Endocrine Abstracts

Studies conducted using knockout mouse model revealed that defects of PROKR2 affect the correct ontogeny of GnRH neurons and, by consequence, neuroendocrine control of reproduction. Nevertheless its exact role during these processes and in the pathogenesis of congenital hypogonadotropic hypogonadism (CHH) remains elusive due to the phenotypic differences observed between mouse and human. Zebrafish (ZF) has emerged in the last ten years as a reliable model organism for studying the GnRH neuronal development and the neuroendocrinology of reproduction. Previous results obtained in our lab identified two well-conserved loci in the ZF genome, on chr1 and chr13, respectively named prokr1a and prokr1b. Whole mount in situ hybridization (WISH) and qRT-PCR experiments conducted at different developmental stages of ZF revealed distinct patterns of expression for prok-receptors suggesting prokr1b as the potential candidate involved in the GnRH-secreting neurons migration process from olfactory placode to their final hypothalamic destination. To verify these indications and better elucidate the function of both prokineticins receptors we recently conducted knockdown experiments using morpholino oligonucleotides sequences. Our results display an alteration of the GnRH fibers network architecture at 48 hours post fertilization (hpf) after downregulation of prokr1b that appeared misguided and reduced in numbers especially at level of pallium commissure and optic chiasm. Moreover, we also generated in ZF the prokr1b knockout model and our preliminary data are confirming the knockdown model observations. On the contrary, the downregulation of prokr1a does not affect GnRH fibers architecture. Taken together these results confirm the role of prokr1b during GnRH neurons migration establishing it as the ZF orthologous of human PROKR2. A deeper characterization of ZF prokr1b KO model could provide new information regarding the early establishment of the forebrain GnRH system, the factors controlling this complex developmental event, and its functional significance.

This work was supported by funds from University of Milan (Dotazione per attività istituzionali—Linea 2 azione B Piano di Sviluppo di Ateneo) and IRCCS Istituto Auxologico Italiano (Ricerca Corrente Funds: 05C202 and GONAFISH).

Funds: 05C202 and GONAFISH).