Sokołowska-Mikołajczyk M, Socha M, Szczerbik P, Epler P
Department of Ichthyobiology and Fisheries, University of Agriculture, ul. Prof. T. Spiczakowa 6, 30-199 Krakow-Mydlniki, Poland.
Comp Biochem Physiol A Mol Integr Physiol. 2009 Aug;153(4):386-90. doi: 10.1016/j.cbpa.2009.03.012. Epub 2009 Mar 27.
In fish, like in mammals, ghrelin affects gonadotropin release acting at the level of the hypothalamus as well as directly on the pituitary gland. In the present study, enzymatically dispersed pituitary cells obtained from sexually mature male and female carp (Cyprinus carpio L.) were incubated in the presence of human ghrelin at the concentration of 10(-7) or 10(-6) M, salmon GnRH analogue (Des-Gly(10), D-Arg(6), Trp(7), Leu(8), Pro(9))-LHRH (sGnRH-A) at the concentration of 10(-8) M or the combination of ghrelin (both concentrations) and sGnRH-A. ELISA method was used for carp LH levels determination in the media collected after 10 or 24 h of incubation. Ghrelin at the concentration of 10(-6) M caused the increase of the spontaneous LH secretion from female pituitary cells only. The combination of ghrelin (both concentrations) with sGnRH-A resulted in the significant elevation of LH levels in the incubations of both male and female pituitary cells in comparison with control incubations as well as with sGnRH-A alone treated cells. The results obtained in this study show that ghrelin functions as LH-stimulating hormone in common carp and that it acts directly on gonadotrophic cells, potentiating also the action of GnRH.
