Changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle

1995 ◽  
Vol 132 (6) ◽  
pp. 771-776 ◽  
Author(s):  
Byung J Lee ◽  
Jin H Kim ◽  
Chae K Lee ◽  
Hae M Kang ◽  
Hyun C Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Estrous Cycle ◽  
Blot Hybridization ◽  
Mrna Level ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
Cytoplasmic Rna ◽  
Slot Blot Hybridization ◽  
Prolactin Gene ◽  
Prolactin Mrna

Lee BJ, Kim JH, Lee CK, Kang HM, Kim HC, Kang SG. Changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle. Eur J Endocrinol 1995;132:771–6. ISSN 0804–4643 The present study examined the changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle. Total cytoplasmic RNA was analyzed by Northern blot and slot-blot hybridization to examine the prolactin mRNA level. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to examine the Pit-1 mRNA level. Proestrous and estrous prolactin mRNA levels were significantly higher than the metestrous and diestrous levels, whereas Pit-1 mRNA levels of the estrous and metestrous stages were about two- to threefold higher than those of the proestrous and diestrous stages. Proestrous Pit-1 mRNA levels increased gradually from 10.00 h to 20.00 h, while prolactin mRNA levels slightly decreased until 14.00 h but increased later until 20.00 h. During the rat estrous cycle, especially in the afternoon of the proestrous day, changes of prolactin mRNA levels seem to follow a prior increase of Pit-1 mRNA. Therefore, Pit-1 may be partly involved in the regulation of prolactin gene expression according to the rat estrous cycle. Estradiol administration to ovariectomized rats significantly increased both the mRNA levels of prolactin and Pit-1, which suggests that the gene expression of Pit-1 is regulated by estrogen through indirect extracellular pathways. Byung Ju Lee, Department of Biology, College of Natural Sciences, University of Ulsan 680-749, Ulsan, South Korea

Gonadotrophin-releasing hormone regulation of gonadotrophin subunit gene expression: studies in tri-iodothyronine-suppressed rats

1989 ◽  
Vol 122 (1) ◽  
pp. 117-125 ◽  
Author(s):  
D. J. Haisenleder ◽  
G. A. Ortolano ◽  
A. C. Dalkin ◽  
S. J. Paul ◽  
W. W. Chin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Blot Hybridization ◽  
Male Rats ◽  
Male Rat ◽  
Mrna Levels ◽  
Dot Blot ◽  
Α Subunit ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Prolactin Mrna

ABSTRACT We have previously shown that a pulsatile gonadotrophin-releasing hormone (GnRH) stimulus can increase steady-state levels of α and LH-β subunit mRNAs in the male rat pituitary. Since α subunit is produced in both thyrotroph and gonadotroph cells, the effect of GnRH specifically on gonadotroph α gene expression is uncertain. To address this tissue, adult male rats were given injections of tri-iodothyronine (T3; 20 μg/100 g body wt, i.p.) daily for 8 days (day 8 = day of death) in order to decrease thyrotroph α mRNA levels (+ T3 group). Saline injections (i.p.) were given to control animals (− T3 group). Three days before GnRH administration, the animals were castrated and testosterone implants inserted s.c., to inhibit endogenous GnRH secretion. GnRH pulses (25 ng/pulse; 30-min interval) were given to freely moving animals (saline pulses to controls) via an atrial cannula for 12, 24 or 48 h. Serum LH and FSH were measured before and 20 min after the last GnRH pulse. Pituitary RNA was extracted and α, LH-β, FSH-β and prolactin mRNA levels were determined by dot-blot hybridization using 32P-labelled cDNA probes. Castration and testosterone replacement reduced α and LH-β mRNA levels by 30 and 40% respectively, compared with levels in untreated intact males, but did not decrease FSH-β concentrations. T3 administration further decreased α mRNA to 30% of values seen in intact males, but LH-β mRNA levels were unchanged. FSH-β mRNA concentrations were decreased by 23% in T3-treated rats (P < 0·05 vs intact controls). In −T3 rats, 12 h of GnRH pulses increased FSH-β mRNA levels (twofold) vs saline-pulsed controls, but significant increases in α or LH-β mRNA levels were not seen until after 24 h of GnRH pulses. In the +T3 group, an increase in α mRNA was observed earlier, after 12 h of GnRH pulses. After 24 and 48 h of GnRH, the increments in α and LH-β were of similar magnitude in both the +T3 and − T3 groups (4–5 and 3–4 fold increases in α and LH-β respectively; P < 0·05 vs saline-pulsed controls). In contrast, the stimulatory effect of GnRH on FSH-β mRNA was lost in + T3 animals after 48 h of pulses. In order to examine whether this loss in FSH-β mRNA responsiveness to GnRH was related to an inhibitory interaction of T3 in the presence of testosterone, a second study was conducted in castrated animals. The results showed that α mRNA levels were decreased by 33% in +T3 compared with −T3 castrated animals (P < 0·05), but LH-β and FSH-β mRNAs were unaffected by T3 administration. In castrated animals given GnRH pulses, T3 inhibited subunit mRNA responses and this effect was most marked for FSH-β mRNA. In contrast, prolactin mRNA levels were significantly higher (P < 0·05) in all +T3 experimental groups compared with their −T3 controls. These data indicate that T3 can inhibit FSH-β mRNA responses to pulsatile GnRH and that this action occurs in the absence of testosterone. Journal of Endocrinology (1989) 122, 117–125

