Effect of tandem repeats of antimicrobial peptide CC34 on production of target proteins and activity of Pichia pastoris

Antimicrobial peptides (AMPs) are attracting attention in the fields of medicine, food, and agriculture because of their broad-spectrum antibacterial properties, low resistance, and low-residue in the body. However, the low yield and instability of the prepared AMP drugs limit their application. In this study, we designed a tetramer of the AMP CC34, constructed and transfected two recombinant expression vectors with pGAPZαA containing a haploid CC34 and tetraploid CC34 (CC34-4js) into Pichia pastoris to explore the effect of biosynthesized peptides. The results showed that CC34 and CC34-4js expression levels were 648.2 and 1105.3 mg/L, respectively, in the fermentation supernatant of P. pastoris. The CC34-4js tetramer showed no antibacterial activity, could be cleaved to the monomer using formic acid, and the hemolytic rate of the polyploid was slightly lower than that of monomeric CC34. The average daily gain, average daily feed intake, feed conversion ratio and immune organ index of rats fed CC34 and CC34-4js showed no differences. In conclusion, CC34-4js exhibited a higher yield and lower hemolysis in P. pastoris than those of CC34. Finally, CC34 and CC34-4js enterokinase lysates showed similar antibacterial activity and both expressed peptides potentially improved the growth performance and organ indices of rats.

[Deletion of Aldh4a1 Leads to Impaired Sperm Maturation in Mice]

ALDH4A1, a member of the aldehyde dehydrogenase superfamily, is a key enzyme in the mitochondrial proline metabolism pathway. Recent studies have shown that mutations in aldh4a1 lead to reduced fertility and reproductive premature aging of male nematodes. However, the effect of ALDH4A1 on fertility of male mice has not been studied. In this study, we used CRISPR-Cas9 technology to construct a knockout mouse model of Aldh4a1 for the first time to explore the effect of this gene on the reproduction of male mice. The results showed that compared with WT male mice, Aldh4a1^(-/-) male mice were fertile, had normal spermatogenesis but defect in sperm maturation in the epididymis documented by impaired motility, increased morphological abnormalities and increased spontaneous acrosome reaction. In addition, transmission electron microscopy showed vacuoles in the sperm mitochondria, and fracture in the neck of sperms and vacuoles in these mice. These results revealed that ALDH4A1 plays a vital role in the structure of sperm flagellum and the process of sperm maturation in mice.

Toxic effects of hexavalent chromium (Cr6+) on bioaccumulation, apoptosis, oxidative damage and inflammatory response in Channa asiatica

The objective of this study was to evaluate the toxic effects of Cr⁶⁺ on bioaccumulation, digestion, immunity, oxidative stress, apoptosis and inflammation-related genes in Channa asiatica. The fish was exposed to waterborne Cr⁶⁺ concentrations (0, 0.5, 1.0 and 2.0 mg/L) for 28 and 56 days. Our results demonstrated that the accumulation of Cr⁶⁺ in tissues increased in a concentration-dependent manner, and the content in tissue was liver > gill > gut > muscle. Meanwhile, Cr⁶⁺ exposure led to a remarkable suppression of digestion, immunity and antioxidant capacity in C. asiatica. Inversely, MDA and PC content were positively correlated with Cr⁶⁺ exposure concentration. Furthermore, the expression of genes went up with the increase of waterborne Cr⁶⁺ concentration. Among them, HSP90, NF-κB and TNF-α have a sharp increase. These results elucidate that waterborne Cr⁶⁺ exposure may induce bioaccumulation, inhibit digestion and immunity, promote oxidative stress and up-regulate the expression of apoptosis and inflammation-related genes in C. asiatica.

Bioflocs attenuates lipopolysaccharide-induced inflammation, immunosuppression and oxidative stress in Channa argus

The regulation of C/N in aquaculture water is an important means of environmental regulation, of which the most common is bioflocs technology (BFT). Here, an eight-week feeding experiment and a lipopolysaccharide (LPS) challenge test were proceed to investigate the growth, oxidative stress, immunosuppression and GR-NF-κB related genes expression of Channa argus rearing in the BFT. Four groups were set, the control group was a basic diet (C/N = 7.6:1), and the other three groups were adjusted by glucose, which was C/N 10: 1, C/N 15: 1 and C/N 20:1, respectively. And we detected the two-stage test indexes of C. argus before and after the LPS challenge. The results showed that the bioflocs of C/N 15:1 group significantly (P < 0.05) promoted the growth performance. Similarly, the trend of immune enzyme activity was the same before and after LPS challenge, but decreased after challenge (except AKP and IgM). The best group is still treatment C/N 15:1. Liver and intestine SOD, CAT, GPX, ASA and T-AOC levels of juveniles in treatment C/N 15:1 were markedly increased (P < 0.05) compared to control before and after the LPS challenge. Simultaneously, the content of MDA in control group was considerably higher than that in treatment C/N 15:1 (P < 0.05). Furthermore, C/N 15:1 group significantly down-regulated the expression level of pro-inflammatory factors (NF-κB, TNF-α, IL-1β and IL-8), and up-regulated IκBα, GR, HSP70 and HSP90 expression levels considerably (P < 0.05). Also, intestinal morphology appeared injury in control group, while intestinal integrity was better in treatment C/N 10:1 and C/N 15:1 after challenge. Taken together, these upshot indicated that bioflocs could enhance growth and alleviate C. argus from LPS-induced oxidative stress, immunosuppression and inflammation through restraining GR-NF-κB signaling pathway. The best C/N ratio for alleviating LPS is 15:1.

