ECE2019 Poster Presentations Pituitary and Neuroendocrinology 1 (72 abstracts)
1Neuroendocrinology Department, Clinic for Endocrinology, Diabetes and Metabolic Diseases, Clinical Centre of Serbia, Belgrade, Serbia; 2University of Belgrade, Medical Faculty, Belgrade, Serbia; 3Department of Medicine for Endocrinology, Diabetes and Nutritional Medicine, Charité Universitätsmedizin, Campus Mitte, Berlin, Germany; 4Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK; 5Insitute of Medical Statistics and Informatics, Belgrade, Serbia.
Background and aim: Aryl hydrocarbon receptor-interacting protein (AIP) is evolutionary conserved and widely distributed throughout organism. Broad interest for AIP comes from involvement of loss-of-function AIP mutations in pituitary adenoma pathogenesis. The role of AIP in normal pituitary function is largely unknown. AIP is co-localized with GH in somatotroph secretory vesicles. Serum AIP protein was proteomically identified. We aimed at investigating whether AIP and GH are co-secreted by measuring serum AIP and GH levels at baseline and after GH stimulation and suppression tests using in vivo human models of normal GH secretion, patients with GH deficiency (GHD) and patients with GH hypersecretion - acromegaly.
Subjects and methods: ITT was performed in GHD patients (n=13) and age-BMI-matched non-GHD controls (n=31). OGTT was performed in patients with active acromegaly (n=26) and age-BMI-matched controls (n=18) with normal GH suppressibility. In-house immunometric AIP assay was developed and employed.
Results: Serum AIP was independent of gender, age or BMI. Baseline AIP levels did not differ in GHD and non-GHD subjects nor did AIPmax, AIP-AUC or AIP-Delta in ITT. AIP levels did not correlate with GH, PRL or cortisol levels in ITT. Baseline AIP, AIPmax, AIP-AUC or AIP-Delta did not differ between patients with active acromegaly versus control subjects at baseline and during GH suppression test (OGTT). Serum AIP values did not significantly change during ITT or OGTT.
Conclusions: A novel immunometric assay was employed for the first time to assess human circulating serum AIP in vivo. Serum AIP levels were independent of age, sex or BMI, and were unaffected by hypoglycemia or hyperglycemia. Contrary to expectations based on secretory vesicles co-localization of AIP and GH, no correlation was found between serum AIP and GH secretion at baseline nor during GH stimulation (ITT) and GH suppression tests (OGTT). A platform of reliable serum AIP measurement is established for further research of the circulatory source, role and impact for this highly conserved protein essential for survival.