Regulation of LH subunit mRNA levels by gonadal hormones in female rats

1988 ◽  
Vol 1 (1) ◽  
pp. 49-60 ◽  
Author(s):  
S. D. Abbot ◽  
K. Docherty ◽  
R. N. Clayton
Keyword(s):  
Gene Expression ◽  
Physiological Role ◽  
Gonadal Hormones ◽  
Ovariectomized Rats ◽  
Mrna Levels ◽  
Subunit Gene ◽  
Progesterone Treatment ◽  
Serum Lh ◽  
Pituitary Prolactin ◽  
Prolactin Mrna

ABSTRACT To determine the physiological role of the ovaries in regulation of LH subunit gene expression, levels of cytoplasmic mRNA were measured in a cDNA-RNA dot-blot hybridization assay. An increase (twofold) in α mRNA was first detected 8 days after ovariectomy and then remained stable for 4 weeks. In contrast, LH-β mRNA increased by 60–79% within 12 h of removing the ovaries and then rose progressively to six times the intact values at 3 and 4 weeks. Increases in LH-β mRNA were always greater than those of α mRNA. Oestradiol, and oestradiol plus progesterone, but not progesterone alone, prevented the rise in α and LH-β mRNA 10 days after ovariectomy. Three days after ovariectomy, α mRNA, but not LH-β mRNA, was suppressed to below intact control values by oestradiol and oestradiol plus progesterone, indicating greater sensitivity of α mRNA to oestradiol inhibition at this stage. A single injection of oestradiol (1 μg s.c.) to rats ovariectomized 14 days previously transiently suppressed α and LH-β mRNA levels and serum LH concentrations in parallel for 1–8 h, after which high preinjection values were restored. However, pituitary LH content remained suppressed after LH mRNA levels had returned to the control values of ovariectomized rats. In most instances there was a qualitative positive correlation between changes in α and LH-β mRNA, pituitary LH content and serum LH concentrations. LH content reflected LH-β mRNA changes more closely than those of α mRNA. However, in oestradiol-treated rats ovariectomized 10 days previously, LH content remained increased despite normalization of the LH-β and α mRNA levels, suggesting differential sensitivity to oestradiol of the gene expression and translational processes. Thus divergence of pre- and post-translational regulation of LH biosynthesis was demonstrated. These results imply an important physiological role for female sex hormones in the control of LH gene expression and LH biosynthesis. Prolactin mRNA fell by 30–50% for the first 2 weeks after ovariectomy, but by 3 and 4 weeks values were similar to those of intact controls. Serum and pituitary prolactin levels were reduced by 50% or more at all time-points, despite normalization of mRNA. Treatment of ovariectomized rats for 10 days with oestradiol and progesterone, either alone or combined, reversed the fall in prolactin mRNA and serum and pituitary prolactin levels. These changes in prolactin gene expression and synthesis were opposite to those of LH subunits in response to the same in-vivo hormone manipulations. Growth hormone mRNA levels were unchanged by ovariectomy, oestradiol or progesterone treatment. Levels of TSH-β mRNA increased slightly (maximum up to 50%) after ovariectomy, but were unaltered by oestradiol and progesterone treatment for 10 days. These results support the view that α mRNA changes, resulting from ovariectomy, oestradiol and progesterone treatment, occur in gonadotrophs and not thyrotrophs, which also express the α subunit gene.

