Effects of esophageal mucosai acid exposure on expression of c-fos protein in central nervous system in ovaibumin sensitized rats / 中华消化杂志

ABSTRACT

Objective To investigate the distribution of neurons expressing Fos protein in central nervous system (CNS) following esophageal mucosal acid exposure,and to map the contribution of spe- cific brain areas in sensitizing responsivity and emphasize the coding change of CNS to the esophageal acid stimulation.Methods Thirty-six healthy Sprague-Dwley rats were randomly divided into five groups. Group A (n=6) was normal group of home cage control animals to which no stimulation was given. Group B (n=7) was saline group which received esophageal perfusion with normal saline solution (0.9% NaCl).Group C (n=8) was treated with esophageal mucosal acid exposure containing 0.1 mol/L HCl. Group D (n=7) was sensitized by ovalbumin.Group E (n=8) received basal ovalbumin-sensitization plus esophageal mucosal acid exposure.The rat model of esophageal visceral hypersensitivity was estab- lished by the basic ovalbumin-sensitization combined with intra-esophageal mucosal acid exposure.The neuronal expressions of c-fos proto-oncogene were detected with immunohistochemical counter-staining and computerized color image analyzer under various conditions.Results The rats in model group with basic ovalbumin-sensitization plus esophageal acid perfusion initiated a high density expression of c-fos- immunoreactive(Fos-IR) neurons in multineuronal networks.A significantly higher number of Fos positive neurons was found in the model group than those in the corresponding regions of other groups (P＜0.05) in the following brain areasfrontal and parietal cortex,insular cortex,cingulated cortex,central amyg- daloid nucleus,the K(?)lliker-Fuse nucleus,the nucleus ambiguus,parabrachial nucleus,hypothalamic paraventricular nucleus,paraventricular thalamic nucleus,paratrigeminal nucleus,the nucleus of solitary tract,area postrema,reticular nucleus of medulla,whereas no significant difference was found in the dorsal motor nucleus of the vagus,supraoptic nucleus,periaqueductal gray matter or orbital part of infe- rior frontal gyrus.The values of Fos-IR neurons were also increased in the central amygdala,parabrachi- al nucleus,paraventricular nucleus,the paratrigeminal nucleus and NTS in the model group than that in the corresponding regions of other groups (P＜0.05).Conclusion The basic ovalbumin-sensitization fa- cilitated dramatically the c-fos expression evoked by esophageal acid perfusion,suggesting that visceral hypersensitivity induced by ovalbumin may alter cortical reactivity processing of esophageal acid stimula- tion in brain areas.