Changes of c-Fos Immunoreactivity in Midbrain by Deep Pain and Effects of Aspirin.
- Author:
Jin A JUNG
1
;
Ki Soo YOO
;
Kyu Keun HWANG
Author Information
1. Department of Pediatrics, College of Medicine, Dong-A University, Busan, Korea. jina1477@daunet.donga.ac.kr
- Publication Type:Original Article
- Keywords:
Aspirin;
Pain;
Formalin;
c-Fos;
PAG
- MeSH:
Animals;
Aspirin*;
Body Regions;
Brain;
Formaldehyde;
Humans;
Male;
Mesencephalon*;
Neurons;
Nociceptive Pain;
Rats;
Rats, Sprague-Dawley
- From:Journal of the Korean Pediatric Society
2003;46(7):695-701
- CountryRepublic of Korea
- Language:Korean
-
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.