scholarly journals Altered Patterns of Gene Expression in Arabidopsis Elicited by Cauliflower Mosaic Virus (CaMV) Infection and by a CaMV Gene VI Transgene

1999 ◽  
Vol 12 (5) ◽  
pp. 377-384 ◽  
Author(s):  
Chiara Geri ◽  
Edi Cecchini ◽  
Maria E. Giannakou ◽  
Simon N. Covey ◽  
Joel J. Milner
Keyword(s):  
Gene Expression ◽  
Transgenic Plants ◽  
Mosaic Virus ◽  
Rna Binding ◽  
Important Determinant ◽  
Blot Hybridization ◽  
Cauliflower Mosaic Virus ◽  
Slot Blot Hybridization ◽  
Pcr Products ◽  
Polymerase Chain

Cauliflower mosaic virus (CaMV) gene VI protein (P6) is an important determinant of symptom expression. Differential display polymerase chain reaction (PCR) was used to identify changes in gene expression in Arabidopsis elicited by a P6 transgene that causes a symptomatic phenotype. We used slot blot hybridization to measure the abundance of mRNAs complementary to 66 candidate PCR products in transgenic, CaMV-infected, and uninfected Arabidopsis plants. CaMV-infected and P6 transgenic plants showed broadly similar changes in abundance of mRNA species. In P6 transgenic plants we detected 18 PCR products that showed unambiguous changes in abundance plus another 15 that showed more limited changes (approximately twofold). CaMV-infected plants showed 17 unambiguous and 13 limited changes. Down-regulated species include those encoding a novel, phenol-like sulfotransferase, and a glycine-rich, RNA-binding protein. Up-regulated species included ones encoding an myb protein, glycine-rich and stress-inducible proteins, and a member of a previously unreported gene family. CaMV infection causes alterations in expression of many Arabidopsis genes. Transgene-mediated expression of P6 mimics virus infection in its effect on host gene expression, providing a potential mechanism for this process.

scholarly journals GDF-9 and BMP-15 mRNA Levels in Canine Cumulus Cells Related to Cumulus Expansion and the Maturation Process

Animals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 462 ◽  
Author(s):  
George Ramirez ◽  
Jaime Palomino ◽  
Karla Aspee ◽  
Monica De los Reyes
Keyword(s):  
Gene Expression ◽  
Estrous Cycle ◽  
Expression Patterns ◽  
Cumulus Cells ◽  
Mrna Levels ◽  
Cumulus Expansion ◽  
Polymerase Chain ◽  
Specific Regulation ◽  
Reproductive Phases

The competence to undergo expansion is a characteristic of cumulus cells (CCs). The aim was to investigate the expression of GDF-9 and BMP-15 mRNA in canine cumulus cells in relation to cumulus expansion and meiotic development over the estrous cycle. CCs were recovered from nonmatured and in vitro-matured (IVM) dog cumulus oocyte complexes (COCs), which were obtained from antral follicles at different phases of the estrous cycle. Quantitative real-time polymerase chain reaction (q-PCR) was used to evaluate the relative abundance of GDF-9 and BMP-15 transcripts from the CCs with or without signs of expansion. The results were evaluated by ANOVA and logistic regression. The maturity of the oocyte and the expansion process affected the mRNA levels in CCs. There were differences (p < 0.05) in GDF-9 and BMP-15 gene expression in CCs isolated from nonmatured COCs when comparing the reproductive phases. Lower mRNA levels (p < 0.05) were observed in anestrus and proestrus in comparison to those in estrus and diestrus. In contrast, when comparing GDF-9 mRNA levels in IVM COCs, no differences were found among the phases of the estrous cycle in expanded and nonexpanded CCs (p < 0.05). However, the highest (p < 0.05) BMP-15 gene expression in CCs that did not undergo expansion was exhibited in anestrus and the lowest (p < 0.05) expression was observed in estrus in expanded CCs. Although the stage of the estrous cycle did not affect the second metaphase (MII )rates, the expanded CCs obtained at estrus coexisted with higher percentages of MII (p < 0.05). In conclusion, the differential expression patterns of GDF-9 and BMP-15 mRNA transcripts might be related to cumulus expansion and maturation processes, suggesting specific regulation and temporal changes in their expression.

