Relationships between glutamine, glutamate, and GABA in nerve endings under Pb-toxicity conditions

Direct and indirect effects of corticosteroids on astrocyte function

Corticosteroids are used for a variety of conditions; among the most well-known uses are for asthma and eczema. We review here the direct and indirect effects of corticosteroids on astrocyte physiology. Astrocytes play an important role in communication between neural cells, as one astrocyte can communicate with many neurons. They are also central in bringing nutrients through the blood-brain barrier (BBB) to the brain areas they serve. Therefore, any chemical or pharmaceutical product entering the brain via the BBB will first come into contact with the astrocytes. We discuss the direct effects that corticosteroids have on astrocyte physiology and functioning; these include inhibited glucose transport, decreased glycogen synthesis and decreased glutamate uptake. Furthermore, the indirect effects of corticosteroids on astrocytes are also reviewed. We know that corticosteroids lower neural serotonin. Lowered serotonin affects astrocyte functioning, and particularly astrocytic cAMP activities, a decrease in cytokine activities and impaired GABA uptake. These can be seen as the indirect effects of corticosteroids on astrocyte physiology. Corticosteroids therefore have a pertinent effect on neuro-energetics due to astrocyte physiology impairment, and this may ultimately be the reason for memory impairment of patients who chronically use corticosteroids.