Melanocortin signaling is regulated by the binding of naturally occurring antagonists, agoutisignaling protein (ASIP) and agouti-related protein (AGRP) that compete with melanocortin peptides by binding to melanocortin receptors.ASIP overexpression in transgenic zebrafish results in alterations of dorso-ventral pigment pattern.We further demonstrate that ASIP overexpression results in increased growth but not obesity. The differential growth is explained by increased food efficiency and food intake levels, mediated by a differential sensitivity of the satiety system. Brain transcriptome analysis unravels the flow of melanocortinergic information through the central pathways that controls the energy balance. These melanocortin-induced differences are both sex-dependent and independent. Our data also provide information on the transcriptomic differences between the male and female brain. Results provide direct evidences on the involvement of melanocortin systems in fish feeding behavior and growth by melanocortin-induced inhibitory actions on satiety neural circuits. The information provided herein will help to elucidate new central systems involved in control of obesity but should be of invaluable use for sustaining fish production systems.

Background/Aims: The natural anthraquinone derivative emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a component of several Chinese medicinal herbal preparations utilized for more than 2000 years. The substance has been used against diverse disorders including malignancy, inflammation and microbial infection. The substance is effective in part by triggering suicidal death or apoptosis. Similar to apoptosis of nucleated cells erythrocytes may enter suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the triggering of eryptosis include increase of cytosolic Ca²⁺ activity ([Ca²⁺]_i), oxidative stress and ceramide. The present study aimed to test, whether emodin induces eryptosis and, if so, to elucidate underlying cellular mechanisms. Methods: Phosphatidylserine abundance at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca²⁺]_i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: Exposure of human erythrocytes for 48 hours to emodin (≥ 10 µM) significantly increased the percentage of annexin-V-binding cells, and at higher concentrations (≥ 50 µM) significantly increased forward scatter. Emodin significantly increased Fluo3-fluorescence (≥ 10 µM), DCFDA fluorescence (75 µM) and ceramide abundance (75 µM). The effect of emodin on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca²⁺. Conclusions: Emodin triggers phospholipid scrambling of the erythrocyte cell membrane, an effect at least in part due to stimulation of Ca²⁺ entry and paralleled by oxidative stress and ceramide appearance at the erythroctye surface.

Background/Aims: The bioactive steroid sapogenin diosgenin is considered for a wide variety of applications including treatment of malignancy. The substance counteracts tumor growth in part by stimulating apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the stimulation of eryptosis includes increase of cytosolic Ca²⁺ activity ([Ca²⁺]_i), oxidative stress and ceramide. The present study explored, whether diosgenin induces eryptosis and, if so, to decipher cellular mechanisms involved. Methods: Flow cytometry was employed to estimate phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca²⁺]_i from Fluo3-fluorescence, ROS formation from DCF dependent fluorescence, and ceramide abundance utilizing specific antibodies. Hemolysis was quantified by determination of haemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to diosgenin significantly increased the percentage of annexin-V-binding cells (≥ 5 µM), significantly decreased forward scatter (15 µM), significantly increased Fluo3-fluorescence (≥ 10 µM), significantly increased DCF fluorescence (15 µM), significantly increased ceramide abundance (15 µM) and significantly increased hemolysis (15 µM). The effect of diosgenin (15 µM) on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca²⁺. Conclusions: Diosgenin stimulates eryptosis with erythrocyte shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect paralleled by and at least in part due to Ca²⁺ entry, oxidative stress and ceramide.

Background/Aims: The CDC25B inhibitor NSC-95397 triggers apoptosis of tumor cells and is thus considered for the treatment of malignancy. The substance is effective in part by modification of gene expression. Similar to apoptosis of nucleated cells erythrocytes may undergo eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Eryptosis may be triggered by increase of cytosolic Ca²⁺ activity ([Ca²⁺]_i), oxidative stress, ceramide, as well as activation of protein kinases. The present study explored, whether NSC-95397 induces eryptosis and, if so, to shed some light on the mechanisms involved. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca²⁺]_i from Fluo3-fluorescence, ROS formation from DCFDA dependent fluorescence, and ceramide abundance utilizing specific antibodies. Results: A 48 hours exposure of human erythrocytes to NSC-95397 significantly increased the percentage of annexin-V-binding cells (≥ 1 µM), significantly decreased forward scatter (≥ 2.5 µM), and significantly increased Fluo3-fluorescence (≥ 1 µM), DCFDA fluorescence (5 µM) and ceramide abundance (≥ 5 µM). The effect of NSC-95397 (5 µM) on annexin-V-binding was slightly, but significantly blunted by removal of extracellular Ca²⁺ and by addition of the protein kinase C inhibitor staurosporine (1 µM). Conclusions: NSC-95397 triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect in part requiring entry of Ca²⁺ and activation of staurosporine sensitive kinase(s).