Increased neurokinin B (Tac2) expression in the mouse arcuate nucleus is an early marker of pubertal onset with differential sensitivity to sex steroid-negative feedback than Kiss1
| Autor: | John C. Gill, Ursula B. Kaiser, Shuyun Xu, Cecilia Martin, Cecilia Kwong, Víctor M. Navarro, Rona S. Carroll, Donald K. Clifton, Sekoni D. Noel, Robert A. Steiner |
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| Rok vydání: | 2012 |
| Předmět: |
medicine.medical_specialty
medicine.drug_class Neurokinin B Gonadotropin-releasing hormone Biology Gonadotropin-Releasing Hormone chemistry.chemical_compound Mice Endocrinology Kisspeptin Internal medicine Tachykinins medicine Animals Sexual Maturation Protein Precursors Receptor Feedback Physiological Mice Knockout Neurons Kisspeptins Arc (protein) Estradiol Antagonist Arcuate Nucleus of Hypothalamus Neuroendocrinology Luteinizing Hormone chemistry Sex steroid Estrogen Female Signal Transduction |
| Zdroj: | Endocrinology. 153(10) |
| ISSN: | 1945-7170 |
| Popis: | At puberty, neurokinin B (NKB) and kisspeptin (Kiss1) may help to amplify GnRH secretion, but their precise roles remain ambiguous. We tested the hypothesis that NKB and Kiss1 are induced as a function of pubertal development, independently of the prevailing sex steroid milieu. We found that levels of Kiss1 mRNA in the arcuate nucleus (ARC) are increased prior to the age of puberty in GnRH/sex steroid-deficient hpg mice, yet levels of Kiss1 mRNA in wild-type mice remained constant, suggesting that sex steroids exert a negative feedback effect on Kiss1 expression early in development and across puberty. In contrast, levels of Tac2 mRNA, encoding NKB, and its receptor (NK3R; encoded by Tacr3) increased as a function of puberty in both wild-type and hpg mice, suggesting that during development Tac2 is less sensitive to sex steroid-dependent negative feedback than Kiss1. To compare the relative responsiveness of Tac2 and Kiss1 to the negative feedback effects of gonadal steroids, we examined the effect of estradiol (E2) on Tac2 and Kiss1 mRNA and found that Kiss1 gene expression was more sensitive than Tac2 to E2-induced inhibition at both juvenile and adult ages. This differential estrogen sensitivity was tested in vivo by the administration of E2. Low levels of E2 significantly suppressed Kiss1 expression in the ARC, whereas Tac2 suppression required higher E2 levels, supporting differential sensitivity to E2. Finally, to determine whether inhibition of NKB/NK3R signaling would block the onset of puberty, we administered an NK3R antagonist to prepubertal (before postnatal d 30) females and found no effect on markers of pubertal onset in either WT or hpg mice. These results indicate that the expression of Tac2 and Tacr3 in the ARC are markers of pubertal activation but that increased NKB/NK3R signaling alone is insufficient to trigger the onset of puberty in the mouse. |
| Databáze: | OpenAIRE |
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