Calcium, modulator of the expression of intracellular gonadoliberin message

GnRH has been entrapped in liposomes. Chromatographic studies and enzymatic peptidase treatments show the efficiency of the encapsulation. Superfused hypophyses respond to the message of the internalized GnRH only when calcium is present in the extracellular medium. The intensity of the response depends on the duration of the entrapped GnRH infusion. The decrease observed in the response intensity after a long stay of the GnRH in the cytoplasm shows that GnRH controls its own expression. The binding of GnRH to the membrane receptor during the early phase induces a calcium uptake necessary to the expression of the internalized GnRH, this being the late phase in LH release. A too low calcium concentration does not allow GnRH expression.