Effects and mechanisms of L-glutamate microinjected into nucleus ambiguus on gastric motility in rats  

作　　者：SUN Hong-zhao ZHAO Shu-zhen CUI Xi-yun AI Hong-bin 

机构地区：[1]Key Laboratory of Animal Resistance, College of Life Science, Shandong Normal University, Ji'nan, Shandong 250014, China [2]Department of Biological Science and Technology, Shandong Institute of Education, Ji'nan, Shandong 250013, China

出　　处：《Chinese Medical Journal》2010年第8期1052-1057,共6页中华医学杂志（英文版）

基　　金：This study was supported by the grants from the National Natural Science Foundation of China （No. 30770277 and No. 30970354）.

摘　　要：Background L-glutamate （L-GLU） is a major neurotransmitter in the nucleus ambiguus （NA）, which can modulate respiration, arterial pressure, heart rate, etc. This study investigated the effects and mechanisms of L-GLU microinjected into NA on gastric motility in rats. Methods A latex balloon connected with a pressure transducer was inserted into the pylorus through the forestomach for continuous recording of the gastric motility. The total amplitude, total duration, and motility index of gastric contraction waves within 5 minutes before microinjection and after microinjection were measured. Results L-GLU （5 nmol, 10 nmol and 20 nmol in 50 nl normal saline （PS） respectively） microinjected into the right NA significantly inhibited gastric motility, while microinjection of physiological saline at the same position and the same volume did not change the gastric motility. The inhibitory effect was blocked by D-2-amino-5-phophonovalerate （D-AP5, 5 nmol, in 50 nl PS）, the specific N-methyI-D-aspartic acid （NMDA） receptor antagonist, but was not influenced by 6-cyaon-7-nitroquinoxaline-2,3-（1H,4H）-dione （CNQX） （5 nmol, in 50 nl PS）, the non-NMDA ionotropic receptor antagonist. Bilateral subdiaphragmatic vagotomy abolished the inhibitory effect by microinjection of L-GLU into NA. Conclusions Microinjection of L-GLU into NA inhibits the gastric motility through specific NMDA receptor activity, not non-NMDA receptor activity, and the efferent pathway is the vagal nerves.Background L-glutamate （L-GLU） is a major neurotransmitter in the nucleus ambiguus （NA）, which can modulate respiration, arterial pressure, heart rate, etc. This study investigated the effects and mechanisms of L-GLU microinjected into NA on gastric motility in rats. Methods A latex balloon connected with a pressure transducer was inserted into the pylorus through the forestomach for continuous recording of the gastric motility. The total amplitude, total duration, and motility index of gastric contraction waves within 5 minutes before microinjection and after microinjection were measured. Results L-GLU （5 nmol, 10 nmol and 20 nmol in 50 nl normal saline （PS） respectively） microinjected into the right NA significantly inhibited gastric motility, while microinjection of physiological saline at the same position and the same volume did not change the gastric motility. The inhibitory effect was blocked by D-2-amino-5-phophonovalerate （D-AP5, 5 nmol, in 50 nl PS）, the specific N-methyI-D-aspartic acid （NMDA） receptor antagonist, but was not influenced by 6-cyaon-7-nitroquinoxaline-2,3-（1H,4H）-dione （CNQX） （5 nmol, in 50 nl PS）, the non-NMDA ionotropic receptor antagonist. Bilateral subdiaphragmatic vagotomy abolished the inhibitory effect by microinjection of L-GLU into NA. Conclusions Microinjection of L-GLU into NA inhibits the gastric motility through specific NMDA receptor activity, not non-NMDA receptor activity, and the efferent pathway is the vagal nerves.

关 键 词：gastric motility L-GLUTAMATE nucleus ambiguus glutamate receptor VAGOTOMY 

分 类 号：R686[医药卫生—骨科学]