Abstract
Neuropeptide Y (NPY) is considered the most potent orexigenic peptide, increasing before meal time and during fasting. In teleost, most studies on NPY action upon growth hormone (GH) and luteinizing hormone (LH) were conducted in females or group of animals without sex discrimination. The aim of this study was to evaluate whether NPY modulates the expression and release of GH and gonadotropins in both sexes of Cichlasoma dimerus. By double-label immunofluorescence, we first determined the association between NPY fibers and pituitary cells. In addition, we performed in vitro studies to evaluate the effect of NPY on GH and gonadotropins expression by real-time PCR, and release by Western blot, in males and females separately. Contacts between NPY fibers and GH and follicle-stimulating hormone (FSH)-producing cells were detected, indicating possible functional relationships. We observed an increase in GH release in the culture medium at 2 nM for males (p = 0.043) and 20 nM for females (p = 0.028). Pituitary FSH release was stimulated at 20 nM (p = 0.026) and 200 nM (p = 0.033) for males and females, respectively. Finally, NPY only increased β-LH mRNA expression at 20 nM in females (p = 0.028) and its release at 2 nM (p = 0.049) and 200 nM for males (p = 0.005) and 200 nM for females (p = 0.018). In conclusion, NPY acts as a GH-, LH- and FSH-releasing factor, in a dose- and sex-dependent way.
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Acknowledgments
We thank Dr. Kawauchi for the GH antisera, Dr Akio Shimizu through Dr. M. Pandolfi for the LH and FSH antisera, and Dr. Gustavo M. Somoza, Dr. Alicia G. Faletti, Mr Martín R Ramallo, and Dr. Dante Paz for their valuable contributions. This work was supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Grant Number: PIP: 0276. P.V.), Agencia Nacional de Promoción Científica y Tecnológica References (Grant Number: PICT 2008–2005. P.V.), and Universidad de Buenos Aires (Grant Number: 20020120100280 P.V.).
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Di Yorio, M.P., Delgadin, T.H., Pérez Sirkin, D.I. et al. Growth hormone, luteinizing hormone, and follicle-stimulating hormone regulation by neuropeptide Y in both sexes of the cichlid fish, Cichlasoma dimerus . Fish Physiol Biochem 41, 843–852 (2015). https://doi.org/10.1007/s10695-015-0051-z
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DOI: https://doi.org/10.1007/s10695-015-0051-z