The effects of lithium and physostigmine on rat brain acetylcholinesterase activity
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The anti-cholinesterase activity of lithium and physostigmine have been investigated. The purpose of the study was two-fold: 1. to determine whether lithium could inhibit acetylcholinesterase, and 2. to determine whether repeated injections of physostigmine, a known cholinesterase inhibitor, could result in tolerance. It was found that lithium had no anti-cholinesterase activity in vivo (100 or 200 mg/kg LiCl), and slight anti-cholinesterase activity in vitro. The latter effect was evident only under markedly unphysiological conditions, i.e., concentrated lithium (10−2−10−1 M) and dilute acetylcholinesterase (1∶10000 dilution; w∶v). It was also found that repeated injections of physostigmine (0.75 mg/kg) did not result in tolerance to the anti-cholinesterase effects of the drug. A single challenge dose of physostigmine (0.75 mg/kg, in vivo) or a series of concentrations of physostigmine (10−8−10−5 M, in vitro) resulted in similar inhibition of AChE from animals which had or had not received a 5 day regimen of repeated physostigmine injections. The relationship of these findings to the treatment of mania is discussed.
Key wordsAcetylcholinesterase Lithium Physostigmine Rat Brain
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