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The influence of different cellular environments on PET radioligand binding: an application to D2/3-dopamine receptor imaging.

Quelch DR, Withey SL, Nutt DJ, Tyacke RJ, Parker CA - Neuropharmacology (2014)

Bottom Line: Extension of in vivo competition imaging to other receptor systems has been relatively unsuccessful.These studies suggest that sensitivity to endogenous dopamine release in vivo is related to a decrease in affinity in the endosomal environment compared with those found at the cell surface.This pharmacological approach is fully translatable to other receptor systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, UK. Electronic address: d.quelch09@imperial.ac.uk.

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A. Comparison of [3H]raclopride, [3H]PhNO and [3H]spiperone “Total Homogenate RSA values”. Total homogenate binding observed following sub-cellular fractionation of pig striatal membranes; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean). One-way ANOVA with Tukey post-test were performed using SigmaStat 3.0. ∗p < 0.05 and ∗∗p < 0.01 represent comparison of [3H]spiperone RSA to both [3H]raclopride and [3H]PhNO. B. Microsomal fraction RSA values with [3H]raclopride, [3H]PhNO and [3H]spiperone. [3H]Raclopride and [3H]PhNO n = 3; n = 2 for [3H]spiperone (mean ± s.e.mean). ∗p < 0.05 represent comparison of [3H]raclopride P3 RSA with [3H]spiperone and [3H]PhNO P3 RSA. C. Representation of homogenate binding as a function of cell protein. Relative specific activity (RSA) versus percent total protein per fraction histogram for [3H]raclopride, [3H](+)PhNO and [3H]spiperone from pig striatal sub-cellular fractionation; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean).
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fig1: A. Comparison of [3H]raclopride, [3H]PhNO and [3H]spiperone “Total Homogenate RSA values”. Total homogenate binding observed following sub-cellular fractionation of pig striatal membranes; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean). One-way ANOVA with Tukey post-test were performed using SigmaStat 3.0. ∗p < 0.05 and ∗∗p < 0.01 represent comparison of [3H]spiperone RSA to both [3H]raclopride and [3H]PhNO. B. Microsomal fraction RSA values with [3H]raclopride, [3H]PhNO and [3H]spiperone. [3H]Raclopride and [3H]PhNO n = 3; n = 2 for [3H]spiperone (mean ± s.e.mean). ∗p < 0.05 represent comparison of [3H]raclopride P3 RSA with [3H]spiperone and [3H]PhNO P3 RSA. C. Representation of homogenate binding as a function of cell protein. Relative specific activity (RSA) versus percent total protein per fraction histogram for [3H]raclopride, [3H](+)PhNO and [3H]spiperone from pig striatal sub-cellular fractionation; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean).

Mentions: When both “Percentage Bound per Fraction” and “Percentage Total Protein per Fraction” are both taken into account i.e. using Equation (3), relative specific activity (RSA) values are generated. The total striatal homogenate RSA values for [3H]spiperone were found to be significantly greater than those obtained for both [3H]raclopride and [3H]PhNO (Fig. 1A, Table 3). Similar to the distribution of “Percentage total homogenate Bound per Fraction”, RSA distribution was highest in the P2-plasma membrane fraction for all ligands (Table 3).


The influence of different cellular environments on PET radioligand binding: an application to D2/3-dopamine receptor imaging.

Quelch DR, Withey SL, Nutt DJ, Tyacke RJ, Parker CA - Neuropharmacology (2014)

A. Comparison of [3H]raclopride, [3H]PhNO and [3H]spiperone “Total Homogenate RSA values”. Total homogenate binding observed following sub-cellular fractionation of pig striatal membranes; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean). One-way ANOVA with Tukey post-test were performed using SigmaStat 3.0. ∗p < 0.05 and ∗∗p < 0.01 represent comparison of [3H]spiperone RSA to both [3H]raclopride and [3H]PhNO. B. Microsomal fraction RSA values with [3H]raclopride, [3H]PhNO and [3H]spiperone. [3H]Raclopride and [3H]PhNO n = 3; n = 2 for [3H]spiperone (mean ± s.e.mean). ∗p < 0.05 represent comparison of [3H]raclopride P3 RSA with [3H]spiperone and [3H]PhNO P3 RSA. C. Representation of homogenate binding as a function of cell protein. Relative specific activity (RSA) versus percent total protein per fraction histogram for [3H]raclopride, [3H](+)PhNO and [3H]spiperone from pig striatal sub-cellular fractionation; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean).
© Copyright Policy - CC BY
Related In: Results  -  Collection

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fig1: A. Comparison of [3H]raclopride, [3H]PhNO and [3H]spiperone “Total Homogenate RSA values”. Total homogenate binding observed following sub-cellular fractionation of pig striatal membranes; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean). One-way ANOVA with Tukey post-test were performed using SigmaStat 3.0. ∗p < 0.05 and ∗∗p < 0.01 represent comparison of [3H]spiperone RSA to both [3H]raclopride and [3H]PhNO. B. Microsomal fraction RSA values with [3H]raclopride, [3H]PhNO and [3H]spiperone. [3H]Raclopride and [3H]PhNO n = 3; n = 2 for [3H]spiperone (mean ± s.e.mean). ∗p < 0.05 represent comparison of [3H]raclopride P3 RSA with [3H]spiperone and [3H]PhNO P3 RSA. C. Representation of homogenate binding as a function of cell protein. Relative specific activity (RSA) versus percent total protein per fraction histogram for [3H]raclopride, [3H](+)PhNO and [3H]spiperone from pig striatal sub-cellular fractionation; n = 3 for [3H]raclopride and [3H]PhNO; n = 2 for [3H]spiperone (mean ± s.e.mean).
Mentions: When both “Percentage Bound per Fraction” and “Percentage Total Protein per Fraction” are both taken into account i.e. using Equation (3), relative specific activity (RSA) values are generated. The total striatal homogenate RSA values for [3H]spiperone were found to be significantly greater than those obtained for both [3H]raclopride and [3H]PhNO (Fig. 1A, Table 3). Similar to the distribution of “Percentage total homogenate Bound per Fraction”, RSA distribution was highest in the P2-plasma membrane fraction for all ligands (Table 3).

Bottom Line: Extension of in vivo competition imaging to other receptor systems has been relatively unsuccessful.These studies suggest that sensitivity to endogenous dopamine release in vivo is related to a decrease in affinity in the endosomal environment compared with those found at the cell surface.This pharmacological approach is fully translatable to other receptor systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, UK. Electronic address: d.quelch09@imperial.ac.uk.

Show MeSH