The role of glutamate receptors in the pressor and depressor areas of pontomedulla in cats

• Main Authors: Chen, Shu-Ying, 陳淑瑩
• Other Authors: Chai,C.Y.
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/03855312505635153690

碩士 === 國防醫學院 === 藥理學研究所 === 82 === In our previous studies, using sodium glutamate (Glu) as a tool, we have demonstrated the existence of pressor neurons in the locus ceruleus-parabrachial nucleus (LC-PBN), giganto- cellular tegmental field (FTG), rostral ventrolateral medulla (RVLM) and dorsal medulla (DM). In the present study attempt was made to examine the role of glutamate receptors in the neurons of above pressor or depressor areas that responded to Glu. 55 cats anesthetized with mixture of urethane and .alpha.- chloralose. The following responses were recorded: systemic arterial pressure , mean systemic arterial pressure, heart rate and sympathetic nerve activities. The later included those of the vertebral nerve (VNA), and renal nerve (RNA). In order to determine the nature of receptor responsible for Glu actions, GDEE was microinjected into the cardiovascular-reactive areas to block the action of quisqualate receptors, while D-AP5 to blockthe NMDA receptors. Also, microinjection of angiotensin II (Ang II) into the same areas, which responded to Glu, was performed to examine whether they could produce the same or different actions. Our results showed that the above mentioned pressor areas, GDEE completely blocked pressor response of SAP increase and augmentation of nerve activities induced by Glu, while D-AP5 was effective only for SAP action but not nerves action. In CVLM, neither GDEE and D-AP5 could block the depressor responses, either SAP or nerves, elicited by Glu. AngII produced similar effects as the same pressor or depressor areas responded to Glu. Our results suggest that: (1) the pressor responses elicited by Glu are primarily mediated by quisqualate receptors, while the depressor responses are not mediated by quisqualate and NMDA receptors, (2) VNA is more closely related with the SAP change than RNA, (3) Glu-sensitive neurons areas are sensitive to Ang II , highly suggested the coexistence of Glu and Ang II receptors in the same neurons.