Substance P in Dorsal Root Ganglion Neurons in Young and Adult Rats, after Nociceptive Stimulation during the Neonatal Period

Author(s)

Bertoncini Simoes, Ana Leda ^[1] ; Rodrigues Silva, Greice Anne ^[2] ; Giorgetto, Carolina ^[2] ; do Carmo-Campos, Elisabete de Cassia ^[2] ; Dias, Fernando Jose ^[3] ; Sassoli Fazan, Valeria Paula ^{[2, 1]}

Affiliation

^[1] Univ Sao Paulo, Dept Surg & Anat, Sch Med Ribeirao Preto, BR-14049900 Ribeirao Preto - Brazil

^[2] Univ Sao Paulo, Dept Neurosci & Behav Sci, Sch Med Ribeirao Preto, BR-14049900 Ribeirao Preto - Brazil

^[3] Univ La Frontera, Sch Dent, Dept Integral Dent, CICO Res Ctr Dent Sci, Temuco - Chile

• Document type: Journal article
• Source: Anatomical Record-Advances in Integrative Anatomy and Evolutionary Biology; v. 301, n. 5, p. 849-861, MAY 2018.
• Web of Science Citations: 1

Abstract

The nervous system is highly plastic during the neonatal period, being sensitive to noxious stimuli, which may cause short- and long-term pain responsivity changes. Understanding plasticity in peripheral pain pathways is crucial, particularly when the nervous system is still under development and remodeling process. Substance P (SP) is widely used as a marker for peripheral neurons with unmyelinated and small myelinated fibers. We investigated the number of SP immunoreactive neurons in the dorsal root ganglion (DRG) of male and female Wistar rats, 15 and 180 days after nociceptive stimulation during the neonatal period. Right and left 5th lumbar (L5) DRG were incubated in rabbit polyclonal anti-substance P primary followed by biotinylated donkey anti-rabbit secondary antibodies. Reaction was revealed with a nickel-diaminobenzidine solution. Labeled neurons were counted and compared between ages, genders and groups. Gender differences were present in both ages, with the number of SP-positive DRG neurons being larger in 15-days-old males on both sides. After 180 days, males showed a larger number of SP-positive neurons than females only on the nociceptive stimulated side. An increased number of SP-positive neurons in the DRG on the stimulated side was present in females, immediately after nociceptive stimulation, but not after 180 days. In conclusion, neonatal noxious stimulation caused a permanent increase in SP-positive DRG neurons in males that was not observed in females, suggesting that differences in pain processing/responsivity between genders could be related to morphological alterations of the nervous system. Anat Rec, 301:849-861, 2018. (c) 2017 Wiley Periodicals, Inc. (AU)

• FAPESP's process: 13/20549-7 - New insights in cardiovascular regulation under physiological and pathophysiological condition
• Grantee: Helio Cesar Salgado
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/07253-4 - Effect of the association between the low-level laser and the purified protein from natural latex (Hevea brasiliensis) on the crush injured sciatic nerve in wistar rats: functional, sensorial, morphometric and ultrastructural study
• Grantee: Fernando José Dias
• Support Opportunities: Scholarships in Brazil - Post-Doctoral