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Circadian and Ultradian Variations in Corticosterone Level Influence Functioning of the Male Mouse Basolateral Amygdala.

Abstract：

:The hypothalamic-pituitary-adrenal axis involves timed signaling between the hypothalamus, pituitary, and adrenal glands and back to the brain, causing an inherently oscillating system. Corticosteroids such as corticosterone (CORT) are secreted in a circadian rhythm, characterized by low and high levels at the start of the inactive and active phases, respectively. The circadian rhythm overarches ultradian CORT pulses, with approximate 1-hour interpulse intervals. We examined the physiological relevance of pulsatile CORT exposure for neurons of the basolateral amygdala (BLA), an area important for fear learning. We first applied four pulses of equal, high CORT concentration and measured the frequency of miniature excitatory postsynaptic currents (mEPSCs) reflecting spontaneous glutamate signaling. BLA neurons responded differently to each pulse, showing "metaplasticity," extending earlier studies. Next, we mimicked the progression of the inactive and active phases by four CORT pulses of increasing and decreasing concentrations, respectively. CORT pulses of increasing concentration were necessary and sufficient to gradually increase baseline (between-pulse) mEPSC frequency during the mimicked inactive phase, whereas the opposite was seen with decreasing CORT levels during the mimicked active phase. To study the relevance of changed glutamate transmission on behavior, mice were tested in tone-cued fear conditioning during the active or inactive phase. Animals tested at the inactive compared with the active phase showed efficient fear learning; this was also observed when animals tested during the active phase were treated with the CORT synthesis blocker metyrapone. This suggests that natural CORT rhythms influence electrical activity in the BLA, possibly contributing to altered behavioral function.

journal_name

Endocrinology

journal_title

Endocrinology

authors

den Boon FS,de Vries T,Baelde M,Joëls M,Karst H

doi

10.1210/en.2018-00767

subject

Has Abstract

pub_date

2019-04-01 00:00:00

pages

791-802

issue

4

eissn

0013-7227

issn

1945-7170

pii

5297087

journal_volume

160

pub_type

杂志文章

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