Chronic dihydroergotoxine administration increases muscarinic cholinergic receptor binding in aged-rat brain.

Changes in the distribution and densities of muscarinic cholinergic receptors (mCh-R) and the effects of dihydroergotoxine (DHET) administration on these changes were studied in the aged-rat brain by in vitro autoradiography. mCh-R binding in the brain was markedly reduced in aged rats as compared with young adult rats, but chronic administration of DHET specifically recovered mCh-R binding in the temporal cortex and hippocampus.