Neuropeptide Y: Distribution of Immunoreactivity and Quantitative Analysis in Diencephalic Structures and Cerebral Cortex of Dwarf Hamsters under Different Photoperiods

Abstract

The distribution of neuropeptide Y-like immunoreactivity (NPY-LI) was investigated by immunohistochemistry and radioimmunoassay (RIA) in the brain of the Djungarian hamster (Phodopus sungorus) held under either long or short photoperiods. In the diencephalic and telencephalic structures studied, distinct patterns of NPY-LI were basically consistent in male and female animals of both groups. NPY levels detected by RIA from tissue samples taken at six time points throughout the 24-hour cycle were in the range of 15-60 pmol/ mg protein in the diencephalon or below 5 pmol/mg protein in cerebral cortex. In the diencephalon, immunoreactive structures were seen in the preoptic, peri- and paraventricular, supraoptic, anterior, lateral, dorso- and ventromedial hypothalamic nuclei and in the median eminence. The suprachiasmatic nuclei exhibited a dense innervation by NPY-LI terminals mainly in its ventrolateral subdivision. NPY levels in the suprachiasmatic nucleus were nocturnal-ly augmented under long-day, but not under short-day conditions. The quantification of NPY in the paraventricular nucleus revealed a decrease at night in long-day animals and a small nocturnal augmentation in short-day hamsters. In the pineal gland and habenular nuclei, varicose fibers were observed which appeared mainly perivascular in location (pineal) or formed a dense plexus (habenular nuclei). Pineal NPY contents fell during the night in long-day animals and were relatively constant in short-day hamsters. NPY-LI structures were also observed in the metathalamic intergeniculate leaflet and in a variety of telencephalic structures including the cerebral cortex, caudate nucleus puta-men, lateral septal nucleus, bed nucleus of the stria terminalis and amygdala.

Components and connections of the circadian timing system in mammals

“…A candidate site is the habenular region, to which the pineal is thought to be connected via its stalk (see below). NPY fibres have been indeed found in the pineal stalk of rat and cow (Reuss and Moore 1989;Phansuwan-Pujito et al 1993) and a relatively dense NPY-immunoreactive fibre plexus has been seen in the habenular nuclei of the ground squirrel and hamster (Reuss et al 1990a;Reuss and Olcese 1995). The persistence of fibres in the pineal upon SCGX has also been reported in other studies in which, for example, presumed serotonergic fibres have been found in dog .…”

“…A radioimmunological determination has shown high NPY concentrations in the pineal of rat (Chronwall et al 1985;Olcese 1994) and hamster (Reuss and Olcese 1995). In the latter, the amount decreases at the light-dark transition (Reuss and Olcese 1995).…”

“…NPY, which has been mainly colocalized to noradrenergic systems, has been observed by immunohistochemistry in pineal fibres in various species, including rat (Schon et al 1985;Reuss and Moore 1989), guinea pig (Schröder and Vollrath 1986), gerbil (Shiotani et al 1986), ground squirrel (Reuss et al 1990a), monkeys (Bons et al 1990) and golden and dwarf hamster (Schröder 1986;Reuss and Olcese 1995). A radioimmunological determination has shown high NPY concentrations in the pineal of rat (Chronwall et al 1985;Olcese 1994) and hamster (Reuss and Olcese 1995).…”

Coordinated seasonal regulation of metabolic and reproductive hypothalamic peptides in the desert jerboa

“…It binds to receptors located in various brain nuclei involved in feeding regulation, notably the ARC, and it regulates food intake in various mammalian species (Lotter et al, 1981;Danguir, 1988;Fehlmann et al, 2000;Stengel et al, 2010Stengel et al, , 2015. Interestingly, independent studies have reported that Kp (Revel et al, 2006a;Smith et al, 2008), RFRP-3 (Revel et al, 2008;Smith et al, 2008), NPY (Lakhdar-Ghazal et al, 1995Reuss and Olcese, 1995;Skinner and Herbison, 1997), b-endorphin (Roberts et al, 1985;Ebling and Lincoln, 1987), and somatostatin (Webb et al, 1985;Herwig et al, 2012;Klosen et al, 2013;Dumbell et al, 2015) display significant variations in the brain of different mammalian species placed in artificial long or short photoperiods.…”

Neuropeptide Y as a presynaptic modulator of norepinephrine release from the sympathetic nerve fibers in the pig pineal gland

“…Among neurotransmitters occurring in the pineal nerve endings, norepinephrine (NE) and neuropeptide Y (NPY) are present in the highest amounts (Williams et al 1989, Møller 1990, Møller et al 1990, 1996, Zhang et al 1991, Cozzi et al 1992, Olcese 1994, Reuss and Olcese 1995, Drijfhout et al 1996a, Mikkelsen and Møller 1999, Simonneaux and Ribelayga 2003. Both substances co-exist in the sympathetic nerve fibers, but NPY also occurs in a small population of non-sympathetic fibers, probably of the central origin , Zhang et al 1991, Møller et al, 1996, Møller 1999.…”