In vitro release of gonadotropin-releasing hormone from the brain preoptic-anterior hypothalamic region and pituitary of female goldfish

Yu, Kei Li; Rosenblum, Paul M.; Peter, Richard

doi:10.1016/0016-6480(91)90010-4

Cited by 124 publications

(76 citation statements)

References 43 publications

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“…The inhibiting effect of dopamine is not limited to the pituitary gland, because studies with crucian carp proved its inhibitory effect on both LHRH synthesis and secretion (Yu and Peter 1990). This hypothesis was also confirmed by in vitro studies (Yu et al 1991, Yu andPeter 1992). The release of LHRH by the dopamine D2 receptor is inhibited probably via neuronal projections of neighbouring dopamine fibres and LHRH fibres (Yu and Peter 1992).…”

Section: Introductionmentioning

confidence: 80%

Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression

Popek¹,

Łuszczek‐Trojnar²,

Drąg‐Kozak³

et al. 2005

Acta Ichthyol. Piscat.

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Epler P. 2005. Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression. Acta Ichthyol. Piscat. 35 (2): 65-71.Background. Melatonin regulates various physiological and neuroendocrinological processes that occur rhythmically, and stimulates or inhibits endocrine activity of various body glands. This acts on the hypothalamic-pituitary-gonadal axis by synchronizing animals with their reproductive cycles. The proximity of melatonin receptors and dopamine and gonadoliberin production sites has led to a hypothesis that dopamine may be a link between melatonin and hypothalamic LHRH. Melatonin may have an indirect influence on animal reproduction through dopaminergic structures of the hypothalamus, but the mechanism involved remains unknown, also in fish, for this reason, the present experiment was conducted. The aim of the study was to determine the effect of melatonin on dopamine release from hypothalamic cells of mature female carp in vitro. Material and Methods. Hypothalami were perifused with a mineral medium containing melatonin (group 1), in the presence of implanted pineal glands (group 2), and with a pure mineral medium (control). Perifusion was 180 min long and samples of the effluent perifusate were collected at 15-minute intervals. Dopamine concentration in the medium was analysed radioenzymatically. The experiment was carried out in the summer during spawning and in the winter during regression. Results.The results indicate that melatonin inhibits the release of dopamine from hypothalamic cells. This effect was only noticeable in the experiment conducted during the spawning period. Conclusion. The present findings show that melatonin may have a role in the hypothalamic control of hypophyseal activity during the spawning period of carp.Key words: pineal gland, melatonin, dopamine, perifusion, carp, fish their reproductive cycles (Reiter 1991a, b, Zachmann et al. 1991.In looking for a link between the pineal gland and the hypothalamus, Zisapel and Laudon (1983) and Zisapel et al. (1985) showed that melatonin is able to inhibit dopamine secretion from the hypothalamic cells of the rat. The results of other studies, which showed that even picomolal concentrations of melatonin can inhibit dopamine release from the retina of birds and mammals (Cardinali et al. 1979, Dubocovich 1983, 1985, seemed to support this theory. Also in humans, the high nocturnal level of melatonin reduces dopaminergic activity in the hypothalamus (Rao and Mager 1987). In the brain of mammals, melatonin receptors are most abundant in the hypothalamus and in the anterior lobe of the pituitary gland, and much less abundant in the other parts of the brain (Weaver et al. 1991, Stankov et al. 1993. It is therefore conjectured that the hypothalamus acts as a functional link between melatonin and the endocrine system (Maywood et al. 1996). In the hypothalamus, the highest concentration of melatonin receptors is found in the medial eminence, next to the ...

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Section: Introductionmentioning

confidence: 80%

Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression

Popek¹,

Łuszczek‐Trojnar²,

Drąg‐Kozak³

et al. 2005

Acta Ichthyol. Piscat.

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“…To test whether dopamine influences the activity of A. burtoni GnRH1 neurons in the POA, we isolated the soma of GnRH1 neurons by cutting acute brain slices of the POA, which excluded two previously identified sites of dopaminergic control of gonadotropin release -pituitary GnRH1 axonal terminals and gonadotropes (Levavi-Sivan et al, 1995;Vacher et al, 2002;Van Goor et al, 1998;Yu and Peter, 1992;Yu et al, 1991). We bath applied dopamine (1-100 µmol l …”

Section: Dopamine Inhibits Gnrh1 Neuronsmentioning

confidence: 99%

“…Previous studies demonstrate that in tetrapods, dopamine inhibits GnRH1 release (Ching and Lin, 1994;Lacau-Mengido et al, 1993;Owens et al, 1980;Tasaka et al, 1985) via actions at both the hypothalamic soma of GnRH1 neurons and their synaptic terminals within the portal vasculature (Contijoch et al, 1992;Corio et al, 1990;Kuljis and Advis, 1989;Lehman et al, 1988;Pehrson et al, 1983;Ugrumov et al, 1989). In fish, dopamine was thought to act primarily within the pituitary, reducing gonadotropin release either indirectly, by suppressing GnRH1-releasing axons, or directly, by inhibiting pituitary gonadotropes (Levavi-Sivan et al, 1995;Vacher et al, 2002;Van Goor et al, 1998;Yu and Peter, 1992;Yu et al, 1991). Although early studies suggested a hypothalamic site of dopaminergic GnRH1 inhibition in fish (Yu and Peter, 1992;Yu et al, 1991), it remained unknown whether dopamine directly interacts with GnRH1 neurons within the hypothalamic compartment.…”