HPV16 infection promotes an M2 macrophage phenotype to promote the invasion and metastasis of esophageal squamous cell carcinoma

OBJECTIVES

High-risk human papillomavirus (HR-HPV) is an important risk factor for esophageal cancer. Macrophages constitute a crucial immune medium for regulating HPV-related tumors; however, the specific regulatory mechanisms remain unknown. Therefore, the purpose of our current study was to investigate the mechanism by which HPV16E6 regulates macrophages to promote the invasion and metastasis of esophageal cancer.

METHODS

HPV16E6 infection was detected by polymerase chain reaction. Immunohistochemistry was used to verify the distribution of tumor-associated macrophages (TAMs) and MMP-9 expression in esophageal squamous cell carcinoma tissues (ESCCs), and cancer adjacent normal tissues (CANs) from Kazakh patients. ESCC cells were transfected with a plasmid over-expressing HPV16E6 and non-contact cocultured with macrophages.

RESULTS

The infection rate of HPV16E6 in Kazakh ESCCs was clearly higher than that in CANs (P < 0.05). The density of CD163-positive TAMs was significantly positively correlated with HPV16E6 infection in ESCCs (P < 0.05). After coculturing macrophages and EC9706 cells transfected with the HPV16E6 plasmid, the phenotype of macrophages transformed into M2 macrophages. The migration and invasion ability of ESCC cells were higher in the HPV16E6-transfected and coculture group than in the HPV16E6 empty vector-transfected and non-cocultured HPV16E6-transfected groups (all P < 0.05). The density of M2-like TAMs in ESCCs was positively correlated with the level of MMP-9 expression. MMP-9 expression in the HPV16E6-ESCC coculture macrophages group was substantially higher than that in controls (all P < 0.05).

CONCLUSIONS

HPV16 infection mediates tumor-associated macrophages to promote ESCC invasion and migration.

Amelioration of hexavalent chromium-induced bioaccumulation, oxidative stress, tight junction proteins and immune-related signaling factors by Allium mongolicum Regel flavonoids in Ctenopharyngodon idella

Chromium (Cr) is the most common heavy metal and that becomes toxic when present at higher concentrations in aquatic environments. Allium mongolicum Regel flavonoids (AMRF) has been documented to possess detoxification, antioxidant and anti-inflammatory properties. The aim of this study was to explore the potential of dietary AMRF and Cr exposure on bioaccumulation, oxidative stress, and immune response in Ctenopharyngodon idella. After acclimation, 360 fish were randomly distributed into six groups. The fish were fed with diets supplemented with Cr and/or AMRF for 4 weeks (28 days), the Cr concentrations were 0, 120, and 240 mg/kg and the concentrations of AMRF were 0 or 40 mg/kg, respectively. The results shown that Cr accumulation in the kidney, liver, spleen, intestine and gill were significantly increased following Cr exposure, dietary AMRF supplementation attenuated the increased in Cr accumulation. Dietary AMRF supplementation significantly reduced the levels of malondialdehyde (MDA) and protein carbonyl (PC) in liver, spleen and gill compared with the same Cr dose groups. When fish were supplemented with AMRF significantly increased lysozyme activity (LZM), complement 3 (C3) in kidney and intestine compared with the same Cr dose groups. Serum glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased following exposure to Cr. Dietary AMRF supplementation significantly decreased GOT and GPT activity in the serum. In addition, AMRF supplementation can decrease the expression of inflammatory (NF-κB p65, TNF-α and IL-1β) and increased the expression of tight junction proteins (occludin and ZO-1) following Cr exposure in C. idella. These results indicate that AMRF has the potential to alleviate the effects of Cr toxicity in C. idella.

