TV were significantly lower and the lung injuries were more serious in CCK-2R antagonist group. As well as the concentrations of TNF-α、IL-1 and IL-6 in lung homogenates were higher.Conclusion: CCK-2 receptor plays a major role in the effect of CCK-8 on lung injury in ETM rats.

Influence of octapeptide of cholecystokinin, vasoactive intestinal peptide and substance P on dynamics of biliary system and cardiovascular system

Objective To examine the effects of cholecystokinin octapeptide (CCK OP), vasoactive intestinal peptide (VIP) and substance P (SP) on the dynamics of the biliary system and cardiovascular system, and the relationship between the dynamics of the biliary system and cardiodynamics. Methods In 91 anesthetized guinea pigs, a triple lumen, side hole perfusion catheter (1.0 mmOD) was inserted through the duodenal papilla into the common bile duct (CBD) and the sphincter of Oddi (OS). An end hole PE 50 catheter was inserted into the left ventricle of heart through the left jugular artery. The left ventricle of heart motility, OS motility and CBD pressure were recorded during the intravenous administration of CCK OP, VIP, SP and the combination of CCK OP and VIP. Results Intravenous CCK OP increased the fasted OS motility index (MI), decreased the basal pressure in OS, increased CBD pressure, and inhibited the motility of the left ventricle of heart. VIP alone showed no significant effect on the biliary system and cardiovascular system, but when infused together with CCK OP, it inhibited the effects of CCK OP on both systems. Exogenous SP acted like CCK OP on both biliary system and cardiovascular system, but less potently. Conclusions The gastrointestinal peptides have important effects on both biliary system and cardiovascular system. There is an important negative correlation between CBD pressure and the motility of the left ventricle of the heart during the infusion of peptides.

CENTRAL CHOLECYSTOKININ OCTAPEPTIDE ACCELERATING THE RECOVERY OF THE RAT FROM HEMORRHAGIC SHOCK

There have been data showing that central cholecystokinin oetapeptide (CCK-8) could antagonize the analgesia induced by exogenous and endogenoust opioid peptides. Recently, we found that the hypotension produced by opioid peptides could also be reversed by central administration of CCK-8 (Mei Lin et al., unpublished result). The above-mentioned results either in physiology or in pharmacology suggested that CCK-8 appeared to have a potent antagonistic effect against opioid peptides and may be the endogenous anti-opioid substance.

The Antagonistic Effect of Cholecystokinin Octapeptide (CCK-8) on Opioid Effects in Cardiovascular Activities Was Mediated by CCK-B Receptor

Previous studies have shown that CCK-8 has distinct antiopioid effect in the central sites related with pain control and blood pressure control. The aim of this study was to explore the receptor mechanism by which CCK-8 antagonized the depressor effect of u- and k-opioid(?) agonists, and to observe whether CCK-8 could antagonize the depressor effect induced by muscimol, a nonopioid substance. The results showed that (i) The antagonistic effect of CCK-8 on opioid-induced hypotension could be blocked by intrathecal (i.t.) administration of CCK-B antagonist L-365, 260 at nanogram doses, or by CCK-A antagonist devazepide at doses 20—40 times higher than L-365, 260, indicating that it was the CCK-B receptor which mediates the antiopioid effect. (ⅱ) The depressor effect induced by intrathecal muscimol, a GABA agonist, was blocked neither by naloxone nor by CCK-8, supporting the notion that CCK-8 is an endogenous opioid antagonist rather than a universal anti-hypotension agent.

Search and Analysis of Identical Reverse Octapeptides in Unrelated Proteins

For the past few decades, intensive studies have been carried out in an attempt to under- stand how the amino acid sequences of proteins encode their three dimensional structures to perform their specific functions. In order to understand the sequence-structure relationship of proteins, sev- eral sub-sequence search studies in non-redundant sequence-structure databases have been under- taken which have given some fruitful clues. In our earlier work, we analyzed a set of 3124 non- redundant protein sequences from the Protein Data Bank （PDB） and retrieved 30 identical octapep- tides having different secondary structures. These octapeptides were characterized by using different computational procedures. This prompted us to explore the presence of octapeptides with reverse sequences and to analyze whether these octapeptides would adopt similar structures as that of their parent octapeptides. Our identical reverse octapeptide search resulted in the finding of eight octapep- tide pairs （octapeptide and reverse octapeptide） with similar secondary structure and 23 octapeptide pairs with different secondary structures. In the present work, the geometrical and biophysical char- acteristics of identical reverse octapeptides were explored and compared with unrelated octapeptide pairs by using various computational tools. We thus conclude that proteins containing identical reverse octapeptides are not very abundant and residues in the octapeptide pairs do not contribute to the stability of the protein. Furthermore, compared to unrelated octapeptides, identical reverse octapeptides do not show certain biophysical and geometrical properties.

