Effects and Mechanisms of Electroacupuncture at Zhongwan （CV12） on Gastric Nociceptive Response Induced by Gastric Acid Stimulation in Rats / 中医杂志

ObjectiveTo observe the effects of electroacupuncture at Zhongwan （CV12） on gastric nociceptive response induced by gastric acid stimulation and explore the underlying mechanisms associated with nuclei of the medullary viscerosensory and visceral motor neurons. MethodsTwenty SD rats were given intragastric administration of 0.5 mol/L diluted hydrochloric acid （0.5 ml/100 g） to induce gastric nociceptive response induction. Eight rats were randomly selected to record the gastric slow wave （GSW） area under the curve， and extracellular discharge frequency of neurons in the nucleus of the solitary tract （NTS） and dorsal motor nucleus of the vagus nerve （DMV） before intragastric administration and at 1， 5， 10， 15， 20， 25， 30， 35， 40， 45， 50， 55， and 60 minutes after intragastric administration. The remaining 12 rats received electroacupuncture intervention at Zhongwan within 5 to 25 minutes after intragastric administration of diluted hydrochloric acid， with a duration of one minute. The GSW area under the curve and extracellular discharge frequency of NTS and DMV neurons were compared between the 1-minute intervals before and after electroacupuncture intervention. ResultsCompared to the baseline before intragastric administration， the area under the curve of GSW significantly increased at 1， 5， 10， 15， 20， and 25 minutes after intragastric administration， and the extracellular discharge frequency of excitatory neurons in the NTS （accounting for 90%， 57/63） significantly increased at 1， 5， 10， 15， 20， 25， 30， 35， and 40 minutes， both reaching peak values at 1 minute after intragastric administration （P＜0.01 or P＜0.05）. The extracellular discharge frequency of inhibitory neurons in the DMV （accounting for 91%， 20/22） showed a non-significant increase at 1 minute after intragastric administration （P＞0.05）， but significantly decreased at other timepoints （P＜0.05）. Compared to the baseline before electroacupuncture intervention， the GSW area under the curve and the extracellular discharge frequency of excitatory neurons in the NTS significantly decreased （P＜0.05）， while the extracellular discharge frequency of inhibitory neurons in the DMV showed no significant difference （P＞0.05）. ConclusionElectroacupuncture at Zhongwan can improve gastric nociceptive response induced by gastric acid stimulation， possibly by reducing the transmission of visceral sensation and decreasing the excitability of NTS neurons in the medulla.

Composition and biological activities of the aqueous extracts of three scleractinian corals from the Mexican Caribbean: Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea

Background: Scleractinian corals (stony corals) are the most abundant reef-forming cnidarians found in coral reefs throughout the world. Despite their abundance and ecological importance, information about the diversity of their toxins and their biological activities is very scarce. In this study, the chemical composition and the biological activities of the aqueous extracts of Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea, three scleractinian corals from the Mexican Caribbean, have been assessed for the first time. Methods: Toxicity of the extracts was assessed in crickets; the presence of cytolysins was detected by the hemolysis assay; the vasoconstrictor activity was determined by the isolated rat aortic ring assay; the nociceptive activity was evaluated by the formalin test. The presence of phospholipases A2 (PLA2), serine proteases, and hyaluronidases was determined by enzymatic methods. Low-molecular-weight fractions were obtained by gel filtration chromatography and ultrafiltration. Results: Extracts from the three species were toxic to crickets, induced hemolysis in human and rat erythrocytes, produced vasoconstriction on isolated rat aortic rings, and presented phospholipase A2 and serine-protease activity. Despite the fact that these corals are not considered to be harmless to humans, the extracts generated significant nociceptive responses. The matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of the low-molecular-weight fractions revealed the presence of peptides within a mass range of 3000 to 6000 Da. These fractions were toxic to crickets and two of them induced a transitory vasoconstrictor effect on isolated rat aortic rings. Conclusion: This study suggests that scleractinian corals produce low-molecular-weight peptides that are lethal to crickets and induce vasoconstriction.(AU)

Composition and biological activities of the aqueous extracts of three scleractinian corals from the Mexican Caribbean: Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea

