Sensitive radioimmunoassays for histamine and tele-methylhistamine in the brain.
Serum albumin conjugates of histamine or tele-methylhistamine, a major catabolite, were prepared using 1,4-benzoquinone as the coupling agent and used to raise polyclonal antibodies in rabbits. The same reagent was used to prepare the [125I]iodinated tracer and treat tissue extracts submitted to the radioimmunoassays. The IC50 values of prederivatized histamine and tele-methylhistamine in the radioimmunoassays were 0.3 nM and 0.5 nM, respectively, whereas nonderivatized histamine or tele-methylhistamine, histidine, a variety of histamine derivatives, amines, etc., had at least 1,000-fold higher IC50 values. Application of the radioimmunoassays to nonpurified extracts of rat brain allowed the quantification of the two amine immunoreactivities in samples corresponding to less than 1 mg of hypothalamus. The tissue immunoreactivity corresponded to authentic histamine or tele-methylhistamine, as shown by (a) the parallel 125I-tracer displacement curves, (b) the similar elution patterns from HPLC columns, (c) the regional levels of histamine and tele-methylhistamine in brain, similar to those obtained with other methods, and (d) the clearcut effects of treatments with inhibitors of L-histidine decarboxylase or monoamine oxidase. The two radioimmunoassays appear as simple and sensitive tools to evaluate steady-state levels and turnover rates of histamine and tele-methylhistamine.
Garbarg
M
M
Unité de Neurobiologie et Pharmacologie (U. 109) de l'INSERM, Centre Paul Broca, Paris, France.
Pollard
H
H
Trung Tuong
M D
MD
Schwartz
J C
JC
Gros
C
C
D000818:Animals; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D006632:Histamine / Q000032:analysis* / Q000378:metabolism; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors; D008297:Male; D008761:Methylhistamines / Q000032:analysis* / Q000378:metabolism; D008762:Methylhistidines / Q000494:pharmacology; D009928:Organ Specificity; D010293:Pargyline / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D014316:Tritium
D008761:Methylhistamines; D008762:Methylhistidines; D010880:Piperidines; D014316:Tritium; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D010293:Pargyline; D006640:Histidine Decarboxylase; C052075:thioperamide; C020404:tele-methylhistamine