Nitric oxide is involved in phosphorus deficiency-induced cluster-root development and citrate exudation in white lupin

*White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organic anions under phosphorus (P) deficiency. Here, the role of nitric oxide (NO) in P deficiency-induced cluster-root formation and citrate exudation was evaluated. *White lupin plants were treated with the NO donor sodium nitroprusside (SNP) and scavenger or inhibitor of NO synthase under conditions of P deficiency (0 muM) or P sufficiency (50 muM). *Phosphorus deficiency enhanced NO production in primary and lateral root tips, with a greater increase in cluster roots than in noncluster roots. NO concentrations decreased with cluster root development from the pre-emergent stage, through the juvenile stage, to the mature stage. The P deficiency-induced increase in NO production was inhibited by antagonists of NO synthase and xanthine oxidoreductase, suggesting the involvement of these enzymes in NO production. SNP markedly increased the number of cluster roots. Citrate exudation from different root segments in P-deficient roots was positively correlated with endogenous root NO concentrations. *These findings demonstrate differential patterns of NO production in white lupin, depending on root zone, developmental stage and P nutritional status. NO appears to play a regulatory role in the formation of cluster roots and citrate exudation in white lupin under conditions of P deficiency.

Biphasic manner of melittin on isolated guinea pig atria

AIM

To investigate the effect of melittin (Mel) on isolated guinea pig atria.

METHODS

The effect of Mel on the contraction and heart rate of isolated guinea pig atria at different concentrations was determined.

RESULTS

Mel at a lower concentration (0.1-0.8 mumol.L-1) enhanced the contraction of left atria in a concentration-dependent manner; but at a higher concentration (1.6-12.8 mumol.L-1) it exerted an inhibitory effect. At 0.1-30 mumol.L-1 it was found to increase heart rate of right atria. In addition, verapamil (Ver) 0.3 mumol.L-1 was found to depress the effect of Mel.

CONCLUSION

Mel possesses a biphasic effect on left atria and a positive chronotropic effect on right atria. Its mechanism might be related with Ca2+ channel.

Melatonin decreases production of hydroxyl radical during cerebral ischemia-reperfusion

AIM

To study the effect of melatonin on hydroxyl radical (.OH) contents during cerebral ischemia-reperfusion in rats.

METHODS

Ischemia was induced by occluding left lateral middle cerebral artery for 30 min following reperfusion. The salicylate trapping method coupled with ipsilateral striatal microdialysis for measurement of hydroxyl radicals generated during ischemia and reperfusion.

RESULTS

The contents of dihydroxybenzoic acid (DHBA) were increased at 15 min after ischemia and remained high for 30 min after reperfusion. Melatonin (4 mg.kg-1, sc, 30 min before ischemia) decreased the production of DHBA during ischemia for 16-30 min and reperfusion for 1-30 min.

CONCLUSION

Melatonin inhibits the production of hydroxyl radicals in rat brain during ischemia and reperfusion.

Inhibitory effects of dextromethorphan on c-fos protein expression during focal cerebral ischemia in rats

AIM

To study the effect of dextromethorphan (DM) in focal cerebral ischemia.

METHODS

The c-fos protein was detected immunohistochemically in the brain of rats after focal cerebral ischemia (induced by placing a nylon thread in the lumen of the internal carotid artery) with and without treatment with DM.

RESULTS

Focal cerebral ischemia induced c-fos protein expression outside the core territory of the middle cerebral artery (MCA) and neuronal damage in the core territory of the MCA. There was an evident expression of c-fos protein in the ipsilateral regions outside the MCA territory (e.g. cingulate cortices, piriform cortices and entorhinal cortices), and in the contralateral regions of hippocampus after 4-h reperfusion following 1-h MCA occlusion. But morphological results showed severe edema and neuronal damage in the core territory and the ipsilateral hippocampus. DM blocked both the c-fos protein induction and neuronal damage in all regions.

CONCLUSION

DM reduced c-fos protein expression and blocked the neuronal damage after focal cerebral ischemia.

Effects of sigma and phencyclidine receptor ligands on electric field-stimulated rabbit ear artery constriction in vitro

