Análise morfológica das alterações periféricas e centrais em modelo experimental de neuralgia

Abstract

Introduction: Trigeminal neuralgia (TN) is a severe chronic disease characterized by lancinating pain and it is limited on one or more branches of the trigeminal nerve. The partial ligation model has been shown as an effectively simulate many of the characteristics of human neuropathic pain syndromes. Objectives: To evaluate morphological changes in the trigeminal pathway in induced neuropathy by infraorbital nerve ligation (ION) in rats. Methods: Wistar rats were used with 6 animals per group, being: C, TN and TN-Sham. TN was induced through ION constriction. The nociceptive threshold was measured through the use of analgesimeters in the region of the skin of the vibrissae (SV). The animals were euthanized and collected skin, ION, trigeminal ganglion (TG) and trigeminal spinal tract (ST - Sp5c region) on the 21st day after surgical procedure. Immunofluorescence was performed with DAPI, anti-PGP 9.5, anti-NeuN, anti-ATF-3, anti-c-Fos, anti-PBM antibodies. Results: In the evaluation of mechanical nociception it was verify a reduction of the nociceptive threshold in the neuropathic group. In immunofluorescence, a significant increase of c-Fos expression was observed in the TN group in TG and ST, whereas the ATF-3 labeling showed an expressive increase only in TG. There was a significant increase in the expression of MBP in ION and of PGP 9.5 in VS only in the neuropathic group. Conclusion: Morphological changes were observed along the nociceptive pathway, suggesting that they may be responsible for and perpetuating the neuropathic condition in the ION model of rats. Significance: The recognition of alterations in the trigeminal nociceptive pathway is useful for the understanding of the onset and factors that maintain trigeminal pain, serving as a basis for the adoption of pharmacological and non-pharmacological therapies.