Possible cholinergic-dopaminergic link in memory facilitation induced by oxotremorine in mice

Abstract

The immediate post-trial injection of the centrally active muscarinic agonist oxotremorine (0.025, 0.050 and 0.100 mg/kg, IP) can facilitate the retention of a passive-avoidance response in mice, as indicated by performance on a retention test 24 h later. Injections given 10 min after training also significantly facilitated retention, but given 120 min after training did not affect retention. These findings suggest an action of oxotremorine on memory mechanisms. The enhanced retention was neither the result of a punishing effect of oxotremorine nor of a nonspecific proactive pharmacological action of the drug. The memory facilitation produced by oxotremorine (0.050 mg/kg, IP) was not antagonized by pretreatment with phentolamine (10 mg/kg, 30 min, IP), phenoxybenzamine (10 mg/kg, 120 min, IP) or piperoxane (20 mg/kg, 30 min, IP). The alpha-noradrenergic blocking agents had no effect by themselves. On the other hand, the immediate post-trial injection of oxotremorine (0.050 mg/kg, IP) did not enhance retention when mice were pretreated with haloperidol (0.5 mg/kg, 120 min, IP). Haloperidol injected either before training or before the retention test did not alter performance during the retention test. This suggests that haloperidol impairs neither acquisition of the avoidance response nor its retrieval. Thus, it is probable that haloperidol pretreatment impaired oxotremorine-induced memory facilitation. We suggest a possible participation of brain catecholamines in memory facilitation induced by oxotremorine in mice.

The role of interactions between the cholinergic system and other neuromodulatory systems in learing and memory

“…Interactions between cholinergic and dopaminer c enhanced retention of inhibitory avoidance training induced by post-training administration of the muscarinic agonist oxotremorine is blocked by catecholamine de letion induced b alpha-methyl-para-tyrosine (Huygens et al, 1980). Although aMPT depletes both NE and DA, the effect of aMPT in this case may primaril be due to the depletion of DA, since NE de letion oxotremorine in this task , and the -enhancing effects of oxotremorine can also be Ez%y by haloperidol pretreatment (Baratti et al, 1983 o amine/acetylory in rats tested in the radial arm maze. These studies have robed the pharmacological nature of the interacmanipulations.…”

Facilitation of acquisition and performance of operant and spatial learning tasks in self-stimulation experienced rats.

“…The cholinergic-dopaminergic system interaction is involved in the facilitation of memory processes in mice (Baratti, Introini, Huygens, & Gusovsky, 1983). Hence, we propose that facilitation of operant and spatial learning might have occurred in the same manner, as evidenced by increased dopamine and acetylcholinesterase activity in the hippocampus following ICSS experience (Shankaranarayana Rao, Raju, & Meti, 1993, 1995.…”

“…The frontal cortex is also likely to be involved in the spatial learning task and, interestingly, the D1 agonists have been shown to modulate cortical ACh release in a manner analogous to that of the hippocampus (Day & Fibiger, 1993). The cholinergic–dopaminergic system interaction is involved in the facilitation of memory processes in mice (Baratti, Introini, Huygens, & Gusovsky, 1983). Hence, we propose that facilitation of operant and spatial learning might have occurred in the same manner, as evidenced by increased dopamine and acetylcholinesterase activity in the hippocampus following ICSS experience (Shankaranarayana Rao, Raju, & Meti, 1993, 1995).…”

Urinary levels of biogenic atnine metabolites in mentally retarded children

“…Moreover, the learning and memory process involves interaction of various systems such as cholinergic neurons, protein synthesis, biogenic amines, dopamine, opioid peptides and peptide hormones. Combinations of adrenergic and dopaminergic drugs have produced more improvement in performance than individual drugs alone (Hershenson & Marriott, 1984) and there is also a suggestion that cholinergic influences upon memory may involve dopaminergic mechanisms (Baratti et al, 1983). Further, there are reports stating that dopamine may be reduced in the brains of Down's syndrome patients (Yates et al, 1983).…”