Swim stress enhances the NADPH-diaphorase histochemical staining in the paraventricular nucleus of the hypothalamus

Regulatory control of the hypothalamic-pituitary-adrenocortical axis (HPA) originates principally from the paraventricular nucleus (PVN), which contai ns an important population of nitric oxide synthesizing (NOS) neurons. In t he present study, the effect of swim stress upon these neurons was investig ated by means of the NADPH-diaphorase (ND) histochemical technique. A signi ficant increase in the number of ND-neurons was observed following forced s wim, especially after 30 min. These data confirm the involvement of NOS-neu rons of the PVN in the response to different types of acute stressors. (C) 1999 Elsevier Science B.V. All rights reserved.