| 1. |
- Rung, Johan P., 1973, et al.
(author)
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Effects of (-)-OSU6162 and ACR16 on motor activity in rats, indicating a unique mechanism of dopaminergic stabilization.
- 2008
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In: Journal of neural transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 115:6, s. 899-908
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Journal article (peer-reviewed)abstract
- Dopaminergic stabilizers can be defined as drugs that stimulate or inhibit dopaminergic signalling depending on the dopaminergic tone. (-)-OSU6162 and ACR16 appear to possess such a profile. They have been proposed to act as partial dopamine receptor agonists or as antagonists with preferential action on dopaminergic autoreceptors. Previous studies have shown either stimulation or inhibition of behaviour in response to (-)-OSU6162 and ACR16, which has been suggested to reflect their dual effects on dopaminergic signalling. The aims of the present work are to (1) examine the relation between behavioural response to these drugs and activity baseline, and (2) test the suggested mechanisms of action by means of close comparisons with the known partial D2-receptor agonists (-)-3-PPP and aripiprazole, and the D2 autoreceptor preferring antagonist amisulpride with respect to effects on behaviour. From the results of these experiments it can be concluded that: (1) The direction of the response to (-)-OSU6162 and ACR16 is dependent on activity baseline, which in turn, under physiological conditions, is determined primarily by test arena size of and degree of habituation to the environment. (2) The effects of (-)-OSU6162 and ACR16 cannot be explained on the basis of either partial dopamine receptor agonism or preferential dopamine autoreceptor antagonism. Nevertheless, the current data suggest at least two different D2-receptor-associated targets which mediate opposite effects on activity. This result fits in with a mechanism proposed from a recent in vitro study, according to which (-)-OSU6162 has a dual action on dopamine D2 receptors, (a) an allosteric effect causing an enhanced response to dopamine, and (b) the previously proposed orthosteric effect antagonizing the action of dopamine.
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| 2. |
- Rung, Johan P., 1973, et al.
(author)
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Effects of the dopamine stabilizers (S)-(-)-OSU6162 and ACR16 on prolactin secretion in drug-naive and monoamine-depleted rats.
- 2011
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In: Naunyn-Schmiedeberg's archives of pharmacology. - : Springer Science and Business Media LLC. - 1432-1912 .- 0028-1298.
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Journal article (peer-reviewed)abstract
- Dopaminergic stabilizers may be conceptualized as drugs with normalizing effects on dopamine-mediated behaviours and neurochemical events. (S)-(-)-OSU6162 (OSU6162) and ACR16 are two structurally related compounds ascribed such properties, principally because of their stabilizing effects on motor activity in rodents. Reports in the literature indicate possible partial D2 receptor agonist effects using various in vitro systems. This study aimed to measure D2 receptor antagonist and agonist effects of OSU6162 and ACR16 in vivo. To address this, we have studied the effects of both compounds on prolactin secretion in drug-naive and dopamine-depleted rats; dopamine depletion was induced by pretreatment with reserpine plus α-methyl-DL: -p-tyrosine. We find that OSU6162 and ACR16 both stimulate prolactin secretion in drug-naive rats with OSU6162 being considerably more potent and efficacious. Both compounds show a non-significant trend towards reversal of the increased secretion caused by dopamine depletion, whereas the D2 receptor antagonist haloperidol further increased prolactin secretion. Thus, this study suggests that OSU6162 and ACR16 act as D2 receptor antagonists under normal conditions in vivo, possibly with minor agonist effects in a state of dopamine depletion.
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| 3. |
- Shao, Linus Ruijin, 1964, et al.
(author)
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Nuclear progesterone receptor A and B isoforms in mouse fallopian tube and uterus: implications for expression, regulation, and cellular function
- 2006
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In: American journal of physiology. - : American Physiological Society. - 0193-1849. ; 291:1
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Journal article (peer-reviewed)abstract
- Progesterone and its interaction with nuclear progesterone receptors (PR) PR-A and PR-B play a critical role in the regulation of female reproductive function in all mammals. However, our knowledge of the regulation and possible cellular function of PR protein isoforms in the fallopian tube and uterus in vivo is still very limited. In the present study, we revealed that equine chorionic gonadotropin (eCG) treatment resulted in a time-dependent increase in expression of both isoforms, reaching a maximal level at 48 h in the fallopian tube. Regulation of PR-A protein expression paralleled that of PR-B protein expression. However, in the uterus PR-B protein levels increased and peaked earlier than PR-A protein levels after eCG treatment. With prolonged exposure to eCG, PR-B protein levels decreased, whereas PR-A protein levels continued to increase. Furthermore, subsequent treatment with human (h)CG decreased the levels of PR protein isoforms in both tissues in parallel with increased endogenous serum progesterone levels. To further elucidate whether progesterone regulates PR protein isoforms, we demonstrated that a time-dependent treatment with progesterone (P(4)) decreased the expression of PR protein isoforms in both tissues, whereas decreases in p27, cyclin D(2), and proliferating cell nuclear antigen protein levels were observed only in the uterus. To define the potential PR-mediated effects on apoptosis, we demonstrated that the PR antagonist treatment increased the levels of PR protein isoforms, induced mitochondrial-associated apoptosis, and decreased in epidermal growth factor (EGF) and EGF receptor protein expression in both tissues. Interestingly, immunohistochemistry indicated that the induction of apoptosis by PR antagonists was predominant in the epithelium, whereas increase in PR protein expression was observed in stromal cells of both tissues. Taken together, these observations suggest that 1) the tissue-specific and hormonal regulation of PR isoform expression in mouse fallopian tube and uterus, where they are potentially involved in regulation of mitochondrial-mediated apoptosis depending on the cellular compartment; and 2) a possible interaction between functional PR protein and growth factor signaling may have a coordinated role for regulating apoptotic process in both tissues in vivo.
