Induction of nitric oxide synthase and heme oxygenase activities by endotoxin in the rat adrenal cortex: involvement of both signaling systems in the modulation of ACTH-dependent steroid production.

The present study was designed to investigate the effect of lipopolysaccharide (LPS) on the expression levels and activities of the nitric oxide synthase (NOS) and heme oxygenase (HO) systems in the rat adrenal gland. Both enzymatic activities were significantly increased in this tissue after in vivo treatment with LPS. The concurrent induction of the HO-1, NOS-1, and NOS-2 gene products was also detected as both mRNAs and protein levels were augmented by this treatment in a time-dependent way.

Adrenocorticotropin induces heme oxygenase-1 expression in adrenal cells.

Heme oxygenase (HO) catalyzes the first and rate-controlling step of heme catabolism into biliverdin, iron and carbon monoxide. Three isoforms of HO have been identified so far: the inducible HO-1 and the constitutive HO-2 and HO-3. Both HO-1 and HO-2 were expressed in zona fasciculata (ZF) adrenal cells and in a mouse adrenocortical cell line (Y1).

Expression of nitric oxide synthases in rat adrenal zona fasciculata cells.

Nitric oxide (NO) synthase (NOS) expression was analyzed in rat adrenal zona fasciculata. Both neuronal NOS and endothelial NOS mRNAs were detected by RT-PCR, immunohistochemistry, and immunoblot analysis. The biochemical characterization of adrenal zona fasciculata NOS enzymatic activity confirmed the presence of a constitutive isoform.