Effects of Carbamylated Darbepoetin on Mitochondrial Contacts in Primary Neuronal Cultures

Erythropoietin (EPO) is a hormone that plays a dual role: it regulates erythropoiesis and works as a neuroprotector, the synthesis of which is activated by brain cells in response to hypoxia. Several clinical trials showed that administration of EPO against anemia caused the improvement of cognitive brain functions, however the mechanisms of this action have not yet been characterized. Recently, the usage of Carbamylated darbepoetin (CdEpo), which is neuroprotective but lacks hematopoietic activity and has a more prolonged half-life, has become an attractive tool. The influence of administration of 100 ng/mL CdEpo on the activity and ultrastructural organization of mature hippocampal cultures in normoxic conditions was assessed. It was found that the application of CdEpo in normoxic conditions causes a negative neurotropic influence on neuronal activity that was measured via calcium imaging. Calcium imaging data revealed that CdEpo caused a decrease in the frequency of calcium oscillations; however, the duration of calcium events slightly increased. The decrease in neuronal activity upon administration of CdEpo coincided with compartment-dependent ultrastructural changes. In axons, there was an increase in total mitochondrial area with a decrease in mitochondrial and endoplasmic reticulum contact surface, and in neuronal soma, there was an increase in the surface of intermitochondrial contacts.