Expression of neuronal nitric oxide synthase mRNA in stress-related brain areas after restraint in rats

The objective of the present study was to investigate the expression of neu ronal nitric oxide synthase (nNOS) mRNA in stress-related areas after restr aint. Male Wister rats (n = 4-6/group) submitted to 2 h of restraint during one (acute) or seven (chronic) days were sacrificed 24 h after the last re straint period. In situ hybridisation was performed with oligonucleotide pr obes radiolabeled with S-35. Acute restraint induced a significant increase in nNOS mRNA in the paraventricular hypothalamic nucleus (PVN), medial par vocellular part, dorsolateral periaqueductal grey (DLPAG) and medial amygda loid nucleus, but not in the hippocampal formation. This effect persisted a fter chronic restraint in the PVN and DLPAG, These results suggest that res traint stress induces changes in gene expression of nNOS in areas related t o stress reactions. (C) 2000 Elsevier Science Ireland Ltd. All rights reser ved.