Gabaergic pharmacological activity of propofol related compounds as possible enhancers of general anesthetics and interaction with membranes

GABRIELA N. REINER; LETICIA E. DELGADO-MARÍN; SARA SANCHEZ REDONDO; MARIELA SANCHEZ BORZONE; DANIEL A. GARCÍA; CRISTINA SUÑOL

CELL BIOCHEMISTRY AND BIOPHYSICS

HUMANA PRESS INC

Lugar: Oregon; Año: 2013

1085-9195

ABSTRACT Phenol compounds, such as propofol and thymol, have been shown to act on the GABAA receptor through interaction with specific sites of this receptor. In addition, considering the high lipophilicity of phenols, it is possible that their pharmacological activity may be also the result of the interaction of phenol molecules with the surrounding lipid molecules modulating the supramolecular organization of the receptor environment. Thus, in the present work, we study the pharmacological activity of some propofol- and thymol-related phenols on the native GABAA receptor by using primary cultures of cortical neurons, and investigate the effects of these compounds on the microviscosity of artificial membranes by means of fluorescence anisotropy. The phenol compounds analyzed in this article are carvacrol, chlorothymol and eugenol. All compounds were able to enhance the binding of [3H]flunitrazepam with EC50 values in the micromolar range and to increase the GABA-evoked Cl- influx in a concentration-dependent manner, both effects being inhibited by the competitive GABAA antagonist bicuculline. These results strongly suggest that the phenols studied are positive allosteric modulators of this receptor. Chlorothymol showed a bell-type effect, reducing its positive effect at concentrations > 100 μM. The concentrations necessary to induce positive allosteric modulation of GABAA receptor were not cytotoxic. Although all compounds were able to decrease the microviscosity of artificial membranes, chlorothymol displayed a larger effect, which could explain its effects on [3H]flunitrazepam binding and on cell viability at high concentrations. Finally, it is suggested that these compounds may exert depressant activity on the central nervous system and potentiate the effects of general anesthetics.