PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE (PACAP) STIMULATESADENYLATE-CYCLASE AND PROMOTES PROLIFERATION OF MOUSE PRIMORDIAL GERM-CELLS

During migration and for about 2 days after their arrival in the gonad al ridges, primordial germ cells (the embryonic precursors of gametes of the adult animal) proliferate actively. Certain growth factors, suc h as stem cell factor and leukemia inhibitory factor, seem to be essen tial for survival, proliferation and possibly differentiation of mouse primordial germ cell in vivo and/or in vitro, Similarly, increase in intracellular cAMP is followed by a marked enhancement of primordial g erm cell proliferation, at least in culture, In the present study, we show that pituitary adenylate cyclase-activating polypeptides (PACAP-2 7 and PACAP-38), two neuropeptides of the secretin-glucagon-vasoactive intestinal polypeptide-GH-releasing hormone family, stimulate in vitr o proliferation of mouse primordial germ cells, bind to primordial ger m cells and gonadal somatic cells (possibly to type I PACAP receptor) and activate adenylate cyclase in the same cells, Moreover, PACAP-like immunoreactivity was found in gonadal ridges, mostly on germ cell sur face, In conclusion, evidence is provided that PGC proliferation can b e stimulated by certain bioactive polypeptides, thus suggesting a nove l regulatory role for such compounds in early gonad development.