Benzodiazepine receptor and neurotransmitter studies in the brain of suicides

The characteristics of benzodiazepine binding sites (affinity, number heterogeneity) were studied on frozen sections of hippocampus of 7 suicides and 5 controls subjects, using biochemical and autoradiographic techniques. 3H flunitrazepam was used as ligand, clonazepam and CL 218,872 as displacing agents. Some neurotransmitters or their derivatives (GABA, catecholamines, hydroxy-indols) were evaluated quantitatively in parallel in the hippocampal tissue by liquid chromatography. We observed mainly an increase in the Ki of CL 218,872 subtype I binding sites in suicides, (7.48 +/- 1.7 to 17.24 +/- 1.7 nM, P less than 0.01), (m +/- SEM) and an increase in % of type I binding sites (30 +/- 4.2 to 42 +/- 2.5, P = 0.01). Among neurotransmitters, only norepinephrine differed significantly between controls and suicides (11.34 +/- 1.9 to 24.34 ng/g tissue, P = 0.02).