MRI contrast enhancement by Mn-TPPS in experimental rat brain tumor with peripheral benzodiazepine receptors.
Recent studies have disclosed that Mn-TPPS, a paramagnetic metalloporphyrin, may be a tumor-specific contrast media for magnetic resonance (MR) imaging. We investigated whether or not Mn-TPPS enhancement of the glioma could be mediated by peripheral benzodiazepine receptor. Using a transplanted rat C6 glioma model, Mn-TPPS enhancement was performed with or without pretreatment by peripheral or central benzodiazepine-specific receptor ligands. Signal intensity analysis disclosed that the enhancement was not inhibited by these ligands. Post-contrast replacement studies showed that neither of these ligands reduced Mn-TPPS enhancement. Although the tissue concentration of Mn-TPPS was significantly higher in the glioma than in the contralateral brain, PK11195 pretreatment did not replace the intratumoral Mn-TPPS. This data suggested that the tumor-specific enhancement of Mn-TPPS was not mediated by peripheral type benzodiazepine receptor.
Department of Neurosurgery, Faculty of Medicine, Kyushu University, Japan.
K
K
Ikezaki
T
T
Nomura
M
M
Takahashi
B F
BF
Zieroth
M
M
Fukui
D000818:Animals; D001921:Brain / Q000473:pathology; D001929:Brain Edema / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D002460:Cell Line; D003287:Contrast Media; D005910:Glioma / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011166:Porphyrins / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*
D003287:Contrast Media; D011166:Porphyrins; D011963:Receptors, GABA-A; C016136:tetraphenylporphine sulfonate