Abstract
Benzodiazepine (BZ) receptor ligands interact with specific binding sites on the GABAA receptor/chloride channel complex on neurons in the central nervous system (CNS) (1) (Figure 1). Such ligands could contribute to or ameliorate hepatic encephalopathy (HE) if the supra-molecular complex itself is involved in this syndrome. The complex includes distinct receptors for BZ ligands and GABA, and a chloride ionophore on which there are binding sites for barbiturates and cage convulsants, such as Picrotoxin. Activation of the effector component of this complex, the chloride channel, is mediated by the binding of GABA to its receptor and is potentiated by the binding of a BZ agonist or a barbiturate to discrete loci on the complex. Activation induces conformational changes in the complex which result in opening of the chloride channel and hyperpolarization of the neuron (1) (Figure 1). This GABA-gated chloride ion conductance is the basis of GABA-mediated inhibitory neurotransmission or “GABAergic tone.”
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Paul S.M., Marangos P.J., and Skolnick P. (1981) The benzodiazepine-GABA-chloride ionophore receptor complex. Common site of minor tranquillizer action. Biol. Psych. 16, 213–229.
Bassett M.L., Mullen K.D., Skolnick P. et al. (1987) Amelioration of hepatic encephalopathy by pharmacologic antagonism of the GABAA/benzodiazepine receptor complex in a rabbit model of fulminant hepatic failure. Gastroenterology 93, 1069–1077.
Schafer D.F. Pappas S.C., Brody L.E. et al. (1984) Visual evoked potentials in a rabbit model of hepatic encephalopathy. I. Sequential changes and comparisons with drug-induced comas. Gastroenterology 86, 540–545.
Jones D.B., Mullen K.D., Roessle M. et al. (1987) Hepatic encephalopathy: application of visual evoked responses to test hypotheses of its pathogenesis in rats. J. Hepatol. 4, 118–126.
Gammal S.H., Jones E.A., Bassett M.L. et al. (1988) Antagonists of the GABA/benzodiazepine receptor complex ameliorate hepatic encephalopathy in two models of fulminant hepatic failure, in Advances in Ammonia Metabolism and Hepatic Encephalopathy. (Soeters P.B., Wilson J.H.P., Meijer A.J., and Holm E. eds), pp. 325–332. Excerpta Medica, Amsterdam.
Study R.E., and Barker J.L. (1981) Diazepam and (-)-pentobarbital Fluctuation analysis reveals different mechanisms for potentiation of γ-aminobutyric acid responses in cultured neurons. Proc. Natl. Acad. Sci. USA 78, 7180–7184.
Schafer D.F., Fowler J.M., Brody L.E. et al. (1980) Hepatic coma and inhibitory neurotransmission: the enteric bacterial flora as a source of γ-aminobuty-ric acid. Gastroenterology 79, 1052. (Abstract).
Schafer D.F. Jones E.A. (1982) Hepatic encephalopathy and the γ-aminobutyric acid neuro-transmitter system. Lancet i, 18–20.
Blitzer B.L., Waggoner J.G., Jones E.A. et al. (1978) A model of fulminant hepatic failure in the rabbit. Gastroenterology 74, 664–671.
Jones E.A., and Skolnick P. (1989) Benzodiazepine receptor ligands and the syndrome of hepatic encephalopathy, in Progress in Liver Diseases, volume IX. (Popper H., Schaffner F., eds). W.B. Saunders, Philadelphia, ‘In press’.
Ferreira M.R., Gammal S.H., and Jones E.A. (1983) Hepatic encephalopathy (HE); Evidence of increased GABA-mediated neurotransmission in a rat model of fulminant hepatic failure (FHF). Gastroenterology 94, A616. (Abstract).
Olsen R.W. (1982) Drug interactions at the GABA receptor-ionophore complex. Ann. Rev. Pharmacol. Toxicol. 22, 245–277.
Karlsson A., Fonnum F., Malthe-Sorrenssen D. et al. (1974) Effect of the convulsive agent 3, mercapto-propionic acid on the levels of GABA, other anino acids and glutamate decarboxylase in different regions of the rat brain. Biochem. Pharmacol. 23, 3053–3061.
Basile A.S., Gammal S.H., Milien K.D. et al. (1988) Differential responsiveness of cerebellar Purkinje neurons to GABA and benzodiazepine receptor ligands in an animal model of hepatic encephalopathy. J. Neurosc. 8, 2414–2421.
Baraldi M., and Zeneroli M.L. (1982) Experimental hepatic encephalopathy: changes in the binding of γ-aminobutyric acid. Science 216, 427–429.
Schafer D.F., Fowler J.M., Munson P.J. et al. (1983) Gamma-aminobutyric acid and benzodiazepine receptors in an animal model of fulminant hepatic failure. J. Lab. Clin. Med. 102, 870–880.
Maddison J.E., Dodd P.R., Morrison M. et al. (1987) Plasma GABA, GABA-like activity and the brain GABA-benzodiazepine receptor complex in rats with chronic hepatic encephalopathy. Hepatology 7, 621–628.
Roy S., Pomier-Layrargues G., Butterworth R.F. et al. (1988) Hepatic encephalopathy in cirrhotic and portacaval shunted dogs: lack of changes in brain GABA uptake, brain GABA levels, brain glutamic acid decarboxylase activity and brain postsynaptic GABA receptors. Hepatology 8, 845–849.
