| RESEARCH PAPER
|Year : 1992 | Volume
| Issue : 3 | Page : 147-153
Reversal of scopolamine- and dizocilpine- induced memory dysfunction by angiotensin converting enzyme inhibitors in rats and mice
AC Sharma, SK Kulkarni
Cholinergic muscarinic antagonists, atropine (1-5 mg/kg) and scopolamine (0.1-0.5 mg/kg) produced learning and memory deficits in step-down passive avoidance task paradigm in mice.
NMDA-receptor antagonist (noncompetitive), MK 801 (0.1 mgikg) produced complete disruption of acquisition and retention, however, lower doses (0.025-0.05 mg/kg) showed improvement in retention parameters. Scopolamine potentiated memory disruptive effects of MK 801 (0.05 mg/kg). Combined administration of MK 801 (0.01 mg/kg) and scopolamine (0.3 mg/kg) - induced deficits were not reversed by physostigmine in step-down passive avoidance paradigm.
Piracetam and aniracetam decreased number of mistakeson step-down task in scopolamine -treated and-untreated mice. These agents also showed reduction in shortened transfer latency (TL) on elevated plus-maze apparatus. The effect was reversed by MK 801 and scopolamine, both in rats and mice.
Captopril (30 mg/kg) and enalapril (30 and 60 mgikg) attenuated scopolamine- induced deficits on step-down task paradigm, but not on elevated plus maze in rats and mice. The effects were being comparable to piracetam. However, captopril at lower doses (5-15 mgikg) did not show impairment of latency in reaching shock free zone (SFZ), unlike enalapril and prove to be more potent than enalapril on both paradigms.
The results suggested a unidirectional pattern of activity of NMDA- and cholinergic- antagonism in the bahavioural expression of amnesia. Captopril was found to be more potent than enalapril in improving retention or consolidation phase of memory, the effect com-parable to nootropics, and proposed to involve central cholinergic and NMDA receptor
A C Sharma
Source of Support: None, Conflict of Interest: None