Mechanisms mediating CCK-8S-induced contraction of proximal colon in guinea pigs

AIM:To investigate the effects of sulfated cholecystokinin octapeptide (CCK-8S) on the contractile activity of guinea-pig proximal colon.METHODS:Proximal colonic smooth muscle (PCSM) strips were obtained from adult female guinea pigs and contractile response of PCSM strips was recorded using a polyphysiograph.PCSM cells were isolated by enzymatic digestion.Resting potential (RP),action potential (AP),large conductance potassium channel currents (IBKCa) and L-type calcium currents (ICa-L) were recorded by patch-clamp techniques.RESULTS:(1) CCK-8S (10-7 mol/L) enhanced the mean contractile amplitude of colonic circular muscle and longitudinal muscle (LM) strips by 56.53% ± 11.92%(P=0.038) and 65.93% ± 12.98% (P=0.019),respectively,as well as the mean frequency of LM by 31.69% ± 13.58% (P=0.023),which were significantly attenuated by pretreating strips with devazepide,nifedipine,iberiotoxin,thapsigargin (TG) and BAPTA-AM (BA) respectively;(2) CCK-8S (10-7 mol/L) increased the AP amplitude by 38.6% ± 3.2% (P=0.015),decreased AP duration by 36.9% ± 8.7% (P=0.026),and depolarized the RP from-61.3 ± 2.7 mV to-29.8 ± 5.9 mV (P=0.032);and (3) Compared with the normal control group,CCK-8S (10-7 mol/L) enhanced the peak current of IBKCa by 18.7% ± 2.1% (from 916 ± 183 pA to 1088 ± 226 pA;at +60 mV;P=0.029),which was inhibited by respective pretreatment with iberiotoxin and devazepide.Additionally,CCK-8S (10-7 mol/L) intensif ied the peak current of ICa-L by 40% (from 60 ± 8 pA to 84 ± 11 pA;at +10 mV;P=0.012),compared to the normal control group,which was apparently suppressed by respective pretreatment with nifedipine,devazepide,TG and BA.In the respective presence of heparin and staurosporine,CCK-8S did not signif icantly enhance IBKCa and ICa-L.CONCLUSION:The results suggest that CCK-8S promotes guinea-pig proximal colon contraction by CCK1 receptors,following activation of the inositol triphosphate-protein kinase C signal transduction pathway.

Effect of devazepide reversed antagonism of CCK-8 against morphineon electrical and mechanical activities of rat duodenum in vitro

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突触末梢递质小泡再循环机制的研究

突触末梢递质小泡再循环机制的研究神经末梢突触小泡在胞吐（ｅｘｏｃｙｔｏｓｉｓ）后继以局部的再循环，这被认为是非肽类神经递质分泌的典型特征的具体机制还不很清楚。Ｒｙａｎ等人在分离的大鼠海马神经元上，采用Ｒｅｔｚ等发明的荧光染料标记突触小泡的方法，结合快...

Relationship between the analgesic effect of electroacupuncture and CCK-8 content in spinal perfusate in rats

There exists significant individual variation in electroacupuncture (EA) induced analgesia.Rats may be classified as high- and low-responders according to their response to EA analgesia. The content of cholecystokinin octapeptide like immunoreactivity (CCK-8-ir) in the spinal perfusate of highresponder (HR) and low-responder (LR) rats was measured with radioimmunoassay. The result showed that the CCK-8-ir content in LR rats was significantly lower than that in HR rats. There exists a negative correlation between the EA effect and the CCK-8-ir content during EA stimulation. It is concluded that the spinal release of CCK-8 may be one of the key factors determining the effect of EA analgesia.