G protein-coupled receptors (GPCRs) are seven transmembrane-spanning proteins belonging to a large family of cell-surface receptors involved in many intracellular signaling cascades. Despite GPCRs lack intrinsic tyrosine kinase activity, tyrosine phosphorylation of a tyrosine kinase receptor (RTK) occurs in response to binding of specific agonists of several such receptors, triggering intracellular mitogenic cascades. This suggests that the notion that GPCRs are associated with the regulation of post-mitotic cell functions is no longer believable. Crosstalk between GPCR and RTK may occur by different molecular mechanism such as the activation of metalloproteases, which can induce the metalloprotease-dependent release of RTK ligands, or in a ligand-independent manner involving membrane associated non-receptor tyrosine kinases, such as c-Src. Reactive oxygen species (ROS) are also implicated as signaling intermediates in RTKs transactivation. Intracellular concentration of ROS increases transiently in cells stimulated with GPCR agonists and their deliberated and regulated generation is mainly catalyzed by enzymes that belong to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family. Oxidation and/or reduction of cysteine sulfhydryl groups of phosphatases tightly controls the activity of RTKs and ROS-mediated inhibition of cellular phosphatases results in an equilibrium shift from the non-phosphorylated to the phosphorylated state of RTKs. Many GPCR agonists activate phospholipase C, which catalyze the hydrolysis of phosphatidylinositol 4,5-bis-phosphate to produce inositol 1,4,5-triphosphate and diacylglicerol. The consequent mobilization of Ca²⁺ from endoplasmic reticulum leads to the activation of protein kinase C (PKC) isoforms. PKCα mediates feedback inhibition of RTK transactivation during GPCR stimulation. Recent data have expanded the coverage of transactivation to include Serine/Threonine kinase receptors and Toll-like receptors. Herein, we discuss the main mechanisms of GPCR-mediated cell-surface receptors transactivation and the pathways involved in intracellular responses induced by GPCR agonists. These studies may suggest the design of novel strategies for therapeutic interventions.

Context: Polycystic ovary syndrome (PCOS) is an endocrine disease closely related to several risk factors for cardiovascular disease. An impaired cardiopulmonary functional capacity was previously demonstrated in PCOS women. No data regarding the effects of a structured exercise training (ET) program on cardiopulmonary functional capacity in PCOS women are available. Objective: Our objective was to evaluate the effects of a 3-month ET program on cardiopulmonary functional capacity in young PCOS women. Design and Setting: A prospective baseline-randomized clinical study was conducted at the University “Federico II” of Naples, School of Medicine (Italy). Patients: Ninety young overweight PCOS women were enrolled. Mean Outcome Measures: Ninety young PCOS women were randomly subdivided into two groups, each composed of 45 subjects. The PCOS-T (trained) group underwent a 3-month structured ET program, whereas the PCOS-UnT (untrained) group did not. Hormonal and metabolic profiles and cardiopulmonary and exercise parameters were evaluated. Results: After 3-month ET, PCOS-T showed a significant improvement in peak oxygen consumption (+35.4%; P < 0.001) and in maximal workload (+37.2%; P < 0.001). In PCOS-T we also observed a significant reduction in body mass index (−4.5%; P < 0.001) and in C-reactive protein (−10%; P < 0.001), and a significant (P < 0.001) improvement in insulin sensitivity indexes. After 3 months, no changes were observed in PCOS-UnT. Conclusions: A 3-month structured ET program improves cardiopulmonary functional capacity in young PCOS women.

Ectopic thyroid tissue remains a rare developmental abnormality involving defective or aberrant embryogenesis of the thyroid gland during its passage from the floor of the primitive foregut to its usual final position in pre-tracheal region of the neck. Its specific prevalence accounts about 1 case per 100.000-300.000 persons and one in 4.000-8.000 patients with thyroid disease show this condition. The cause of this defect is not fully known. Despite genetic factors have been associated with thyroid gland morphogenesis and differentiation, just recently some mutation has been associated with human thyroid ectopy. Lingual region in the most common site of thyroid ectopy but ectopic thyroid tissue were found in other head and neck locations. Nevertheless, aberrant ectopic thyroid tissue has been found in other places distant from the neck region. Ectopic tissue is affected by different pathological changes that occur in the normal eutopic thyroid. Patients may present insidiously or as an emergency. Diagnostic management of thyroid ectopy is performed by radionuclide thyroid imaging, ultrasonography, CT scan, MRI, biopsy and thyroid function tests. Asymptomatic euthyroid patients with ectopic thyroid do not usually require therapy but are kept under observation. For those with symptoms, treatment depends on size of the gland, nature of symptoms, thyroid function status and histological findings. Surgical excision is often required as treatment for this condition.

Women with polycystic ovary syndrome (PCOS) have been reported to have subclinical cardiovascular disease (CVD) and increased abdominal fat. The aim of this study was to evaluate the relationship between visceral fat (VF) and early markers of CVD in PCOS women. Two hundred overweight PCOS women [(mean ± SD) age 24.6 ± 3.2 years, body mass index (BMI) 28.5 ± 2.8 kg/m²] and 100 healthy age- and BMI-matched volunteer controls entered this cross-sectional study. In all subjects, the amount of VF was measured by ultrasonography. Anthropometric measurements [BMI and waist circumference (WC)], complete hormonal and metabolic pattern, carotid intima-media thickness (IMT), brachial arterial flow-mediated dilation (FMD) and inflammatory biomarkers [C-reactive protein (CRP), fibrinogen, white blood cells count and plasminogen activated inhibitor-1] were also obtained from all subjects. A stepwise linear regression model was used in PCOS patients to verify if IMT or FMD as dependent variables are affected by other independent variables. VF amount was significantly (P < 0.001) higher in PCOS subjects than in healthy controls [31.4 ± 7.3 versus 28.0 ± 6.1 (mean±SD) mm, respectively] and directly related to insulin resistance: HOMA (r = 0.918, P < 0.001) and AUC_INS (r = 0.879, P < 0.001), and to WC (r = 0.658; P < 0.001). In PCOS, the two linear regression analyses showed that IMT is positively affected by VF and CRP, whereas FMD is positively affected by IMT and negatively by VF and CRP. VF amount is associated with subclinical CVD in PCOS patients.

It is extremely important for the health to understand the regulatory mechanisms of energy expenditure. These regulatory mechanisms play a central role in the pathogenesis of body weight alteration. The hypothalamus integrates nutritional information derived from all peripheral organs. This region of the brain controls hormonal secretions and neural pathways of the brainstem. Orexin-A is a hypothalamic neuropeptide involved in the regulation of feeding behavior, sleep-wakefulness rhythm, and neuroendocrine homeostasis. This neuropeptide is involved in the control of the sympathetic activation, blood pressure, metabolic status, and blood glucose level. This minireview focuses on relationship between the sympathetic nervous system and orexin-A in the control of eating behavior and energy expenditure. The “thermoregulatory hypothesis” of food intake is analyzed, underlining the role played by orexin-A in the control of food intake related to body temperature. Furthermore, the paradoxical eating behavior induced orexin-A is illustrated in this minireview.