Concurrent muscarinic and beta-adrenergic blockade in rats impairs place-learning in a water maze and retention of inhibitory avoidance.
These experiments examined the effects of separate and concurrent muscarinic cholinergic and beta-adrenergic blockade on inhibitory (passive) avoidance performance and spatial learning in the Morris water maze. Pretraining systemic administration of either scopolamine (0.3 or 1.0 mg/kg) or propranolol (3.0 or 10.0 mg/kg) had no significant effect on one-day retention of step-through inhibitory avoidance training. Similarly, pretraining administration of either 0.3 mg/kg scopolamine or 10 mg/kg propranolol did not affect spatial learning in the Morris water maze. However, combined administration of scopolamine and 10.0 mg/kg of propranolol impaired performance on these tasks. These findings further support a role for interactions between norepinephrine and acetylcholine in the modulation of learning and memory and implicate the participation of beta-adrenergic mechanisms in this interaction. Because cholinergic and noradrenergic deterioration is found in aging and Alzheimer's disease, these results also have implications regarding the role of age-related noradrenergic and cholinergic dysfunction in cognitive decline.
Decker
M W
MW
Department of Psychobiology, University of California, Irvine 92717.
Gill
T M
TM
McGaugh
J L
JL
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology*
D011943:Receptors, Adrenergic, beta; D011976:Receptors, Muscarinic; D011433:Propranolol; D012601:Scopolamine