Enhanced behavioral response to nicotine in an animal model of Alzheimer's disease.

Three groups of rats received either kainic acid or vehicle in the ventral pallidum or no operation, and were then tested in photocell activity cages following recovery from surgery. Locomotor activity was measured following injections of saline, nicotine (0.1, 0.2, 0.4 mg/kg) or d-amphetamine (0.5, 1.0 mg/kg). The lesioned rats showed an enhanced locomotor response after injections of nicotine compared with sham operated or unoperated controls. In contrast, both lesioned and control rats showed increased activity after amphetamine; this effect was not influenced by the lesion. Since these lesions are known to produce neurochemical and cellular changes resembling those seen in human Alzheimer's disease, this increased response to nicotine might also be found in Alzheimer's patients and serve as the basis for a diagnostic test.