IBYME   02675
INSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
artículos
Título:
Experimental data supporting the expression of the highly conserved GnRH-II in the brain and pituitary gland of rats
Autor/es:
MONGIAT LA; FERNANDEZ MO; LUX-LANTOS VA; GUILGUR LG; SOMOZA GM; LIBERTUN C
Revista:
REGULATORY PEPTIDES
Referencias:
Año: 2006 vol. 136 p. 50 - 57
ISSN:
0167-0115
Resumen:
The second GnRH form, originally identified in chickens (cGnRH-II or GnRH-II), is the most ubiquitous peptide of the GnRH neuropeptide family, being present from jawed fish to human beings. However, the presence of GnRH-II in such an important experimental model as the rat is still object of discussion. Here we present chromatographic, immunologic and biologic activity evidences supporting the expression of GnRH-II in the rat. Olfactory bulb, hypothalamus, remnant brain and anterior pituitary from a pool of 50 female adult rats were extracted and subjected to RP-HPLC on a C-18 column. The fractions were collected and evaluated by using two different RIA systems, specific for GnRH-I and GnRH-II respectively. Under these conditions the GnRH-I standard eluted in fraction 21 (f21) and was only detected with the GnRH-I RIA system, whereas the GnRH-II standard was only detected in the fraction 27 (f27) by using a GnRH-II RIA system. In the olfactory bulbs extract, the fractions analyzed by the GnRH-I RIA systems showed a single peak in f21, whereas by using the GnRH-II RIA system a single peak at f27 was observed. In the hypothalamus GnRH-I was detected in f21 meanwhile GnRH-II could not be detected. When the remnant brain and pituitary gland extracts were analyzed, both GnRH forms were detected. To the best of our knowledge, this is the first report concerning GnRH-II detection in a mammalian pituitary. The immunological properties of f27 were further tested in displacement experiments in comparison to GnRH-II, and no differences were found. Moreover, after 60 minutes stimulation, both f27 and GnRH-II had similar LH and FSH releasing activity in 12 day-old rat pituitary primary cell cultures. However, we failed in characterize the GnRH-II gene in this model. These results provide strong evidence for the expression of GnRH-II in the rat brain and pituitary gland.