Pituitary expression of LHbeta- and FSHbeta-subunit mRNA, cellular distribution of LHbeta-subunit mRNA and LH and FSH synthesis during and after treatment with a gonadotrophin-releasing hormone agonist in heifers.
The aim was to examine transcriptional and post-transcriptional regulation of LH and FSH biosynthesis. Female cattle were allocated to three groups: (i) Group 1, control (n = 6), synchronized to be at around Day 11 of the oestrous cycle on Day 31; (ii) Group 2 (n = 6), treated with gonadotrophin-releasing hormone (GnRH) agonist (deslorelin) for 31 days; and (iii) Group 3 (n = 6), treated with deslorelin for 28 days. All animals were slaughtered on Day 31. For animals in Group 2, pituitary content of LHbeta-subunit mRNA was suppressed 60% (P < 0.001) and LH 95% (P < 0.001), whereas FSHbeta-subunit mRNA was suppressed 25% (P > 0.05) and FSH 90% (P < 0.001). Three days after treatment with deslorelin (Group 3) LHbeta-subunit mRNA and LH remained suppressed (50% and 95%, respectively; P < 0.001). At the same time, FSHbeta-subunit mRNA did not differ from controls (P > 0.05) whereas FSH remained reduced by 80% (P < 0.001). The ratio of LHbeta-subunit mRNA present in the nucleus versus cytoplasm of gonadotroph cells was reduced (P < 0.05) in heifers during treatment with deslorelin (0.59 +/- 0.05) compared with the ratio in control heifers (1.31 +/- 0.22) and heifers 3 days after discontinuation of treatment (1.01 +/- 0.05). The findings indicated that treatment with GnRH agonist can suppress LHbeta-subunit mRNA expression without any significant effect on FSHbeta-subunit mRNA. As LH and FSH contents were suppressed to a greater degree than their beta-subunit mRNAs, it would appear that treatment with a GnRH agonist might influence gonadotrophin biosynthesis by a post-transcriptional mechanism(s). For LHbeta-subunit mRNA, this would appear not to be reduced export of message from the nucleus.
Aspden
W J
WJ
Animal Sciences and Production Group, Primary Industries Research Centre, Central Queensland University, Rockhampton, Qld, Australia.
Jackson
A
A
Trigg
T E
TE
D'Occhio
M J
MJ
D000818:Animals; D002417:Cattle; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D037201:Follicle Stimulating Hormone, beta Subunit / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists*; D017403:In Situ Hybridization; D007986:Luteinizing Hormone / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D037101:Luteinizing Hormone, beta Subunit / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism; D014158:Transcription, Genetic
D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone