NOS1 and Huntington disease: Striatal GABAergic interneurons are also compromised in HD models, particularly the fast-spiking parvalbumin expressing interneurons (FSIs) (Reiner et al., 2013), as well as the low threshold-spiking interneurons which colocalize neuronal nitric oxide synthase (nNOS), neuropeptide Y, somatostatin, and GABA (Holley et al., 2019).