Quantitative analysis of Pharmacological effects of psychiatic drugs using neuronal cultured cells

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In this study, we were successful in obtaining mouse cerebellar granule cells in monolayer culture. They were GABA neuron because we found out specific binding of ^3H-mucizol to them. In the presence time, however, we were unsuccessful in measuring the glucose utilization by using these cells. Therefore, we measured the glucose utilization by using isolated brain cells and ^<14>C-2-deoxyglucose.Furthermore, the effect of muscimol, a GABAA receptor agonist, on the basic metabolic activity was investigated in the mouse barin and was correlated with its receptor occupancy. For the quantitative evaluation of the functional activity of the mouse brain, the cerebral glucose utilization was measured by the double tracer technique, using ^<14>C-2-deoxyglucose and ^3H-3-O-methylglvcose. The dose-dependent reduction in the cerebral glucose utilization was observed after i. v. administration of various doses of muscizol. O. n the other hand, the GABAA receptor occupancy of muscimol was determined by using the values of the unbound drug concentration in the brain tissue and the receptor dissociation constant based on the in vitro binding experiments use in the dissociated brain cells. The tissue unbound concentration of muscimol was calculated by multiplying the total concentration in the brain after administration of muscimol and the tissue unbound fraction, which was measured by the equilibrium dialysis method using brain tissue homogenate. A linear relationship was observed between the GABAA receptor occupancy of muscimol and the decrease in the cerebral glucose utilization. This finding indicates that the simple receptor occupancy theory holds for this receptorligand system and there is a large difference in the effect of glucose metabolic response between GABA_A receptor-agonist interaction and benzodiazepine receptor-agonist interaction.