P1.49. OMENTIN-1 IS REGULATED BY KISSPEPTIN AND ESTRADIOL AND MODULATES GNRH SIGNALING VIA PKC, ERK1/2, AND CAMP PATHWAYS IN MOUSE GT1-7 NEURONS
Natalia Respekta-Długosz1,2, Dominika Wachowska1,2, Pascal Froment3, Joëlle Dupont3, Agnieszka Rak1
1 Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, Krakow, Poland
2 Doctoral School of Exact and Natural Sciences, Jagiellonian University, Łojasiewicza 11, Krakow, Poland
3 INRAE, Physiologie de la Reproduction et des Comportments, Nouzilly, France
INTRODUCTION: The hypothalamus regulates hormone release critical for reproduction, growth, metabolism, and stress. Omentin-1 (OMNT1) is an adipokine that acts by insulin receptor (INSR) and involved in metabolic and reproductive regulation, but its role in central neuroendocrine control remains unknown.
AIM(S): This study aimed to investigate the expression and regulation of OMNT1 in hypothalamic neurons, and its role in neuroendocrine function and intracellular signaling pathways.
METHOD(S): The GnRH-secreting mouse hypothalamic cell line GT1-7 was used as an in vitro model. Firstly, OMNT1 localization with GnRH and the INSR was assessed by immunocytochemistry. Secondly, GT1-7 neurons were treated with kisspeptin (10, 100 and 1000 nM) or estradiol (1, 10 and 100 nM) for 24 h to measured OMNT1 protein expression by western blot. Next, effect of OMNT1 (10, 50 and 100 ng/mL) was studied on GnRH secretion (ELISA) for 15 and 30 min or GnRH expression (RT-qPCR, western blot) for 24 h. Moreover, OMNT1 effects on ERK1/2, PKC (western blot), and cAMP (ELISA) were determined. Using pharmacological inhibitor of ERK1/2 (PD098059 10 μM), PKC (Bisindolylmaleimide I,2 nM) or cAMP (SQ22536, 150 μM) GnRH secretion induced by OMNT was measured. Data were analyzed by Student’s t-test or one-way ANOVA with Tukey’s post hoc test (p < 0.05; n = 6).
RESULTS: OMNT1 expression was confirmed in GT1-7 neurons and colocalized with both GnRH and the INSR. Kisspeptin and estradiol modulated effect on OMNT1 protein levels. OMNT1 increased GnRH secretion after 30 min of incubation but reduced GnRH expression after 24 h. OMNT1 induced phosphorylation of ERK1/2 and PKC, while decreased intracellular cAMP levels. Inhibition of these signaling pathways confirmed their involvement in OMNT1-mediated GnRH secretion.
CONCLUSIONS: OMNT1 modulates GnRH neuron function via key signaling pathways, linking metabolic signals with reproductive control and providing new insight into adipokine action in the brain.
FINANCIAL SUPPORT: This research was supported by a grant from the Priority Research Area (Research Support Module) under the Strategic Programme Excellence Initiative at Jagiellonian University