Evidence that sensitivity to steroid
anesthetics appears late in evolution
by
Oliver AE, Deamer DW, Akeson M.
Department of Zoology,
University of California,
Davis 95616.
Brain Res. 1991 Aug 23;557(1-2):298-302

ABSTRACT

The effects of pregnanolone, a steroid anesthetic, were compared with diethyl ether and short chain alkanols in 21 aquatic species from 7 phyla. Loss of righting reflex and escape response were used as indicators of anesthesia. All organisms were anesthetized by diethyl ether and short chain alkanols, but pregnanolone affected only organisms belonging to the phylum Chordata. It is probable that pregnanolone exerts its effect on the gamma-aminobutyric acid (GABA) receptor. Because many invertebrates do possess GABA receptors, our results suggest that a binding site at which steroid binding causes organismal anesthesia appeared early in chordate evolution on a previously existing GABA receptor. The results also appear to exclude a primary lipid bilayer site for steroid anesthetic action.

People
Anaesthesia
Adverse effects
Obstetric anaesthesia
Molecular mechanisms
Inhalational techniques
Contemporary anaesthesia
Anaesthesia and anaesthetics
Nitrous oxide: adverse effects
Anaesthesia: rivalries and discoveries
Consciousness, anaesthesia and anaesthetics
First use of anaesthetics in different countries
Early religious/military opposition to anaesthetics

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