Knockout of luteinizing hormone receptor abolishes the effects of follicle-stimulating hormone on preovulatory maturation and ovulation of mouse graafian follicles.
It is considered a dogma that a secretory peak of LH is indispensable as the trigger of ovulation. However, earlier studies on hypophysectomized rodents have shown that stimulation with recombinant FSH, devoid of any LH activity, is able to boost the final stages of follicular maturation and trigger ovulation. As the expression of ovarian LH receptors (LHRs) still persists after hypophysectomy, such studies cannot totally exclude the possibility that LHR activation is involved in the apparently pure FSH effects. To revisit this question, we analyzed in LHR knockout (LuRKO) mice the progression of folliculogenesis and induction of ovulation by human chorionic gonadotropin and human recombinant FSH treatments. The results provide clear evidence that follicular development and ovulation could not be induced by high doses of FSH in the absence of LHR expression. Ovarian histology and oocyte analyses indicated that follicular maturation did not advance in LuRKO mice beyond the antral follicle stage. Neither were ovulations detected in LuRKO ovaries after any of the gonadotropin treatments. The ovarian resistance to FSH treatment in the absence of LHR was confirmed by real-time RT-PCR and immunohistochemical analyses of a number of gonadotropin-dependent genes, which only responded to the treatments in wild-type control mice. Negative findings were not altered by estradiol priming preceding the gonadotropin stimulations. Hence, the present study shows that, in addition to ovulation, the expression of LHR is essential for follicular maturation in the progression from antral to preovulatory stage.
Pakarainen
Tomi
T
Department of Physiology, University of Turku, Fin-20500 Turku, Finland.
Zhang
Fu-Ping
FP
Nurmi
Laura
L
Poutanen
Matti
M
Huhtaniemi
Ilpo
I
D000818:Animals; D001483:Base Sequence; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D005498:Follicular Phase / Q000187:drug effects / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011974:Receptors, LH / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015415:Biomarkers; D012333:RNA, Messenger; D011974:Receptors, LH; D011994:Recombinant Proteins; D005640:Follicle Stimulating Hormone