Linked Life Data

19173265

Source:http://linkedlifedata.com/resource/pubmed/id/19173265

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2009-3-9
pubmed:abstractText
Binding studies in vitro have demonstrated that the dopamine D2 receptor may exist in two affinity states for agonists. The high affinity state is thought to represent the functional state of the receptor and proportions might alter during disease. In vitro studies further indicate that agonists induce measurable D(2) receptor occupancy at clinically relevant concentrations but only when measured at the high affinity state. Recently developed PET-radioligands, such as [11C]MNPA, have now made it possible to directly study agonist binding in vivo. The aim of this study was to compare the inhibition by apomorphine of agonist and antagonist radioligand binding to D(2/3) receptors in vivo. A total of 36 PET measurements were performed with the D(2/3) antagonist [11C]raclopride or the D(2/3) agonist [11C]MNPA in two cynomolgus monkeys. On each study day, a baseline measurement was followed by two consecutive pretreatment studies with rising doses of apomorphine (0.01, 0.05, 0.15, 0.5, 1.0, and 3.0 mg/kg). Binding potential (BP(ND)) values were calculated for the striatum with cerebellum as reference region. Apomorphine inhibited [11C]raclopride and [11C]MNPA binding in a dose-dependent manner and to a similar extent. ID(50) and K(i) values were 0.26 mg/kg and 29 ng/ml for [11C]raclopride and 0.50 mg/kg and 31 ng/ml for [11C]MNPA. The present observations do not support the existence of two affinity states in vivo. It might thus be speculated that all D(2/3) receptors are in the high affinity state at in vivo conditions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
1098-2396
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
63
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
378-89
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Dopamine D(2/3) receptor occupancy of apomorphine in the nonhuman primate brain--a comparative PET study with [11C]raclopride and [11C]MNPA.
pubmed:affiliation
Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Stockholm, Sweden. sjoerd.finnema@ki.se
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't