Prolongation of hippocampal inhibitory postsynaptic potentials by barbiturates

Nicoll, RA; Eccles, John C.; Oshima, Tomokazu; Rubia, Francisco J.

doi:10.1038/258625a0

Cited by 352 publications

(105 citation statements)

References 22 publications

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“…We hypothesize that an up-regulation of Kv4 channels is the condition for such a low dose to be effective, either on E-S translation or on behavior, as discussed below (see paragraphs on long-term plasticity results and spatial learning performances). This lack of effect on basal transmission could be also due to the strong inhibition exerted by GABAergic interneurons observed in vivo in DG (Buckmaster and Schwartzkroin 1995), particularly when using a barbiturate anesthetic that enhances and prolongs inhibitory postsynaptic potential (Nicoll et al 1975).…”

Section: Ammtx3 Prolongs the E-s Component Of Ltpmentioning

confidence: 99%

Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Truchet¹,

Manrique²,

Sréng³

et al. 2012

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Kv4 channels regulate the backpropagation of action potentials (b-AP) and have been implicated in the modulation of longterm potentiation (LTP). Here we showed that blockade of Kv4 channels by the scorpion toxin AmmTX3 impaired reference memory in a radial maze task. In vivo, AmmTX3 intracerebroventricular (i.c.v.) infusion increased and stabilized the EPSP-spike (E-S) component of LTP in the dentate gyrus (DG), with no effect on basal transmission or short-term plasticity. This increase in E-S potentiation duration could result from the combination of an increase in excitability of DG granular cells with a reduction of GABAergic inhibition, leading to a strong reduction of input specificity. Radioactive in situ hybridization (ISH) was used to evaluate the amounts of Kv4.2 and Kv4.3 mRNA in brain structures at different stages of a spatial learning task in naive, pseudoconditioned, and conditioned rats. Significant differences in Kv4.2 and Kv4.3 mRNA levels were observed between conditioned and pseudoconditioned rats. Kv4.2 and Kv4.3 mRNA levels were transiently up-regulated in the striatum, nucleus accumbens, retrosplenial, and cingulate cortices during early stages of learning, suggesting an involvement in the switch from egocentric to allocentric strategies. Spatial learning performance was positively correlated with the levels of Kv4.2 and Kv4.3 mRNAs in several of these brain structures. Altogether our findings suggest that Kv4 channels could increase the signal-to-noise ratio during information acquisition, thereby allowing a better encoding of the memory trace.

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Section: Ammtx3 Prolongs the E-s Component Of Ltpmentioning

confidence: 99%

Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Truchet¹,

Manrique²,

Sréng³

et al. 2012

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“…Pentobarbital prolongs the open time of GABA-activated chloride channels (Nicoll et al, 1975;MacDonald et al, 1989), whereas ketamine is a noncompetitive NMDA receptor antagonist (Franks and Lieb, 1994) that also reduces AMPA-mediated depolarization (Leong et al, 2004). Partial substitution of ketamine for barbiturate is advantageous, because ketamine is believed to be less suppressive of neural activity (Astl et al, 1996;Wehr and Zador, 2005).…”

Section: Anesthetic Effects On Temporal Codingmentioning

confidence: 99%

Transformation of Temporal Properties between Auditory Midbrain and Cortex in the Awake Mongolian Gerbil

Ter-Mikaelian¹,

Sanes²,

Semple³

2007

Journal of Neuroscience

165

106

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The neural representation of meaningful stimulus features is thought to rely on precise discharge characteristics of the auditory cortex. Precisely timed onset spikes putatively carry the majority of stimulus-related information in auditory cortical neurons but make a small contribution to stimulus representation in the auditory midbrain. Because these conclusions derive primarily from anesthetized preparations, we reexamined temporal coding properties of single neurons in the awake gerbil inferior colliculus (IC) and compared them with primary auditory cortex (AI). Surprisingly, AI neurons displayed a reduction of temporal precision compared with those in the IC. Furthermore, this hierarchical transition from high to low temporal fidelity was observed for both static and dynamic stimuli. Because most of the data that support temporal precision were obtained under anesthesia, we also reexamined response properties of IC and AI neurons under these conditions. Our results show that anesthesia has profound effects on the trial-to-trial variability and reliability of discharge and significantly improves the temporal precision of AI neurons to both tones and amplitude-modulated stimuli. In contrast, IC temporal properties are only mildly affected by anesthesia. These results underscore the pitfalls of using anesthetized preparations to study temporal coding. Our findings in awake animals reveal that AI neurons combine faster adaptation kinetics and a longer temporal window than evident in IC to represent ongoing acoustic stimuli.

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“…These findings suggest that, in addition to the effects of barbiturates upon the GABA/BZ/barbiturate receptor/chloride channel complex, there may be other actions upon GABA receptors that are coupled to channels with somewhat less ionic selectivity. To complicate matters further, responses to antidromic stimulation of the CA 1 pyramidal neurons clearly consist of 2 components (present results), but previous studies of hippocampal recurrent inhibition have not determined whether barbiturates affect one or both components of this response (Alger and Nicoll, 1982a;Nicoll et al, 1975).…”

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confidence: 81%

“…Nicoll et al (1975) reported that the time courses of these spontaneous IPSPs were prolonged by pentobarbital. Therefore, we characterized the effects of etomidate upon these spontaneous IPSPs using KC1 microelectrodes.…”

Section: The Journal Of Neurosciencementioning

confidence: 99%

“…In the hippocampus, GABA facilitation is apparent not only as an increase in the amplitude of GABAergic IPSPs, but also as a prolongation of these inhibitory potentials (Alger and Nicoll, 1982b;Gage and Robertson, 1985;Nicoll et al, 1975;Roth et al, 1983). The mechanism underlying these effects appears likely to be the prolongation of the mean channel lifetime for GABA-activated chloride channels (Study and Barker, 1981).…”

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confidence: 99%

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Facilitatory action of etomidate and pentobarbital on recurrent inhibition in rat hippocampal pyramidal neurons

Proctor¹,

Mynlieff²,

Dunwiddie³

1986

J. Neurosci.

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Biochemical studies have shown that the non-barbiturate anesthetic etomidate can interact in a stereoselective, barbiturate-like fashion with the GABA/benzodiazepine receptor complex, enhancing both benzodiazepine and GABA binding, but its electrophysiological effects upon the mammalian CNS are largely unknown. The present investigations were designed to characterize the electrophysiological effects of etomidate on the recurrent GABAergic inhibitory pathway in the CA1 region of the rat in vitro hippocampal slice and to compare the actions of etomidate to those of pentobarbital. Electrical stimulation of the alveus elicited a biphasic hyperpolarizing response, consisting of an initial bicuculline-sensitive GABAergic IPSP. This was followed by a second component, termed the late hyperpolarizing potential (LHP), which is thought to reflect an increase in potassium conductance. Both pentobarbital (100 microM) and (+)-etomidate (10 microM) markedly increased the duration of the initial GABA-mediated IPSP, and frequently increased its amplitude as well. However, no significant effects of either of these drugs were observed on the LHP. Together with previous biochemical findings, our data suggest that the depressant effects of etomidate and barbiturates on the nervous system may reflect a common action upon a stereoselective receptor site intimately associated with bicuculline-sensitive GABA receptors and the chloride ion channel.

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Prolongation of hippocampal inhibitory postsynaptic potentials by barbiturates

Cited by 352 publications

References 22 publications

Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Transformation of Temporal Properties between Auditory Midbrain and Cortex in the Awake Mongolian Gerbil

Facilitatory action of etomidate and pentobarbital on recurrent inhibition in rat hippocampal pyramidal neurons

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