AIM: To investigate the effects of electroacupuncture (EA) at neiguan (PC6) on gastric distention-induced transient lower esophageal sphincter relaxations (TLESRs) and discuss the mechanisms of this treatment. METHODS...AIM: To investigate the effects of electroacupuncture (EA) at neiguan (PC6) on gastric distention-induced transient lower esophageal sphincter relaxations (TLESRs) and discuss the mechanisms of this treatment. METHODS: ProtocolⅠ: Twelve healthy cats underwent gastric distention for 60 min on the first day. Electrical acupoint stimulation was applied at the neiguan or a sham point on the hip in randomized order before gastric distention, on the third day and fifth day. Those cats that underwent EA at neiguan on the fifth day were named "Neiguan Group" and the cats that underwent EA at a sham acupoint on the fifth day were named "Sham Group" (control group). During the experiment the frequency of TLESRs and lower esophageal sphincter (LES) pressure were observed by a perfused sleeve assembly. Plasma levels of gastrin (GAS) and motilin (MTL) were determined by radioimmunoassay. Nitrite/nitrate concentration in plasma and tissues were measured by Griess reagent. The nuclei in the brain stem were observed by immunohistochemistry method of c-Fos and NADPH-d dyeing. Protocol Ⅱ: Thirty six healthy cats were divided into 6 groups randomly. We gave saline (2 mL iv. control group), phaclofen (5 mg/kg iv. GABA-B antagonist), cholecystokinin octapeptide (CCK-8) (1 μg/kg per hour iv.), L-Arginine (200 mg/kg iv.), naloxone (2.5 μmol/kg iv.) and tacrine (5.6 mg/kg ip. cholinesterase inhibitor) respectively before EA at Neiguan and gastric distention. And the frequencies of TLESRs in experimental groups were compared with the control group.RESULTS: ProtocolⅠ: Not only the frequency of gastric distention-induced TLESR in 60 min but also the rate of common cavity during TLESRs were significantlydecreased by EA at neiguan compared to that of sham acupoint stimulation. C-Fos immunoreactivity and NOS reactivity in the solitarius (NTS) and dorsal motor nucleus of the vagus (DMV) were significantly decreased by EA at neiguan compared to that of the sham group. However, the positive nuclei of C-Fos and NOS in reticular formation of the medulla (RFM) were increased by EA at neiguan. Protocol Ⅱ: The inhibited effect of EA at neiguan on TLESR’s frequency was completely restored by pretreatment with CCK (23.5/h vs 4.5/h, P < 0.05), L-arginine (17.5/h vs 4.5/h, P < 0.05) and naloxone(12/h vs 4.5/h, P < 0.05). On the contrary, phaclofen (6/h vs 4.5/h, P > 0.05) and tacrine (9.5/h vs 4.5/h, P > 0.05) did not influence it. CONCLUSION: Electric acupoint stimulation at Neiguan significantly inhibits the frequency of TLESR and the rate of common cavity during TLESR in cats. This effect appears to act on the brain stem, and may be mediated through nitric oxide (NO), CCK-A receptor and mu-opioid receptors. But the GABAB receptor and acetylcholine may not be involved in it.展开更多
Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey...Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey to predation,but can also modify the behavior of prey.We investigated susceptibility of common birds to predation by domestic cats Felis catus,relying on an extensive data set on prey abundance and prey availability as determined by standardized bird counts.Susceptibility to cat predation for different species of birds was not significantly correlated with susceptibility to predation by sparrowhawk Accipiter nisus,but with susceptibility to goshawk Accipiter gentilis predation. Susceptibility to goshawk predation was independently predicted by susceptibility to cat and sparrowhawk predation.We cross-validated our estimate of susceptibilityto cat predation by showing that the frequency of birds with tail loss increased strongly with sus-ceptibility to cat predation.Male birds were disproportionately preyed upon,especially if havingsong posts low in the vegetation,and if having short flight distances when singing.Colonially breeding species were less susceptible to predation than solitary species.Bird species with high levels of innate immune defense against bacterial infections had high susceptibility to cat predation.These findings suggest that predation by cats has been an important selection pressure affecting anti-predation behavior,sexual display and immune function in common birds.展开更多
In nature, animals are exposed to a broad range of threats imposed by predators, which may strongly influence the ecology of prey species directly or indirectly by affecting their behavior via fear of predation. Here,...In nature, animals are exposed to a broad range of threats imposed by predators, which may strongly influence the ecology of prey species directly or indirectly by affecting their behavior via fear of predation. Here, we studied wood mice Apodemus sylvaticus behavioral and physiological responses to simulated predation risk. Risk avoidance was analyzed by live trapping with control traps and traps treated with feces of common genet Genetta genetta （direct cue of risk） under new moon nights and following by simulated full moon conditions （indirect cue）. The time devoted to foraging behavior and capture time were analyzed by video recording mice activity around traps. Food intake was calculated based on the amount of bait remaining in each trap. Fecal cortico- sterone metabolites （FCMs） were measured by enzyme-immunoassay as indicators of physio- logical stress responses. Fewer wood mice were captured during full moon, yet only non-breeding adult males clearly avoided common genet odor. Mice were captured sooner at night during the simulated full moon conditions and later in predator-treated traps. Foraging activity was lower when individuals faced predator＇s feces, but neither food intake nor FCM levels were affected by predation risk cues. Direct and indirect cues of predation risk selectively affected wood mice behavior, although behavioral responses seem to be modulated by different costs-benefit balances related to the individual＇s perception of risk. The lack of physiological responses to predation risk cues suggests that wood mice did not perceive them as reliable stressors or the response was too small or transient to be measured by FCM.展开更多
