Objective To investigate the effect of histamine H3 receptors in nucleus tractus solitarius(NTS) on substance P(SP) in airways of asthma rats. Methods Male Sprague-Dawley(SD) rats were intravenously sensitized with ovalbumin. The model rats,randomly divided into four groups,were placed on a stereotaxic frame,and then were inserted a tube into NTS according the rat brain atlas. When the rat were challenged with ovalbumin iv,NS,R-methylhistamine(RMHA,a H3 receptor receptors agonist) and Thioperamide(Thio,a H3 receptors antagonist) were injected into NTS respectively. SP was detected by immunohistochemistry SABC method and glucose-DAB-nickel technique respectively. The density of SP were quantitatively analyzed by computer image analysis system Results After RMHA were injected into NTS in the asthmatic rats,the number and density of positive fibers in the airways of asthmatic rats decreased significantly(P<0.01). These effects were blocked by pre-microinjecting thioperamide,a H3 receptors antagonist. Conclusion This study suggests that histamine H3 receptors in NTS can ameliorate rat’s asthma by inhibiting the release of SP in airways. |