Roles of sphincter of Oddi motility and serum vasoactive intestinal peptide,gastrin and cholecystokinin octapeptide

AIM: To investigate roles of sphincter of Oddi (SO) motility played in pigment gallbladder stone formation in model of guinea pigs.

Selective cyclooxygenase-2 inhibitor ameliorates cholecystokinin-octapeptide-induced acute pancreatitis in rats

AIM： To investigate the effect of selective Cyclooxygenase-2 （COX-2） inhibitor 4-[5-（4-Chloro-phenyl）-3- （trifluoromethyl）- 1H-pyrazol- 1-yl] benzenesulfonamide （SC-236）, on the cholecystokinin （CCK）-octapeptideinduced acute pancreatitis （AP） in rats. METHODS： Wistar rat weighing 240 g to 260 g were divided into three groups. （1） Normal DMSO treated group, （2） SC-236 at 4 mg/kg treated group; SC-236 systemically administered via the intravenous （i.v.） catheter, followed by 75 μg/kg CCK octapeptide subcutaneously three times, after 1, 3 and 5 h. This whole procedure was repeated for 5 d. （3） Dimethyl sulfoxide （DMSO） treated group： an identical protocol was used in this group as in the SC-236 cohort （see 2. above）. Repeated CCK octapeptide treatment resulted in a typical experimentally induced pancreatitis in the Wistar rats. RESULTS： SC-236 improved the severity of CCK- octapeptide-induced AP as measured by laboratory criteria [the pancreatic weight/body weight （p.w/ b.w） ratio, the level of serum amylase and lipase]. The SC-236 treated group showed minimal histologic evidence of pancreatitis and a significant reduction in myeloperoxidase activity. SC-236 also increased heat shock protein （HSP）-60 and HSP72 compared with the DMSO-treated group in the CCK-octapeptide-induced AP and also reduced the pancreatic levels of COX-2. Furthermore, SC-236 reduced proinflammatory cytokine synthesis and inhibited NF-KB activation compared with the DMSO-treated group in the CCK-octapeptide-induced AP. CONCLUSION： Our results suggested that COX-2 plays pivotal role in the development of AP and COX-2 inhibitors may play a beneficial role in preventing AP.

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.

Cholecystokinin octapeptide improves cardiac function by activating Cholecystokinin octapeptide receptor in endotoxic shock rats

AIM: To explore the effect of sulfated cholecystokinin octapeptide (sCCK-8) on cardiac functions and its receptor mechanism in endotoxic shock (ES) rats. METHODS: The changes of the mean arterial pressure (MAP), heart rate (HR), the left ventricular pressure (LVP) and the maximal/minimum rate of LVP (±LVdp/dt max) were measured by using physiological record instrument in eight groups of rats. The expression of cholecystokinin-A receptor (CCK-AR) and cholecystokinin-B receptor (CCK-BR) mRNA of myocardium in ES rats was examined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) Low doses of sCCK-8 (0.4 μg/kg) caused tachycardia (441±27, normal control 391±22 s/min) and slight increase in MAP, LVP and ±LVdp/dtmax (16.96±1.79, 18.21±1.69 and +768.85±31.28/-565.04±27.71 kPa, respectively, all P<0.01), while medium doses (4.0 μg/kg) and high doses of sCCK-8 (40 μg/kg) elicited bradycardia and marked increase in MAP, LVP and ±LVdp/dtmax (17.29±1.63, 19.46±2.57 and +831.46±22.57/-606.08 ±31.32; 17.46±1.08, 19.83±2.91 and +914.52±35.95/ -639.15±30.23 kPa, respectively, all P<0.01). Proglumide (1.0 mg/kg), a nonselective antagonist of CCK-receptor (CCK-R), significantly inhibited the pressor effects of sCCK-8 (15.96±1.38, 17.36±0.66 and +748.18±19.29/-512.12±14.39 kPa, respectively, all P<0.01), whilst reversing the bradycardiac responses. (2) High doses of LPS (8 mg/kg) elicited marked decrease in MAP, LVP and ±LVdp/dtmax. (7.16±0.59, 7.6±0.68 and +298.01±25.52/ -166.96±19.25 kPa, respectively, all P<0.01). Pretreatment with sCCK-8 (40 μg/kg) could reverse the decline of cardiac functions (10.71±0.45, 11.7±1.26 and +446.04±67.18/ -347.90±36.98 kPa, respectively, all P<0.01), while proglumide could cause further decline of cardiac function in ES rats (4.71±0.67, 5.58±1.25 and +226.48±15.84/ -142.83±20.23 kPa, respectively, all P<0.01). (3) CCK-A/BR mRNAs were expressed in myocardium of control rats. Gene expression of CCK-AR and CCK-BR significantly increased in myocardium of ES rats. The increase of CCK-AR mRNA induced by LPS began at 0.5 h, peaked at 2 h, kept a high level at 6 h and declined at 12 h, respectively. Similar to CCK-AR mRNA, the expression of CCK-BR mRNA peaked at 2 h and kept a high level at 6 h, but it did not change at the first 0.5 h and was stable at a high level at 12 h. CONCLUSION: The above results indicate that endogenous and exogenous sCCK-8 may significantly improve cardiac function and intractable hypotension of ES rats, which was likely related to high expression of CCK-A/BR in myocardium induced by LPS.

