TY - JOUR T1 - Evaluation of specific lesion of ventrolateral PAG projecting to NRM by ibotenic acid using formalin test TT - بررسی اثر تخریب اختصاصی مسیر شکمی- جانبی PAG به NRM توسط نوروتوکسین Ibotenic Acid در آزمون فرمالین JF - Physiol-Pharmacol JO - Physiol-Pharmacol VL - 4 IS - 2 UR - http://ppj.phypha.ir/article-1-217-en.html Y1 - 2000 SP - 213 EP - 218 KW - Excitatory amino acids; Analgesia; NRM KW - VL PAG; Formalin test N2 - It has been reported that neurons in the VL PAG projecting to nucleus raphe magnus (NRM) utilize excitatory amino acids as neurotransmitter. This projection plays an important role in the descending pain modulatory system. In order to determine the role of this pathway in pain perception, male rats received unilateral injection of ibotenic acid stereotaxically. For lesioning VL PAG, unilateral injection of ibotenic acid (0.2 and 0.5 µl) (a specific neurotoxin for EAA-containing neurons) was made. After a week recovery period, the nociception was evaluated using formalin test for a period of 60 min. At the end of experiments, animals were perfused by formaldehyde 10%. Serial sections (80 µm) wee prepared using vibratome. The sections were then Nissl stained and examined to determine the lesion location. The results revealed a significant increase in the first phase of formalin test. However, in the second phase, only 0.5 µl of the neurotoxin caused a significant decrease in pain perception. It is concluded that NMDA receptors within the PAG are involved in the perception of pain as measured in the formalin test. M3 ER -