Radioiodinated tracers for the evaluation of dopamine receptors in the neonatal rat brain after hypoxic-ischemic injury.
In order to evaluate in vivo single-photon emission tomography (SPET) method of assessing cerebral function after hypoxic-ischemic injury in human neonates, we studied D1 and D2 dopamine receptors in a rat model. Seven-day-old rats underwent permanent unilateral common carotid ligation followed by exposure to 8% O2. Two weeks later, in brains with no visible loss of hemispheric volume, striatal dopaminergic receptors were studied, with [125I]TISCH and [125I]IBZM for the D1 and D2 dopamine receptors, respectively. Using [125I]TISCH, we observed no modifications of D1 receptors, but in contrast, ex vivo and in vitro autoradiographic experiments showed a 40% decrease in the striatal binding of [125I]IBZM on both the ipsilateral and the contralateral side to the carotid ligation. These alterations were detected with IBZM, a D2 dopamine receptor ligand usable for SPET imaging. Therefore, exploration of D2 receptors by SPET in human neonates suffering from perinatal hypoxia-ischemia may be valuable for the diagnosis and follow-up of cerebral function damages.
Zouakia
A
A
INSERM U316, Laboratoire de Biophysique médicale et pharmaceutique, Tours, France.
Chalon
S
S
Kung
H F
HF
Dognon
A M
AM
Saliba
E
E
Besnard
J C
JC
Guilloteau
D
D
D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D001549:Benzamides; D001552:Benzazepines; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism*; D003287:Contrast Media; D065127:Dopamine D2 Receptor Antagonists; D002534:Hypoxia, Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000032:analysis*; D017448:Receptors, Dopamine D2 / Q000032:analysis*; D015899:Tomography, Emission-Computed, Single-Photon
D001549:Benzamides; D001552:Benzazepines; D003287:Contrast Media; D065127:Dopamine D2 Receptor Antagonists; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C067811:7-chloro-8-hydroxy-1-(3'-iodophenyl)-3-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide