Stress-induced c-fos expression in the medial prefrontal cortex of male rats differentially involves the main glial cell phenotypes

AbstractStress poses a challenge to the body’s equilibrium and triggers a series of responses that enable organisms to adapt to stressful stimuli. The prefrontal cortex (PFC), particularly in acute stress conditions, undergoes significant physiological changes to cope with the demands associated with cellular activation. The proto-oncogene c-fos and its protein product c-Fos have long been utilized to investigate the effects of external factors on the central nervous system (CNS). While c-Fos expression has traditionally been attributed to neurons, emerging evidence suggests its potential expression in glial cells. In this study, our main objective was to explore the expression of c-Fos in glial cells and examine how acute stress influences these activity patterns. We conducted our experiments on male Wistar rats, subjecting them to acute stress and sacrificing them two hours after the stressor initiation. Using double-labelling fluorescent immunohistochemistry targeting c-Fos, along with markers such as GFAP, Iba-1, Olig2, NG2, and NeuN, we analyzed a series of 35 μm brain slices obtained from the medial PFC. Our findings compellingly demonstrate that c-Fos expression extends beyond neurons and is present in astrocytes, oligodendrocytes, microglia, and NG2 cells—the diverse population of glial cells. Moreover, we observed distinct regulation of c-Fos expression in response to stress across the different phenotypes. These results emphasize the importance of considering glial cells and their perspective in studies investigating brain activity, highlighting c-Fos as a response marker in glial cells. By shedding light on the differential regulation of c-Fos expression in response to stress, our study also contributes to the understanding of glial cell involvement in stress-related processes.