Gene expression of NMDA receptor subunits in rat adrenals under basal and stress conditions.

In addition to the central nervous system, glutamate receptors have been recently identified in a number of peripheral tissues, including adrenals. Pharmacological evidence indicates that adrenal glutamate receptors may be involved in stress response, particularly in catecholamine release. However, possible stress-induced changes at the level of local receptors themselves have not been evaluated yet. This study was aimed to investigate gene expression of N-methyl-D-aspartate (NMDA) receptor subunits (NR1, NR2A, NR2B) in rat adrenal gland under basal and stress conditions, using RT-PCR. NR1 mRNA was found to be present in the adrenal gland, while mRNAs coding for NR2-type subunits failed to be detected in adrenal tissue. The distribution of NR1 mRNA in rat adrenals showed higher concentrations in the adrenal medulla (228%) compared to those in the cortex. Single stress stimulus (immobilization) induced a significant increase of NR1 gene expression in both medullar (by 25%) and cortical (by 66%) regions of the adrenal gland at 24 h, while no changes were observed at 3 h after the stress exposure. It is possible that delayed rise in adrenal NR1 gene expression following stress exposure represents one of the factors by which stress exerts long-term effects on adrenal function at the molecular level.