Ferenci P., Zimmerman C., and Ebner J. (1988) Post-synaptic γ-aminobutyric acid (GABA) receptors in thioacetamide-induced acute liver failure in rats, in Advances in Ammonia Metabolism and Hepatic Encephalopathy. (Soeters P.B., Wilson J.H.P. Meijer A.J. and Holm E. eds), pp. 218–224. Excerpta Medica, Amsterdam.
Bassett M.L. Mullen K.D. Scholz B., et al. (1985) Increased brain GABA uptake in precoma encephalopathy in a rabbit model of fulminant hepatic failure. Hepatology 5, 1032. (Abstract).
Squires R.F. (1984) Benzodiazepine receptors, in Handbook of Neurochemistry, 2nd ed. Volume 6. (Lajtha A. ed), pp. 261–306. Plenum, New York.
Mullen K.D., Martin J.V., Mendelson W.B. et al. (1988) Could an endogenous benzodiazepine ligand contribute to hepatic encephalopathy? Lancet i, 457–459.
Chiappa K.H., and Ropper A.H. (1982) Evoked potentials in clinical medicine. N. Eng. J. Med. 306, 1140–1147.
Zemon V. Kaplan E., and Katloff F. (1980) Bicuculline enhances a negative component and diminishes a positive component of the visual evoked cortical potential in the cat. Proc. Natl. Acad. Sci. USA 77, 7476–7478.
Nakayama K., (1982) The relationship of visual evoked potentials to cortical physiology. Ann. N. Y. Acad. Sci. 388, 21–36.
Dyer R.S., Jensen K.F. and Boyer W.K. (1987) Focal lesion of visual cortex: effects on visual evoked potentials in rats. Exp. Neurol. 95, 100–115.
Traber P.G. Ganger D.R., and Blei A.T. (1986) Brain edema in rabbits with galactosamine-induced fulminant hepatitis. Regional differences and effects of intracranial pressure. Gastroenterology 91, 1347–1356.
Traber P.G., Canto M.D., Ganger D.R. et al. (1987) Electron microscopic evaluation of brain edema in rabbits with galactosamine-induced fulminant hepatic failure. Ultrastructure and integrity of the blood brain barrier. Hepatology 7, 1272–1277.
Mullen K.D., Schafer D.F., Cuchi P. et al. (1988) Evaluation of the suitability of galactosamineinduced fulminant hepatic failure as a model of hepatic encephalopathy in the rat and the rabbit, in Advances in Ammonia Metabolism and Hepatic Encephalopathy. (Soeters P.B. Wilson J.H.P., Meijer A.J., and Holm E. eds), pp. 205–212. Excerpta Medica, Amsterdam.
Hunkeler W., Mohler H., Pieri L. et al. (1981) Selective antagonists of benzodiazepines. Nature 290, 514–516.
Bonetti E., Pieri L., Cumin R. et al. (1982) Benzo-diazepine antagonist Ro 15–1788: Neurological and behavioral effects. Psychopharmacology 78, 8–18.
Haefely W. (1983) Antagonists of benzodiazepines: functional aspects, in Benzodiazepine Recognition Site Ligands: Biochemistry and Pharmacology. (Biggio G., and Costa E. eds), pp. 73–93. Raven Press, New York.
Geller D. Gammal S.H., Mullen K.D. et al. (1988) An improved rat model of hepatic encephalopathy due to fulminant hepatic failure. The importance of supportive therapy, in Advances in Ammonia Metabolism and Hepatic Encephalopathy. (Soeters P.B., Wilson J.H.P., Meijer A.J., and Holm E. eds), pp. 213–217. Excerpta Medica, Amsterdam.
Gammal S.H., Basile A.S., Geller D. et al. Involvement of the benzodiazepine receptor in hepatic encephalopathy: Quantitative behavioral and electrophysiological evidence in a rat model. (In preparation).
Baraldi M., Zeneroli M.L., Ventura E. et al. (1984) Supersensitivity of benzodiazepine receptors in hepatic encephalopathy due to fulminant hepatic failure in the rat: reversal by a benzodiazepine antagonist. Clin. Sci. 67, 167–175.
Mullen K.D. Szanter K.M., Kaminsky K. et al. (1989) Detection and characterization of endogenous benzodiazepine activity in both animal models and humans with hepatic encephalopathy. (This volume).
Basile A.S., Ostrowski N.L., Gammal S.H. et al. (1989) The GABAA receptor complex in hepatic encephalopathy: Autoradiographic evidence for the presence of an endogenous benzodiazepine receptor ligand. Gastroenterology. (Abstract).
Basile A.S. Gammal S.H., Jones E.A. et al. (1989) The GABAA receptor complex in an experimental model of hepatic encephalopathy: Evidence for elevated levels of an endogenous benzodiazepine receptor ligand. Gastroenterology. (Abstract).
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1989 The Humana Press Inc.
About this chapter
Cite this chapter
Jones, E.A. et al. (1989). Hepatic Encephalopathy and Benzodiazepine Receptor Ligands. In: Butterworth, R.F., Layrargues, G.P. (eds) Hepatic Encephalopathy. Experimental Biology and Medicine, vol 22. Humana Press. https://doi.org/10.1007/978-1-4612-4506-3_19
Download citation
DOI: https://doi.org/10.1007/978-1-4612-4506-3_19
Publisher Name: Humana Press
Print ISBN: 978-1-4612-8851-0
Online ISBN: 978-1-4612-4506-3
eBook Packages: Springer Book Archive