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Androstanolone

The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform

Aren Waarde – 1st expert on this subject based on the ideXlab platform

  • Steroid hormones affect binding of the sigma ligand ^11C-SA4503 in tumour cells and tumour-bearing rats
    European Journal of Nuclear Medicine and Molecular Imaging, 2009
    Co-Authors: Anna A. Rybczynska, Philip H. Elsinga, Jurgen W. Sijbesma, Kiichi Ishiwata, Johan R. Jong, Erik F. Vries, Rudi A. Dierckx, Aren Waarde

    Abstract:

    Purpose Sigma receptors are implicated in memory and cognitive functions, drug addiction, depression and schizophrenia. In addition, sigma receptors are strongly overexpressed in many tumours. Although the natural ligands are still unknown, steroid hormones are potential candidates. Here, we examined changes in binding of the sigma-1 agonist ^11C-SA4503 in C6 glioma cells and in living rats after modification of endogenous steroid levels. Methods ^11C-SA4503 binding was assessed in C6 monolayers by gamma counting and in anaesthetized rats by microPET scanning. C6 cells were either repeatedly washed and incubated in steroid-free medium or exposed to five kinds of exogenous steroids (1 h or 5 min before tracer addition, respectively). Tumour-bearing male rats were repeatedly treated with pentobarbital (a condition known to result in reduction of endogenous steroid levels) or injected with progesterone. Results Binding of ^11C-SA4503 to C6 cells was increased (~50%) upon removal and decreased (~60%) upon addition of steroid hormones (rank order of potency: progesterone > allopregnanolone = testosterone = Androstanolone > dehydroepiandrosterone-3-sulphate, IC_50 progesterone 33 nM). Intraperitoneally administered progesterone reduced tumour uptake and tumour-to-muscle contrast (36%). Repeated treatment of animals with pentobarbital increased the PET standardized uptake value of ^11C-SA4503 in tumour (16%) and brain (27%), whereas the kinetics of blood pool radioactivity was unaffected. Conclusions The binding of ^11C-SA4503 is sensitive to steroid competition. Since not only increases but also decreases of steroid levels affect ligand binding, a considerable fraction of the sigma-1 receptor population in cultured tumour cells or tumour-bearing animals is normally occupied by endogenous steroids.

Anna A. Rybczynska – 2nd expert on this subject based on the ideXlab platform

  • Steroid hormones affect binding of the sigma ligand ^11C-SA4503 in tumour cells and tumour-bearing rats
    European Journal of Nuclear Medicine and Molecular Imaging, 2009
    Co-Authors: Anna A. Rybczynska, Philip H. Elsinga, Jurgen W. Sijbesma, Kiichi Ishiwata, Johan R. Jong, Erik F. Vries, Rudi A. Dierckx, Aren Waarde

    Abstract:

    Purpose Sigma receptors are implicated in memory and cognitive functions, drug addiction, depression and schizophrenia. In addition, sigma receptors are strongly overexpressed in many tumours. Although the natural ligands are still unknown, steroid hormones are potential candidates. Here, we examined changes in binding of the sigma-1 agonist ^11C-SA4503 in C6 glioma cells and in living rats after modification of endogenous steroid levels. Methods ^11C-SA4503 binding was assessed in C6 monolayers by gamma counting and in anaesthetized rats by microPET scanning. C6 cells were either repeatedly washed and incubated in steroid-free medium or exposed to five kinds of exogenous steroids (1 h or 5 min before tracer addition, respectively). Tumour-bearing male rats were repeatedly treated with pentobarbital (a condition known to result in reduction of endogenous steroid levels) or injected with progesterone. Results Binding of ^11C-SA4503 to C6 cells was increased (~50%) upon removal and decreased (~60%) upon addition of steroid hormones (rank order of potency: progesterone > allopregnanolone = testosterone = Androstanolone > dehydroepiandrosterone-3-sulphate, IC_50 progesterone 33 nM). Intraperitoneally administered progesterone reduced tumour uptake and tumour-to-muscle contrast (36%). Repeated treatment of animals with pentobarbital increased the PET standardized uptake value of ^11C-SA4503 in tumour (16%) and brain (27%), whereas the kinetics of blood pool radioactivity was unaffected. Conclusions The binding of ^11C-SA4503 is sensitive to steroid competition. Since not only increases but also decreases of steroid levels affect ligand binding, a considerable fraction of the sigma-1 receptor population in cultured tumour cells or tumour-bearing animals is normally occupied by endogenous steroids.

Erik F. Vries – 3rd expert on this subject based on the ideXlab platform

  • Steroid hormones affect binding of the sigma ligand ^11C-SA4503 in tumour cells and tumour-bearing rats
    European Journal of Nuclear Medicine and Molecular Imaging, 2009
    Co-Authors: Anna A. Rybczynska, Philip H. Elsinga, Jurgen W. Sijbesma, Kiichi Ishiwata, Johan R. Jong, Erik F. Vries, Rudi A. Dierckx, Aren Waarde

    Abstract:

    Purpose Sigma receptors are implicated in memory and cognitive functions, drug addiction, depression and schizophrenia. In addition, sigma receptors are strongly overexpressed in many tumours. Although the natural ligands are still unknown, steroid hormones are potential candidates. Here, we examined changes in binding of the sigma-1 agonist ^11C-SA4503 in C6 glioma cells and in living rats after modification of endogenous steroid levels. Methods ^11C-SA4503 binding was assessed in C6 monolayers by gamma counting and in anaesthetized rats by microPET scanning. C6 cells were either repeatedly washed and incubated in steroid-free medium or exposed to five kinds of exogenous steroids (1 h or 5 min before tracer addition, respectively). Tumour-bearing male rats were repeatedly treated with pentobarbital (a condition known to result in reduction of endogenous steroid levels) or injected with progesterone. Results Binding of ^11C-SA4503 to C6 cells was increased (~50%) upon removal and decreased (~60%) upon addition of steroid hormones (rank order of potency: progesterone > allopregnanolone = testosterone = Androstanolone > dehydroepiandrosterone-3-sulphate, IC_50 progesterone 33 nM). Intraperitoneally administered progesterone reduced tumour uptake and tumour-to-muscle contrast (36%). Repeated treatment of animals with pentobarbital increased the PET standardized uptake value of ^11C-SA4503 in tumour (16%) and brain (27%), whereas the kinetics of blood pool radioactivity was unaffected. Conclusions The binding of ^11C-SA4503 is sensitive to steroid competition. Since not only increases but also decreases of steroid levels affect ligand binding, a considerable fraction of the sigma-1 receptor population in cultured tumour cells or tumour-bearing animals is normally occupied by endogenous steroids.