Sulfated glycoprotein-1 (SGP-1) expression in ovine endometrium during the oestrous cycle and early pregnancy

1995 ◽  
Vol 7 (5) ◽  
pp. 1053 ◽  
Author(s):  
TE Spencer ◽  
GH Graf ◽  
FW Bazer
Keyword(s):  
Early Pregnancy ◽  
Blot Hybridization ◽  
Immunohistochemical Localization ◽  
Oestrous Cycle ◽  
Northern Hybridization ◽  
Mrna Levels ◽  
Slot Blot ◽  
Slot Blot Hybridization ◽  
Endometrial Epithelium ◽  
Sulfated Glycoprotein

This study determined effects of day of oestrous cycle and early pregnancy on sulfated glycoprotein-1 (SGP-1) expression in ovine endometrium. A 364-bp clone of the ovine SGP-1 mRNA was amplified from reverse transcribed Day-15 cyclic endometrial mRNA using the polymerase chain reaction (PCR) and primers specific for the rat SGP-1 mRNA sequence. Nucleotide sequence of the ovine SGP-1 cDNA shared significant identity with rat SGP-1 and human prosaposin. Ewes (n = 40) were hysterectomized on either Day 1, 6, 11, 13 or 15 of the oestrous cycle or on Day 11, 13, 15, 17 or 25 of early pregnancy. Total cellular RNA was isolated from endometrium and subjected to Northern and slot blot hybridization analyses using an antisense cRNA probe transcribed from the ovine SGP-1 cDNA clone. A single 2.6-kb mRNA transcript was detected by Northern hybridization analyses. Slot blot hybridization analyses indicated that steady-state levels of endometrial SGP-1 mRNA varied during the oestrous cycle (cubic, P < 0.02) and increased between Day 11 and Day 25 of early pregnancy (linear, P < 0.01). On Days 11, 13 and 15, endometrial SGP-1 mRNA levels were greater in pregnant ewes than in cyclic ewes (day x pregnancy status, P < 0.01). Immunohistochemical localization of SGP-1 in uterine tissues with rabbit anti-rat SGP-1 antibody revealed intense immunoreactivity associated primarily with the endometrial epithelium. These results indicate that the ovine endometrium expresses SGP-1, a prosaposin, and that SGP-1 expression varies during the oestrous cycle and is enhanced by the conceptus. The presence of SGP-1 in the endometrium suggests intracellular and extracellular roles for this protein in glycosphingolipid metabolism or transport in the uterine environment.

scholarly journals Differential Gene Expression of Steroid 5α-Reductase 2 in Core Needle Biopsies from Malignant and Benign Prostatic Tissue1

1997 ◽  
Vol 82 (7) ◽  
pp. 2210-2214
Author(s):  
Catarina Bjelfman ◽  
Torbjörn G. Söderström ◽  
Einar Brekkan ◽  
Bo Johan Norlén ◽  
Lars Egevad ◽  
...  
Keyword(s):  
Gene Expression ◽  
Messenger Rna ◽  
Mrna Level ◽  
Transrectal Ultrasound ◽  
Mrna Levels ◽  
Prostate Hyperplasia ◽  
Noncancerous Tissue ◽  
Core Needle ◽  
Total Rna ◽  
Prostate Diseases