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 thana 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.

Inhibitory effect of Patrinia scabiosaefolia on acute pancreatitis

AIM： To investigate the effect of Patrinia scabiosaefolia （PS） on the cholecystokinin （CCK） octapeptide-induced acute pancreatitis （AP） in rats.METHODS： Wistar rats weighing 240-260 g were divided into three groups： （1） Normal saline-treated group; （2） treatment with PS at 100 mg/kg group, in which PS was administered orally, followed by subcutaneous administration of 75μg/kg CCK octapeptide three times after 1, 3 and 5 h, and this whole procedure was repeated for 5 d; （3） treatment with saline group, in which the protocols were the same as in treatment group with PS. We determined the pancreatic weight/ body weight ratio, the levels of pancreatic HSP60, HSP72 and the secretion of pro-inflammatory cytokines. Repeated CCK octapeptide treatment resulted in the typical laboratory findings of experimentally induced pancreatitis.RESULTS： PS reduced the pancreatic weight/body weight ratio, the levels of serum amylase and lipase, and inhibited expressions of pro-inflammatory cytokines in the CCK octapeptide-induced AP. Furthermore, PS pretreatment increased the pancreatic levels of HSP60 and HSP72.CONCLUSION： Pretreatment with PS has an antiiinflammatory effect on CCK octapeptide-induced AP.

Therapeutic proteasome inhibition in experimental acute pancreatitis

AIM： To establish the therapeutic potential of proteasome inhibition, we examined the therapeutic effects of MG132 （Z-Leu-Leu-Leu-aldehyde） in an experimental model of acute pancreatitis. METHODS： Pancreatitis was induced in rats by two hourly intraperitoneal （ip） injections of cholecystokinin octapeptide （CCK; 2×100μg/kg） and the proteasome inhibitor MG132 （10 mg/kg ip） was administered 30 min after the second CCK injection. Animals were sacrificed 4 h after the first injection of CCK. RESULTS： Administering the proteasome inhibitor MG132 （at a dose of 10 mg/kg, ip） 90 min after the onset of pancreatic inflammation induced the expression of cell-protective 72 kDa heat shock protein （HSP72） and decreased DNA-binding of nuclear factor-κB （NF-κB）. Furthermore MG132 treatment resulted in milder inflammatory response and cellular damage, as revealed by improved laboratory and histological parameters of pancreatitis and associated oxidative stress. CONCLUSION： Our findings suggest that proteasome inhibition might be beneficial not only for the prevention, but also for the therapy of acute pancreatitis.

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

AIM To study the antagonism of cholecystokinin octapeptide (CCK 8) against effect of morphine and its mechanism. METHODS The electrical and mechanical activities of rat duodenum in vitro were recorded simultaneously. RESULTS Acetylcholine (ACh) could increase the amplitude and the number of the spike potential (SPA and SPN) of rat duodenum in vitro , followed by the increase of the duodenal contraction amplitudes (CA), showing a positive correlation. Morphine, on the contrary, inhibited the potentiation of ACh, showing a negative correlation. CCK 8 could antagonize the effects of morphine, i.e. SPA and SPN were increased again, followed by the increase of CA. CCK A receptor antagonist Devazepide could reverse the antagonism of CCK 8 to the effect of morphine. CONCLUSION CCK 8 could antagonize the effect of morphine which inhibited the potentiation of ACh on the duodenal activities in vitro . The antagonistic effect of CCK 8 on morphine was mainly mediated by CCK A receptor.

Synthetic and biological studies on a cyclopolypeptide of plant origin

Objective:A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling of tetrapep-tide units Boc-Leu-Pro-Trp-Leu-OMe and Boc-Ile-Ala-Ala-Gly-OMe after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment. Methods:Solution phase technique was adopted for the synthesis of cyclooctapeptide-sarcodactylamide. Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz. Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-OMe and Ala-Gly-OMe. Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method. The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis. The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities. Results:Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide(DCC) as coupling agent. Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites(DLA) and Ehrlich's ascites carcinoma(EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp. Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin. Conclusion:Solution phase technique employing DCC and triethylamine(TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide. N-methyl morpholine(NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.