Several ligands of phencyclidine (Phe) receptors: Phe, dizocilpine maleate (Diz, MK-801), 1-[1-(2-thionyl)cyclohexyl] piperidine (TCP), and ligands of sigma (sigma) receptors: dl-N-allylnormetazocine (dl-SK&F-10047), 1, 3-di-ortho-tylyl-guanidine (DTG), dl-pentazocine, were tested on rabbit ear arteries in vitro. It was found that the ligands of Phe receptors enhanced the electric field stimulated vasoconstriction (ESV). Their concentration-effect curves of these compounds were parallel in the order of potencies: Phe > Diz > TCP. The ligands of sigma receptors had no effect on ESV of the arteries, but 5 mumol.L-1 reduced or increased the effect of Phe (5 mumol.L-1) on ESV. d-SK&F-10047, d-pentazocine, and DTG inhibited the effect of Phe on ESV from 364 +/- 22 mg to 142 +/- 49 mg (n = 5, P < 0.01), 262 +/- 95 mg (n = 5, P < 0.05), and 291 +/- 80 mg (n = 5, P > 0.05), respectively. The levoisomers: l-SK&F-10047 and l-pentazocine enhanced the effect of Phe on ESV from 364 +/- 22 mg to 484 +/- 78 mg (n = 5, P < 0.05), and 466 +/- 95 mg (n = 5, P < 0.05), respectively. These results revealed that there were mainly Phe receptors but hardly any sigma receptors in the arteries.

Effects of kappa, sigma, and phencyclidine receptors agonists in rat tail arteries of spontaneously hypertensive rats

The effects of the kappa receptor agonist trans-4-dichloro-N-methyl-N-(2-(1-pyrrolidin)cyclohexyl)-benzen eacefamide methane sulfonate (U-50 488H), etorphine, the sigma (sigma) receptor agonists (+)-3-(3-hydroxychenyl)-N-(1-propyl) piperidine ((+)-3-PPP), 1, 3-di-o-tolyl-guanidine (DTG), and the phencyclidine (Phe) receptor agonists Phe, N-(1-(2-thienyl)cyclohexyl) piperidine (TCP), and dizocilipine maleate (MK-801) on electrically stimulated constriction (ESC) were investigated in the rat tail arteries (RTA) of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Etorphine and U-50 488H inhibited the response to ESC in SHR more than that in WKY. The effects of U-50 488H were greater than those of etorphine. The IC50 and Kact of U-50 488H in SHR were 2.5 +/- 2.0 and 0.43 +/- 0.22 mumol.L-1, respectively, while the corresponding figures in WKY were 23 +/- 15 and 2.3 +/- 1.0 mumol.L-1, respectively (P < 0.05). The inhibitory effects of (+)-3-PPP on ESC in RTA of SHR were weaker than those in WKY. Its IC50 and Kact in SHR were 11.6 +/- 5.4 and 0.87 +/- 0.30 mumol.L-1, respectively, while the corresponding figures in WKY were 0.63 +/- 0.16 and 0.35 +/- 0.18 mumol.L-1, respectively (P < 0.05). But the inhibitory effect of DTG was very slight and the difference of Kact between WKY and SHR was not significant. The enhancing effects of Phe, TCP, and MK-801 in SHR were not at all different from those in WKY at each concentration tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuroprotective effects of phencyclidine on acute cerebral ischemia and reperfusion injury of rabbits

Acute cerebral ischemia and reperfusion injury of rabbits was produced by permanently occluding the vertebral arteries and temporarily clamping the common carotid arteries for 30 min. Phencyclidine [1-(phenylcyclohexyl)piperidine, PCP] 40-80 micrograms.kg-1 icv 30 min before ischemia significantly attenuated the decrease of the total power of electroencephalogram (EEG) within 30 min of ischemia and improved the recovery of brain electric activity following reperfusion. PCP 20-80 micrograms.kg-1 dose-dependently suppressed the creatine kinase (CK) release during cerebral ischemia and reperfusion, and PCP 40-80 micrograms.kg-1 reduced brain ischemic damage. These improvements indicated that PCP has protective effects on acute cerebral ischemia and reperfusion injury.

[Effects of phencyclidine on rabbit basilar artery in vitro and rabbit cerebral blood flow in vivo]

The effect of phencyclidine [1-(1-phenylcyclohexyl)piperidine, PCP] on rabbit basilar arteries was studied with an in vitro model of ring segment arteries. PCP 0.05-500 mumol.L-1 caused vasoconstriction of basilar arteries in a concentration-dependent manner. Its maximal effect (Emax) was 94 +/- 21 mg and the concentration causing half maximal effect (EC50) was 25 +/- 18 mumol.L-1. PCP 0.01-10 mumol.L-1 also concentration-dependently augmented the vasoconstriction induced by electric stimulation in rabbit basilar arteries. Its Emax was 91 +/- 18 mg and EC50 was 0.27 +/- 0.17 mumol.L-1. The effects of PCP on mean arterial blood pressure (MABP) and heart rate (HR) of rabbits were observed. PCP iv 4 mg.kg-1 reduced MABP from 14.3 +/- 0.8 to 12.2 +/- 1.0 kPa and HR from 300 +/- 0 to 278 +/- 5 bpm in 5 min. Using the technique of radionuclide imaging in rabbit brain in vivo, we studied the effect of PCP on cerebral blood flow. After iv PCP 4 mg.kg-1, the tp of radiocerebrogram was increased from 4.5 +/- 1.1 to 6.1 +/- 1.0 s, the tg of radiocerebrogram was increased from 11.7 +/- 0.6 to 18.2 +/- 3.3 s and the rate of clearance was decreased. After iv PCP 2 mg.kg-1, only tg increased from 12.6 +/- 2.1 to 15.9 +/- 0.6 s. Hence PCP increased the transit time of nondiffusible indicators (99mTc) through the cerebral circulation. These results suggest that PCP causes constriction of basilar artery and slows down the cerebral blood flow.

