Radioligand binding assay of M-cholinergic receptors in brains of hypothyroid mice

M-receptors in the brains of hypothyroid mice were analysed by radioligand binding assay with 3H-QNB. The data were processed by a computer programme using the woolf model. The non-specific binding was less than 20% of the total binding, the mean RT was 1019 +- 107 (x-bar +- SD) fmol/mg protein, n = 16) and the mean KD was 0.147 +- 0.063 nmol/L in normal mice. The mean RT of hypothyroid mice (1240 +- 187 fmol/mg protein, n = 16) was significantly higher than normal while the mean KD, showed no statistical difference from the controls. The results of the single point method (RT determined with a single ligand concentration in the saturated region) were compared with the classical muti-point method. The RT data of the two methods highly correlated to each other, indicating that the latter may be replaced by the former for determining RT values in some situations where the measurement of KD values were not needed