Changes in brain and pituitary GnRH levels during ovarian maturation in wild female Japanese flounder

Pham, Ky Xuan; Amano, Masafumi; Amiya, Noriko; Kurita, Yutaka; Yamamori, Kunio

doi:10.1007/s10695-006-9006-8

Cited by 10 publications

(13 citation statements)

References 20 publications

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“…The functions of FSH and LH in terms of oocyte maturation in the Japanese flounder should be further examined in vitro by using an organ culture technique. In the wild Japanese flounder, the intensity of FSH and LH immunostaining was relatively high toward the end of the spawning period, accompanied by a high level of pituitary sbGnRH and low plasma levels of steroid hormones (Pham et al 2006). Similar results were obtained on reared fish -a high level of FSH and LH immunostaining and a low plasma level of steroid hormones were also observed in the postovulatory fish.…”

Section: Discussionsupporting

confidence: 73%

“…The fish were sacrificed and the ovaries used for GSI calculation and for histological analysis. The ovarian development of the wild fish was classified into the previtellogenic (PV), early yolk (EY), late yolk (LY), early spawning (ES), late spawning (LS), and termination (TM) stages as described previously (Pham et al 2006). The plasma steroid hormone concentrations were also measured, as in Experiment 1.…”

Section: Methodsmentioning

confidence: 99%

“…cDNAs for the genes encoding FSHb and LHb in the pituitary gland of this species have been cloned and sequenced and their expressions during gametogenesis demonstrated (Kajimura et al 2001). In addition, immunohistochemical analyses have clarified the distribution of FSH-and LH-producing cells in the pituitary (Pham et al 2007), and the role of seabream gonadotropin-releasing hormone (sbGnRH) as a major hormone involved in GTH secretion has been discussed (Pham et al 2006).…”

Section: Introductionmentioning

confidence: 99%

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Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

Pham

Amano

Kurita

et al. 2008

Fish Physiol Biochem

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The role of gonadotropin (GTH) in the reproduction of the Japanese flounder, Paralichthys olivaceus, was studied by assessing the changes in the apparent activity of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary gland during gonadal maturation by immunohistochemical analyses. Corresponding changes in plasma levels of testosterone (T), estradiol-17beta (E(2)), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP) were also studied. Reared fish at the early spawning to termination stages were sampled from May to August and wild fish at the previtellogenic to termination stages were caught at 3- to 4-week intervals between April and September offshore from the northern mainland of Japan by gill nets. The gonadosomatic index of the reared fish decreased from the early spawning stage to the termination stage, while that of the wild fish increased significantly from the previtellogenic stage to the early spawning stage and decreased thereafter. In the reared fish, the immunostaining intensities of FSH and LH were high during the spawning period, accompanied by high plasma levels of T, E(2), and DHP. In the wild fish, the immunostaining intensities of FSH and LH were low during the previtellogenic stage but increased during the maturing and spawning stages. These results indicate that both FSH and LH are likely associated with oocyte maturation in the Japanese flounder.

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Section: Discussionsupporting

confidence: 73%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

Pham

Amano

Kurita

et al. 2008

Fish Physiol Biochem

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“…sbGnRH‐ir fibers in the PPD of the pituitary were closely associated with FSH and LH cells, indicating that both FSH and LH cells are the targets of sbGnRH. Moreover, previous results also showed that sbGnRH levels in the telencephalon, hypothalamus, and pituitary changed during ovarian maturation in this species 36 . Taking all results into consideration, it is possible to conclude that sbGnRH is involved in ovarian maturation in the Japanese flounder via stimulating GTH secretion.…”

Section: Discussionmentioning

confidence: 52%

“…Moreover, previous results also showed that sbGnRH levels in the telencephalon, hypothalamus, and pituitary changed during ovarian maturation in this species. 36 Taking all results into consideration, it is possible to conclude that sbGnRH is involved in ovarian maturation in the Japanese flounder via stimulating GTH secretion. Although FSH and LH can be produced under stimulation by sbGnRH in the pituitary, the activity of FSH and LH cells in the pituitary during gonadal development should be examined to clarify the precise role of these hormones in Japanese flounder reproduction.…”

Section: Fisheries Sciencementioning

confidence: 98%

Immunohistochemical localization of three GnRH systems in brain and pituitary of Japanese flounder

et al. 2007

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To clarify the possible roles of gonadotropin-releasing hormone (GnRH) in the reproduction of Japanese flounder Paralichthys olivaceus, localization of salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II), and sea bream GnRH (sbGnRH) immunoreactive (ir) cell bodies and fibers in the brain and pituitary were examined together with follicle stimulating hormone (FSH) and luteinizing hormone (LH)-ir cells in the pituitary by immunohistochemistry. sGnRH-ir cell bodies were localized in the ventromedial part of the rostral olfactory bulb and cGnRH-II-ir cell bodies were restricted to the midbrain tegmentum, while sbGnRH-ir cell bodies were evident in the preoptic area. sGnRH-ir fibers were distributed throughout the brain, especially abundant in the forebrain. cGnRH-II-ir fibers were also scattered in many areas of the brain with abundance in the midbrain, but sbGnRH-ir fibers were observed in the preoptic-hypothalamic area and innervated the pituitary. In the pituitary, neither sGnRH-ir fibers nor cGnRH-II-ir fibers were found, but sbGnRH-ir fibers were profuse in the neurohypophysis and invaded the proximal pars distalis, targeting FSH and LH cells. These results suggest that three GnRH systems can play different physiological roles in the brain of Japanese flounder. Among them, sbGnRH is considered to be involved in reproduction by stimulating gonadotropin secretion, while sGnRH and cGnRH-II can function as a neurotransmitter and/or neuromodulator within the brain in this species.

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Long photoperiod on sea cages delays timing of first spermiation and enhances growth in male European sea bass (Dicentrarchus labrax)

et al. 2010

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12Two large groups of fingerling (3.2g) male European sea bass (around 75,000 13 individuals each) reared in net sea cages for a period of two years were exposed to two 14 different photoperiods starting in June: either ambient photoperiod (37º 24´ N) (NP) or a 15 constant long photoperiod (LP; 18 hours light: 6 hours dark, 18L: 6D). Long days had limited 16 effect on somatic growth at the time of incipient gonad development (IGD, 1 st annual cycle; 17 November-March), while they were effective at the time of full gonad development (FGD, 2 nd 18 annual cycle). Moreover, the annual patterns of morphological indices, i.e., Fulton's condition 19 factor (CF), visceral fat index (VFI) and particularly gonadosomatic index (GSI), were 20 delayed by one or two months as the result of the long days compared to the control group 21 (NP). LP did not prevent the onset of puberty but delayed spermiation by one month, and 22 modified accordingly the phase and/or amplitude of the annual rhythms of pituitary 23Gonadotropin Releasing Hormone (sbGnRH) content and plasma levels of Luteinising 24 Hormone (LH) and sex steroids, particularly that of 11-Ketotestosterone (11-KT). In general, 25 high levels of sbGnRH (≥4 ng/pit) were associated with elevated plasma LH (1-3 ng/ml at 26 *Manuscript levels and gonadal development. 30

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Changes in brain and pituitary GnRH levels during ovarian maturation in wild female Japanese flounder

Cited by 10 publications

References 20 publications

Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

Immunohistochemical localization of three GnRH systems in brain and pituitary of Japanese flounder

Long photoperiod on sea cages delays timing of first spermiation and enhances growth in male European sea bass (Dicentrarchus labrax)

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