Localization of glucocorticoid-induced leucine zipper (GILZ) expressing neurons in the central nervous system and its relationship to the stress response

The glucocorticoid-induced leucine zipper (GILZ) is a 137 amino acid protein, which was originally identified as a dexamethasone-inducible gene, and is characterized by a leucine zipper domain, an N-terminal domain and a C-terminal proline and glutamic acid rich domain. In this study, we performed in situ hybridization analyses and found that many neurons from the olfactory bulb to the spinal cord express GILZ mRNA, suggesting that GILZ is involved in fundamental and common cellular events of neurons. In addition, the predominant expression of GILZ mRNA in the motor nuclei indicated a strong relationship between GILZ and the motor nervous system. On the other hand, real-time RT-PCR analyses of brains of animals exposed to water-immersion restraint stress (WRS) showed that WRS significantly up-regulated GILZ expression in the medial prefrontal cortex (mPFC) and hippocampus, which are known to be mental stress-related areas, suggesting the multiple roles of GILZ in the brain. This up-regulation was not observed in adrenalectomized mice, confirming its dependency on hypothalamic–pituitary–adrenal axis activation.