Immunocytochemical localization and ontogenic development of ?-melanocyte-stimulating hormone (?-MSH) in the brain of a pleuronectiform fish, barfin flounder

Abstract

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a pituitary hormone derived by post-translational processing from proopiomelanocortin and is involved in background adaptation in teleost fish. It has also been reported to suppress food intake in mammals. Here, we examined the immunocytochemical localization of alpha-MSH in the brain and pituitary of a pleuronectiform fish, the barfin flounder (Verasper moseri), as a first step in unraveling the possible function of alpha-MSH in the brain. The ontogenic development of the alpha-MSH system was also studied. In the pituitary, alpha-MSH-immunoreactive (ir) cells were preferentially detected in the pars intermedia. In the brain, alpha-MSH-ir neuronal somata were located in the nucleus tuberis lateralis of the basal hypothalamus, and alpha-MSH-ir fibers were located mainly in the telencephalon, hypothalamus, and midbrain. Alpha-MSH-ir neuronal somata did not project their axons to the pituitary. The alpha-MSH-ir neurons differed from those immunoreactive to melanin-concentrating hormone. Alpha-MSH cells in the pituitary and alpha-MSH-ir neuronal somata in the brain were first detected 1 day and 5 days after hatching, respectively. The distribution of alpha-MSH-ir cells, neuronal somata, and fibers showed a pattern similar to that in adult fish 30 days after hatching. These results indicate that the functions of alpha-MSH in the brain and pituitary are different and that alpha-MSH plays physiological roles in the early development of the barfin flounder.

Conserved neurochemical pathways involved in hypothalamic control of energy homeostasis

“…Similar to our findings, ␣-MSH-ir somata in the hypothalamus are detected at 5 days post hatching in the barfin flounder, just prior to the onset of feeding (Amano et al, 2005). In Cichlasoma, ␣-MSH-ir cells are detected at 6 days after hatching in the NLT and also in the nucleus periventricularis posterior (NPP; equivalent in part to the dorsal periventricular hypothalamus [Hd] of Braford and Northcutt, 1983).…”

“…Kishida et al (1988) also report a population of ␣-MSH-ir cells in this area, and in carp but not trout (S. fario), approximately half of these express melanin-concentrating hormone-ir. In contrast, this lateral population was not reported in another species of trout (S. gairdneri; Vallarino et al, 1989) or in the barfin flounder (Amano et al, 2005). In all of the above studies, antisera specific to ␣-MSH were used, and therefore species and/or condition differences may result in variable expression of ␣-MSH-ir in this area.…”

“…Several studies have consistently identified ␣-MSH-ir cells in the nucleus lateral tuberis of the hypothalamus (NLT; equivalent to Hv of Braford and Northcutt, 1983) of teleosts (two species of trout, Salmo fario and Salmo gairdneri, Chinese grass carp Ctenopharyngodon idellus, a cichlid, Cichlasoma dimerus, and the barfin flounder, Verasper moseri) with various antisera (Kishida et al, 1988;Vallarino et al, 1989;Pandolfi et al, 2003;Amano et al, 2005), but few describe the precise fiber distribution outside of the diencephalon, although high-performance liquid chromatography (HPLC)-RIA has identified ␣-MSH in all major brain areas in trout and carp (Kishida et al, 1988;Vallarino et al, 1989). We found ␣-MSH-ir somata in the anterior and medial Hv, as well as in an area just lateral to Hv, unlabeled in the zebrafish atlas (Wullimann et al, 1996), but probably comparable to the NLT-l (pars lateralis) in Peter and Gill (1975).…”

“…Levels of ␣-MSH in the hypothalamus, however, were not investigated, and obesity is thought to be a function of depressed lipid mobilization (Yada et al, 2002). Although several studies have documented the expression of POMC and AgRP by in situ hybridization (ISH) (Cerda-Reverter and Peter, 2003;Cerda-Reverter et al, 2003a;Song et al, 2003;de Souza et al, 2005) or detected ␣-MSH immunoreactivity (ir) (Kishida et al, 1988;Vallarino et al, 1989;Pandolfi et al, 2003;Amano et al, 2005) in the lateral tuberal hypothalamus of teleosts, no studies have investigated the distribution of AgRP-ir somata and projections or, most importantly, the relationship of AgRP to ␣-MSH-ir in any teleost species or, for that matter, in any nonmammalian vertebrate. In this study, we tested the hypothesis that neurochemical pathways involved in energy homeostasis are conserved throughout vertebrate evolution by detailed neuroanatomical mapping of two central players, ␣-MSH and AgRP, in the brain of adult zebrafish, Danio rerio, by double-label immunocytochemistry.…”

A systematic immunohistochemical survey of the distribution patterns of GH, prolactin, somatolactin, β–TSH, β–FSH, β–LH, ACTH, and α–MSH in the adenohypophysis of Oreochromis niloticus, the Nile tilapia

“…Most studies deal with single hormones or hormone families (e.g. Amemiya et al 1999;Amano et al 2005;Dores et al 1996;García Ayala et al 2003;Huang and Specker 1994;Joss et al 1990;Kagawa et al 1998;Kawauchi et al 1986Kawauchi et al , 1989Mousa and Mousa 1999a,b;Nagahama et al 1981;Naito et al 1983;Nishioka et al 1993;Nozaki et al 1990;Olivereau and Rand-Weaver 1994;Parhar et al 2003;Power 1992;Rand-Weaver et al 1991;Saga et al 1993;Shimizu et al 2003;Siegmund et al 1987;Weltzien et al 2003a). A few more extensive studies have been performed (e.g.…”