Endocrine Abstracts

Introduction: Ghrelin is known to strongly stimulate growth hormone release from the pituitary. It was also found to be produced locally in hypothalamus and anterior pituitary and in different types of pituitary adenomas. It’s been suggested that ghrelin synthesized locally in hypothalamo–pituitary area or within pituitary tumours can be an important factor contributing to pituitary tumorogenesis.

Aim: The aim of the study was the immunohistochemical assessment of ghrelin expression in somatotroph and non-functioning pituitary tumours and the comparison of the presence of ghrelin in somatotropinomas treated and untreated preoperatively with a long acting somatostatin analogue.

Materials and methods: The studied material consisted of somatotroph and non-functioning pituitary tumours tissues obtained during neurosurgical removal of the tumour. There were somatotropinomas obtained from patients treated with a somatostatin analogue (octreotide LAR) before the surgery and not treated (paraffin sections collected in the past when SS analogues were not routinely used in presurgical farmacotherapy). As a control for immunohistochemical analysis, the mucous membranes of the stomach (obtained during gastrectomy due to stomach neoplasms) as well as normal pituitary tissues (obtained during autopsy) were used. Tumour tissue samples were placed in formaline and then in paraffine. Immunohistochemical study was done with the use of rabbit polyclonal antibodies against human ghrelin 1:400 in TBS (Phoenix Pharmaceuticals, Inc).

Results: Immunohistochemical analysis confirmed that ghrelin is present in non-functioning pituitary tumours and somatotroph adenomas, even after the treatment with octreotide LAR. Characteristic staining was observed in the cytoplasm of cells, in some of them predominantly in perinuclear area. The expression of ghrelin was also shown in normal pituitary, it was, however, restricted only to few cells.

Conclusions: The results of the study confirmed the presence of ghrelin in non-functioning adenomas and somatotropinomas, also after farmacotherapy. Further studies would allow a better understanding of pituitary tumours pathogenesis.