Portal de Periódicos da CAPES

Membrane fluidity regulates development of gonadotrope desensitization to GnRH

1987; Elsevier BV; Volume: 53; Issue: 1-2 Linguagem: Inglês

10.1016/0303-7207(87)90199-7

1872-8057

William C. Gorospe, P. Michael Conn,

Ovarian function and disorders

Development of GnRH-mediated gonadotrope desensitization was examined under conditions in which membrane fluidity was altered by temperature and/or chemical means. Cultured pituitary cells were preincubated at temperatures ranging from 4°C to 37°C for 3 h with a desensitizing concentration of GnRH (10−9 M) or with vehicle alone. Cells were then rinsed and responsiveness assessed by a second 3 h incubation with GnRH at 37°C. As preincubation temperatures decreased from 37°C to 23°C, development of desensitization in gonadotropes was progressively reduced. At 23°C and below, gonadotropes failed to become desensitized to GnRH. Decreases in membrane fluidity occurred over the same temperature range as measured directly by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene incorporated into plasma membrane. When membrane fluidity was increased by incubating cells with the membrane mobilizing agent 2-(2-methoxy-ethoxy)-ethyl-8-(cis-2-n-octylcyclopropyl)-octanoate (A2C), low temperature blockade of GnRH-mediated gonadotrope desensitization was reversed. A2C had no measurable effects on either GnRH receptor binding or number and caused no cytotoxic effects. These studies suggest that development of gonadotropine desensitization to GnRH can be regulated by the state of membrane fluidity.