[Antagonistic effect of phencyclidine on cerebral ischemic damage of rats]

Dynorphin and catecholamine were measured in ischemic rat produced by four-vessel (2 vertebral arteries and 2 common carotid arteries) occlusion for 10 min. The results showed that: (1) The contents of dynorphine (pg/mg tissue) in cerebral cortex were 5.5 +/- 0.6 (n = 7) in normal rats and decreased to 4.9 +/- 0.5 (n = 9, P less than 0.05) in cerebral ischemic rats; with immediate ip phencyclidine (1-(1-phenylcyclophexyl)piperidine, PCP, 1 mg.kg-1), the contents of dynorphin were increased to 5.3 +/- 0.4 (n = 5, P less than 0.05 vs the ischemic rats). (2) The contents of DOPAC (pg/mg tissue) in cerebral cortex were 38 +/- 6 (n = 7) and increased to 120 +/- 60 (n = 5, P less than 0.05) in 10 min cerebral ischemic rats; with immediately ip PCP (1 mg.kg-1), the contents of DOPAC were decreased to 26 +/- 13 (n = 7, P less than 0.05 vs the ischemic rats). (3) The release of DA (pg/mg tissue) in cortical slices in vitro, in high K+ solution were 24 +/- 3 (n = 5) and significantly increased to 57 +/- 15 (n = 5, P less than 0.05) in ischemic rat brain slices; with immediate ip PCP (1 mg.kg-1), the contents of DA were decreased to 38 +/- 10 (n = 5, P less than 0.05 vs the ischemic rats). These results suggest PCP play an antagonistic role in cerebral ischemic damage of rats.

[Effects of l-stepholidine on isolated rabbit basilar artery, mesenteric artery, and thoracic aorta]

l-Stepholidine (SPD) has been shown to be effective in treating migraine, but its mechanism is not clear. So the effects of SPD on isolated rabbit basilar artery (BA), mesenteric artery (MA) and thoracic aorta (TA) were studied. The contractions of BA and MA were induced by KCl (10-160 mmol.L-1) and the contraction of TA was caused by 5-HT (0.1-100 mumol.L-1). Ketanserin was used as reference. SPD (0.1-0.2 mmol.L-1) relaxed the contractions of BA and MA induced by KCl in a noncompetitive manner with pD'2 3.4 +/- 0.3 and 4.0 +/- 0.3, respectively. SPD had no selectivity in BA and MA. SPD also inhibited the contraction of TA induced by 5-HT with pA2 9.7 +/- 2.0 and pD'2 5.4 +/- 0.6, which showed a dual of both competitive and noncompetitive antagonisms. These results suggested that SPD had a blockade effect on the calcium channel and 5-HT2 receptors.

[Antagonistic effects of dextromethorphan on vasoconstriction of phencyclidine in vitro]

Bioassay and spectrophotofluorometry were used to study the antagonistic effect of dextromethorphan (DM) on phencyclidine (PCP) vasoconstriction in rabbit ear artery. DM (5 mumols.L-1) antagonized enhancement of PCP, N-[1-(2-thienyl) cyclohexyl] piperidine (TCP) and dizocilpine maleate (MK-801) (5 mumols.L-1) on electrical stimulation-induced vasoconstriction by 86 +/- 18%, 84 +/- 17%, and 86 +/- 18%, respectively (n = 6, P less than 0.01), but had no obvious bioactivity itself at the same concentration. DM (1, 2.5, and 5 mumols.L-1) inhibited the PCP effect and reduced the maximal effect of PCP with pD2' = 5.3 +/- 0.3 (n = 4). The contents of norepinephrine (NE) in control, PCP, and DM + PCP groups were 5 +/- 6, 12 +/- 8, and 5 +/- 6 ng.ml-1, respectively (n = 9). PCP (10 mumols.L-1) increased the NE release (P less than 0.05) but DM (10 mumols.L-1) inhibited it (P less than 0.01). The results suggest DM may be a noncompetitive blockader for PCP receptors.

