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Progesterone may directly inhibit GnRH neuronal activity via progesterone receptor membrane component 1

Wednesday, October 26, 2011 — Poster Session IV

2:00 p.m. – 4:00 p.m.

Natcher Conference Center




  • NM Bashour
  • S Wray


Gonadotropin-releasing hormone-1 (GnRH-1) neurons are essential for reproduction, being an integral component of the hypothalamic-pituitary-gonadal (HPG) axis. Progesterone (P4), a steroid hormone, modulates reproductive behaviour and GnRH secretion. Specific mechanisms by which P4 rapidly affects the HPG axis are unknown. Progesterone receptor membrane component 1 (PgRMC1) and its partner SERPINE1 mRNA binding protein 1 (SERBP1) have been shown to mediate rapid progestin actions in various tissues. This study examined the expression of these proteins in GnRH-1 neurons and the role they may have in mediating action of P4 on GnRH-1 neurons. PgRMC1 and SERBP1 were found in GnRH-1 neurons in the hypothalamus in adult mice as well as during embryonic development. Expression during development allowed GnRH-1 neurons maintained in embryonic nasal explants to be used to investigate the effect of P4 on GnRH-1 neuronal activity via calcium imaging. Application of 10nM P4 caused a 30-43% inhibition in 56% of GnRH-1 neurons tested. Future experiments will determine: 1) the role of GABAergic and glutamatergic input in mediating P4-induced inhibition in GnRH-1 neurons and 2) the signal transduction pathway activated after P4 application.

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