基金the National Natural Science Foundation of China, No. C030503039
文摘AIM: To investigate the effects of electroacupuncture (EA) at neiguan (PC6) on gastric distention-induced transient lower esophageal sphincter relaxations (TLESRs) and discuss the mechanisms of this treatment. METHODS: ProtocolⅠ: Twelve healthy cats underwent gastric distention for 60 min on the first day. Electrical acupoint stimulation was applied at the neiguan or a sham point on the hip in randomized order before gastric distention, on the third day and fifth day. Those cats that underwent EA at neiguan on the fifth day were named "Neiguan Group" and the cats that underwent EA at a sham acupoint on the fifth day were named "Sham Group" (control group). During the experiment the frequency of TLESRs and lower esophageal sphincter (LES) pressure were observed by a perfused sleeve assembly. Plasma levels of gastrin (GAS) and motilin (MTL) were determined by radioimmunoassay. Nitrite/nitrate concentration in plasma and tissues were measured by Griess reagent. The nuclei in the brain stem were observed by immunohistochemistry method of c-Fos and NADPH-d dyeing. Protocol Ⅱ: Thirty six healthy cats were divided into 6 groups randomly. We gave saline (2 mL iv. control group), phaclofen (5 mg/kg iv. GABA-B antagonist), cholecystokinin octapeptide (CCK-8) (1 μg/kg per hour iv.), L-Arginine (200 mg/kg iv.), naloxone (2.5 μmol/kg iv.) and tacrine (5.6 mg/kg ip. cholinesterase inhibitor) respectively before EA at Neiguan and gastric distention. And the frequencies of TLESRs in experimental groups were compared with the control group.RESULTS: ProtocolⅠ: Not only the frequency of gastric distention-induced TLESR in 60 min but also the rate of common cavity during TLESRs were significantlydecreased by EA at neiguan compared to that of sham acupoint stimulation. C-Fos immunoreactivity and NOS reactivity in the solitarius (NTS) and dorsal motor nucleus of the vagus (DMV) were significantly decreased by EA at neiguan compared to that of the sham group. However, the positive nuclei of C-Fos and NOS in reticular formation of the medulla (RFM) were increased by EA at neiguan. Protocol Ⅱ: The inhibited effect of EA at neiguan on TLESR’s frequency was completely restored by pretreatment with CCK (23.5/h vs 4.5/h, P < 0.05), L-arginine (17.5/h vs 4.5/h, P < 0.05) and naloxone(12/h vs 4.5/h, P < 0.05). On the contrary, phaclofen (6/h vs 4.5/h, P > 0.05) and tacrine (9.5/h vs 4.5/h, P > 0.05) did not influence it. CONCLUSION: Electric acupoint stimulation at Neiguan significantly inhibits the frequency of TLESR and the rate of common cavity during TLESR in cats. This effect appears to act on the brain stem, and may be mediated through nitric oxide (NO), CCK-A receptor and mu-opioid receptors. But the GABAB receptor and acetylcholine may not be involved in it.
文摘Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey to predation,but can also modify the behavior of prey.We investigated susceptibility of common birds to predation by domestic cats Felis catus,relying on an extensive data set on prey abundance and prey availability as determined by standardized bird counts.Susceptibility to cat predation for different species of birds was not significantly correlated with susceptibility to predation by sparrowhawk Accipiter nisus,but with susceptibility to goshawk Accipiter gentilis predation. Susceptibility to goshawk predation was independently predicted by susceptibility to cat and sparrowhawk predation.We cross-validated our estimate of susceptibilityto cat predation by showing that the frequency of birds with tail loss increased strongly with sus-ceptibility to cat predation.Male birds were disproportionately preyed upon,especially if havingsong posts low in the vegetation,and if having short flight distances when singing.Colonially breeding species were less susceptible to predation than solitary species.Bird species with high levels of innate immune defense against bacterial infections had high susceptibility to cat predation.These findings suggest that predation by cats has been an important selection pressure affecting anti-predation behavior,sexual display and immune function in common birds.
文摘In nature, animals are exposed to a broad range of threats imposed by predators, which may strongly influence the ecology of prey species directly or indirectly by affecting their behavior via fear of predation. Here, we studied wood mice Apodemus sylvaticus behavioral and physiological responses to simulated predation risk. Risk avoidance was analyzed by live trapping with control traps and traps treated with feces of common genet Genetta genetta （direct cue of risk） under new moon nights and following by simulated full moon conditions （indirect cue）. The time devoted to foraging behavior and capture time were analyzed by video recording mice activity around traps. Food intake was calculated based on the amount of bait remaining in each trap. Fecal cortico- sterone metabolites （FCMs） were measured by enzyme-immunoassay as indicators of physio- logical stress responses. Fewer wood mice were captured during full moon, yet only non-breeding adult males clearly avoided common genet odor. Mice were captured sooner at night during the simulated full moon conditions and later in predator-treated traps. Foraging activity was lower when individuals faced predator＇s feces, but neither food intake nor FCM levels were affected by predation risk cues. Direct and indirect cues of predation risk selectively affected wood mice behavior, although behavioral responses seem to be modulated by different costs-benefit balances related to the individual＇s perception of risk. The lack of physiological responses to predation risk cues suggests that wood mice did not perceive them as reliable stressors or the response was too small or transient to be measured by FCM.
