EFFECT OF INTRAVENTRICULAR ADMINISTRATION OF CALCIUM ON THE LOWERING OF BRAIN DOPAMINE LEVEL IN EPILEPTIC MICE

Dopamine (DA) levels in the various brain regions of epileptic mice (El mice) were compared immunohistochemically with those in ddY mice (the mother strain of El mice) using a fluorescence microphotometry system. The fluorescence intensities of DA in the neostriatum and nucleus accumbens septi in El mice were approximately 11-15% (P < 0.01) and 13% (P < 0.01) lower than in ddY mice. On the other hand, the lower DA amounts in these regions of El mice were improved by intraventricular administration of CaCl2 (10 μmol/kg). The brain regions in which the amount of DA was increased by calcium were areas where high levels of calmodulin and tyrosine hydroxylase are distributed. This finding reconfirmed our previous report that the biogenic amine level disorder in El mice was related to a calcium non level disorder through a central calcium-calmodulin-dependent biogenic amine-synthesizing mechanism, and this might increase their susceptibility to epileptic convulsions. © 1990.