Discordant levels of serum bioactive LH in man as measured in different in-vitro bioassay systems using rat and mouse interstitial cells and human granulosa-luteal cells.
Serum samples from healthy men (n = 6), perimenopausal women (n = 9) and patients with polycystic ovarian disease (n = 4) were analysed for LH bioactivity by the two widely used in-vitro bioassay systems: the mouse and rat interstitial cell testosterone-formation assays. The results were compared with an assay employing LH-stimulated cyclic AMP production by cultured human granulosa-luteal cells. Average bioactive LH levels in the mouse cell assay were 1.6-fold higher than those measured using the rat assay. A good correlation (r = 0.89, P less than 0.01) was observed between the bioactive LH levels measured by these two assays. No significant difference was found between the sensitivities of the two assays: 0.009 +/- 0.003 IU/l (mean +/- S.E.M., n = 10) with rat cells and 0.011 +/- 0.003 IU/l (n = 10) with mouse cells. The LH level resulting in half-maximal stimulation of testosterone production in the mouse model was twofold higher than that in the rat model (0.185 +/- 0.020 vs 0.083 +/- 0.022 IU/l, P less than 0.01). The bioactive LH levels measured by the human granulosa-luteal cell assay averaged 12% higher than those obtained with the rat assay (r = 0.84, P less than 0.01), but 58% lower than levels measured with the mouse assay (r = 0.86, P less than 0.01). The data indicate that the target cell model used in the in-vitro bioassay of LH contributes to the documented discrepancies in reports on serum levels of bioactive LH.(ABSTRACT TRUNCATED AT 250 WORDS)
Ding
Y Q
YQ
Department of Physiology, University of Turku, Finland.
Ranta
T
T
Nikkanen
V
V
Huhtaniemi
I
I
D000328:Adult; D000818:Animals; D001681:Biological Assay; D000242:Cyclic AMP / Q000096:biosynthesis; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D051379:Mice; D008875:Middle Aged; D011085:Polycystic Ovary Syndrome / Q000097:blood; D051381:Rats; D013737:Testis / Q000187:drug effects / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis*
D013739:Testosterone; D007986:Luteinizing Hormone; D000242:Cyclic AMP