Abstract
1. Whole-cell, patch-clamp recordings from cultured hippocampal neurones have been used to characterize the action of the GABAA ligand, 5-(4-piperidyl)isoxazol-3-ol (4-PIOL). The action of 4-PIOL was compared with that of the established GABAA agonist, isoguvacine. 2. With a symmetrical Cl- gradient across the membrane and a holding potential of -60mV, both isoguvacine and 4-PIOL evoked an inward current. The reversal potentials of the responses to both agents were identical (+8.8 mV, n = 4) and the current/voltage relationships showed outward-going rectification. 3. The response to 300 microM 4-PIOL was completely blocked by the GABAA antagonist, bicuculline methobromide (BMB, 10 microM). The pA2 of BMB was greater than 6.46. With 2 mM 4-PIOL about 15% of the response remained in the presence of 100 microM BMB. This may represent a non-specific component of the response to large concentrations of 4-PIOL. 4. 4-PIOL was about 200 times less potent as an agonist than isoguvacine. because of the rapid fade (desensitization) of isoguvacine-induced currents, the maximum response to this agonist was not determined. However, the response to 2 mM 4-PIOL was only a small fraction of that evoked by submaximal concentrations of isoguvacine. 5. Setting the response to 1 mM 4-PIOL as maximum, the EC50 for 4-PIOL was 91 microM (95% confidence limits:73-114 microM). 6. 4-PIOL antagonized the response to isoguvacine with a parallel shift to the right of the dose-response curve.(ABSTRACT TRUNCATED AT 250 WORDS)
Full text
PDF





Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Brewer G. J., Cotman C. W. Survival and growth of hippocampal neurons in defined medium at low density: advantages of a sandwich culture technique or low oxygen. Brain Res. 1989 Aug 7;494(1):65–74. doi: 10.1016/0006-8993(89)90144-3. [DOI] [PubMed] [Google Scholar]
- Byberg J. R., Labouta I. M., Falch E., Hjeds H., Krogsgaard-Larsen P., Curtis D. R., Gynther B. D. Synthesis and biological activity of a GABAA agonist which has no effect on benzodiazepine binding and of structurally related glycine antagonists. Drug Des Deliv. 1987 May;1(4):261–274. [PubMed] [Google Scholar]
- Carbone E., Lux H. D. Kinetics and selectivity of a low-voltage-activated calcium current in chick and rat sensory neurones. J Physiol. 1987 May;386:547–570. doi: 10.1113/jphysiol.1987.sp016551. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edwards F. A., Konnerth A., Sakmann B., Takahashi T. A thin slice preparation for patch clamp recordings from neurones of the mammalian central nervous system. Pflugers Arch. 1989 Sep;414(5):600–612. doi: 10.1007/BF00580998. [DOI] [PubMed] [Google Scholar]
- Foster N. L., Chase T. N., Denaro A., Hare T. A., Tamminga C. A. THIP treatment of Huntington's disease. Neurology. 1983 May;33(5):637–639. doi: 10.1212/wnl.33.5.637. [DOI] [PubMed] [Google Scholar]
- Gray R., Johnston D. Rectification of single GABA-gated chloride channels in adult hippocampal neurons. J Neurophysiol. 1985 Jul;54(1):134–142. doi: 10.1152/jn.1985.54.1.134. [DOI] [PubMed] [Google Scholar]
- Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
- Huguenard J. R., Alger B. E. Whole-cell voltage-clamp study of the fading of GABA-activated currents in acutely dissociated hippocampal neurons. J Neurophysiol. 1986 Jul;56(1):1–18. doi: 10.1152/jn.1986.56.1.1. [DOI] [PubMed] [Google Scholar]
- Izquierdo I. A game with shifting mirrors. Trends Pharmacol Sci. 1989 Dec;10(12):473–476. doi: 10.1016/0165-6147(89)90040-0. [DOI] [PubMed] [Google Scholar]
