Comparison of in vivo biological activities of luteinizing hormone releasing hormone (LHRH) analogues in 60-day-old cockerels

Nakamura, Toshio; Nagata, Tamotsu; Tanabe, Yuji; Yanaihara, Noboru; Hasegawa, Yoshihisa

doi:10.1016/0016-6480(91)90033-3

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…Initial studies in chickens found that GnRH II was indeed a potent releaser of LH, both in vitro from dispersed pituitary cells and in vivo [61,62]. Since then, it has been determined that exogenously administered GnRH II can also promote LH secretion in a variety of mammalian species.…”

Section: Role Of Mammalian Gnrh II In Gonadotropin Releasementioning

confidence: 98%

Role of gonadotropin-releasing hormone II in the mammalian nervous system

Kauffman

Rissman

2006

Expert Review of Endocrinology & Metabolism

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Gonadotropin-releasing hormone (GnRH) is a small neuropeptide of which there are multiple structural variants. The first variant identified in mammals, GnRH I, controls the release of pituitary gonadotropins. More recently, a second isoform, GnRH II, first isolated in the bird, was identified in the mammalian brain and periphery. Although it is unlikely to be a primary regulator of gonadotropin release, GnRH II appears to have a wide array of physiological and behavioral functions. GnRH II-containing fibers are present in several nuclei known to regulate reproduction and/or feeding, and its concentration in several of these areas fluctuates in response to changes in food availability, and thus energetic status. In musk shrews, GnRH II acts as a permissive regulator of female reproductive behavior based on energy status, as well as an inhibitor of short-term food intake. In this regard, GnRH II is similar to leptin, neuropeptide Y and several other neurotransmitters that regulate both feeding and reproduction. At least two GnRH receptors are present in the mammalian brain, and increasing evidence suggests that the behavioral effects of GnRH II are mediated by receptor subtypes distinct from the type-1 GnRH receptor (which mediates GnRH I action); the most probable candidate is the type-2 GnRH receptor. GnRH II also regulates the density and/or activity of calcium and potassium channels in the nervous systems of amphibians and fish, a function that may also exist in mammalian neurons. It is likely that the highly conserved GnRH II system has been co-opted over evolutionary time to possess multiple regulatory functions in a broad range of neurobiological aspects.

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Section: Role Of Mammalian Gnrh II In Gonadotropin Releasementioning

confidence: 98%

Role of gonadotropin-releasing hormone II in the mammalian nervous system

Kauffman

Rissman

2006

Expert Review of Endocrinology & Metabolism

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“…Furthermore, it is plausible that GnRH-II may help regulate gonadotropin secretion because several investigators have demonstrated that GnRH-II is a potent gonadotropin-releasing factor in nonmammalian vertebrates (23)(24)(25), and phylogenetic studies indicate that GnRH-II is the most primitive and conserved form of GnRH in vertebrates (for reviews, see Refs. 26 and 27).…”

Section: Discussionmentioning

confidence: 99%

Relative Effect of Gonadotropin-Releasing Hormone (GnRH)-I and GnRH-II on Gonadotropin Release

Densmore

Urbanski

2003

The Journal of Clinical Endocrinology & Metabolism

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Two forms of GnRH (GnRH-I and GnRH-II) are expressed in the hypothalamus of humans and rhesus monkeys, but their relative abilities to stimulate LH and FSH release are unknown. Therefore, young (8 -12 yr) and old (21-23 yr) female rhesus monkeys were treated iv with bolus injections of either GnRH-I or GnRH-II (dose range, 0.01-10 g/kg body weight); serial blood samples were remotely collected through a vascular catheter for up to 2 h after injection. Overall, plasma LH concentrations were similarly elevated after treatment with GnRH-I and GnRH-II, and the responses were slightly greater in the younger animals. Although plasma FSH concentrations were unaffected by a single exposure to GnRH-I or GnRH-II, they showed a similar significant increase after repeated exposures (every 2 h for 24 h). In a subsequent experiment, antide, a GnRH-I receptor antagonist, was administered (100 g/kg body weight) together with a single injection of GnRH-I or GnRH-II (1 g/kg body weight). As expected, GnRH-Iinduced LH release was significantly attenuated by this combined treatment; moreover, GnRH-II-induced LH release was completely blocked. Taken together, these data show that GnRH-II can potently stimulate gonadotropin release in vivo and that this action is likely mediated through the GnRH-I receptor. (J Clin Endocrinol Metab 88: 2126 -2134, 2003)

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“…stimulation of gonadotropin release). Initial studies in chickens found that GnRH II was indeed a potent releaser of LH, both in vitro from dispersed pituitary cells and in vivo (37, 38). Subsequently, it has been determined that GnRH II also can promote LH secretion in a variety of mammalian species; however, it does so with a much lower potency than GnRH I (approximately 2% as effective) (39, 40).…”

Section: Gonadotropin Releasementioning

confidence: 99%

Emerging Functions Of Gonadotropin‐Releasing Hormone II in Mammalian Physiology and Behaviour

Kauffman

2004

J Neuroendocrinology

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Gonadotropin-releasing hormone (GnRH) is the central neuroendocrine regulator of the hypothalamic-pituitary-gonadal axis. Multiple structural variants of GnRH are present in vertebrates. The first isoform isolated in the mammalian brain (GnRH I) was shown to regulate the release of pituitary gonadotropins. Recently, a second form has been discovered in mammals (GnRH II), both in the brain and periphery. Although it is unlikely to be a primary regulator of gonadotropin release, the highly conserved GnRH II variant appears to have a wide array of physiological functions. In the periphery, GnRH I and II have similar roles in regulating cell proliferation and mediating hormonal secretion from the ovary and placenta in an autocrine/paracrine manner. In the brain, GnRH I and II apparently modulate mammalian reproductive behaviours in different but complementary ways: GnRH I stimulates luteinizing hormone/follicle-stimulating hormone secretion (and thus gonadal steroids) and promotes sexual behaviour in ad libitum fed animals. By contrast, GnRH II acts as a permissive regulator of female reproductive behaviour based on energy status, as well as a modifier of short-term food intake. GnRH II has also been implicated in the regulation of calcium and potassium channels in nervous systems of amphibians, functions which may also be present in mammals. Increasing evidence suggests that the effects of GnRH II in both the periphery and brain may be mediated by GnRH receptor subtypes distinct from the type-1 GnRH receptor. It is likely that this evolutionarily conserved peptide has been co-opted over evolutionary time to possess multiple regulatory functions in a broad range of biological aspects, including, but not limited to, reproduction. Here, the proposed actions of both neural and peripheral GnRH II in affecting physiology and behaviour are summarized, and an outline of critical directions for future research is proposed.

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Comparison of in vivo biological activities of luteinizing hormone releasing hormone (LHRH) analogues in 60-day-old cockerels

Cited by 7 publications

References 19 publications

Role of gonadotropin-releasing hormone II in the mammalian nervous system

Role of gonadotropin-releasing hormone II in the mammalian nervous system

Relative Effect of Gonadotropin-Releasing Hormone (GnRH)-I and GnRH-II on Gonadotropin Release

Emerging Functions Of Gonadotropin‐Releasing Hormone II in Mammalian Physiology and Behaviour

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