Computer assisted quantitative densitometric analysis of ¹²⁵I-apamin binding sites in the central nervous system

The binding sites for ¹²⁵I-monoiododerivative of apamin in the central nervous system of rat, guinea-pig, chicken and frog were analysed and compared by computer assisted quantitative densitometric autoradiography on X-ray film. The highest level of binding sites in the rat and guinea-pig brain was found in the limbic-olfactory system and in the substantia gelatinosa of the spinal cord. In the chicken brain apamin binds preferentially to the tectum opticum and nuclei isthmi. In the frog brain no specific apamin binding sites were found. The role of presented topography for apamin binding sites is discussed in relation to neurotoxic properties of apamin.