Immunoreactivity in brain glial cells in young and adults rats after pain stimuli during the neonatal period

Abstract

The aim of the present study is to evaluate the sensorimotor development of female and male Wistar rats submitted to painful or tactile procedures on birth. The morphological and morphometric parameters of sural nerve in these animals will be investigated. Furthermore, this study aims to determine possible changes in the prefrontal areas, anterior insula, anterior cingulated and somatosensory cortex resulting from painful procedures. Therefore, we used 48 animals, divided into eight groups: I (6 control rats at 15 days of life), II (6 control rats at 15 days of life), III (6 rats with controls 180 days of life), IV (6 control rats with 180 days of life), V (6 rats with 15 days of life, stimulated with painful procedures in neonatal period), VI (6 rats at 15 days old, stimulated with painful procedures in neonatal period); VII (6 rats with 180 days old, stimulated with painful procedures in neonatal period), VIII (6 rats of 180 days, stimulated with painful procedures in neonatal period). The animals were tested behaviorally for mechanical withdrawal thresholds of the paw and muscle, and for gait alterations. On the day of the experiment (on either day 15 on the last day of stimulation or when they reached 6 months of age), the right and left sural nerves were dissected and immersed in glutaraldehyde 2.5% in continuous orbital agitation for 72 hours. Afterwards, the rats were perfused with buffered saline solution (0.1 M PBS, pH 7.4), followed by 4% of paraformoldehyde, so the brains could be dissected. After preparation with conventional histological techniques, cross-sections of sural nerves were obtained for analysis by light microscopy. The morphometric analysis was performed with a software (KS 400, version 2.0). The analysis of the sural nerve in transmission electron microscopy will be performed abroad, using a JEM-1230 (JEOL Ltd.), on the "Central Microscopy Facility," at the University of Iowa. In addition, double labeling and immunofluorescence analysis of glial cells in the brain will be performed during the internship abroad on the "Neurobiology of Pain Laboratory" at the University of Iowa. The statistical analysis will be performed by specific statistical tests. Significant differences will be consider when p <0.05. (AU)