[Effects of phencyclidine analogs and phencyclidine/sigma ligands on vasoconstrictor response of rat mesenteric arteries induced by electrical field stimulation]

Using the model of perfused mesenteric arteries of rat, we studied the effect of phencyclidine (PCP), N-[1-(2-thienyl)cyclohexyl] piperidine (TCP), N,N-dimethylphenylcyclohexylamine (PCDA), N-(iso-propyl)-1-phenylcyclohexylamine (PCIPA), (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801), (+),(-)-N-allylnormetazocine (SKF 10 047), dextrorphan, and levorphanol on vasoconstrictor response induced by electrical field stimulation. PCP, TCP, PCDA, PCIPA, MK-801, levorphanol, and (-)-SKF 10 047 were found to increase the vasoconstrictor response in dose-dependent manner. The dose-effect curves of these compounds were similar to the curve of PCP. Although dextrorphan, an antagonist for PCP receptors, did not affect the vasoconstrictor response, it could non-competitively antagonize PCP's action. These studies suggest that some PCP analogs and PCP/sigma ligands may enhance the vasoconstrictor response induced by electrical field stimulation via action on PCP receptors.

[Phencyclidine receptors in porcine cerebral arteries]

A specific, saturable, reversible, and selective binding site with Kd = 87 +/- 33 nmol/L, Bmax = 0.78 +/- 0.11 pmol/mg protein was detected in the binding of [3H] phencyclidine (PCP) to porcine cerebral blood vessels. Only ligands of PCP/sigma series were able to bind to the PCP receptors. [3H]PCP bound to its receptors was not displaced by etorphine or norepinephrine 0.1 mmol/L. A specific [3H]PCP binding site was found in porcine brain with Kd = 75 +/- 34 nmol/L, Bmax = 0.61 +/- 0.23 pmol/mg protein. Bioassay in vitro showed PCP enhanced the perfusion pressure of porcine cerebral blood vessels in a dose-dependent manner. This study provides direct evidence for PCP receptors on cerebral blood vessels, and suggests that PCP may produce cerebral vasospasm via PCP receptor interaction.

[Mechanism of dynorphin inhibition on vasoconstriction in vitro]

Bioassay and HPLC detection were used to analyze the mechanism of inhibition of stimulation-induced vasoconstriction by dynorphin 1-13 (D1-13). Bioassay showed that D1-13 inhibited the contraction of rabbit ear artery and mesenteric artery induced by electrical field stimulation with IC50s of 8.5 +/- 1.2 x 10(-8) mol/L (n = 4) and 5.02 +/- 1.3 x 10(-7) mol/L (n = 5), respectively. D1-13 was ineffective in rabbit femoral artery at a concentration even larger than 10(-6) mol/L. D1-13 did not alter the basal tension of the blood vessel, nor the vasoconstriction induced by adding norepinephrine (NE) into the bath medium, and both constriction were markedly inhibited by phentolamine, an alpha-adrenoceptor blocker. With HPLC detection, the contents of NE in the bath medium were significantly reduced by D1-13 (5 x 10(-7) mol/L) from 340.56 +/- 73.13 pg/ml to 76.91 +/- 10.26 pg/ml as compared with control group (P less than 0.05). The effect could be completely reversed by naloxone at a concentration of 10(-6) mol/L (P less than 0.05). The results suggest that D1-13 reduces stimulation-induced vasoconstriction probably through a presynaptic inhibition of NE release from the nerve terminals.

[Autoradiographic study on etorphine and phencyclidine specific binding sites in rabbit mesenteric artery]

Autoradiography was used to study the localization of kappa and PCP/sigma receptors in the blood vessels. Slices of rabbit mesenteric arteries were incubated with 0.4 nmol/L [3H]etorphine or/and 10 mumol/L etorphine for 45 min at 25 degrees C, or incubated with 5.2 nmol/L [3H]PCP or/and 20 mumol/L PCP for 60 min at 4 degrees C. Then, slices were covered with emulsion coated coverslip and kept for 8-10 wk at 4 degrees C. The results were as follows: Microscopy Autoradiographic analysis indicated that etorphine and PCP specific binding sites were both located in the outer-layer and the smooth muscle of the artery. However, most of these binding sites were lost in the 6-OHDA pretreated arteries in which the adrenergic nerve endings were destroyed. Microspectrophotometry The absorbance (A) of [3H]etorphine autoradiographic density for total binding (TB) and nonspecific binding (NSB) in control group were 0.416 +/- 0.056 and 0.044 +/- 0.011, respectively (P less than 0.01), and for TB after incubation with 6-OHDA was 0.068 +/- 0.013 which was different from the A value of TB in the control (P less than 0.01). The A value of [3H]PCP autoradiographic density for TB and NSB in the control were 0.546 +/- 0.087 and 0.023 +/- 0.060, respectively (P less than 0.01), and for TB after incubation with 6-OHDA was 0.065 +/- 0.015 which was significantly less than that of TB in the control group (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Dextrorphan: an antagonist for phencyclidine receptors

