Octreotide modulates the expression of somatostatin receptor subtypes in inflamed rat jejunum induced by Cryptosporidium parvum

Somatostatins are proteins that are involved in gastrointestinal function. However, little is known with regard to somatostatin receptor subtype (SSTR) expression changes that occur in the jejunum during low-grade inflammation and during subsequent octreotide treatment. The aim of the present study was to investigate the expression of SSTRs in the jejunums of Cryptosporidium parvum (C. parvum)-infected rats by immunohistochemisty, reverse transcription (RT) PCR and quantitative real-time RT-PCR assays. Five-day-old suckling Sprague-Dawley rats (n = 15 for each group) were orally gavaged with 105 Nouzilly isolate (NoI) oocysts. Rats then received 50 μg/kg/day of octreotide by intraperitoneal injection from day 10 to day 17 post-infection. Animals were sacrificed on days 7 and 14 post-infection for immunohistochemical analysis and on days 14, 35 and 50 for mRNA expression analysis of SSTR subtypes. Histological analysis of jejunum tissues demonstrated infection of C. parvum along the villus brush border on day 7 post-infection and infection clearance by day 14 post-infection. Real-time PCR analysis indicated that in the inflamed jejunum, a significant increase in SSTR1 and SSTR2 expression was observed on day 14 post-infection. Octreotide therapy down-regulated the expression of SSTR2 on day 37 post-infection but significantly increased expression of SSTR1, SSTR2 and SSTR3 on day 50 post-infection. The results indicate that specific SSTRs may regulate the inflammatory pathway in the rat intestinal inflammation model.