Gonadotropin-releasing hormone II: a multi-purpose neuropeptide

Schneider, Johanna S.; Rissman, Emilie F.

doi:10.1093/icb/icn018

Cited by 27 publications

(19 citation statements)

References 92 publications

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“…Another neuropeptide whose activity is related to energetic status is GnRH-II, a second form of GnRH that is highly conserved across almost all vertebrates (Schneider & Rissman 2008). In the Musk Shrew Suncus murinus midbrain levels of GnRH-II show the opposite response to negative energetic status as compared to that of NPY: GnRH-II content declined in response to food restriction and increased after refeeding (Kauffman et al 2006).…”

Section: T H E G N I H -N P Y S Y S T E Mmentioning

confidence: 99%

Food availability, energetic constraints and reproductive development in a wild seasonally breeding songbird

et al. 2015

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Summary In many organisms, food availability is a proximate cue that synchronizes seasonal development of the reproductive system with optimal environmental conditions. Growth of the gonads and secondary sexual characteristics is orchestrated by the hypothalamic–pituitary–gonadal (HPG) axis. However, our understanding of the physiological mechanisms by which food availability modulates activity of the HPG axis is limited.It is thought that many factors, including energetic status, modulate seasonal reproductive activation. We tested the hypothesis that food availability modulates the activity of the HPG axis in a songbird. Specifically, we food‐restricted captive adult male Abert's Towhees Melozone aberti for 2 or 4 weeks during photoinduced reproductive development. A third group (control) received ad libitum food throughout. We measured multiple aspects of the reproductive system including endocrine activity of all three levels of the HPG axis [i.e. hypothalamic gonadotropin‐releasing hormone‐I (GnRH‐I), plasma luteinizing hormone (LH) and testosterone (T)], and gonad morphology. Furthermore, because gonadotropin‐inhibitory hormone (GnIH) and neuropeptide Y (NPY; a potent orexigenic peptide) potentially integrate information on food availability into seasonal reproductive development, we also measured the brain levels of these peptides.At the hypothalamic level, we detected no effect of food restriction on immunoreactive (ir) GnRH‐I, but the duration of food restriction was inversely related to the size of ir‐GnIH perikarya. Furthermore, the number of ir‐NPY cells was higher in food‐restricted than control birds. Food restriction did not influence photoinduced testicular growth, but decreased plasma LH and T, and width of the cloacal protuberance, an androgen‐sensitive secondary sexual characteristic. Returning birds to ad libitum food availability had no effect on plasma LH or T, but caused the cloacal protuberance to rapidly increase in size to that of ad libitum‐fed birds.Our results support the tenet that food availability modulates photoinduced reproductive activation. However, they also suggest that this modulation is complex and depends upon the level of the HPG axis considered. At the hypothalamic level, our results are consistent with a role for the GnIH and NPY systems in integrating information on energetic status. There also appears to be a role for endocrine function at the anterior pituitary gland and testicular levels in modulating reproductive development in the light of energetic status and independently of testicular growth.

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Section: T H E G N I H -N P Y S Y S T E Mmentioning

confidence: 99%

Food availability, energetic constraints and reproductive development in a wild seasonally breeding songbird

et al. 2015

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“…GnRH II plays a critical role by orchestrating the coordination of reproduction with the availability of nutritional support [163]. …”

Section: Metabolic Signals That Control Energy Balance Linked To Rmentioning

confidence: 99%

Integrative Control of Energy Balance and Reproduction in Females

García-García

2012

ISRN Veterinary Science

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There is a strong association between nutrition and reproduction. Chronic dietary energy deficits as well as energy surpluses can impair reproductive capacity. Metabolic status impacts reproductive function at systemic level, modulating the hypothalamic GnRH neuronal network and/or the pituitary gonadotropin secretion through several hormones and neuropeptides, and at the ovarian level, acting through the regulation of follicle growth and steroidogenesis by means of the growth hormone-IGF-insulin system and local ovarian mediators. In the past years, several hormones and neuropeptides have been emerging as important mediators between energy balance and reproduction. The present review goes over the main sites implicated in the control of energy balance linked to reproductive success and summarizes the most important metabolic and neuroendocrine signals that participate in reproductive events with special emphasis on the role of recently discovered neuroendocrine peptides. Also, a little overview about the effects of maternal nutrition, affecting offspring reproduction, has been presented.

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“…In most vertebrates, GnRH1 is mainly synthesized and released from a group of neurons located in the preoptic area (POA) and hypothalamus, and is essential for controlling pituitary-gonadal functions (4). GnRH2 located in midbrain tegmentum and GnRH3 in terminal nerve associated with the olfactory region are not hypophysiotropic; rather they play neuromodulatory roles that may be indirectly linked to the reproductive neuroendocrine axis (5, 6). The zebrafish genome is missing an ortholog to mammalian GnRH1, but expresses GnRH2 in midbrain tegmentum and GnRH3 widely in forebrain areas of terminal nerve, ventral telencephalon, POA, and hypothalamus (7, 8).…”

Section: Introductionmentioning

confidence: 99%

Early Development of the Gonadotropin-Releasing Hormone Neuronal Network in Transgenic Zebrafish

Zhao¹,

Lin²,

Farajzadeh³

et al. 2013

Front. Endocrinol.

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Understanding development of gonadotropin-releasing hormone (GnRH) neuronal circuits is fundamental to our understanding of reproduction, but not yet well understood. Most studies have been focused on GnRH neurons located in the hypothalamus and preoptic area (POA), which directly regulate the pituitary-gonadal axis. In zebrafish (Danio rerio), two forms of GnRH have been identified: GnRH2 and GnRH3. GnRH3 neurons in this species plays two roles: hypophysiotropic and neuromodulatory, depending on their location. GnRH3 neurons in the ventral telencephalon, POA, and hypothalamus control pituitary-gonadal function; in other areas (e.g., terminal nerve), they are neuromodulatory and without direct action on reproduction. To investigate the biology of GnRH neurons, a stable line of transgenic zebrafish was generated in which the GnRH3 promoter drives expression of a bright variant of green fluorescent protein (Emerald GFP, or EMD). This provides unprecedented sensitivity in detecting and imaging GnRH3 neurons during early embryogenesis in the transparent embryo. Using timelapse confocal imaging to monitor the time course of GnRH3:EMD expression in the live embryo, we describe the emergence and development of GnRH3 neurons in the olfactory region, hypothalamus, POA, and trigeminal ganglion. By 50 h post fertilization, these diverse groups of GnRH3 neurons project broadly in the central and peripheral nervous systems and make anatomical connections with each other. Immunohistochemistry of synaptic vesicle protein 2 (a marker of synaptic transmission) in this transgenic model suggests synaptic formation is occurring during early development of the GnRH3 neural network. Electrophysiology reveals early emergence of responsiveness to the stimulatory effects of kisspeptin in terminal nerve GnRH3 neurons. Overall, our findings reveal that the GnRH3 neuronal system is comprised of multiple populations of neurons as a complicated network.

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Gonadotropin-releasing hormone II: a multi-purpose neuropeptide

Cited by 27 publications

References 92 publications

Food availability, energetic constraints and reproductive development in a wild seasonally breeding songbird

Food availability, energetic constraints and reproductive development in a wild seasonally breeding songbird

Integrative Control of Energy Balance and Reproduction in Females

Early Development of the Gonadotropin-Releasing Hormone Neuronal Network in Transgenic Zebrafish

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