| Title | General anesthetics distinctly enhance recurrent inhibition in dorsal and ventral hippocampus | |
| Authors | Panagiotis Georgopoulos*, Theodoros Petrides*, George Kostopoulos and Costas Papatheodoropoulos (*equal contribution)
University of Patras, Dept. of Physiology, Medical School |
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| Citation | Georgopoulos, P., Petrides, T., Kostopoulos, G., Papatheodoropoulos, C.: General anesthetics distinctly enhance recurrent inhibition in dorsal and ventral hippocampus, Epitheorese Klin. Farmakol. Farmakokinet. 20(2): 162-164 (2006) | |
| Publication Date | Accepted for publication: 19-20 May 2006 | |
| Full Text Language | English | |
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| Keywords | GABAA, recurrent inhibition, hippocampus, anesthetics, longitudinal axis. | |
| Other Terms | review article | |
| Summary | General anesthetics exert their effects primarily by modulating GABAA receptors. Furthermore, these effects presumably depend on the presence of α and β subunits. Since the expression of these subunits have been found different between dorsal (DH) and ventral hippocampus (VH) we compared the effects of three general anesthetics (alfaxalone, thiopental and propofol) on the GABAergic recurrent inhibition (RI) between the two hippocampal poles. Field recordings in the CA1 region of transverse rat hippocampal slices and the paired-pulse stimulation protocol were used. According to this protocol, an antidromic stimulation, which activates the RI network, suppresses the firing of CA1 pyramidal cells synaptically evoked by a following orthodromic stimulus. Using this protocol we examined the strength of RI in suppressing the CA1 pyramidal neuron firing, recorded extracellularly as a population spike (PS). Varying the interpulse intervals (IPI) between the two stimuli from 10 to 270 ms, we estimated the duration of the RI effect. In general, all drugs enhanced RI in both DH and VH slices with greater effects those of thiopental and alfaxalone. At IPIs: 50 ms thiopental and propofol similarly strengthened RI in DH and VH slices. However, the respective effect of alfaxalone at relatively short IPIs was more pronounced in VH. The most prominent common effect of all drugs was the significantly longer duration of RI enhancement in DH (n=66) compared to that in VH (n=65) slices. The present results show distinct effects of general anesthetics between the two hippocampal poles and provide support to the concept of functional diversification of GABAA receptors between DH and VH. | |
| References | 1. Rudolph U., Antkowiak B.: Molecular and neuronal substrates for general anaesthetics. Nat. Rev. Neurosci. 5: 709- 720 (2004)
2. Orser B.A., McAdam L.C., Roder S., MacDonald J.F.: General anaesthetics and their effects on GABA(A) receptor desensitization. Toxicol. Lett. 100-101: 217-224 (1998) 3. Sotiriou E., Papatheodoropoulos C., Angelatou F.: Differential expression of gamma-aminobutyric acid-A receptor sub-units in rat dorsal and ventral hippocampus. J. Neurosci. Res. 82: 690-700 (2005) 4. Papatheodoropoulos C., Kostopoulos G.: Development of a transient increase in recurrent inhibition and paired-pulse facilitation in hippocampal CA1 region. Brain Res. Dev. Brain Res. 108: 273-285 (1998) 5. Amaral D.G., Witter M.P.: Hippocampal Formation. In: (Paxinos G., ed.) The Rat Nervous System. Academic Press, 1995 6. Lambert J.J., Belelli D., Peden D.R., Vardy A.W., Peters J.A.: Neurosteroid modulation of GABAA receptors. Prog. Neurobiol. 71: 67-80 (2003) |
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| Relative Papers |
Online ISSN 1011-6575
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Articles published in this Journal are Indexed or Abstracted in: • Chemical Abstracts • Elsevier’s Bibliographic Databases: Scopus, EMBASE, EMBiology, Elsevier BIOBASE SCImago Journal and Country Rank Factor
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