Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.

Jessica Rose, Iain Clarke, Adam Hamlin, Alda Pereira, Alexandra Rao, Christopher Scott

Research output: Other contribution to conferencePoster

Abstract

Testosterone exerts a negative feedback action on the secretion of gonadotrophin releasing hormone (GnRH) and the gonadotrophins in males. The mechanism by which this occurs is unclear, as GnRH neurons do not express androgen receptors or oestrogen receptor-α. One possibility is that the feedback effect is transmitted through GnIH cells. GnIH is a peptide produced in the dorsomedial nucleus (DMH) and GnIH neurons project to GnRH cells and to the median eminence in the sheep brain. GnIH is secreted into the hypophysial portal blood in this species and acts to inhibit GnRH action on gonadotropes. To test the hypothesis that testicular hormones regulate GnIH gene expression, we used in situ hybridisation histochemistry to measure levels of mRNA in the hypothalamus of rams and wethers (n=5/group). Using 20µm cryostat sections of perfusion-fixed ram tissue 5 regions of the hypothalamus were examined. The number of GnIH cells detected was higher (P<0.05) in rams (55.5±12.21) than in wethers (11.5±7.54) in the caudal region of the DMH. Expression/cell was measured counting silver grains with the 35S-labelled riboprobe, but this was similar in rams and wethers. We conclude that testicular hormones increase GnIH mRNA expression in the ram hypothalamus and that this contributes to the negative feedback effect on GnRH and gonadotropin secretion. Future work will determine whether this feedback effect is due to testosterone.
Original languageEnglish
Publication statusPublished - 26 Aug 2013
EventAnnual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology - Melbourne Convention & Exhibition Centre, Melbourne, Australia
Duration: 24 Aug 201427 Aug 2014

Conference

ConferenceAnnual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology
CountryAustralia
CityMelbourne
Period24/08/1427/08/14

Fingerprint

Testicular Hormones
Gonadotropins
Hypothalamus
Sheep
Hormones
Gene Expression
Gonadotropin-Releasing Hormone
Dimenhydrinate
Testosterone
Mediodorsal Thalamic Nucleus
Neurons
Messenger RNA
Median Eminence
Androgen Receptors
Silver
Estrogen Receptors
In Situ Hybridization
Perfusion

Cite this

Rose, J., Clarke, I., Hamlin, A., Pereira, A., Rao, A., & Scott, C. (2013). Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.. Poster session presented at Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology, Melbourne, Australia.
Rose, Jessica ; Clarke, Iain ; Hamlin, Adam ; Pereira, Alda ; Rao, Alexandra ; Scott, Christopher. / Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep. Poster session presented at Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology, Melbourne, Australia.
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title = "Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.",
abstract = "Testosterone exerts a negative feedback action on the secretion of gonadotrophin releasing hormone (GnRH) and the gonadotrophins in males. The mechanism by which this occurs is unclear, as GnRH neurons do not express androgen receptors or oestrogen receptor-α. One possibility is that the feedback effect is transmitted through GnIH cells. GnIH is a peptide produced in the dorsomedial nucleus (DMH) and GnIH neurons project to GnRH cells and to the median eminence in the sheep brain. GnIH is secreted into the hypophysial portal blood in this species and acts to inhibit GnRH action on gonadotropes. To test the hypothesis that testicular hormones regulate GnIH gene expression, we used in situ hybridisation histochemistry to measure levels of mRNA in the hypothalamus of rams and wethers (n=5/group). Using 20µm cryostat sections of perfusion-fixed ram tissue 5 regions of the hypothalamus were examined. The number of GnIH cells detected was higher (P<0.05) in rams (55.5±12.21) than in wethers (11.5±7.54) in the caudal region of the DMH. Expression/cell was measured counting silver grains with the 35S-labelled riboprobe, but this was similar in rams and wethers. We conclude that testicular hormones increase GnIH mRNA expression in the ram hypothalamus and that this contributes to the negative feedback effect on GnRH and gonadotropin secretion. Future work will determine whether this feedback effect is due to testosterone.",
author = "Jessica Rose and Iain Clarke and Adam Hamlin and Alda Pereira and Alexandra Rao and Christopher Scott",
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day = "26",
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Rose, J, Clarke, I, Hamlin, A, Pereira, A, Rao, A & Scott, C 2013, 'Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.' Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology, Melbourne, Australia, 24/08/14 - 27/08/14, .

Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep. / Rose, Jessica; Clarke, Iain; Hamlin, Adam; Pereira, Alda; Rao, Alexandra; Scott, Christopher.

2013. Poster session presented at Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology, Melbourne, Australia.

Research output: Other contribution to conferencePoster

TY - CONF

T1 - Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.

AU - Rose, Jessica

AU - Clarke, Iain

AU - Hamlin, Adam

AU - Pereira, Alda

AU - Rao, Alexandra

AU - Scott, Christopher

PY - 2013/8/26

Y1 - 2013/8/26

N2 - Testosterone exerts a negative feedback action on the secretion of gonadotrophin releasing hormone (GnRH) and the gonadotrophins in males. The mechanism by which this occurs is unclear, as GnRH neurons do not express androgen receptors or oestrogen receptor-α. One possibility is that the feedback effect is transmitted through GnIH cells. GnIH is a peptide produced in the dorsomedial nucleus (DMH) and GnIH neurons project to GnRH cells and to the median eminence in the sheep brain. GnIH is secreted into the hypophysial portal blood in this species and acts to inhibit GnRH action on gonadotropes. To test the hypothesis that testicular hormones regulate GnIH gene expression, we used in situ hybridisation histochemistry to measure levels of mRNA in the hypothalamus of rams and wethers (n=5/group). Using 20µm cryostat sections of perfusion-fixed ram tissue 5 regions of the hypothalamus were examined. The number of GnIH cells detected was higher (P<0.05) in rams (55.5±12.21) than in wethers (11.5±7.54) in the caudal region of the DMH. Expression/cell was measured counting silver grains with the 35S-labelled riboprobe, but this was similar in rams and wethers. We conclude that testicular hormones increase GnIH mRNA expression in the ram hypothalamus and that this contributes to the negative feedback effect on GnRH and gonadotropin secretion. Future work will determine whether this feedback effect is due to testosterone.

AB - Testosterone exerts a negative feedback action on the secretion of gonadotrophin releasing hormone (GnRH) and the gonadotrophins in males. The mechanism by which this occurs is unclear, as GnRH neurons do not express androgen receptors or oestrogen receptor-α. One possibility is that the feedback effect is transmitted through GnIH cells. GnIH is a peptide produced in the dorsomedial nucleus (DMH) and GnIH neurons project to GnRH cells and to the median eminence in the sheep brain. GnIH is secreted into the hypophysial portal blood in this species and acts to inhibit GnRH action on gonadotropes. To test the hypothesis that testicular hormones regulate GnIH gene expression, we used in situ hybridisation histochemistry to measure levels of mRNA in the hypothalamus of rams and wethers (n=5/group). Using 20µm cryostat sections of perfusion-fixed ram tissue 5 regions of the hypothalamus were examined. The number of GnIH cells detected was higher (P<0.05) in rams (55.5±12.21) than in wethers (11.5±7.54) in the caudal region of the DMH. Expression/cell was measured counting silver grains with the 35S-labelled riboprobe, but this was similar in rams and wethers. We conclude that testicular hormones increase GnIH mRNA expression in the ram hypothalamus and that this contributes to the negative feedback effect on GnRH and gonadotropin secretion. Future work will determine whether this feedback effect is due to testosterone.

M3 - Poster

ER -

Rose J, Clarke I, Hamlin A, Pereira A, Rao A, Scott C. Testicular hormones increase gonadotrophin inhibitory hormone (GnIH) gene expression in the hypothalamus of the male sheep.. 2013. Poster session presented at Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology, Melbourne, Australia.