Radio-binding assay, bioassay and HPLC detection were used to observe the antagonistic effects of dextrorphan on PCP's actions. Dextrorphan displayed high affinity to PCP receptor in the rabbit mesenteric blood vessels. It had weak PCP-like bioactivity, but could antagonize PCP's action dose-dependently in vitro study with the rabbit ear artery preparation and shifted the dose-response curve of PCP to the right. After PCP administration, the content of norepinephrine in the vascular bath medium was increased, which was reversed by dextrorphan. Thus suggests that dextrorphan is an antagonist with very mild agonistic action for PCP receptors.

Roles of opioid peptides of PAG in analogous electro-acupuncture inhibition of experimental arrhythmia: analyzed by specific antisera microinjection

Using specific antisera microinjected into periaqueductal grey (PAG), we further studied the mechanism of the analogous electroacupuncture, deep peroneal nerve stimulation (DPNS), inhibition on the experimental arrhythmia, hypothalamic stimulation-induced ventricular extrasystoles (HVE). Neither normal serum nor anti-leu-enkephalin antiserum interfered with DPNS inhibition; anti-dynorphin A (1-8) tended to attenuate the inhibition; and anti-beta-endorphin antiserum blocked it. The results provided further evidence for the hypothesis that beta-endorphin in PAG plays an important role in the neural circuit of DPNS inhibition on HVE.

The analgesic and respiratory depressant actions of metorphamide in mice and rabbits

Metorphamide (MET) elicited a potent, dose-dependent analgesia and respiratory depression in mice and rabbits. MET induced-analgesia was naloxone reversible and potentiated by bestatin. Naloxonazine, a relatively selective mu 1 blocker, at certain dosage (50 micrograms per rabbit, icv), could abolish the analgesia but not the respiratory inhibition produced by MET. Our result indicates that mu 1 receptors mediate the MET induced-analgesia but not its respiratory effect. Since MET is a mu- and kappa-ligand with very low delta activity, the MET induced respiratory depression may be mediated by mu 2 or kappa binding sites.

Dynorphin receptor in the blood vessel

Using (3H)etorphine, (3H)E, in binding studies, the KD and Bmax for rabbit mesentery and aorta membrane preparations were 0.61 nM and 0.17 fmol/mg tissue respectively, while it was 0.30 nM and 12 fmol/mg tissue in the brain. The IC50 of dynorphin (1-13) (D1-13) for displacing (3H)E binding in the blood vessel was 20 +/- 2.8 nM (S,E,M,), while PLO17, D-ala2-D-leu5-enkephalin (DADLE) and met5-enkephalin-arg6-phe7 showed very weak inhibition (IC50 greater than 1000nM) though they displaced (3H)E binding very well in the brain. In vitro study showed that D1-13 inhibited electric field stimulation induced vasoconstriction with an IC50 of 53 +/- 12 (rabbit ear artery) and 510 +/- 120 (dog mesenteric artery)nM. Such effect was partially reversed by 1 microM of naloxone. D-ala2-met5-enkephalin and metorphamide displayed much weaker inhibition and DADLE was completely ineffective at doses up to 1 microM. D1-13 did not antagonize noradrenaline (NA) induced vasoconstriction, while phentolamine could abolish vasoconstriction induced either by stimulation or by NA. The result suggests that D1-13 acts presynaptically on neuronal kappa receptor in the blood vessel and inhibits NA release, thus causes vasodilation.

Lower CSF level of dynorphin(1-8) immunoreactivity in schizophrenic patients

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-8) (D 1-8), and a singly blind test design, we measured D(1-8) immunoreactivity (ir D 1-8) in CSF of 35 first break cases of acute schizophrenic patients. All patients were free of psychotropic medication for at least one week before the study. Another 31 neurological patients suffered from cervical arthrosis, tumor, myelopathy etc. were studied as controls. The ir D(1-8) in CSF of schizophrenic patients were significantly lower than that of controls (91.8 +/- 5.6, means +/- S.E.M., and 131.9 +/- 6.8 fmol/ml CSF respectively, p less than 0.001).

Inhibitory effect of analogous electro-acupuncture on experimental arrhythmia

Rabbits were used to study the inhibitory effect of analogous electro-acupuncture on the experimental arrhythmias, i.e. hypothalamic stimulation-induced ventricular extrasystole (HVE). The result revealed that HVE, which was due to an increased cardiac sympathetic activity, could be inhibited by deep peroneal nerve stimulation with an electrical current of low frequency and low intensity. Such effect is related to endogenous opioid peptides and serotonin in the arcuatus area, the periaqueductal gray and and the medial medulla. The acupuncture correction of arrhythmias may have the same mechanism.

