Muscarinic cholinergic receptors in the hippocampus of the aged rat: effects of long-term hydergine administration.
The effects of senescence and of long-term hydergine treatment on the density and the pattern of muscarinic cholinergic receptors in rat hippocampus were studied using combined radioreceptor binding and autoradiography with [3H]-quinuclidinyl-benzilate ([3H]-QNB) as a ligand. [3H]-QNB accumulated in the hippocampus of 3 month old rats, primarily in the stratum oriens of the CA1 and CA2 fields, followed in descending order by the molecular layer of granule cells of the dentate gyrus and the CA3 field. The density and pattern of [3H]-QNB binding sites in the hippocampus of 16 month old rats were the same. In contrast, the density of [3H]-QNB binding sites in the hippocampus of 22 months old rats was significantly reduced, mainly in the granule cells of the dentate gyrus, next in the CA3 and in the CA1-CA2 fields. Hydergine treatment (0.6 mg/kg and 1 mg/kg, p.o.), started at 16 months of age and continued for 6 months, caused a dose-related restoration of the number of [3H]-QNB binding sites, primarily in the CA1 and CA2 fields and in lesser amounts of the dentate gyrus. The possibility that the therapeutic effects of hydergine administration on memory function in the elderly might be related to an effect on cholinergic muscarinic receptors of the ageing hippocampus is discussed.
Amenta
F
F
Dipartimento di Scienze Neurologiche, Università "La Sapienza," Rome, Italy.
Cavallotti
C
C
Franch
F
F
Ricci
A
A
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D004088:Dihydroergotoxine / Q000494:pharmacology*; D006624:Hippocampus / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011813:Quinuclidinyl Benzilate; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*
D011976:Receptors, Muscarinic; D004088:Dihydroergotoxine; D011813:Quinuclidinyl Benzilate