Microinjection of Glutamate into the Amygdala Modulates Nociceptive and Cardiovascular Response in Freely Moving Rats

• 영문명: Microinjection of Glutamate into the Amygdala Modulates Nociceptive and Cardiovascular Response in Freely Moving Rats
• 발행기관: 대한생리학회-대한약리학회
• 저자명: Dong-Kuk Ahn Yun-Sook Kim Jae-Sik Park
• 간행물 정보: 『The Korean Journal of Physiology & Pharmacology』제2권 제6호, 687~693쪽, 전체 7쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1998.01.01

영문 초록

This study was performed to examine the mean arterial pressure and nociceptive jaw opening reflex after microinjection of glutamate into the amygdala in freely moving rats, and to investigate the mechanisms of antinociceptive action of amygdala. Animals were anesthetized with pentobarbital sodium (40 mg/kg, ip). A stainless steel guide cannula (26 gauge) was implanted in the amygdala and lateral ventricle. Stimulating and recording electrodes were implanted into each of the incisor pulp and anterior digastric muscle. Electrodes were led subcutaneously to the miniature cranial connector sealed on the top of the skull with acrylic resin. After 48 hours of recovery from surgery, mean arterial pressure and digastric electromyogram (dEMG) were monitored in freely moving rats. Electrical shocks (200 Ռsec duration, 0.5∼2 mA intensity) were delivered at 0.5 Hz to the dental pulp every 2 minutes. After injection of 0.35 M glutamate into the amygdala, mean arterial pressure was increased by 8⁑2 mmHg and dEMG was suppressed to 71⁑5% of the control. Injection of 0.7 M glutamate elevated mean arterial pressure by 25⁑5 mmHg and suppressed dEMG to 20⁑7% of the control. The suppression of dEMG were maintained for 30 minutes. Naloxone, an opioid receptor antagonist, inhibited the suppression of dEMG elicited by amygdaloid injection of glutamate from 28⁑4 to 68⁑5% of the control. Methysergide, a serotonin receptor antagonist, also inhibited the suppression of dEMG from 33⁑5 to 79⁑4% of the control. However, phentolamine, an Ձ-adrenergic receptor antagonist, did not affect the suppression of dEMG. These results suggest that the amygdala can modulate both cardiovascular and nociceptive responses and that the antinociception of amygdala seems to be attributed to an augmentation of descending inhibitory influences on nociceptive pathways via serotonergic and opioid pathways.

키워드

Amygdala Glutamate Jaw opening reflex Antinociception Freely moving rats