Co‐localization of heme oxygenase‐2 (HO‐2) and neuronal nitric oxide synthase (nNOS) in the pre‐Bötzinger Complex (pBötC): Does nNOS regulate the oxygen sensitivity of the pBötC?

• Published in: The FASEB journal 2007, Vol.21 (6), p.A916-A916
• Main Authors: Danish, Hasan H, Shivashankar, Raina, Sunderram, Jagadeeshan, Neubauer, Judith A
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.6.A916-c

We have previously shown that the pBötC expresses HO‐2 constitutively and that chronic sustained and intermittent hypoxia induces HO‐1. In addition, we have shown that HO is essential for the oxygen sensing function the pBötC. Since recent work has shown that nNOS modulates the activity of HO‐2 and the induction of HO‐1, we determined whether nNOS is expressed in the pBötC and whether it co‐localizes with HO‐2. Rat pups (P5–7) were transcardially perfused with heparinized saline and 4% paraformaldehyde, their brains removed, cryoprotected, and sectioned (40μm). Sections were incubated with primary antibodies to HO‐2 and nNOS and visualized using secondary antibodies labeled with FITC or Texas Red. Co‐localization was determined using fluorescent microscopy and laser confocal microscopy. Consistent with previous work, HO‐2 was present in the pBötC. Of the 789 immunofluorescent neurons, 594 expressed nNOS. Co‐localization of HO‐2 and nNOS was observed in 80% of the HO‐2 immunoreactive cells. Since HO‐2 mediates the central sensitivity to acute hypoxia and HO‐1 induction is necessary for the central sensitivity to chronic hypoxia, these results suggest that NO may be an important regulator of the hypoxic sensitivity of the pBötC.