Met5-enkephalin-arg6-phe7 and its receptor in lung

The presence of met5-enkephalin-arg6-phe7 (YGGFMRF) and opiate receptors in rat, guinea pig and human lung was investigated with specific and sensitive radio immuno- and radio-receptor assays. 1) High and low molecular weight YGGFMRF-like immunoreactivity were detected in lung extracts using Bio-Gel P-2 column chromatography followed by radioimmunoassay. Using HPLC, we determined that the low molecular weight YGGFMRF-like immunoreactivity is authentic YGGFMRF. 2) The contents of YGGFMRF were 0.68 +/- 0.08, 0.76 +/- 0.12 and 0.63 pmol/mg protein in lung of rat, guinea pig and human, respectively. In the lung of these three species, the content of YGGFMRF is much greater than that of met5-enkephalin. 3) 47 mM KCl released YGGFMRF from rat lung slices in a Ca++ dependent manner. 4) Rat lung membranes were shown to bind [3H]-etorphine in a saturable manner. There are two populations of binding sites with a Kd = 0.6 and 7.1 nM and a Bmax = 7.8 and 28.5 fmol/mg protein, respectively. This binding could be displaced by YGGFMRF with high affinity, the other endogenous opioid peptides were poor displacers. From these results, we infer that YGGFMRF might be a putative neurotransmitter or neuromodulator, its role in the regulation of lung function can now be investigated.

The effect of acupuncture on blood pressure: the interrelation of sympathetic activity and endogenous opioid peptides

Experimental hypertension was produced by intravenous infusion of norepinephrine in 13 conscious dogs. Electroacupuncture at the dogs' "Tsu San-Li" (St. 36) points showed a significant decrease in blood pressure, while the heart rate was not affected. The depressor effect was naloxone (0.2 mg/kg iv) reversible, and accompanied by an increased blood flow at the mesenteric artery, so it is suggested that the depressor effect was due to inhibition of the sympathetic vasoconstrictor tone. This inhibition was mediated by endogenous opioid peptides released by acupuncture. The location of this mediation was further analyzed. The central mechanism was evidenced by the ineffectiveness of acupuncture in reducing blood pressure in anesthetized dogs. On the other hand, the demonstration of opiate receptors in the blood vessels by radio-receptor assay provided evidence of peripheral mediation of blood pressure by opioids. The blood vessel might be a target organ for the plasma opioids, which can also be increased by acupuncture.

Nociception, enkephalin content and dipeptidyl carboxypeptidase activity in brain of mice treated with exopeptidase inhibitors

Thiorphan (60 micrograms intracerebrally) increased the met5-enkephalin content of mouse striatum by 30% in 30 min. This increase was no longer evident at 1 hr. If the dipeptidyl carboxypeptidase, inhibited by thiorphan, were located extraneuronally as suggested by De La Baume, Patey and Schwartz (1981), the met5-enkephalin accumulation represents the rate at which the pentapeptide is released extraneuronally. The increase in met5-enkephalin content was accompanied by an inhibition, greater than 80%, of the dipeptidyl carboxypeptidase that degrades striatal met5-enkephalin. Such an inhibition lasted longer then 2 hr. Thiorphan, given to mice intracerebrally, prolonged the latency time to jump off a 54 degree plate. The effects of thiorphan on brain met5-enkephalin content and hot plate latencies were significantly potentiated by bestatin, which inhibits aminopeptidase B and leucine aminopeptidase.

Ontogeny of opioid pharmacology and receptors: high and low affinity site differences

The development of the high affinity binding of a variety of opiates and enkephalins is distinct from low affinity binding. During the first 2 weeks after birth, low affinity binding in both brain and spinal cord remains relatively constant while high affinity binding increases up to 3-fold. Differences in the development of analgesic and respiratory sensitivity to opiates are also found. Whereas morphine, beta-endorphin and D-Ala2-Met5-enkephalin-amide depress respiratory rates in 2-day old rats at doses equal to or lower than those active in 14-day old rats, morphine's analgesic ED50 is 40-fold greater in 2-day old than in 14-day old rats. Similarly, beta-endorphin and D-Ala2-Met5-enkephalinamide are analgesic in 14-day old rats but not 7-day old rats. The small effect of spinal transections on morphine analgesia in 14-day old rats suggests that the change in analgesic sensitivity is at a segmental spinal level and not a result of descending pathways. These results suggest an interesting correlation between high affinity binding and analgesia and between low affinity binding and respiratory effects.