Arachidonic acid release from rat Leydig cells depends on the presence of luteinizing hormone/human chorionic gonadotrophin receptors.
In this work, the involvement of arachidonic acid (AA) in the luteinizing hormone and human chorionic gonadotrophin (LH/hCG) action on Leydig cells was studied. Experiments were first designed to evaluate [14C]AA incorporation into membrane phospholipids. Subsequently, time-course, pulse-chase and dose-response studies of the effect of hCG on [14C]AA release were performed. Results indicated that 4 h was optimal for maximal incorporation of [14C]AA into membrane phospholipids of viable Leydig cells. Pulse-chase experiments and studies performed to evaluate the effect of different doses of hCG on [14C]AA release demonstrated that this hormone stimulates [14C]AA release in a dose-response and time-dependent manner. Furthermore, using a desensitised animal model, a link between the presence of LH/hCG receptors and LH/hCG-stimulated [14C]AA release in Leydig cells could be established. In fact, the amount of [14C]AA released was significantly dependent on, and directly proportional to, the concentration of LH/hCG binding sites. Thus [14C]AA released from intact rat Leydig cells decreased when animals had been previously injected with a high single dose of hCG (desensitised animals), which is known to cause a dramatic decrease in the number of LH/hCG binding sites. These results demonstrate that the mechanism of AA release in Leydig cells depends on LH/hCG-receptor interaction and also suggest that AA could act as an additional intracellular messenger associated with the hormonal action of LH/hCG.
Moraga
P F
PF
Unidad de Biología de la Reproducción, INTA, Universidad de Chile, Santiago, Chile.
Llanos
M N
MN
Ronco
A M
AM
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011974:Receptors, LH / Q000378:metabolism*; D013997:Time Factors
D006063:Chorionic Gonadotropin; D008563:Membrane Lipids; D010743:Phospholipids; D011974:Receptors, LH; D016718:Arachidonic Acid; D000242:Cyclic AMP