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| 4. |
- Friberg, P. Anders, 1976, et al.
(author)
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Apoptotic effects of a progesterone receptor antagonist on rat granulosa cells are not mediated via reduced protein isoprenylation.
- 2007
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In: Molecular reproduction and development. - : Wiley. - 1040-452X .- 1098-2795. ; 74:10, s. 1317-26
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Journal article (peer-reviewed)abstract
- Progesterone is a survival factor in rat periovulatory granulosa cells. The mechanisms involved are unclear but progesterone receptor (PGR) antagonists have been shown to inhibit cholesterol synthesis and induce apoptosis. Furthermore, reports suggest that statins induce apoptosis by inhibition of protein isoprenylation. Statins inhibit the rate-limiting step of the cholesterol synthesis, thereby reducing availability of intermediates used for the post-translational isoprenylation process. It has been suggested that PGR antagonists in a similar manner induce apoptosis by decreasing cholesterol synthesis and thereby protein isoprenylation. In this study we hypothesized that the mechanism by which the nuclear PGR antagonist Org 31,710 induces apoptosis in rat periovulatory granulosa cells, is by decreasing cholesterol synthesis and thereby general cell protein isoprenylation. Incubation of isolated granulosa cells with Org 31,710 or simvastatin for 22 hr resulted in increased apoptosis and reduced cholesterol synthesis. However, simvastatin caused a substantial inhibition of cholesterol synthesis after 6 hr in culture without inducing apoptosis. In contrast, Org 31,710 had only a modest effect on cholesterol synthesis after 6 hr while it significantly induced apoptosis. Addition of isoprenylation substrates partially reversed apoptosis induced by simvastatin and to a lesser extent apoptosis induced by Org 31,710. In addition, and in contrast to Org 31,710, simvastatin caused a decrease in isoprenylation of a selected isoprenylation marker protein, the Ras-related protein RAB11. In conclusion, we demonstrate that the PGR antagonist inhibits cholesterol synthesis in granulosa cells but reduced protein isoprenylation is not the mediating mechanism of increased apoptosis as previously hypothesized.
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| 5. |
- Rung, Emilia, 1974, et al.
(author)
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Depletion of substrates for protein prenylation increases apoptosis in human periovulatory granulosa cells
- 2006
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In: Molecular reproduction and development. - : Wiley. - 1040-452X .- 1098-2795. ; 73:10, s. 1277-83
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Journal article (peer-reviewed)abstract
- Progesterone receptor (PR) stimulation promotes survival in human and rat periovulatory granulosa cells. PR antagonists, Org 31710 and RU 486, both increase apoptosis and decrease cholesterol synthesis in these cells. The decrease in cholesterol synthesis also causes decreased synthesis of other products branching from the cholesterol synthesis pathway, including substrates for protein prenylation. In this study we focus on the link between apoptosis and prenylation in human periovulatory granulosa cells. A decreased cholesterol synthesis and increased apoptosis was verified in experiments with human periovulatory granulosa cells treated with the PR antagonists Org 31710 or RU 486 by measuring caspase-3/7 activity and incorporation of 14C-acetate into cholesterol and progesterone. Correspondingly, specific inhibition of cholesterol synthesis in periovulatory human granulosa cells using HMG-CoA reductase inhibitors (lovastatin or simvastatin) increased apoptosis, measured as caspase-3/7 activity. The increase in apoptosis caused by simvastatin or Org 31710 was partially reversed by addition of the protein prenylation precursors farnesol or geranylgeraniol. In addition, the prenylation inhibitors FTI R115777 and GGTI 2147 increased apoptosis in these cells. In conclusion our data suggest that PR antagonists increase apoptosis and reduce cholesterol synthesis in periovulatory granulosa cells and that the resulting depletion of substrates for protein prenylation may contribute to the increased apoptosis sensitivity.
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| 6. |
- Rung, Emilia, 1974, et al.
