LXR INCREASE GnRH EXPRESSION IN THE RAT HYPOTHALAMUS IN VIVO

KRUSE, M. S.; SUAREZ, L.; BRUMOVSKY, P.; COIRINI, H.

Chascomus

Congreso; XVI Jornadas Anuales de la Sociedad Argentina de Biología; 2014

Previously we described the expression of LXR receptors in the hypothalamus (HT) and its relation with the metabolism. We evaluated the action of LXR activation on the expression of factors produced in the HT in vitro and in vivo by Western Blot. We studied the expression of the leptin peptide, LHRH and GHRH (as they present LXRE sequences in their promoter region), the αMSH and NPY in male Sprague-Dawley rats. As a positive control, the cholesterol transporter ABCA1 expression was also measured. For in vitro assays, hypothalamic explants were exposed to two synthetic LXR agonists T0901317 (T0) or GW3965 (GW) for 2, 4, 6 and 8 h (10 uM). For in vivo tests, the animals were injected into the third ventricle with either T0 or GW (1.25-2.5μg / 5 ul ICV) and after 3.5 h the HT were taken and processed. Results: No changes were observed in the expression of the factors evaluated in vitro. The HT explants were viable (measured by LDH) and responded to the treatment with an increased ABCA1 expression. In contrast, T0 and GW significantly increase the expression of GnRH in vivo. These results indicate that acute LXR activation in HT affects at least the expression of GnRH in vivo (PIP 860).