Abstract:

Abstract:Objective To study the role of glutamate receptor subtypes in nucleus tractus solitarius(NTS) in cardiac-somatic motor reflex (CMR) induced by intrapericardial administration of capsaicin, and to clarify the modulation mechanism of NTS to cardiac nociceptoion.Methods 60 SD rats were randomly divided into  ibotenic (IBO) group,glutamate group,MK-801 group,MCGP group,MK-801+MCPG group and DNQX group.The NTS microinjected with 130 mmol•L^-1  IBO 100 nL, 100，200，500 mmol•L^-1 L-glutamate 100 nL,NMDA receptor antagonist 40 and 60 mmol•L^-1 MK-801 100 nL,metabotropic glutamate receptors antagonist 25 and 50 mmol•L^-1  MCPG 100 nL,25 mmol•L^-1   MCPG  50 nL plus 40 mmol•L^-1  MK-801 50 nL,non-NMDA receptor antagonist 20 and 50 mmol?L-1DNQX 100 nL,respectively.The changes of CMR of the rats in various groups were observed. Results Compared with control group, the CMR of the rats in IBO group  was decreased (P<0.05);the CMR was increased as the concentration increased in glutamate group(P<0.05)；the CMR  in MK-801 and MCPG groups were decreased (P<0.05)；the CMR in MK-801+MCPG  group was decreased (P<0.05);the CMR  in DXQX group had no changes (P>0.05).Conclusion  NTS play an facilictory role in cardiac nociception,and the NMDA receptors and mGluRs receptors mediate this facilitory modulation.
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Key words: nucleus tractus solitarius, cardiosomatic motor reflex, glutamate, glutamate receptor subtype