Acidic mix of FSH isoforms are better facilitators of ovarian follicular maturation and E2 production than the less acidic.
FSH is secreted as a mix of isoforms with varying biologic attributes. To determine the functional significance of FSH heterogeneity, an acidic (ovine pituitary FSH; C-FSH) and less acidic mix (C-FSH exposed to neuraminidase; N-FSH) were administered to prepubertal lambs. Production of GnRH- induced less acidic FSH was blocked with a competitive GnRH receptor antagonist, Nal-Glu. Beginning 24 h after Nal-Glu, lambs were injected with C-FSH or N-FSH and LH. Controls included untreated, GnRH-treated, and Nal-Glu-treated groups. Blood samples were obtained at 2-h intervals. Plasma FSH levels were similar before treatment and increased over time in the C-FSH but not the N-FSH group (P < 0.001). Three of the six GnRH-treated ewes exhibited an LH surge. Peak E2 concentrations in the GnRH-treated animals were achieved 30-36 h after initiation of treatment. Peak circulating E2 levels tended to be higher in the C-FSH than in the GnRH-treated group. Only two of six N-FSH-treated ewes had a serum E2 rise. The C-FSH ewes had more estrogenic follicles than the GnRH and N-FSH groups (P < 0.05). Our findings show that C-FSH clears more slowly than N-FSH, and C-FSH is a better facilitator of follicular development and maturation than N-FSH.
West
Christine R
CR
Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA.
Carlson
Nichole E
NE
Lee
James S
JS
McNeilly
Alan S
AS
Sharma
Tejinder Pal
TP
Ye
Wen
W
Padmanabhan
Vasantha
V
D000143:Acids / Q000494:pharmacology*; D000818:Animals; D004151:Dipeptides / Q000494:pharmacology; D004338:Drug Combinations; D004958:Estradiol / Q000096:biosynthesis* / Q000097:blood / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism / Q000494:pharmacology*; D015571:Follicular Fluid / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D009439:Neuraminidase / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology*; D010902:Pituitary Gland / Q000737:chemistry; D020033:Protein Isoforms / Q000494:pharmacology; D012756:Sheep
C102118:2-naphthylalanyl-glutamic acid; D000143:Acids; D004151:Dipeptides; D004338:Drug Combinations; D006727:Hormone Antagonists; D020033:Protein Isoforms; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D009439:Neuraminidase