(author)
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Progesterone-receptor antagonists and statins decrease de novo cholesterol synthesis and increase apoptosis in rat and human periovulatory granulosa cells in vitro
- 2005
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In: Biology of reproduction. - : Oxford University Press (OUP). - 0006-3363 .- 1529-7268. ; 72:3, s. 538-45
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Journal article (peer-reviewed)abstract
- Progesterone-receptor (PR) stimulation promotes survival in rat and human periovulatory granulosa cells. To investigate the mechanisms involved, periovulatory rat granulosa cells were incubated in vitro with or without the PR-antagonist Org 31710. Org 31710 caused the expected increase in apoptosis, and expression profiling using cDNA microarray analysis revealed regulation of several groups of genes with functional and/or metabolic connections. This regulation included decreased expression of genes involved in follicular rupture, increased stress responses, decreased angiogenesis, and decreased cholesterol synthesis. A decreased cholesterol synthesis was verified in experiments with both rat and human periovulatory granulosa cells treated with the PR-antagonists Org 31710 or RU 486 by measuring incorporation of [14C]acetate into cholesterol, cholesterol ester, and progesterone. Correspondingly, specific inhibition of cholesterol synthesis in periovulatory rat granulosa cells using 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (lovastatin, mevastatin, or simvastatin) increased apoptosis, measured as DNA fragmentation and caspase-3/7 activity. The increase in apoptosis caused by simvastatin was reversed by addition of the cholesterol synthesis-intermediary mevalonic acid. These results show that PR antagonists reduce cholesterol synthesis in periovulatory granulosa cells and that cholesterol synthesis is important for granulosa cell survival.
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| 7. |
- Rung, Emilia, 1974
(author)
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Progesterone receptor-mediated effects on apoptosis in periovulatory granulosa cells
- 2006
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Doctoral thesis (other academic/artistic)abstract
- The most common fate of developing ovarian follicles is demise due to a process known as atresia. Regulation of atresia is dependent on the developmental stage of the follicles, resulting in a continuous reduction of the number of follicles as they differentiate and grow towards ovulation. The mechanism behind atresia of growing follicles is apoptosis of the granulosa cells. This thesis focuses on progesterone receptor (PR)-mediated regulation of granulosa cell apoptosis during the final phase of follicular development, the periovulatory interval. By using two PR antagonists (RU 486 and the more specific Org 31710) we have shown that PR stimulation is important for the survival of periovulatory rat and human granulosa cells in vitro. PR regulated gene expression in rat periovulatory granulosa was characterised by microarray analysis, comparing the expression profiles after incubation in vitro with or without the addition of 10 µM Org 31710. Close to 100 genes were found to be transcriptionally regulated in the presence of Org 31710. This included downregulation of several genes involved in cholesterol synthesis, and a decreased rate of cholesterol synthesis was verified by measuring the incorporation of 14C-acetate into cholesterol, cholesterol ester and progesterone. Based on this we investigated the granulosa cell dependence on cholesterol synthesis and in particular the branch-point reactions supplying cells with prenylation substrates for post-translational lipid modification of proteins. Blocking the cholesterol synthesis with statins increased apoptosis, as did inhibitors of prenyl transferases. The increase in apoptosis after treatment with statins or PR antagonists was partially reversed by the addition of substrates for prenylation. In conclusion, PR stimulation is important for the survival of periovulatory granulosa cells in both rats and humans. PR stimulation regulates the transcription of several groups of genes including cholesterol synthesis. The cholesterol synthesis also provides the cells with substrates for protein prenylation, which may be one of the factors regulating granulosa cell survival in periovulatory follicles.
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| 8. |
- Shao, Linus Ruijin, 1964, et al.
(author)
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Induction of apoptosis increases SUMO-1 protein expression and conjugation in mouse periovulatory granulosa cells in vitro
- 2006
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In: Molecular reproduction and development. - : Wiley. - 1040-452X .- 1098-2795. ; 73:1, s. 50-60
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Journal article (peer-reviewed)abstract
- The small ubiquitin-related modifier-1 (SUMO-1) with broad cellular expression has been implicated in a range of cellular processes, such as cell proliferation, differentiation, and apoptosis. As shown recently, SUMO-1 is expressed and regulated by gonadotropins, in particular an ovulatory hCG stimulus in mouse granulosa cells in vivo. To test the hypothesis that modulation of granulosa cell apoptosis changes SUMO-1 expression during granulosa cell differentiation in the mouse ovary, we demonstrate that progesterone receptor (PR) proteins are absent in pre-ovulatory granulosa cell nuclei, whereas they are expressed in periovulatory granulosa cell nuclei in parallel with decreases in SUMO-1 expression, caspase-3 activation, and DNA fragmentation in vivo. Second, treatment with either PR antagonists or a cell permeable ceramide analog consistently increases SUMO-1 expression in parallel with an increase in apoptosis as well as a decrease in cell proliferation in periovulatory granulosa cells in vitro. However, we do not observe an increase in SUMO-1 expression in pre-ovulatory granulosa cells that have undergone the same treatment. Third, we have also demonstrated, in pre-ovulatory granulosa cells in vitro, neither induction of spontaneous apoptosis nor the protective effect of EGF against spontaneous apoptosis changes SUMO-1 protein expression. Fourth, we show that induction of apoptosis enhances SUMO-1 conjugation in periovulatory granulosa cells in vitro, pointing to the pivotal link between the SUMO-1 conjugation and cell death. Taken together, our observations suggest that SUMO-1 via sumoylation has an important role in the regulation of granulosa cell apoptosis during granulosa cell differentiation in the mouse ovary.
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| 9. |
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