Immunocytochemical localization of sGnRH and cGnRH‐II in the brain of goldfish, <i>Carassius auratus</i>

Kim, Myung‐Hee; Oka, Yoshitaka; Amano, Masafumi; Kobayashi, Makito; Okuzawa, Koichi; Hasegawa, Yoshihisa; Kawashima, Seiichiro; Suzuki, Yuzuru; Aida, Katsumi

doi:10.1002/cne.903560105

Cited by 132 publications

(83 citation statements)

References 22 publications

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“…But specificity turned out to be a critical problem when it became clear that different forms of GnRH were produced in the brain of a single species (Yu et al 1988). Nevertheless, using wellcharacterized antibodies, several studies succeeded in showing the differential expression pattern of two different GnRHs, for example in the brain of the Masu salmon (Amano et al 1991), the Siberian sturgeon (Leprêtre et al 1993), the European eel (Montero et al 1994) or the goldfish (Kim et al 1995). The cDNA sequences encoding different GnRH forms allowed this problem to be approached by using in situ hybridization.…”

Section: Discussionmentioning

confidence: 99%

The GnRH system in the European sea bass (Dicentrarchus labrax)

Zmora

González-Martı́nez²,

Muñoz‐Cueto³

et al. 2002

Journal of Endocrinology

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The cDNA sequences encoding three GnRH forms, sea bream GnRH (sbGnRH), salmon GnRH (sGnRH) and chicken GnRH II (cGnRH II), were cloned from the brain of European sea bass, Dicentrarchus labrax. Comparison of their deduced amino acid sequences to the same forms in the gilthead sea bream, Sparus aurata, and striped bass, Morone saxatilis, revealed high homology of the prepro-cGnRH II (94% and 98% respectively), and prepro-sGnRH (92% to both species). The sbGnRH exhibited dissimilar identities, with high homology to the striped bass (93%), and lower homology (59%) to the gilthead sea bream. Two transcript types were identified for the GnRH-associated peptide (GAP)-sGnRH as well as for the GAP-cGnRH II, which suggests a possible alternative splicing followed by the addition of an early stop codon. In order to obtain antibodies specific for the three GnRH precursors, recombinant GAP proteins were produced. The differential expression of the three GnRHs previously reported in the brain by means of in situ hybridization, using riboprobes corresponding to the GAP-coding regions, was fully confirmed by immunocytochemistry using antibodies raised against the recombinant GAP proteins, indicating that the transcripts are translated into functional proteins. Moreover, this approach allowed us to follow, for the first time, the specific projections of the different cell groups: sGAP fibers are distributed mainly in the forebrain with few projections reaching the pituitary, sbGAP fibers are mainly present in the preoptic area, mediobasal hypothalamus and predominantly project to the pars distalis of the pituitary, whereas cGnRH II fibers have a widespread distribution primarily in the posterior brain, and do not project to the pituitary. These new tools will be extremely useful to study further the development, regulation and functional significance of three independent GnRH systems in the brain of vertebrate species.

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Section: Discussionmentioning

confidence: 99%

The GnRH system in the European sea bass (Dicentrarchus labrax)

Zmora

González-Martı́nez²,

Muñoz‐Cueto³

et al. 2002

Journal of Endocrinology

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“…Subsequent studies have shown that GnRH neurons and their fibers also exist in various areas of the brain other than the hypothalamus (extrahypothalamic GnRH neurons) (Amano et al 1991;Kim MH et al 1995;Munz et al 1981;Schwanzel-Fukuda and Silverman 1980;Schwanzel-Fukuda et al 1985;Yamamoto et al 1995). Such extrahypothalamic GnRH systems have been identified in the terminal nerve (TN) and midbrain.…”

Section: Introductionmentioning

confidence: 99%

“…The olfactory bulb receives prominent projections of GnRH-containing fibers from the TN (Amano et al 1991;D'Aniello et al 1995;Gonzalez-Martinez et al 2001, 2002Kim KH et al 1999;Kim MH et al 1995;Oka and Ichikawa 1990;Teruyama and Beck 2000;Yamamoto et al 1995) and their GnRH content appears to be affected by the multimodal sensory inputs to the animals (Dluzen and Ramirez 1983; Dluzen et al 1981; Yu and Peter 1990), suggesting that TN regulates the responsiveness of the olfactory bulbar neural circuits in accordance with these sensory inputs. However, it is not yet clear whether the activities of these neural circuits are modulated by GnRH.…”

Section: Introductionmentioning

confidence: 99%

Neuromodulatory Effect of GnRH on the Synaptic Transmission of the Olfactory Bulbar Neural Circuit in Goldfish, Carassius auratus

Kawai

Abe

Akazome

et al. 2010

Journal of Neurophysiology

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Kawai T, Abe H, Akazome Y, Oka Y. Neuromodulatory effect of GnRH on the synaptic transmission of the olfactory bulbar neural circuit in goldfish, Carassius auratus. J Neurophysiol 104: 3540 -3550, 2010. First published October 20, 2010 doi:10.1152/jn.00639.2010. Gonadotropin-releasing hormone (GnRH) is well known as a hypophysiotropic hormone that is produced in the hypothalamus and facilitates the release of gonadotropins from the pituitary gonadotropes. On the other hand, the functions of extrahypothalamic GnRH systems still remain elusive. Here we examined whether the activity of the olfactory bulbar neural circuits is modulated by GnRH that originates mainly from the terminal nerve (TN) GnRH system in goldfish (Carassius auratus). As the morphological basis, we first observed that goldfish TNs mainly express salmon GnRH (sGnRH) mRNA and that sGnRH-immunoreactive fibers are distributed in both the mitral and the granule cell layers. We then examined by extracellular recordings the effect of GnRH on the electrically evoked in vitro field potentials that arise from synaptic activities from mitral to granule cells. We found that GnRH enhances the amplitude of the field potentials. Furthermore, these effects were observed in both cases when the field potentials were evoked by stimulating either the lateral or the medial olfactory tract, conveying functionally different sensory information, separately, and suggesting that GnRH may modulate the responsiveness to wide categories of odorants in the olfactory bulb. Because GnRH also changed the paired-pulse ratio, it is suggested that the increased amplitude of the field potential results from changes in the presynaptic glutamate release of mitral cells rather than the increase in the glutamate receptor sensitivity of granule cells. These results suggest that TN regulates the olfactory responsiveness of animals appropriately by releasing sGnRH peptides in the olfactory bulbar neural circuits.

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“…In contrast to salmonids, goldfish possess both forms of GnRH in the pituitary (Yu et al 1987(Yu et al , 1988Kim et al 1995). Therefore, it is interesting to examine whether both GnRHs have the potency to stimulate FSH and LH secretion in salmonid species.…”

Section: -1 Effects Of Gnrh On Gth Release In Sockeye Salmonmentioning

confidence: 99%

Reproductive Biology of Salmoniform and Pleuronectiform Fishes with Special Reference to Gonadotropin-Releasing Hormone (GnRH)

Amano¹

2010

Aqua-BioSci. Monogr. (ABSM)

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Keywords • GnRH AbstractA salmonid fish, masu salmon Oncorhynchus masou, has salmon gonadotropin-releasing hormone (sGnRH) and chicken GnRH-II (cGnRH-II), while a pleuronectiform fish, barfin flounder Verasper moseri, has sGnRH, cGnRH-II and seabream GnRH (sbGnRH). In masu salmon, sGnRH-immunoreactive (ir) cell bodies are scattered from the olfactory nerve through the ventral telencephalon (VT) and the preoptic area (POA). cGnRH-II-ir cell bodies are located in the midbrain tegmentum (MT). sGnRH but not cGnRH-II is detected in the pituitary. sGnRH peptide levels and sGnRH mRNA levels in the VT and the POA increased during gonadal maturation. sGnRH neurons are derived from the olfactory epithelium and migrate into the brain. In barfin flounder, sGnRH-ir, cGnRH-II-ir, and sbGnRH-ir cell bodies are located in the olfactory bulbs and the terminal nerve ganglion (TN), the MT, and the POA, respectively, and these neurons do not migrate in the brain. sbGnRH is detected in the pituitary. sbGnRH mRNA levels in the brain increased during gonadal maturation. Although three GnRH systems exist in the barfin flounder, anatomical distinction between the TN-and the POA-GnRH systems is not clear in masu salmon. Thus, it is suggested that sGnRH neurons in masu salmon play different roles according to the location in the brain. General introductionGonadotropin-releasing hormone (GnRH) is a decapeptide originally isolated from pig and sheep hypothalami as a physiologic regulator of luteinizing hormone (LH) release from the pituitary (Matsuo et al. 1971;Burgus et al. 1972). At present, it is generally accepted that GnRH regulates synthesis and release of pituitary gonadotropin (GTH) (see King and Millar 1992;Sherwood et al. 1993). It has been shown that two or three molecular forms of GnRH exist, even within the same species (Oka 1997;Okuzawa and Kobayashi 1999;Okubo and Nagahama 2008). In addition, GnRH can act as a neuromodulator and has also been implicated in reproductive behavior in many species including teleost fish such as dwarf gourami Colisa lalia (Yamamoto et al. 1997) and goldfish Carassius auratus (Volkoff and Peter 1999).To date, 15 forms of GnRHs have been identified based on their primary structure or complementary DNAs (cDNAs) in vertebrates, as shown in Fig. 1 (Okubo and Nagahama 2008;Kavanaugh et al. 2008). GnRH forms are traditionally named after the species from which they were first identified. In addition to vertebrate species, GnRH was isolated in invertebrates: e.g., in the protochordate Ciona intestinalis (Powell et al. 1996;Adams et al. 2003), octopus Octopus vulgaris (Iwakoshi et al. 2002) and the sea hare Aplysia californica (Zhang et al. 2008).In mammalian, avian, reptilian, and amphibian animals, GnRH is conveyed to the pituitary via the hypothalamo-hypophyseal portal vessels ( Fig. 2A). In mammals, pulsatile release of mammalian GnRH (mGnRH) by hypothalamic neurons stimulates GTH secretion from the pituitary. However, teleost fishes lack the median eminence. Instead, GnRH neurons are found to directly...

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Immunocytochemical localization of sGnRH and cGnRH‐II in the brain of goldfish, Carassius auratus

Cited by 132 publications

References 22 publications

The GnRH system in the European sea bass (Dicentrarchus labrax)

The GnRH system in the European sea bass (Dicentrarchus labrax)

Neuromodulatory Effect of GnRH on the Synaptic Transmission of the Olfactory Bulbar Neural Circuit in Goldfish, Carassius auratus

Reproductive Biology of Salmoniform and Pleuronectiform Fishes with Special Reference to Gonadotropin-Releasing Hormone (GnRH)

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