- Jensen M. S., Lambert J. D. Electrophysiological studies in cultured mouse CNS neurones of the actions of an agonist and an inverse agonist at the benzodiazepine receptor. Br J Pharmacol. 1986 Aug;88(4):717–731. doi: 10.1111/j.1476-5381.1986.tb16244.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kemp J. A., Marshall G. R., Woodruff G. N. Quantitative evaluation of the potencies of GABA-receptor agonists and antagonists using the rat hippocampal slice preparation. Br J Pharmacol. 1986 Apr;87(4):677–684. doi: 10.1111/j.1476-5381.1986.tb14585.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Korsgaard S., Casey D. E., Gerlach J., Hetmar O., Kaldan B., Mikkelsen L. B. The effect of tetrahydroisoxazolopyridinol (THIP) in tardive dyskinesia: a new gamma-aminobutyric acid agonist. Arch Gen Psychiatry. 1982 Sep;39(9):1017–1021. doi: 10.1001/archpsyc.1982.04290090021005. [DOI] [PubMed] [Google Scholar]
- Krogsgaard-Larsen P., Johnston G. A., Lodge D., Curtis D. R. A new class of GABA agonist. Nature. 1977 Jul 7;268(5615):53–55. doi: 10.1038/268053a0. [DOI] [PubMed] [Google Scholar]
- Lamb T. D. An inexpensive digital tape recorder suitable for neurophysiological signals. J Neurosci Methods. 1985 Oct;15(1):1–13. doi: 10.1016/0165-0270(85)90057-3. [DOI] [PubMed] [Google Scholar]
- Mathers D. A. The GABAA receptor: new insights from single-channel recording. Synapse. 1987;1(1):96–101. doi: 10.1002/syn.890010113. [DOI] [PubMed] [Google Scholar]
- Mattson M. P., Kater S. B. Isolated hippocampal neurons in cryopreserved long-term cultures: development of neuroarchitecture and sensitivity to NMDA. Int J Dev Neurosci. 1988;6(5):439–452. doi: 10.1016/0736-5748(88)90050-0. [DOI] [PubMed] [Google Scholar]
- Meldrum B. Pharmacology of GABA. Clin Neuropharmacol. 1982;5(3):293–316. doi: 10.1097/00002826-198205030-00004. [DOI] [PubMed] [Google Scholar]
- Numann R. E., Wong R. K. Voltage-clamp study on GABA response desensitization in single pyramidal cells dissociated from the hippocampus of adult guinea pigs. Neurosci Lett. 1984 Jun 29;47(3):289–294. doi: 10.1016/0304-3940(84)90528-7. [DOI] [PubMed] [Google Scholar]
- Petersen H. R., Jensen I., Dam M. THIP: a single-blind controlled trial in patients with epilepsy. Acta Neurol Scand. 1983 Feb;67(2):114–117. doi: 10.1111/j.1600-0404.1983.tb04552.x. [DOI] [PubMed] [Google Scholar]
- Segal M., Barker J. L. Rat hippocampal neurons in culture: properties of GABA-activated Cl- ion conductance. J Neurophysiol. 1984 Mar;51(3):500–515. doi: 10.1152/jn.1984.51.3.500. [DOI] [PubMed] [Google Scholar]
- Segal M., Barker J. L. Rat hippocampal neurons in culture: voltage-clamp analysis of inhibitory synaptic connections. J Neurophysiol. 1984 Sep;52(3):469–487. doi: 10.1152/jn.1984.52.3.469. [DOI] [PubMed] [Google Scholar]
- Simmonds M. A. Classification of some GABA antagonists with regard to site of action and potency in slices of rat cuneate nucleus. Eur J Pharmacol. 1982 Jun 4;80(4):347–358. doi: 10.1016/0014-2999(82)90080-2. [DOI] [PubMed] [Google Scholar]
- Tehrani M. H., Hablitz J. J., Barnes E. M., Jr cAMP increases the rate of GABAA receptor desensitization in chick cortical neurons. Synapse. 1989;4(2):126–131. doi: 10.1002/syn.890040206. [DOI] [PubMed] [Google Scholar]
- Thaker G. K., Nguyen J. A., Tamminga C. A. Increased saccadic distractibility in tardive dyskinesia: functional evidence for subcortical GABA dysfunction. Biol Psychiatry. 1989 Jan;25(1):49–59. doi: 10.1016/0006-3223(89)90146-7. [DOI] [PubMed] [Google Scholar]
- Thalmann R. H., Hershkowitz N. Some factors that influence the decrement in the response to GABA during its continuous iontophoretic application to hippocampal neurons. Brain Res. 1985 Sep 9;342(2):219–233. doi: 10.1016/0006-8993(85)91120-5. [DOI] [PubMed] [Google Scholar]
- Weiss D. S., Barnes E. M., Jr, Hablitz J. J. Whole-cell and single-channel recordings of GABA-gated currents in cultured chick cerebral neurons. J Neurophysiol. 1988 Feb;59(2):495–513. doi: 10.1152/jn.1988.59.2.495. [DOI] [PubMed] [Google Scholar]
- Weiss D. S. Membrane potential modulates the activation of GABA-gated channels. J Neurophysiol. 1988 Feb;59(2):514–527. doi: 10.1152/jn.1988.59.2.514. [DOI] [PubMed] [Google Scholar]
- Wong R. K., Watkins D. J. Cellular factors influencing GABA response in hippocampal pyramidal cells. J Neurophysiol. 1982 Oct;48(4):938–951. doi: 10.1152/jn.1982.48.4.938. [DOI] [PubMed] [Google Scholar]
