Neuropeptide Y in the forebrain and retina of the killifish, Fundulus heteroclitus

Abstract

The organization of the neuropeptide Y (NPY)-immunoreactive system in the forebrain, pineal organ and retina of a biweekly spawning fish (Fundulus heteroclitus) was investigated. Immunoreactivity was encountered in neurons of the nucleus olfactoretinalis, in the large population of neurons in the floor of the telencephalon, and in the nucleus entopeduncularis. Isolated somata were encountered in the hypophysiotropic hypothalamic nuclei, viz., the nucleus preopticus periventricularis, nucleus preopticus, and nucleus lateralis tuberis. Immunoreactive somata were also seen in the nucleus dorsomedialis thalami. The olfactory bulb was abundantly innervated by NPY fibers. The telencephalon showed thick radiating processes basally and terminal fields with modest to high densities in the dorsal and lateral regions. NPY-immunoreactive fibers were also conspicuous in the preoptic area, suprachiasmatic nucleus, tuberal hypothalamus, pituitary gland, and paraventricular thalamic regions; discrete CSF-contacting sites were also encountered. Of special interest was the occurrence of NPY immunoreactivity in fibers of the pineal stalk and organ. In the retina, some amacrine cells displayed immunoreactivity, while the inner plexiform layer revealed a well-developed pattern of NPY fibers different from that previously described for the goldfish.

Immunohistochemical Distribution of Neuropeptide Y-Related Substance in the Brain and Hypophysis of the Arctic Lamprey, <i>Lethenteron japonica</i>

“…In the rat hypothalamus, intragranular costorage of NPY and arginine vasopressin in the paraventricular magnocellular neurons was reported, strongly suggesting that the paraventricular nucleus is an origin of the NPY-ir fibers found in the hypophysis [Kagotani et al, 1990]. In the teleosts [Subhedar et al, 1996] and lungfish [Vallarino et al, 1995], the preoptic nucleus includes NPY-ir cells, whereas no NPY-ir cells were demonstrated in the preoptic nuclei of African clawed toad [Tunihof et al, 1994], dogfish [Chiba and Honma, 1992], sturgeon [Chiba and Honma, 1994], and bichir [Chiba, 1997]. Origin(s) of the NPY-ir fibers in the lamprey neurohypophysis should be experimentally analyzed in the future.…”

“…Immunohistochemical data for NPY-ir innervation in the hypophyses of the following fish groups have been reported: Elasmobranchii [Vallarino et al, 1988;Chiba and Honma, 1992], Chondrostei [Chiba and Honma, 1994], Polypteriformes [Chiba, 1997], Dipnoi [Vallarino et al, 1995], and Teleostei [Pontet et al, 1989;Batten et al, 1990;Danger et al, 1991;Vecino and Ekström, 1992;Magliulo-Cepriano and Schreibman, 1993;Chiba et al, 1996;Subhedar et al, 1996]. However, in Agnatha, the NPY-ir innervation in the hypophysis is indistinct or negligible in the brown hagfish [Chiba et al, 1993].…”

“…A number of immunohistochemical studies have provided basic data on the organization of NPY-like-immunoreactive (NPY-ir) structures in the brains of primitive vertebrates including the major fish groups: cyclostomes [Van Dongen et al, 1985;Chiba et al, 1993], elasmobranchs [Vallarino et al, 1988;Chiba and Honma, 1992], primitive bony fishes [Chiba and Honma, 1994;Vallarino et al, 1995;Chiba, 1997], and teleosts [Pontet et al, 1989;Batten et al, 1990;Danger et al, 1991;Vecino and Ekström, 1992;Magliulo-Cepriano and Schreibman, 1993;Chiba et al, 1996;Subhedar et al, 1996].…”

Afferent and Efferent Connections of the Pineal Organ in the European Sea Bass <i>Dicentrarchus labrax:</i> A Carbocyanine Dye Tract-Tracing Study

“…Recently, the presence of kisspeptin 1 and GnRH-II cells was described in the habenula and medial tegmental area of the sea bass, respectively [González-Martínez et al, 2001Zmora et al, 2002;Escobar et al, 2010]; both neuropeptidergic systems are implicated in the processing of environmental and metabolic information . The habenula, dorsal and ventral thalamus, posterior tubercle and mesencephalic tegmentum also contain NPYimmunoreactive neurons in other teleost and non-teleost species [Pontet et al, 1989;Batten et al, 1990;Vecino and Ekström, 1992;García-Fernández et al, 1992;Subhedar et al 1996;Castro et al, 1999;Rodríguez-Gómez et al, 2001;Chiba, 2005]. Interestingly, all these nuclei contain pinealopetal cells in the European sea bass.…”

“…Noradrenaline , FMRFamide [Ekström et al, 1988], GnRH [Ekström and Meissl, 1997;Sakharkar et al, 2005;Servili et al, 2010] and neuropeptide Y (NPY) fibers [Subhedar et al, 1996;Blank et al, 1997] were previously detected in the pineal organ of teleosts. Neuropeptidergic innervation has also been reported in the pineal gland of mammals and amphibians [Ekström et al, 1990;Artero et al, 1991;Leger and Mathieson, 1997;Moller et al, 1998], suggesting that this innervation is a shared characteristic of vertebrates.…”