Androgens are implicated in the development of prostate cancer (CAP) and benign prostate hyperplasia. The conversion of testosterone to the more potent metabolite dihydrotestosterone by prostate-specific steroid 5α-reductase type 2 (5α-red2) is a key mechanism in the action of androgens in the prostate and is important in the promotion and progression of prostate diseases. Manipulation of the turnover of androgens is thus fundamental in the pharmacological treatment strategy. We have developed a sensitive solution hybridization method for quantification of the gene expression of 5α-red2 in core needle biopsies of the prostate. The 5α-red2-specific messenger RNA (mRNA) levels were measured in 50 human prostate transrectal ultrasound-guided core biopsies obtained from 31 outpatients (median age 72, range 57–88 yr) undergoing biopsy for diagnostic purposes. Significant differences were observed in the gene expression of 5α-red2 between cancerous and noncancerous tissue. In the 14 biopsies judged cancerous, the median 5α-red mRNA levels were 3.5 amol/ng total RNA compared with 12.0 amol/ng total RNA in the biopsies showing no cancer (P = 0.0018). The median 5α-red2 mRNA level in noncancerous tissue was thus 3.4 times higher than in the cancerous specimens.

Developmental expression of pIgR gene in sheep mammary gland and hormonal regulation

2002 ◽  
Vol 69 (1) ◽  
pp. 13-26 ◽  
Author(s):  
AURORE RINCHEV-ALARNOLD ◽  
LUCETTE BELAIR ◽  
JEAN DJIANE
Keyword(s):  
Gene Expression ◽  
Mammary Gland ◽  
Hormonal Regulation ◽  
Mrna Level ◽  
Immunohistochemical Analysis ◽  
Developmental Expression ◽  
Secretory Iga ◽  
Mrna Levels ◽  
Immunoglobulin Receptor ◽  
Pregnancy And Lactation

Secretory IgA found in external secretions are constituted by polymeric IgA (pIgA) bound to the extra-cellular part of the polymeric immunoglobulin receptor (pIgR). The receptor mediates transcytosis of pIgA across epithelial cells. The aim of the present study was to analyse the evolution of pIgR expression in the sheep mammary gland during the development of the mammary gland and to analyse its hormonal regulation. Gene expression of the pIgR was analysed in sheep mammary gland during pregnancy and lactation. By Northern Blot analysis, we observed that low levels of pIgR mRNA are expressed until day 70 of pregnancy. Accumulation of pIgR mRNA started during the third part of pregnancy and intensified 3 d after parturition to reach highest levels during established lactation (day 70). In situ hybridization analysis was used to confirm the increase in pIgR gene expression per mammary epithelial cell. In order to examine the hormonal regulation of the pIgR expression, virgin ewes were hormonally treated. Treatment with oestradiol and progesterone increased pIgR mRNA levels slightly. Subsequent addition of glucocorticoids induced a significant accumulation of pIgR mRNA in the mammary gland of the treated animals. Immunohistochemical analysis was performed to verify that the increase of pIgR mRNA level was associated with enhancement of the pIgR protein in mammary cells. No increase of pIgR mRNA levels were observed if PRL secretion was blocked by bromocryptine injections throughout the hormonal procedure. In conclusion, the present experiments suggest that the enhancement of pIgR levels during lactation result from combined effects of both prolactin and glucocorticoids.

scholarly journals Differential regulation of γ-glutamylcysteine synthetase heavy and light subunit gene expression

1997 ◽  
Vol 326 (1) ◽  
pp. 167-172 ◽  
Author(s):  
Jiaxin CAI ◽  
Zong-Zhi HUANG ◽  
Shelly C. LU
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Steady State ◽  
Mrna Level ◽  
Rat Hepatocytes ◽  
Mrna Levels ◽  
Subunit Gene ◽  
Subunit Mrna ◽  
Glutamylcysteine Synthetase ◽  
Steady State Mrna Level

γ-Glutamylcysteine synthetase (GCS) is the rate-limiting enzyme in the biosynthesis of glutathione and is composed of a heavy and a light subunit. Although the heavy subunit is enzymically active alone, the light subunit plays an important regulatory role by making the holoenzyme function more efficiently. In the current study we examined whether conditions which are known to influence gene expression of the heavy subunit also influence that of the light subunit, and the mechanisms involved. Treatment of cultured rat hepatocytes with hormones such as insulin and hydrocortisone, or plating hepatocytes under low cell density increased the steady-state mRNA level of the heavy subunit only. Treatment with diethyl maleate (DEM), buthionine sulphoximine (BSO) and t-butylhydroquinone (TBH) increased the steady state mRNA level and gene transcription rates of both subunits. These treatments share in common their ability to induce oxidative stress and activate nuclear factor κB (NF-κB). Treatment with protease inhibitors 7-amino-1-chloro-3-tosylamido-2-heptanone (TLCK) or L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK) had no influence on the basal NF-κB and GCS subunit mRNA levels, but blocked the activation of NF-κB by DEM, BSO and TBH, and the increase in GCS heavy subunit mRNA level by BSO and TBH. On the other hand, the DEM-, BSO- and TBH-induced increase in GCS light-subunit mRNA level was unaffected by TLCK and TPCK. Thus only the heavy subunit is hormonally regulated and growth sensitive, whereas both subunits are regulated by oxidative stress. Signalling through NF-κB is involved only in the oxidative-stress-mediated changes in the heavy subunit gene expression.

