Unveiling the Importance of Tanycytes in the Control of the Dialogue Between the Brain and the Periphery

The polygamous GnRH neuron: Astrocytic and tanycytic communication with a neuroendocrine neuronal population

“…192 Equally interesting is the fact that the transport of leptin across tanycytes requires the activation of ErbB1 (also termed EGFR), 191 the very receptor shown to trigger the release of PGE 2 in tanycytes 133 and hence influence GnRH release. 193 Together with recent findings showing that gonadal steroids promote structural changes in the hypothalamus of young women during the menstrual cycle 64 and that mutations of the SEMA7A gene can be found in patients with congenital normosmic hypogonadotropic hypogonadism, 155 the recognition that Sema7A-β1-integrin signalling in tanycytes is required for the extension of tanycytic endfeet and normal reproductive cycles may be clinically important for infertility of hypothalamic origin, and a basis for therapeutic strategies. Besides, the disruption of the oestrous cycles, with a predominance of the oestrous phase and elevated circulating levels of LH in mice in which β1-integrin is selectively deleted in tanycytes 152 appears to recapitulate, at least in part, the neuroendocrine reproductive phenotype observed in two models of polycystic ovary syndrome (PCOS): the induction of pathologically elevated levels of LH, increased LH pulse frequency and a lengthening of the oestrous cycle with an increased duration of oestrus by prenatal androgen exposure (PNA) 194,195 and increased GnRH/LH release from acute living median eminence explants and increased LH pulse frequency in vivo following the treatment with anti-Müllerian hormone (AMH), an ovarian hormone of the TGFβ1 superfamily, whose circulating levels are highly elevated in PCOS patients.…”

“…Interestingly, the selective invalidation of leptin shuttles in tanycytes has recently been shown to blunt the adaptive neuroendocrine response to fasting, 191 known to suppress the HPG axis 192 191 the very receptor shown to trigger the release of PGE 2 in tanycytes 133 and hence influence GnRH release 193 …”