Fos-ir and GAD⁺ Single- and double-labeled neurons in the perifornical nucleus, in the posterior hypothalamic area and the supramammillary nucleus after paradoxical sleep hypersomnia.

<p>Low power photomicrographs show Fos and GAD₆₇ double-labeled frontal sections at the level of the caudal part of the perifornical nucleus (A1), the mammillary hypothalamus (B1) and the mammillary nuclei (C1) in a PSR animal. Enlargement in A2 shows several Fos-ir/GAD⁺ neurons characterized by a brown nuclear and a blue diffuse cytoplasmic staining (black stars) and GABAergic singly-labeled cells (open arrows) in the perifornical nucleus. In contrast, B2 show that at mammillary hypothalamic level a majority of Fos-ir are singly-labeled in the posterior hypothalamic area. Finally, C2 shows that neurons of the supramammillary nucleus are all singly-labeled by Fos. In agreement with previous descriptions <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011766#pone.0011766-Esclapez1" target="_blank">[14]</a>, only a few GAD₆₇ labeled cells are located in the suprammammillary and the mammillary nuclei (C1) compared to the other tuberal and mammillary hypothalamic nuclei (A1, A2). Importantly, although the posterior hypothalamic area contains a large number of GAD₆₇ labeled cells, most of them are not Fos-ir in contrast to those located more rostrally in the perifornical and lateral hypothalamic areas (A1). Abbreviations: 3V: 3^rd ventricle; f: fornix; ic: internal capsule; mLH: lateral hypothalamic area, mammillary part; MRe: mammillary recess of the 3^rd ventricle; mt: mammillothalamic tract; PeF: perifornical nucleus; PH: posterior hypothalamic area; pm: mammillary peduncle; SuM: supramammillary nucleus. Scale bars: 500µm for A1, B1 and C1; 25µm for A2 and 50µm for B2 and C2.