Characterization of [3H]pentazocine binding sites in post-mortem human frontal cortex

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Abstract
We investigated binding characteristics of [3H](+)-pentazocine in homogenates of post-mortem human frontal cortex. At equilibrium, specific binding was linear with protein concentration, was saturable, reversible, stereoselective, heat-labile and was nearly absent in the white matter. Saturation experiments revealed a K d of 3.68 ± 0.46nM and a Bmax of 0.636 ± 0.107 pmol/mg protein. The rank order of Ki values of competing substances was: haloperidol < N,N′-di(o-tolyl)guanidine (DTG) < (+)-SKF 10,047 < (—)-SKF 10,047. We also examined the influence of age, gender, hemisphere, post-mortem time and storage time of brain tissue at −80 °C on [3H](+)-pentazocine binding sites. Of these variables, only age was significantly related to [3]H](+)-pentazocine binding (diminished binding with increasing age). Together, our results demonstrate the presence of specific [3H](+)-pentazocine binding sites in post-mortem human brain tissue. Furthermore, the binding sites decrease with increasing age and are apparently independent of gender, hemisphere, post-mortem time and storage time of brain tissue.