“…Indeed, hph mice in this study displayed ∼75% lower plasma nitrite and nitrate concentrations, an index of NO production, compared to WT mice, which is in line with other studies showing markedly reduced NO levels in hph-1 mice (Barker et al, 1998;Lam et al, 2007). In the elevated plus maze test (EPM, the precurser to the EZM), neuronal NO synthase knock-out mice displayed increased anxiety-like behaviours (Weitzdoerfer et al, 2004), and studies in both rats and mice have reported anxiogenic-like effects of NOS inhibitors in the EPM Vale et al, 1998;Zarrindast et al, 2013). While this could indicate that the increased anxiety-like behaviour observed in hph mice is linked to low NO levels, other studies have shown anxiolytic-like properties of NOS inhibitors (Guimarães et al, 1994;Volke et al, 1995;Faria et al, 1997;Spiacci et al, 2008).…”