Octreotide modulates expression of somatostatin receptor subtype 4 and 5 in unweaned rat jejunum inflamed by Cryptosporidium parvum / 中国药理学通报

ABSTRACT

Aim To investigate the effects of intestinal infection induced by Cryptosporidium parvum on the ex-pression pattern of SSTR4 and SSTR5 subtype, and to examine the effect of octreotide on modulating short-term and long-term SSTR4 and SSTR5 subtype expres-sion in rat jejunum. Methods Five-day-old suckling Sprague-Dawley rats were orally gavaged with 105Cryp-tosporidium oocysts to establish the model of post-infec-tion irritable bowel syndrome (PI-IBS). Rats then re-ceived 50 μg·kg-1·d-1of octreotide by intraperito-neal injection from day 10 to day 17 post-infection. Animals were sacrificed on day 17,37 and 50 post-in-fection for immunohistochemical analysis and on day 14,35 and 50 for mRNA expression analysis of SSTR4 and SSTR5 subtypes. Results Immunohistological a-nalysis of jejunum tissues demonstrated that SSTR5 was mainly expressed in submucosa while a little in crypt,while SSTR4 was mainly expressed in crypt while a lit-tle in submucosa and absorptive cells. Real-time PCR analysis indicated a significant increase of SSTR4 and SSTR5 expression in the inflamed jejunum. Octreotide treatment decreased the expression of SSTR4 and SSTR5 on day 50 post-infection. Conclusions SSTR4 and SSTR5 may be involved in the inflammatory reac-tion in PI-IBS rats induced by Cryptosporidium parvu-man, which shows an increase in SSTR4 and SSTR5 mRNA expression in jejunum. Octreotide therapy in-hibits the jejunum hypersensitivity and relieve PI-IBS symptoms, which may be related to the decrease of SSTR4 and SSTR5 expression.