Scleractinian corals (stony corals) are the most abundant reef-forming cnidarians found in coral reefs throughout the world. Despite their abundance and ecological importance, information about the diversity of their toxins and their biological activities is very scarce. In this study, the chemical composition and the biological activities of the aqueous extracts of Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea, three scleractinian corals from the Mexican Caribbean, have been assessed for the first time. Methods: Toxicity of the extracts was assessed in crickets; the presence of cytolysins was detected by the hemolysis assay; the vasoconstrictor activity was determined by the isolated rat aortic ring assay; the nociceptive activity was evaluated by the formalin test. The presence of phospholipases A2 (PLA2), serine proteases, and hyaluronidases was determined by enzymatic methods. Low-molecular-weight fractions were obtained by gel filtration chromatography and ultrafiltration. Results: Extracts from the three species were toxic to crickets, induced hemolysis in human and rat erythrocytes, produced vasoconstriction on isolated rat aortic rings, and presented phospholipase A2 and serine-protease activity. Despite the fact that these corals are not considered to be harmless to humans, the extracts generated significant nociceptive responses. The matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of the low-molecular-weight fractions revealed the presence of peptides within a mass range of 3000 to 6000 Da. These fractions were toxic to crickets and two of them induced a transitory vasoconstrictor effect on isolated rat aortic rings. Conclusion: This study suggests that scleractinian corals produce low-molecular-weight peptides that are lethal to crickets and induce vasoconstriction.

Calcium Ions are Involved in Modulation of Melittin-induced Nociception in Rat: II. Effect of Calcium Chelator

Melittin, a major component of bee venom, produces a sustained decrease in mechanical threshold, and an increase in spontaneous flinchings and paw thickness, which are characteristics similar to those induced by whole bee venom. Melittin-induced nociception has been known to be modulated by the changes in the activity of excitatory amino acid receptors, voltage-dependent calcium channels, cyclooxygenase and serotonin receptors. The present study was undertaken to investigate the role of calcium chelators (TMB-8 & Quin 2) in melittin-induced nociceptive responses. Changes of mechanical threshold and spontaneous flinching behaviors were measured at a given time point following intraplantar injection of melittin (30microgram/paw). Intrathecal or intraplantar pre-administration and intrathecal post-treatment of TMB-8 and Quin 2 significantly prevented the melittin-induced reduction of mechanical threshold, and intraplantar or intrathecal pre-treatment of TMB-8 and Quin 2 suppressed melittin-induced flinching behaviors. These results indicate that calcium ion in the spinal dorsal horn neurons and peripheral nerves plays an important role in the production and maintenance of mechanical allodynia and spontaneous pain by melittin.

INTRATHECAL ADMINISTRATION OF PRODYNORPHIN ANTISENSE OLIGODEOXYNUCLEOTIDE SUPPRESSES BOTH PRODUCTION OF DYNORPHIN A IN DORSAL HORN AND BEHAVIORAL NOCICEPTIVE RESPONSES INDUCED BY FORMALIN TEST / 神经解剖学杂志

By using intrathecal administration of antisense oligodeoxynucleotide (AS-ODN) against preprodynorphin mRNA in rats, we observed that this treatment could block both the formalin-induced behavioral nociceptive responses and the increased expression of dynorphin A (1-8) in the dorsal horn, with the increased expression of c-Fos protein being unchanged. For we have reported that intrathecal administration of AS-ODN against c-fos mRNA blocks the nociceptive responses and both the increased Fos protein and dynorphin A (1-8), the results of the present study suggest that: (1) Nociceptively induced spinal expression of dyorphin and Fos protein is involved in the transmission of nociceptive information at the spinal level and the expression of Fos protein is the up-stream event. (2) dynorphin may act as a pronociceptive, not an antinociceptive, factor in the modulation of the spinal hyperalgesic state.

Antinociceptive response mechanism of tetramethylpyrazine / 中草药

Objective To observe the effects of tetramethylpyrazine (TMP) on acute nociception in rat hindpaw induced by purine 2X (P2X) receptor agonists, such as adenosine triphosphate (ATP) and ?, ?-meATP, prostaglandin E 2 (PGE 2), and substance P (SP). Methods The effects of TMP administered intraplantarlly on the acute nociception induced by P2X receptor agonists, PGE 2, or SP in the rat hindpaw were investigated by the method of the behavioral study. Results TMP (10 mmol/L) significantly depressed the acute nociception induced by ATP (1 ?mol/L) or ?, ?-meATP (0.6 ?mol/L) in the rat hindpaw. TMP (10 mmol/L) could inhibit the acute nociception induced by PGE 2 (5 ?mol/L) or ?, ?-meATP (0.2 ?mol/L) coinjected with PGE 2 (5 ?mol/L). TMP (10 mmol/L) could not affect the acute nociception induced by ?, ?-meATP (0.2 ?mol/L) coinjected with SP (10 ?mol/L). TMP could not obviously affect the inflammatory edema in rat hindpaw induced by the local administration of PGE 2, SP, or ?, ?-meATP coinjected with PGE 2 or SP individually. Conclusion The antinociceptive effects of TMP may mainly be associated with inhibiting the transmission of nociceptive information mediated by P2X receptor activation.