Selective changes in mu, delta and kappa opioid receptor binding in certain limbic regions of the brain in Alzheimer's disease patients.

Total opioid binding and levels of the three major types of opioid binding sites were measured in homogenates of various limbic structures from post-mortem brains of Alzheimer's disease patients and age-matched control individuals. The most consistent finding in Alzheimer's disease brains was an increase in kappa binding in all 6 areas of the limbic system examined, with the putamen and caudate regions showing significant increases of 114% and 53%, respectively. In addition, the Alzheimer's disease putamen showed a significantly higher level of total binding (85% increase). The amygdala of Alzheimer's disease patients exhibited significantly lower levels of mu and delta binding (41% and 55% decrease, respectively). Total binding and binding to mu and delta receptors in frontal cortex, caudate and hippocampus of Alzheimer's disease brains was indistinguishable from levels seen in these brain areas from control individuals.