Chapter 8 GABAc receptors
1994; Elsevier BV; Linguagem: Inglês
10.1016/s0079-6123(08)60769-4
ISSN1875-7855
Autores Tópico(s)Neuroscience and Neuropharmacology Research
ResumoThere is increasing evidence for the existence of classes of gamma-aminobutyric acid (GABA) receptors that are not covered by GABAA receptors, pharmacologically defined as bicuculline-sensitive, baclofen-insensitive receptors, and GABAB receptors, defined as baclofen-sensitive, bicuculline-insensitive receptors. GABAC receptors that are bicuculline-insensitive, baclofen-insensitive, linked to chloride channels, and selectively activated by cis-4-aminocrotonic acid (CACA) and cis-2-(aminomethyl)-cyclopropane carboxylic acid (CAMP) may represent one such class of receptors. GABAC receptors may be more widespread in insects and bacteria than in vertebrates where they may be localized in certain parts of the nervous system, such as the retina. GABAC receptors may represent receptors that subsequently evolved into GABAA receptors by gaining bicuculline-sensitivity, together with altered agonist and modulator specificity. The ρ1 protein, which is highly expressed in retina and has considerable sequence homology with GABAA subunit proteins, yields homooligomeric receptors in Xenopus oocytes that have many but not all of the pharmacological properties of GABAC receptors as deduced from electrophysiological and neurochemical studies on neuronal membranes. A combination of molecular biology, electrophysiology, pharmacology, and medicinal chemistry can provide more comprehensive information on GABAC and other receptors that do not fit the classic definitions of GABAA and GABAB receptors.
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