Section: Introductionmentioning

confidence: 99%

“…In fish, dopamine was thought to act primarily within the pituitary, reducing gonadotropin release either indirectly, by suppressing GnRH1-releasing axons, or directly, by inhibiting pituitary gonadotropes (Levavi-Sivan et al, 1995;Vacher et al, 2002;Van Goor et al, 1998;Yu and Peter, 1992;Yu et al, 1991). Although early studies suggested a hypothalamic site of dopaminergic GnRH1 inhibition in fish (Yu and Peter, 1992;Yu et al, 1991), it remained unknown whether dopamine directly interacts with GnRH1 neurons within the hypothalamic compartment. Here, we demonstrate, for the first time in teleost fish, that dopamine inhibits GnRH1 cells within the hypothalamus via selective activation of dopamine type-2 receptors.…”

Section: Introductionmentioning

confidence: 99%

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Dopaminergic inhibition of gonadotropin-releasing hormone neurons in the cichlid fish,Astatotilapia burtoni

Bryant

Greenwood

Juntti

et al. 2016

Journal of Experimental Biology

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Dopamine regulates reproduction in part by modulating neuronal activity within the hypothalamic-pituitary-gonadal (HPG) axis. Previous studies suggested numerous mechanisms by which dopamine exerts inhibitory control over the HPG axis, ultimately changing the levels of sex steroids that regulate reproductive behaviors. However, it is not known whether these mechanisms are conserved across vertebrate species. In particular, it is unknown whether mechanisms underlying dopaminergic control of reproduction are shared between mammals and teleost fish. In mammals, dopamine directly inhibits gonadotropin-releasing hormone (GnRH1) hypothalamic neurons, the gatekeepers for activation of the HPG axis. Here, we demonstrate, for the first time in teleost fish, dopaminergic control of GnRH1 neurons via direct dopamine type-2-like receptor (D2R)-mediated inhibition within the hypothalamus. These results suggest that direct dopaminergic control of GnRH1 neurons via interactions in the hypothalamus is not exclusive to tetrapod reproductive control, but is likely conserved across vertebrate species.

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“…These morphological observations confirm serotonin involvement in the regulation of pituitary hormone secretion in fish, gonadotropic hormones among others. There is also a direct evidence on the effects of serotonin on gonadotropin secretion in fish: 5HT 2 -like receptors mediate the in vivo and in vitro stimulatory effects of serotonin on gonadotropin release in goldfish (Somoza et al 1988;Somoza and Peter 1991;Wong et al 1998), in Atlantic croaker (Khan and Thomas 1992), and in red seabream (Senthilkumaran et al 2001) at the level of GnRH cell body or nerve terminals (Yu et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Serotonin, GnRH-A, and dopamine interaction in the control of in vivo luteinizing hormone release in Prussian carp (Carassius gibelio Bloch) at the time of gonad recrudescence

Sokolowska-Mikolajczyk¹,

Gajdzinski²,

Gosiewski³

et al. 2015

CZECH J ANIM SCI

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ABSTRACT:The effects of serotonin (5-HT), GnRH analogue (D-Ala 6 LHRH, GnRH-A) and dopamine antagonist -pimozide (PIM), on luteinizing hormone (LH) release in mature Prussian carp female (Carassius gibelio Bloch) were examined at the time of gonad recrudescence. Fish were intraperitoneally injected with 5-HT (10 mg/kg), GnRH-A (20 μg/kg) or PIM (5 mg/kg) or the combinations: 5-HT+GnRH-A, 5-HT+PIM, 5-HT+GnRH-A+PIM. Before the injection and 3, 6, 12 or 24 h after treatment blood samples were collected for LH levels determination by ELISA method. The analysis of LH concentrations, expressed as the percentage of pre-treatment, showed that serotonin alone had no influence on the spontaneous LH release, however the additive effects of serotonin and GnRH-A was observed. Serotonin potentiated the GnRH-A-stimulated LH release and potentiated also the effect of PIM. Extremely strong response to PIM and also to the combination with GnRH-A masked the participation of serotonin in the process of LH release in fish with recrudescing gonads. The interaction of serotonin GnRH-A and PIM in the control of LH release is discussed.

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In vitro release of gonadotropin-releasing hormone from the brain preoptic-anterior hypothalamic region and pituitary of female goldfish

Cited by 124 publications

References 43 publications

Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression

Effect of the pineal gland and melatonin on dopamine release from perifused hypothalamus of mature female carp during spawning and winter regression

Dopaminergic inhibition of gonadotropin-releasing hormone neurons in the cichlid fish,Astatotilapia burtoni

Serotonin, GnRH-A, and dopamine interaction in the control of in vivo luteinizing hormone release in Prussian carp (Carassius gibelio Bloch) at the time of gonad recrudescence

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