Increased density of I2-imidazoline receptors in human glioblastomas.
A glial location has been proposed for the non-adrenoceptor [3H]idazoxan binding site termed the I2-imidazoline receptor. The specific binding of [3H]idazoxan in the presence of (-)adrenaline was measured in membranes from excised human glioblastomas (n = 6), meningiomas (n = 6) and normal brains (n = 6). The pharmacological profile of the [3H]idazoxan binding in astrocytic tumours was similar to that in normal brain, compatible with the presence of I2-imidazoline receptors. There was a higher density of I2-imidazoline receptors in astrocytic tumours (Bmax = 266 +/- 18 fmol mg-1 protein; p < 0.001) than in normal brain (Bmax = 54 +/- 4 fmol mg-1 protein), with no differences in affinity values. Almost no [3H]idazoxan-specific binding was shown in meningiomas. The results suggest that I2-imidazoline receptors may be a selective marker for glial tumours in the evaluation of intracranial neoplasms.
Martín-Gómez
J I
JI
Department of Pharmacology, University of the Basque Country, Leioa, Bizkaia.
Ruiz
J
J
Callado
L F
LF
Garibi
J M
JM
Aguinaco
L
L
Barturen
F
F
Javier Meana
J
J
D000368:Aged; D001932:Brain Neoplasms / Q000378:metabolism* / Q000601:surgery; D016022:Case-Control Studies; D005260:Female; D005909:Glioblastoma / Q000378:metabolism* / Q000601:surgery; D006801:Humans; D019329:Idazoxan / Q000378:metabolism*; D054755:Imidazoline Receptors; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011869:Radioligand Assay; D011955:Receptors, Drug / Q000378:metabolism*
D054755:Imidazoline Receptors; D011955:Receptors, Drug; D019329:Idazoxan