Distribution and Seasonal Variations in Levels of Three Native GnRHs in the Brain and Pituitary of Perciform Fish

Senthilkumaran, B.; Okuzawa, Koichi; Kobashi, Gén; Ookura, Tetsuya; Kagawa, Hirohiko

doi:10.1046/j.1365-2826.1999.00304.x

Cited by 133 publications

(93 citation statements)

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“…The lack of anti sbGnRH immunostaining likely depends on technical reasons, including the non-specificity of the primary antibody used, as well as likely antigen damage during the fixation and paraffin wax embedding. However, since large differences in the levels of sbGnRH have been shown among perciform fishes (Senthilkumaran et al, 1999), a possible explanation is that the bluefin tuna contains such a low amount of the sbGnRH form that it becomes undetectable to the immunostaining. Therefore, other types of studies, including RIA and in situ hybridization might be helpful in finding a solution to this still unanswered question.…”

Section: Discussionmentioning

confidence: 99%

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

Palmieri¹,

Acone²,

Desantis³

et al. 2009

Eur J Histochem

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The present study was focused on the morphology of the diencephalic nuclei (likely involved in reproductive functions) as well as on the distribution of GnRH (gonadotropin-releasing hormone) in the rhinencephalon, telencephalon and the diencephalon of the brain of bluefin tuna (Thunnus thynnus) by means of immunohistochemistry. Bluefin tuna has an encephalization quotient (QE) similar to that of other large pelagic fish. Its brain exhibits well-developed optic tecta and corpus cerebelli. The diencephalic neuron cell bodies involved in reproductive functions are grouped in two main nuclei: the nucleus preopticus-periventricularis and the nucleus lateralis tuberis. The nucleus preopticus-periventricularis consists of the nucleus periventricularis and the nucleus preopticus consisting of a few sparse multipolar neurons in the rostral part and numerous cells closely packed and arranged in several layers in its aboral part. The nucleus lateralis tuberis is located in the ventral-lateral area of the diencephalon and is made up of a number of large multipolar neurones. Four different polyclonal primary antibodies against salmon (s)GnRH, chicken (c)GnRH-II (cGnRH-II 675, cGnRH-II 6) and sea bream (sb)GnRH were employed in the immunohistochemical experiments. No immunoreactive structures were found with anti sbGnRH serum. sGnRH and cGnRH-II antisera revealed immunoreactivity in the perikarya of the olfactory bulbs, preopticus-periventricular nucleus, oculomotor nucleus and midbrain tegmentum. The nucleus lateralis tuberis showed immunostaining only with anti-sGnRH serum. Nerve fibres immunoreactive to cGnRH and sGnRH sera were found in the olfactory bulbs, olfactory nerve and neurohypophysis. The significance of the distribution of the GnRHimmunoreactive neuronal structures is discussed.

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Section: Discussionmentioning

confidence: 99%

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

Palmieri¹,

Acone²,

Desantis³

et al. 2009

Eur J Histochem

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“…Similarly in red seabream and gilthead seabream, GnRH-II mRNA levels increase around the spawning season (Gothilf et al 1997, Okuzawa et al 2003. However, it is unlikely that GnRH-II regulates gonadotropin secretion directly because neither GnRH-II peptide nor fibers have been detected in the pituitaries of these species (Senthilkumaran et al 1999.…”

Section: Discussionmentioning

confidence: 99%

“…Changes in the expression of three GnRH variants in relation to the reproductive stages have been reported previously in only the female phase of two perciform species, gilthead seabream and red seabream, which are protandrous and protogynous hermaphrodites, respectively (Gothilf et al 1997, Senthilkumaran et al 1999, Okuzawa et al 2003. Thus, it is worthwhile to investigate the expression of three GnRH mRNAs in relation to reproductive stages in both males and females of a gonochoristic species, such as red drum.…”

Section: Introductionmentioning

confidence: 90%

“…The slides were fixed in 4% paraformaldehyde for 30 min, washed in PBS and hydrated. Sections were blocked in 10% normal goat serum for 1 h at room temperature and incubated in GnRH-I primary antibody (1:5000 dilution) raised in rabbit (AS-691; Senthilkumaran et al 1999) or 10% normal goat serum (for control) overnight at 4 C in a moist chamber. Sections were washed in PBS (3 10 min) and incubated for 1 h at room temperature in horseradish peroxidase conjugated goat anti-rabbit IgG (Molecular Probes; 1:100 in 1% blocking reagent) and washed three times in PBS.…”

Section: Immunocytochemistrymentioning

confidence: 99%

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Molecular cloning and differential expression of three GnRH mRNAs in discrete brain areas and lymphocytes in red drum

Mohamed¹,

Khan²

2006

Journal of Endocrinology

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Three gonadotropin releasing hormones, seabream GnRH (GnRH-I), chicken GnRH-II (GnRH-II) and salmon GnRH (GnRH-III) cDNAs were isolated from the brain of the red drum, Sciaenops ocellatus. The GnRH cDNA sequences of red drum showed more similarity to those of Atlantic croaker, sea bass and sea bream. The real-time quantitative RT-PCR study revealed expression of GnRH-I and GnRH III mRNAs in the olfactory bulb plus telencephalon (OB+TEL), and preoptic-anterior hypothalamic area (POAH), indicating an overlap of the GnRH-I and GnRH-III systems in these forebrain regions. However, GnRH-II mRNA expression was detected only in the midbrain tegmentum (MT).The GnRH-I mRNA expression in the POAH in fish undergoing gonadal recrudescence was significantly higher than that in gonadally immature individuals, suggesting involvement of the POAH GnRH-I in gonadal maturation. On the other hand, GnRH-III mRNA expression was significantly higher in the OB+TEL region compared with that in the POAH. Moreover, the demonstration of GnRH-I mRNA and peptide expression in red drum lymphocytes indicates that the GnRH-I is synthesized in these cells of the immune system similar to the situation in mammals.

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“…8A, 9A) was done according to Okuzawa et al (1990). sGnRH, cGnRH-II, and sbGnRH contents were measured by respective RIAs established by Okuzawa et al (1990) and Senthilkumaran et al (1999).…”

Section: -2 Identification Of Gnrh Forms By Cdna Cloning In Barfin mentioning

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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Distribution and Seasonal Variations in Levels of Three Native GnRHs in the Brain and Pituitary of Perciform Fish

Cited by 133 publications

References 19 publications

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

Molecular cloning and differential expression of three GnRH mRNAs in discrete brain areas and lymphocytes in red drum

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

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