Endocrine Abstracts

cAMP is implicated in the inhibition or stimulation of proliferation depending on cell type. The activation of cAMP–PKA pathway generates proliferative signals in GH-secreting adenomas whereas this effect is not present, or even opposite, in non-functioning pituitary cells (NFPA). Although cAMP effects were initially attributed to PKA activation, recently the discovery of two cAMP-activated guanine nucleotide exchange factors (Epac1,2) was proposed as a novel mechanism fo...

Dopamine agonists (DA) inhibit prolactin (PRL) secretion and expression on the pituitary lactotrophs by binding dopamine D2 receptor. Prolactinomas are the most common secreting pituitary adenomas, and DA are the first choice for their treatment because they reduce PRL levels and tumor size. However, a subset of patients is resistant to DA. The mechanisms involved in DA resistance are not fully understood, although decreased expression of D2 receptor or altered signal transduc...

Somatostatin exerts inhibitory effects on hormone secretion and cell proliferation by interacting with five different receptors (SST1–SST5) linked to effector systems via G proteins. The receptor structural domains mediating these effects have not been identified. Since SS is the hypothalamic peptide that physiologically inhibits GH secretion, aim of this study was to investigate the molecular determinants mediating the interaction of the human SST5 with G proteins and su...

Dopamine agonist cabergoline (CB) is the first-choice treatment in prolactin-secreting adenomas (PRL-omas). It is effective in reducing PRL secretion and tumour size in about 90% of patients by binding dopamine D2 receptor (DRD2). Although no mutations in DRD2 were found, it has been reported that several polymorphisms of this locus associate with alcoholism and schizophrenia, diseases in which dopaminergic system plays an important role. To assess the possible asso...

Despite the increasing evidence on the relevance of the actin binding protein filamin A (FLNA) in determining an efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors, there is a gap in the knowledge on the mechanisms regulating FLNA itself. FLNA is phosphorylated by PKA on Ser2152 located in a FLNA region crucial for SST2 or partner proteins binding. Although cAMP/PKA pathway plays a crucial role in GH-secreting tumors pathogenesis, the...

Pseudohypoparathyroidism (PHP) is group of heterogeneous disorders characterized by hypocalcemia, hyperphosphatemia and elevated paratormone (PTH) levels as a result of end-organ resistance to PTH. Basal ganglia calcification (BGC) in states of hypoparathyroidism is not uncommon. In PHP, BGC can occur up to 50%; the pathogenesis is poorly defined. The aim of our study was to evaluate the prevalence of BGC at baseline observation in a series of patients with PHP followed at a t...

Currently, the multi-ligand somatostatin (SS) analogue pasireotide (SOM230) is the only pituitary-targeted drug used to treat patients with Cushing’s disease. SOM230 displays the highest affinity to somatostatin receptor type 5 (SSTR5) and compared to octreotide resulted more effective in reducing ACTH release. Despite its anti-secretory role, SOM230 has been associated with tumor shrinkage in patients subjected to long term treatment, although to date the key factors inv...

Background: The treatment of choice in patients with Cushing Disease (CD) is pituitary surgery (PS). A successful PS is generally followed by adrenal insufficiency (AI). Although the remission rate after PS may reach 96.6% of cases, approximately 1/3 of cured patients experience the recurrence of the disease during lifetime. The aim of this study was to analyze the duration of AI in relation with the recurrence of CD.Materials and methods: We performed a...

Introduction: Hypoparathyroidism (HPT), pseudohypoparathyroidism (PHP), and end-organ parathyroid hormone (PTH)-resistance are rare metabolic disorders characterized by low serum calcium and increased serum phosphorus due to a PTH-deficient or resistant state. Various genes/loci have been identified as responsible for the development of congenital/familial forms of HPT, PHP and related diseases.Patients and Methods: A total of 39 patients with a clinical...

Introduction: Testosterone replacement therapy (TRT) in male hypogonadism aims at restoring physiological plasma testosterone (T) levels. According to current guidelines, gel formulations should resemble better the circadian T secretion and offer physiological and consistent T concentrations. However, only a few real-life studies have assessed intra-individual reproducibility of T levels in patients treated with gel formulations.Methods: Thirty patients ...