A lamprey gonadotropin-releasing hormone in the bovine brain

Abstract

Mammalian gonadotropin release from the anterior pituitary is under control of the hypothalamic luteinizing hormone-releasing hormone (LHRH) and a putative analog, follicle stimulating hormone-releasing factor (FSHRF). Analogs of mammalian LHRH and their receptors have been isolated in various animals; of these, the lamprey-gonadotropin-releasing hormone-IH (lampreyGnRH-IH) analog seems the most likely candidate as a possible independent FSHRF in the mammalian system. On the basis of these studies, I hypothesized that lamprey-GhRH-III may be a FSHRF in mammals, and if so, it should be possible to demonstrate the presence of this hormone during bovine brain development. To test this hypothesis, I used immunofluorescence to determine 1) if lamprey-GnRH-in is present in the fetal bovine brain and 2) at what stage during development this hormone is expressed. Additionally, I sought 3) to localize a receptor to which lamprey-GnRH-IH may bind on anterior pituitary cells, and 4) to determine the level of colocalization of GnRH receptor and the downstream effect of this ligand-receptor interaction: FSH. Three trimester ages of brain were studied in order to determine the presence of this gonadotropinreleasing hormone associated with neurons during fetal bovine development The antibody to lamprey-GnRH-in was found bound to neuronal membranes in the diencephalon region of the fetal brain at all ages studied. Additionally, GnRH receptor antibody was found on fetal anterior pituitary cells colocalized with FSH. These results indicate that the lamprey-GnRH-III analog or a closely related peptide is present in the bovine brain, and may be a mammalian FSHRF.