scholarly journals Treatment with PPARαAgonist Clofibrate Inhibits the Transcription and Activation of SREBPs and Reduces Triglyceride and Cholesterol Levels in Liver of Broiler Chickens

PPAR Research ◽  
2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Lijun Zhang ◽  
Chunyan Li ◽  
Fang Wang ◽  
Shenghua Zhou ◽  
Mingjun Shangguan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Broiler Chickens ◽  
Target Genes ◽  
Nuclear Protein ◽  
Mrna Level ◽  
Control Group ◽  
Mrna Levels ◽  
Protein Levels ◽  
Cholesterol Levels ◽  
Regulation Mechanisms

PPARαagonist clofibrate reduces cholesterol and fatty acid concentrations in rodent liver by an inhibition of SREBP-dependent gene expression. In present study we investigated the regulation mechanisms of the triglyceride- and cholesterol-lowering effect of the PPARαagonist clofibrate in broiler chickens. We observed that PPARαagonist clofibrate decreases the mRNA and protein levels of LXRαand the mRNA and both precursor and nuclear protein levels of SREBP1 and SREBP2 as well as the mRNA levels of the SREBP1 (FASNandGPAM) and SREBP2 (HMGCRandLDLR) target genes in the liver of treated broiler chickens compared to control group, whereas the mRNA level ofINSIG2, which inhibits SREBP activation, was increased in the liver of treated broiler chickens compared to control group. Taken together, the effects of PPARαagonist clofibrate on lipid metabolism in liver of broiler chickens involve inhibiting transcription and activation of SREBPs and SREBP-dependent lipogenic and cholesterologenic gene expression, thereby resulting in a reduction of the triglyceride and cholesterol levels in liver of broiler chickens.

scholarly journals Regulation of pituitary inhibin/activin subunits and follistatin gene expression by GnRH in female rats

2011 ◽  
Vol 210 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Petra Popovics ◽  
Zoltan Rekasi ◽  
Alan J Stewart ◽  
Magdolna Kovacs
Keyword(s):  
Gene Expression ◽  
Mrna Level ◽  
Inhibin B ◽  
Female Rats ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Short Term ◽  
Α Subunit ◽  
Long Term Treatment

Pituitary inhibin B, activin B, and follistatin are local regulators of FSH. Activin B is a homodimeric molecule (βB–βB), while inhibin B contains an α and a βB subunit. The regulation of gene expression of α, βB, and follistatin by local and endocrine hormones was examined in pituitaries from female rats and in perifused pituitary cells by RT-PCR. Ovariectomy (OVX) induced an elevation in the mRNA level of α and βB subunits and follistatin. Short-term (4 h) treatment of pituitary cells with GnRH decreased both the inhibin α and the inhibin/activin βB subunit mRNA levels, while long-term treatment (20 h) with 100 nM GnRH stimulated the expression of both subunits. In contrast, the mRNA level of follistatin was elevated after the short-term GnRH treatment. Long-term exposure of pituitary cells to estradiol and inhibin B suppressed the mRNA expression of βB and had no effect on the expression of α subunit and follistatin. Our results demonstrate that the increased expressions of inhibin/activin subunits and follistatin in the post-OVX period can be induced by the lack of gonadal negative feedback, resulting in a high GnRH environment in the pituitary. This study reports for the first time that GnRH administered in high doses and for a long period stimulates the gene expression of inhibin/activin subunits and thereby may contribute to the stimulatory effect of OVX on the expression of these genes.

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