High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

Kole, Maarten H. P.; Koolhaas, Jaap M.; Luiten, P.G.M.; Fuchs, Eberhard

doi:10.1016/s0304-3940(01)01926-7

Cited by 38 publications

(24 citation statements)

References 19 publications

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“…It is noteworthy that in the absence of corticosteroid hormones (or with reduced levels of GRs), sustained calcium current amplitude was also high (Karst et al, 1994;Hesen et al, 1996), revealing a U-shaped dose dependence (Joëls, 2006). A similar U-shaped dose dependence was also described for CA3 neurons, when correlating circulating corticosteroid levels throughout the day with the calcium current amplitude (Kole et al, 2001). By contrast, dentate granule cells do not show an enhanced calcium current amplitude several hours after they have Rapid effects of corticosteroid hormones on cognitive processing in male rodents.…”

Section: A Slow Modulation Of Neural Activitysupporting

confidence: 54%

“…8); this differs from the situation of predominant MR activation (such as occurs under rest), which is characterized by more spikes during a depolarizing pulse than in the absence of steroids (Joëls and de Kloet, 1990), reflecting the same U-shaped dose dependence as observed with respect to calcium current amplitude. Similar effects were also seen in the CA3 area (Kole et al, 2001). The onset of the corticosterone-dependent modulation in firing frequency is slow and requires protein synthesis (Karst and Joëls, 1991).…”

Section: Mr + Gr Mr Adxsupporting

confidence: 53%

“…For instance, a larger spike frequency accommodation and AHP amplitude (Joëls and de Kloet, 1989;Kerr et al, 1989;Kole et al, 2001) could serve as a brake to steady excitatory inputs, particularly when unrelated to the stressful event. The increased AHP amplitude probably develops secondary to enhanced calcium influx.…”

Section: Underlying Mechanisms and Functional Consequencesmentioning

confidence: 99%

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Unraveling the Time Domains of Corticosteroid Hormone Influences on Brain Activity: Rapid, Slow, and Chronic Modes

2012

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Section: A Slow Modulation Of Neural Activitysupporting

confidence: 54%

Section: Mr + Gr Mr Adxsupporting

confidence: 53%

Section: Underlying Mechanisms and Functional Consequencesmentioning

confidence: 99%

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Unraveling the Time Domains of Corticosteroid Hormone Influences on Brain Activity: Rapid, Slow, and Chronic Modes

2012

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“…1 B, C). As glutamate transmission is persistently enhanced by corticosteroids, calcium would continue to enter hippocampal cells [5,136,137] . This would cause NMDA receptors in the hippocampus to desensitize in order to protect the cells from excitotoxicity [138][139][140][141][142] .…”

Section: Effects Of Stress On Hippocampal Synaptic Plasticitymentioning

confidence: 99%

Hormetic and Non-Hormetic Dose-Response Functions in Stress Effects on Memory and Synaptic Plasticity: Issues and Mechanisms

Zoladz¹,

Diamond²

2008

American J. of Pharmacology and Toxicology

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Over a century of behavioral research has shown that stress can exert both positive and negative effects on memory. We have explored the idea that the complex effects of stress on learning and memory can be characterized by hormetic-and non-hormetic dose-response functions, in which stress may either stimulate or impair brain memory mechanisms, depending, in part, on the timing and duration of the stress experience. Extensive work has shown that acute stress or corticosteroid administration has a biphasic effect specifically on hippocampus-dependent learning, memory and synaptic plasticity. We suggest that brief stress exerts a rapid enhancement of memory-related functions of the hippocampus, produced by the amygdala-induced activation of hippocampal synaptic plasticity in conjunction with excitatory effects of neuromodulators, including glucocorticoids, norepinephrine, corticotropin-releasing hormone, acetylcholine and dopamine. We propose that the rapid stress-induced activation of the amygdala-hippocampus brain memory system results in a linear (non-hormetic) dose-response relation between emotional strength and memory formation. In response to more prolonged stress, a delayed inhibition of hippocampal function develops, which can be attributed to compensatory cellular responses which protect hippocampal neurons from excitotoxicity. The inhibition of hippocampal functioning in response to prolonged stress is potentially relevant to the well-described curvilinear (hormetic) dose-response relationship between arousal and memory. In summary, our emphasis on the temporal features of stress-brain interactions addresses how stress can activate, as well as impair, hippocampal functioning to produce differently shaped (nonhormetic/hormetic) stress-memory dose response functions.

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“…Researchers have documented diurnal and circadian differences in long-term potentiation in the hippocampus (10,11). Additional studies have also found that excitability of CA3 neurons is regulated diurnally (12). Thus, some mechanisms exist for learning and memory to be rhythmic.…”

mentioning

confidence: 99%

Circadian modulation of long-term sensitization in Aplysia

Fernandez

Lyons

Levenson

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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As the mechanisms for learning and memory are elucidated, modulation of learning and memory becomes a central issue. We studied the modulation of learning and memory by investigating the circadian regulation of short-and long-term sensitization of the siphon withdrawal reflex in Aplysia. We found that Aplysia exhibited diurnal and circadian rhythms of long-term sensitization (LTS) with significantly greater LTS occurring when animals were trained and tested during the day relative to those trained and tested at night. In contrast to the modulation of LTS, short-term sensitization was not regulated by the circadian clock. Time of training rather than time of testing determined the circadian rhythm of LTS. Animals trained during the subjective day demonstrated LTS when tested during either the day or the night. Conversely, when animals were trained during the night, LTS was not observed when animals were tested either at night or during the day. Thus, the circadian rhythm of LTS is a rhythm in learning rather than a rhythm in recall. The threshold required to elicit siphon withdrawal and the duration of siphon withdrawal were not regulated by the circadian clock. These results indicate that the circadian oscillator exerts strong modulatory influences on one form of long-term memory in Aplysia.H ow organisms learn has been of interest for centuries as people seek to understand and improve learning and memory abilities. One aspect of understanding learning and memory is determining how these processes are normally modulated. What conditions modulate learning and memory, and how does regulation occur? General health, motivation, age, stress, sleep patterns, and time of day may modulate learning and memory. The circadian clock regulates many behavioral and physiological processes, making it likely that circadian modulation of learning and memory also occurs (1).Circadian modulation of learning and memory has been investigated with varied results. Some studies have indicated time of day influences memory in humans (2-4), whereas other studies have found little impact of time of day on memory (5). Researchers studying hippocampus-dependent learning found that rats trained at midday showed decreased retention compared with animals trained earlier or later (6). However, other researchers found no time-of-day effects on multiple learning tasks (7). Furthermore, two laboratories studying contextual fear conditioning in mice reported different effects of the circadian clock on learning and memory (8, 9). The issue of circadian modulation of learning and memory remains to be determined.Indirect evidence for circadian modulation of learning and memory comes from in vitro studies of long-term potentiation. Researchers have documented diurnal and circadian differences in long-term potentiation in the hippocampus (10, 11). Additional studies have also found that excitability of CA3 neurons is regulated diurnally (12). Thus, some mechanisms exist for learning and memory to be rhythmic. Experiments demonstrating that consolidation ...

show abstract

High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

Cited by 38 publications

References 19 publications

Unraveling the Time Domains of Corticosteroid Hormone Influences on Brain Activity: Rapid, Slow, and Chronic Modes

Unraveling the Time Domains of Corticosteroid Hormone Influences on Brain Activity: Rapid, Slow, and Chronic Modes

Hormetic and Non-Hormetic Dose-Response Functions in Stress Effects on Memory and Synaptic Plasticity: Issues and Mechanisms

Circadian modulation of long-term sensitization in Aplysia

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