Taraxacum offlcinale protects against cholecystokinin-induced acute pancreatitis in rats

AIM: Taraxacum officinale (TO) has been frequently used as a remedy for inflammatory diseases. The aim of this study was to investigate the effect of TO on cholecystokinin (CCK)-octapeptide-induced acute pancreatitis in rats.METHODS: TO at 10 mg/kg was orally administered, followed by 75 μg/kg CCK octapeptide injected subcutaneously three times after 1, 3 and 5 h. This whole procedure was repeated for 5 d. We determined the pancreatic weight/body weight ratio, the levels of pancreatic HSP60 and HSP72, and the secretion of pro-inflammatory cytokines. Repeated CCK octapeptide treatment resulted in typical laboratory and morphological changes of experimentally-induced pancreatitis.RESULTS: TO significantly decreased the pancreatic weight/body weight ratio in CCK octapeptide-induced acute pancreatitis. TO also increased the pancreatic levels of HSP60 and HSP72. Additionally, the secretion of IL-6 and TNF-α decreased in the animals treated with TO.CONCLUSION: TO may have a protective effect against CCK octapeptide-induced acute pancreatitis.

Mechanisms of cholecystokinin-induced calcium mobilization in gastric antral interstitial cells of Cajal

AIM:To investigate the effect of sulfated cholecystokinin-8(CCK-8S) on calcium mobilization in cultured murine gastric antral interstitial cells of Cajal(ICC) and its possible mechanisms.METHODS:ICC were isolated from the gastric antrum of mice and cultured.Immunofluorescence staining with a monoclonal antibody for c-Kit was used to identify ICC.The responsiveness of ICC to CCK-8S was measured using Fluo-3/AM based digital microfluorimetric measurement of intracellular Ca2+ concentration([Ca2+]i).A confocal laser scanning microscope was used to monitor [Ca2+]i changes.The selective CCK1 receptor antagonist lorglumide,the intracellular Ca2+-ATPase inhibitor thapsigargin,the type Ⅲ inositol 1,4,5-triphosphate(InsP3) receptor blocker xestospongin C and the L-type voltage-operated Ca2+ channel inhibitor nifedipine were used to examine the mecha-nisms of [Ca2+]i elevation caused by CCK-8S.Immunoprecipitation and Western blotting were used to determine the regulatory effect of PKC on phosphorylation of type Ⅲ InsP3 receptor(InsP3R3) in ICC.Protein kinase C(PKC) activator phorbol 12-myristate 13-acetate(PMA) and inhibitor chelerythrine were used to assess the role of PKC in the CCK-8S-evoked [Ca2+]i increment of ICC.RESULTS:ICC were successfully isolated from the gastric antrum of mice and cultured.Cultured ICC were identified by immunofluorescence staining.When given 80 nmol/L or more than 80 nmol/L CCK-8S,the [Ca2+]i in ICC increased and 100 nmol/L CCK-8S significantly increased the mean [Ca2+]i by 59.30% ± 4.85%(P < 0.01).Pretreatment of ICC with 5 μmol/L lorglumide inhibited 100 nmol/L CCK-8S-induced [Ca2+]i increment from 59.30% ± 4.85% to 14.97% ± 9.05%(P < 0.01),suggesting a CCK1R-mediated event.Emptying of intracellular calcium stores by thapsigargin(5 μmol/L) prevented CCK-8S(100 nmol/L) from inducing a [Ca2+]i increase.Moreover,pretreatment with xestospongin C(1 μmol/L) could also abolish the CCK-8S-induced effect,indicating that Ca2+ release from InsP3R-operated stores appeared to be a major mechanism responsible for CCK-8S-induced calcium mobilization in ICC.On the other hand,by removing extracellular calcium or blocking the L-type voltage-operated calcium channel with nifedipine,a smaller but significant rise in the [Ca2+]i could be still elicited by CCK-8S.These data suggest that the [Ca2+]i release is not stimulated or activated by the influx of extracellular Ca2+ in ICC,but the influx of extracellular Ca2+ can facilitate the [Ca2+]i increase evoked by CCK-8S.CCK-8S increased the phosphorylation of InsP3R3,which could be prevented by chelerythrine.Pretreatment with lorglumide(5 μmol/L) could significantly reduce the CCK-8S intensified phosphorylation of InsP3R3.In the positive control group,treatment of cells with PMA also resulted in an enhanced phosphorylation of InsP3R3.Pretreatment with various concentrations of PMA(10 nmol/L-10 μmol/L) apparently inhibited the effect of CCK-8S and the effect of100 nmol/L PMA was most obvious.Likewise,the effect of CCK-8S was augmented by the pretreatment with chelerythrine(10 nmol/L-10 μmol/L) and 100 nmol/L chelerythrine exhibited the maximum effect.CONCLUSION:CCK-8S increases [Ca2+]i in ICC via the CCK1 receptor.This effect depends on the release of InsP3R-operated Ca2+ stores,which is negatively regulated by PKC-mediated phosphorylation of InsP3R3.

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.