Abstract
During the preovulatory period, the pituitary action of progesterone is biphasic, moving from a severalfold augmentation of the gonadotropin release action of GnRH to a suppression of GnRH efficacy, which occurs in rats over a period of about 12 h, but the extent to which these biphasic effects are dependent on alterations in progesterone receptor (PR) expression is not known. To address this, as well as the localization of PR in cultured rat pituitary cells, we used cells from ovariectomized rats cultured ± 0.2 nM E2 with acute progesterone treatment on day 3. Northern blot of poly(A+) RNA extracts showed multiple PR messenger RNA (mRNA) transcripts between 4.8-10.2 kb; E2 treatment led to a 5- to 6 fold increase in the predominant PR mRNA transcripts (5.1 and 10.1. kb). In the presence or E2, 200 nM progesterone resulted in a decrease in steady-state PR mRNA levels by 3 h of exposure, with the greatest decrease around 6 h (50% or E2 control) and recovery by 12 h. Similarly treated pituitary cultures were subjected to dual immunofluorescence staining for LH and PR. In the absence of E2, PR was undetectable. In the presence of E2, essentially all LH-positive cells were positive for PR and only 1-2% of PR-immunopositive cells were negative for LH, possibly reflecting FSH-exclusive gonadotropes. PR staining was predominantly nuclear, but 20 nM progesterone led to a gradual increase in cytoplasmic staining, with the nuclear-to-cytoplasmic ratio decreasing to near unity by 9-12 h of exposure. In summary, we show for the first time, that PR colocalizes with LH in cultured female rat pituitary cells and that E2 induces expression of PR mRNA, as well as PR protein, in rat gonadotropes. In the presence or E2, progesterone causes a rapid but transient down-regulation of PR message; recovery of PR mRNA is accompanied by an increase in cytoplasmic PR, suggestive of an increase in synthesis. These dynamic changes implicate the gonadotrope PR as having a significant role within the temporal context of the rat preovulatory period.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2318-2325 |
| Number of pages | 8 |
| Journal | Endocrinology |
| Volume | 140 |
| Issue number | 5 |
| State | Published - 1999 |
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ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
Steroid regulation of progesterone receptor expression in cultured rat gonadotropes. / Turgeon, Judith L; Van Patten, S. M.; Shyamala, G.; Waring, D. W.
In: Endocrinology, Vol. 140, No. 5, 1999, p. 2318-2325.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Steroid regulation of progesterone receptor expression in cultured rat gonadotropes
AU - Turgeon, Judith L
AU - Van Patten, S. M.
AU - Shyamala, G.
AU - Waring, D. W.
PY - 1999
Y1 - 1999
N2 - During the preovulatory period, the pituitary action of progesterone is biphasic, moving from a severalfold augmentation of the gonadotropin release action of GnRH to a suppression of GnRH efficacy, which occurs in rats over a period of about 12 h, but the extent to which these biphasic effects are dependent on alterations in progesterone receptor (PR) expression is not known. To address this, as well as the localization of PR in cultured rat pituitary cells, we used cells from ovariectomized rats cultured ± 0.2 nM E2 with acute progesterone treatment on day 3. Northern blot of poly(A+) RNA extracts showed multiple PR messenger RNA (mRNA) transcripts between 4.8-10.2 kb; E2 treatment led to a 5- to 6 fold increase in the predominant PR mRNA transcripts (5.1 and 10.1. kb). In the presence or E2, 200 nM progesterone resulted in a decrease in steady-state PR mRNA levels by 3 h of exposure, with the greatest decrease around 6 h (50% or E2 control) and recovery by 12 h. Similarly treated pituitary cultures were subjected to dual immunofluorescence staining for LH and PR. In the absence of E2, PR was undetectable. In the presence of E2, essentially all LH-positive cells were positive for PR and only 1-2% of PR-immunopositive cells were negative for LH, possibly reflecting FSH-exclusive gonadotropes. PR staining was predominantly nuclear, but 20 nM progesterone led to a gradual increase in cytoplasmic staining, with the nuclear-to-cytoplasmic ratio decreasing to near unity by 9-12 h of exposure. In summary, we show for the first time, that PR colocalizes with LH in cultured female rat pituitary cells and that E2 induces expression of PR mRNA, as well as PR protein, in rat gonadotropes. In the presence or E2, progesterone causes a rapid but transient down-regulation of PR message; recovery of PR mRNA is accompanied by an increase in cytoplasmic PR, suggestive of an increase in synthesis. These dynamic changes implicate the gonadotrope PR as having a significant role within the temporal context of the rat preovulatory period.
AB - During the preovulatory period, the pituitary action of progesterone is biphasic, moving from a severalfold augmentation of the gonadotropin release action of GnRH to a suppression of GnRH efficacy, which occurs in rats over a period of about 12 h, but the extent to which these biphasic effects are dependent on alterations in progesterone receptor (PR) expression is not known. To address this, as well as the localization of PR in cultured rat pituitary cells, we used cells from ovariectomized rats cultured ± 0.2 nM E2 with acute progesterone treatment on day 3. Northern blot of poly(A+) RNA extracts showed multiple PR messenger RNA (mRNA) transcripts between 4.8-10.2 kb; E2 treatment led to a 5- to 6 fold increase in the predominant PR mRNA transcripts (5.1 and 10.1. kb). In the presence or E2, 200 nM progesterone resulted in a decrease in steady-state PR mRNA levels by 3 h of exposure, with the greatest decrease around 6 h (50% or E2 control) and recovery by 12 h. Similarly treated pituitary cultures were subjected to dual immunofluorescence staining for LH and PR. In the absence of E2, PR was undetectable. In the presence of E2, essentially all LH-positive cells were positive for PR and only 1-2% of PR-immunopositive cells were negative for LH, possibly reflecting FSH-exclusive gonadotropes. PR staining was predominantly nuclear, but 20 nM progesterone led to a gradual increase in cytoplasmic staining, with the nuclear-to-cytoplasmic ratio decreasing to near unity by 9-12 h of exposure. In summary, we show for the first time, that PR colocalizes with LH in cultured female rat pituitary cells and that E2 induces expression of PR mRNA, as well as PR protein, in rat gonadotropes. In the presence or E2, progesterone causes a rapid but transient down-regulation of PR message; recovery of PR mRNA is accompanied by an increase in cytoplasmic PR, suggestive of an increase in synthesis. These dynamic changes implicate the gonadotrope PR as having a significant role within the temporal context of the rat preovulatory period.
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M3 - Article
VL - 140
SP - 2318
EP - 2325
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 5
ER -