Somatostatin receptor 1-5; expression profiles during rat development.
BACKGROUND
Somatostatin acts through five receptor subtypes (SSTRs 1-5). We aimed to investigate SSTRs mRNA expression and protein distribution in whole rat embryos, with special emphasis on the pancreas.


METHODS
Rat embryos were collected on embryonal days 10, 11, 12, 14, 15, 17, 19, 21, and at birth. Presence of SSTRs was investigated with RT-PCR techniques and immunohistochemistry.


RESULTS
There was no SSTR5 mRNA expression in the whole rat embryos. All SSTR1-5 proteins were observed at embryonal day 10, but the localization varied between the different subtypes. From day 11 to birth SSTRs protein presence increased with time in major structures such as skin and cartilage. It remained similar over time in the heart and liver. In the fetal pancreas mRNA expression of SSTR2 and 4 was detected at day 14, and there was an increase up to birth. Only SSTR1 protein co-localized to a higher extent with the islet hormones studied. SSTR2 was present in all islet endocrine cells except for β-cells. In contrast, the immunostaining for SSTR3-4 was co-localized with insulin and PP, and, finally, SSTR5 with glucagon and pancreatic polypeptide. In mRNA isolated from whole rat embryos SSTR1-2 and SSTR4 expression showed a peak at day 14, while SSTR3 mRNA was not present until day 15.


CONCLUSIONS
The present data suggest a role for SSTRs during the development of the rat embryo. Subsequent functional studies may elucidate regulatory roles of specific SSTRs for the growth and differentiation of the pancreas as well as other organs.
Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden.
Eva
E
Ludvigsen
Carina
C
Carlsson
Eva
E
Tiensuu Janson
Stellan
S
Sandler
Mats
M
Stridsberg
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism*; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D010179:Pancreas / Q000196:embryology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017481:Receptors, Somatostatin / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059467:Transcriptome
D015415:Biomarkers; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; C115977:Sstr2 protein, rat; C103631:somatostatin receptor 3; C098681:somatostatin receptor subtype-4; C101130:somatostatin receptor type 1; C094573:somatostatin receptor 5
Development; mRNA expression; pancreas; rat embryo; somatostatin receptors