Endocrine Abstracts

Introduction: Somatostatins are physiological down regulatory proteins that act via 5 different transmembrane receptors (SSTR1-5, including isoforms SSTR-2a & 2b) via GTP binding proteins. The aim of this study was to determine the distribution of somatostatin receptors in thyrocytes of different thyroid pathologies.
Method: Formalin fixed paraffin embedded sections from archival tissue were immunostained. Sections underwent dewaxing and rehydration before microwave antigen retieval, followed by blocking. Sections were incubated overnight at 4^oC in primary antibody diluted at 1:10000. Followed by secondary antibody, streptavidin-biotin-peroxidase, amplification and streptavidin-peroxidase. Staining was then visualised with diaminobenzadine.
Results: The number of sections expressing positive SSTR subtype staining in relation to type of thyroid pathology. Follicular adenoma (n=10): SSTR-1 8/10, SSTR-2A 9/10, SSTR-2B 10/10, SSTR-3 10/10, SSTR-4 9/10, SSTR-5 8/10. Hashimotos thyroiditis (n=5): SSTR-1 4/5, SSTR-2a 5/5, SSTR-2B 5/5, SSTR-3 4/5, SSTR-4 4/5, SSTR-5 5/5. Reidels thyroiditis (n=1): SSTR-1 1/1, SSTR-2a 1/1, SSTR-2b 1/1, SSTR-3 1/ 1, SSTR-4 1/1, SSTR-5 1/1. Papillary carcinoma (n=6): SSTR-1 5/6, SSTR-2a 4/6, SSTR-2b 5/6, SSTR-3 5/6, SSTR-4 5/6, SSTR-5 6/6. Graves disease (n=2): SSTR-1 2/2, SSTR-2a 1/2, SSTR-2b 2/2, SSTR-3 2/2, SSTR-4 2/2. SSTR-5 2/2. Anaplastic carcinoma (n=1): SSTR-1 1/1, SSTR-2a 1/1, SSTR-2b 1/1, SSTR-3 1/1, SSTR-4 1/1, SSTR-5 0/1. Follicular carcinoma (n=1): SSTR-1 1/1, SSTR-2a 1/1, SSTR-2b 1/1, SSTR-3 0/1, SSTR-4 1/1, SSTR-5 1/1. Multinodular goitre (n=17): SSTR-1 15/17, SSTR-2a 14/17, SSTR-2b 16/17, SSTR-3 14/17, SSTR-4 14/17, SSTR-5 16/17.
Conclusion: This preliminary data suggests that the SSTRs are widely distributed in thyroidal pathology and their role needs to be defined.