Distribution of mapacalcine receptors in the central nervous system of rat using the [125I]-labeled mapacalcine derivative.
Mapacalcine is a dimeric protein of Mr 19041 extracted from the marine sponge Cliona vastifica. Electrophysiological and pharmacological approaches have demonstrated that mapacalcine was blocking a calcium channel different from N-, L-, P-, T- or Q-type calcium channels on mouse intestinal smooth muscle. Recently a [125I]-labeled derivative of mapacalcine has been synthesized and characterized as a tool usable as a probe to investigate mapacalcine receptors. On rat brain membranes, it binds to its receptor with a K(d)=0.35 nM and a maximal binding capacity of 706 fmol/mg protein. We use here [125I]-mapacalcine to study the mapping of its receptors in the rat brain. Data obtained show a practically homogeneous labeling of the brain. Our experiments suggest that mapacalcine receptors are present on neuronal and glial cells. Interestingly, choroid plexus demonstrates a high density of mapacalcine receptors. These data would suggest that mapacalcine sensitive calcium channels could be involved in the control of calcium homeostasis of the cerebrospinal fluid.
Mourre
C
C
Laboratoire de Neurobiologie Intégrative et Adaptative, CNRS, UMR 6562, Université de Provence, Traverse Ch. Susini, 13388, Marseille, France.
Mokrzycki
N
N
Neuilly
G
G
Richeux
F
F
Creppy
E E
EE
Hugues
M
M
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D001345:Autoradiography; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000493:pharmacokinetics*; D015220:Calcium Channels / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002831:Choroid Plexus / Q000378:metabolism; D007457:Iodine Radioisotopes; D008297:Male; D009457:Neuroglia / Q000378:metabolism; D009928:Organ Specificity; D011506:Proteins / Q000493:pharmacokinetics*; D051381:Rats; D013570:Synaptic Membranes / Q000378:metabolism
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D007457:Iodine Radioisotopes; D011506:Proteins; C106560:mapacalcine