The "antidementia drug" pantoyl-gamma-aminobutyric acid increases high affinity uptake of choline by slices of rat brain

Discriminative stimulus properties of NIK-247 and tetrahydroaminoacridine, centrally active cholinesterase inhibitors, in rats

The discriminative stimulus effect of the novel centrally active cholinesterase inhibitor, NIK-247, was investigated in rats and compared with that of tetrahydroaminoacridine (THA). Rats were trained to discriminate either 10 mg/kg NIK-247 or 1.8 mg/kg THA from saline in a two-lever food-reinforced procedure. The stimulus effect of NIK-247 was substituted for by the cholinesterase inhibitors, THA and physostigmine. The THA stimulus was substituted for by NIK-247 and physostigmine. The muscarinic receptor agonist arecoline substituted for the NIK-247 and THA stimuli. Both stimulus effects of NIK-247 and THA were blocked by the muscarinic antagonist scopolamine. The dopaminergic-activating drugs amantadine and lisuride substituted for the stimulus effects of NIK-247 and THA. However, neither the NIK-247 nor the THA stimulus was antagonized by the dopamine antagonists haloperidol, SCH 23390, and sulpiride. These results suggest that the discriminative stimulus effects of NIK-247 and THA are mediated by muscarinic receptors, and that the dopaminergic activity resulting from cholinergic activation may account for some part of both stimuli.

WEB 1881 FU ameliorates impairment of working memory induced by scopolamine and cerebral ischemia in the three-panel runway task

Using a repeated acquisition procedure in a 3-panel runway apparatus, the effect of WEB 1881 FU on impairment of working memory produced either by scopolamine or by cerebral ischemia was investigated in rats and compared with those of aniracetam and Ca hopantenate. Intraperitoneal injection of scopolamine at 0.56 mg/kg significantly increased the number of errors (pushes made on the two incorrect panels of the three panel-gates located at each choice point). WEB 1881 FU at 10-32 mg/kg, p.o., caused a dose-related reduction in the increase of errors expected in the scopolamine-treated rats. Aniracetam at 10-100 mg/kg, p.o., or Ca hopantenate at 100 and 560 mg/kg, p.o., also significantly diminished the increase in errors induced by 0.56 mg/kg of scopolamine. Cerebral ischemia for 5 min significantly increased errors in the 3-panel runway task. WEB 1881 FU at 32 and 56 mg/kg, administered p.o. immediately after blood flow recirculation and again 1 hr before the runway test, conducted 24 hr after ischemia, significantly reduced the increase in errors expected to occur after 5 min of ischemia. Aniracetam at 32 and 100 mg/kg, p.o., similarly diminished the increase in errors in ischemic rats. These findings suggest that WEB 1881 FU has a beneficial effect on memory that has been impaired by scopolamine or by cerebral ischemia.

Effect of the 'antidementia drug' pantoyl-GABA on high affinity transport of choline and on the contents of choline and acetylcholine in rat brain

1. Effect of pantoyl-gamma-aminobutyric acid (pantoyl-GABA) on high affinity transport of choline into synaptosomes and on the choline (Ch) and acetylcholine (ACh) concentrations of rat brain were studied. 2. Pantoyl-GABA was injected intraperitoneally four times at a dose of 500 mg kg-1 at intervals of 30 min. One hour after the last injection, rats were killed by decapitation for measurement of high affinity transport of Ch into synaptosomes or by microwave irradiation for the measurement of Ch and ACh concentrations. 3. Transport of Ch was increased into synaptosomes prepared from the cerebral cortex and hippocampus, but not into those from the striatum. 4. In the cerebral cortex and hippocampus, Ch concentration was increased and ACh concentration decreased. 5. Since treatments that enhance the activity of cholinergic neurones in vivo are reported to increase high affinity transport of Ch measured in vitro, the present results suggest that pantoyl-GABA may increase cholinergic activity in vivo. This action of the drug may be related to changes in the Ch and ACh concentrations.

Effect of quinolinic acid in the nucleus basalis magnocellularis on cortical high-affinity choline uptake

A transient 45% increase in cortical high-affinity choline uptake (HACU) was observed after an injection of quinolinic acid (QUIN) into the nucleus basalis magnocellularis (nbM) of the rat. This was followed by a steady decline in choline uptake, which resulted in a 46% decrease by day 7. Specific [3H]hemicholinium-3 binding to coronal brain sections showed a similar pattern following injections of QUIN into the nbM. The increase in cortical HACU elicited by QUIN appeared to be dose dependent.