Effect of human chorionic gonadotropin derivatives on leydig cell function.
BACKGROUND
Several human chorionic gonadotropin (hCG) derivatives have been detected in healthy human subjects, indicating that they may play a role in cell function. These hCG derivatives include deglycosylated hCG, proteolytic digestion products of hCG and free alpha and beta subunits of the hormone. It is well documented that testicular Leydig cells are responsive to luteinising hormone (LH) or its analogue hCG. These hormones have high affinity for LH/hCG receptors on the plasma membrane.


METHODS
We designed functional and binding studies to compare the effects of native hCG and several hCG derivatives on a rat Leydig cell system. The molecular weight of the hCG derivatives was determined by SDS-PAGE and the binding affinity to LH/hCG receptors was measured by a radioligand assay. In addition, their ability to produce testosterone, cyclic AMP and arachidonic acid release was also studied.


RESULTS
These hCG derivatives, with the exception of the free beta subunit, were able to bind to LH/hCG plasma membrane receptors with different affinities than that of native hCG. In addition, hCG derivatives did not increase intracellular cAMP levels or arachidonic acid release. However, they did increase testosterone production.


CONCLUSIONS
Taken together, the results of this study lead us to suggest that these hCG derivatives may regulate the action of the native hormone in Leydig cells and are, thus, molecules of physiological relevance.
Ronco
A M
AM
Unidad de Biología de la Reproducción, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile. amronco@uec.inta.uchile.cl
Llanos
M N
MN
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006801:Humans; D007457:Iodine Radioisotopes; D019272:Leukocyte Elastase / Q000378:metabolism; D007985:Leydig Cells / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D008970:Molecular Weight; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D011974:Receptors, LH / Q000378:metabolism; D013739:Testosterone / Q000096:biosynthesis
D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D007457:Iodine Radioisotopes; D011974:Receptors, LH; D016718:Arachidonic Acid; D013739:Testosterone; D000242:Cyclic AMP; D019272:Leukocyte Elastase