Journal of the Korean Pediatric Society 2003;46(7):695-701.
Published online July 15, 2003.
Changes of c-Fos Immunoreactivity in Midbrain by Deep Pain and Effects of Aspirin
Jin A Jung1, Ki Soo Yoo2, Kyu Keun Hwang1
1Department of Pediatrics, College of Medicine, Dong-A University, Busan, Korea
2Department of Anatomy, College of Medicine, Dong-A University, Busan, Korea
심부통증이 흰쥐 중뇌에 미치는 c-Fos 면역반응성의 변화와 아스피린의 효과
정진아1, 유기수2, 황규근1
1동아대학교 의과대학 소아과학교실
2동아대학교 의과대학 해부학교실
Abstract
Purpose
: It had been suggested that pain arising from deep somatic body regions influences neural activity within periaqueductal gray(PAG) of midbrain via distinct spinal pathways. Aspirin is one of the popular non-steroidal anti-inflammatory drugs used in the management of pain. Fos expression was used as a marker for neuronal activity throughout central neurons following painful peripheral stimulation. This study was prepared to investigate changes of c-Fos immunoreactivity in midbrain by deep pain and effects of aspirin.
Methods
: Male Sprague-Dawley rats were injected with 0.1 mL of 5% formalin in the plantar muscle of the right hindpaw. For experimental group II, aspirin was injected intravenously before injection of formalin. An aspirin-untreated group was utilized as group I. Rats were sacrificed at 0.5, 1, 2, 6 and 24 hours after formalin injection. Rat's brains were removed and sliced in rat brain matrix. Brain slices were coronally sectioned at interaural 1.00-1.36 mm. Serial sections were immunohistochemically reacted with polyclonal c-Fos antibody. The numbers of c-Fos protein immunoreactive neurons in ventrolateral periaqueductal gray(VLPAG) and dorsomedial periaqueductal gray(DMPAG) were counted and analyzed statistically with Mann-Whitney U tests.
Results
: Higher numbers of c-Fos protein immunoreactive neurons were found in VLPAG. In both VLPAG and DMPAG of formalin-treated group, the numbers of c-Fos protein immunoreactive neurons were significantly higher at all time points than the formalin-untreated group, which peaked at two hours. The numbers of c-Fos immunoreactive neuron of the aspirin-treated group were less compared to the aspirin-untreated group at each time point.
Conclusion
: These results provide some basic knowledge in understanding the mechanism of formalin-induced deep somatic pain and the effects of aspirin.
Key Words: Aspirin, Pain, Formalin, c-Fos, PAG


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