Cloned microglial cells but not macrophages synthesize beta-endorphin in response to CRH activation

The properties of microglial cell clones, obtained from embryonic mouse brain primary cultures immortalized with recombinant retroviruses, have been investigated and compared with the properties of macrophage clones similarly obtained. Macrophage clones differed from microglial clones in some functions but shared most of the immunological properties. Interestingly, microglial cells were able to produce beta-endorphin, and this production was regulated differently in microglial cell clones when compared with macrophages clones. Although lipopolysaccharide (LPS) treatment induces an increase in beta-endorphin concentration in both cell types, only microglial clones and primary microglial cell cultures respond to the neuroendocrine stimulus corticotropin releasing hormone (CRH). In addition, in these cells, beta-endorphin release is regulated by a classical neurotransmitter, such as noradrenaline, adding some evidence of communication between neurons and microglial cells.