RESEARCH: Zopiclone (Cyclopyrrolone): A novel hypnosedative; hypnosedation caused by Zopiclone does not impair memory-learning in albino mice.
OBJECTIVE
To evaluate hypnosedative action of Zopiclone by using animal models for hypnosis and sedation (anxiolysis); and to further evaluate whether this hypnosedation impairs memory-learning in albino mice like conventional hypnosedatives.


METHODS
For evaluation of hypnosedation, following experiments were performed in albino mice: (1) righting reflex test, (2) pentobarbitone sleeping time potentiation, (3) open field apparatus behavior, and (4) elevated plus maze performance. For evaluation of effects on impairment of memory-learning, elevated plus maze retention test was performed in albino mice.


RESULTS
Zopiclone (7.5 mg/kg p.o.) did not inhibit the righting reflex. Significant (P < 0.001) potentiation of pentobarbitone sleeping time and increase in exploration in open field apparatus was observed. Elevated plus maze performance also showed significant (P < 0.01) increase in number of entries to open arm at the same time significant (P < 0.02) increase in time spent in open arm was observed. Elevated plus maze retention test showed significant (P < 0.01) increase in transfer latency on second day of experiment.


CONCLUSIONS
Zopiclone (7.5 mg/kg p.o.) has selective hypnosedative activity but not CNS-depressant activity similar to BZDs. Hypnosedative action of Zopiclone does not impair memory-learning in albino mice like conventional hypnosedatives.
Kadam
Uma
U
Department of Pharmacology, SKNMC, Narhe, Ambegaon, Pune, India. umabhosale2000@gmail.com
Bhosale
Anand
A
D000818:Animals; D053961:Azabicyclo Compounds / Q000737:chemistry / Q000494:pharmacology*; D016009:Chi-Square Distribution; D004357:Drug Synergism; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D006993:Hypnotics and Sedatives / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D051379:Mice; D010424:Pentobarbital / Q000494:pharmacology; D010879:Piperazines / Q000737:chemistry / Q000494:pharmacology*; D057897:Reflex, Righting / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects*; D012890:Sleep / Q000187:drug effects
D053961:Azabicyclo Compounds; D006993:Hypnotics and Sedatives; D010879:Piperazines; C515050:zopiclone; D010424:Pentobarbital