Antagonistic effect of physostigmine on ketamine-induced anesthesia

Abstract

Effects of physostigmine on ketamine-induced anesthesia and analgesia were studied in male Sprague-Dawley rats using behavioral tests. Rats were divided into six groups. Immediately after loss of the righting reflex following an intraperitoneal injection of ketamine 75 mg/kg, each group of rats was given an intraperitoneal injection of either physostigmine 0.05, 0.1, 0.2, 0.4, 0.6 mg/kg or saline as the control, respectively. Physostigmine 0.1 mg/kg caused the greatest antagonistic effect on ketamine anesthesia as indicated by sleeping time, duration of ataxia and motor coordination. The antagonistic effects of physostigmine were reduced by a dose of physostigmine of greater than 0.1 mg/kg. However, at no dose did physostigmine antagonize ketamine analgesia as indicated by the tail-flick latency. Physostigmine (0.4 and 0.6 mg/kg) itself had analgesic and motor-suppressive actions. It can therefore be presumed that there is a limited threshold of the dose of physostigmine which develops an antagonistic effect on ketamine anesthesia due to the motor-suppressive action. It is also confirmed that physostigmine itself produces analgesia, and does not antagonize ketamine-induced analgesia.

Psychoneuropharmacological activities and chemical composition of essential oil of fresh fruits of Piper guineense (Piperaceae) in mice

“…Ketamine-induced hypnosis test is used normally to investigate the sedative effect of an agent (Mimura et al, 1990). The EOPG at the test doses (50, 100, and 200 mg/kg) significantly (po0.01) decreased SL compared to the vehicle-treated animals and significantly (po0.05) prolonged TST compared to vehicle (Fig.…”

“…The effect of the EOPG on ketamine-induced sleeping time was measured as described by Mimura et al (1990). The animals were pre-treated 30 min prior to administration of ketamine (100 mg/ kg, i.p.).…”

Anxiolytic effects of Stachys lavandulifolia Vahl on the elevated plus-maze model of anxiety in mice

“…The effect of plant extracts on ketamine-induced sleeping time was measured as described by Mimura et al (1990). After 30 min pretreatment with the plant extracts or vehicle, animals were injected with ketamine (100 mg/kg, i.p.).…”

Central nervous system activity of an aqueous acetonic extract of Ficus carica L. in mice

“…Hypnotic drugs decrease the latency to sleep and prolong the duration of sleep in ketamine-induced sleep test after single dose of ketamine (100 mg/kg). [16] Both the doses of AAEFC significantly prolonged the ketamine-induced sleeping time. Hence the probable mechanism could be either increase in the brain levels of 5-HT or NE, GABA.…”