Steroid hormones and growth factors act in an integrated manner at the levels of hypothalamic astrocytes: a role in the neuroendocrine control of reproduction.
Several growth factors (e.g., transforming growth factors beta and alpha, basic fibroblast growth factor), produced by hypothalamic astrocytes, participate in the control of hypothalamic gonadotrophin-releasing hormone (GnRH) neurons. On this basis, we have hypothesized that steroid hormones, like estrogens and progestagens, influence the GnRH neurons by modulating in glial cells the synthesis and the release of these growth factors. Data reported here indicate that the expression of transforming growth factor beta 1 is modulated in hypothalamic astrocytes by a progesterone derivative (i.e., dihydroprogesterone), while estrogens modulate that of basic fibroblast growth factor. Moreover, it is interesting to highlight that the effect of estrogens on basic fibroblast growth factor is mediated by another growth factor (i.e., transforming growth factor alpha). Altogether, the present findings support the concept that steroid hormones and growth factors act in an integrated manner at the level of hypothalamic astrocytes, thus adding a further piece of knowledge in the understanding of the mechanisms controlling GnRH neurons.
Department of Endocrinology and Center of Excellence on Neurodegenerative Diseases, Via Balzaretti 9, 20133, Milan, Italy. rita.galbiati@unimi.it
Mariarita
M
Galbiati
Simona
S
Saredi
Roberto C
RC
Melcangi
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D012739:Gonadal Steroid Hormones / Q000378:metabolism* / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D009490:Neurosecretory Systems / Q000187:drug effects / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects / Q000502:physiology*
D012739:Gonadal Steroid Hormones; D006133:Growth Substances; D007987:Gonadotropin-Releasing Hormone