Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Oct;600(19):4347-4359.
doi: 10.1113/JP283328. Epub 2022 Sep 12.

Regulation of corticotropin-releasing hormone neuronal network activity by noradrenergic stress signals

Julia M Gouws  1 , Aidan Sherrington  1 , Shaojie Zheng  1 , Joon S Kim  1 , Karl J Iremonger  1
Affiliations

Regulation of corticotropin-releasing hormone neuronal network activity by noradrenergic stress signals

Julia M Gouws et al. J Physiol. 2022 Oct.

Abstract

Noradrenaline is a neurotransmitter released in response to homeostatic challenge and activates the hypothalamic-pituitary-adrenal axis via stimulation of corticotropin-releasing hormone (CRH) neurons. Here we investigated the mechanism through which noradrenaline regulates activity within the CRH neuronal network. Using a combination of in vitro GCaMP6f Ca2+ imaging and electrophysiology, we show that noradrenaline induces a robust increase in excitability in a proportion of CRH neurons with many neurons displaying a bursting mode of activity. Noradrenaline-induced activation required α1 -adrenoceptors and L-type voltage-gated Ca2+ channels, but not GABA/glutamate synaptic transmission or sodium action potentials. Exposure of mice to elevated corticosterone levels was able to suppress noradrenaline-induced activation. These results provide further insight into the mechanisms by which noradrenaline regulates CRH neural network activity and hence stress responses. KEY POINTS: GCaMP6f Ca2+ imaging and on-cell patch-clamp recordings reveal that corticotropin-releasing hormone neurons are activated by noradrenaline with many neurons displaying a bursting mode of activity. Noradrenaline-induced activation requires α1 -adrenoceptors. Noradrenaline-induced Ca2+ elevations persist after blocking GABAA , AMPA, NMDA receptors and voltage-gated Na+ channels. Noradrenaline-induced Ca2+ elevations require L-type voltage-gated Ca2+ channels. Corticosterone suppresses noradrenaline-induced excitation.

Keywords: CRH; hypothalamus; noradrenaline; stress.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Noradrenaline induces heterogeneous patterns of excitation in CRH neurons
A, four examples of GCaMP6f calcium responses from different CRH neurons in response to bath‐application of noradrenaline. B, repeated bath‐applications of noradrenaline (NA) to the same neuron evoke responses with similar kinetics. C, images showing on‐cell patch clamp recording from a CRH neuron expressing GCaMP6f in an acute brain slice of the PVN. a, transmitted light image; b, confocal image of GCaMP6f fluorescence; c, merged image. D, simultaneous electrical (black) and GCaMP6f fluorescence (green) traces from the soma of a CRH neuron. Traces illustrate that spontaneous bursts of spikes coincide with increases in GCaMP6f fluorescence. Region inside dashed box expanded in E. F, relationship between total cumulative fluorescence and spike count per burst from a single representative neuron. G, correlation r 2 and P‐values of total cumulative fluorescence and spike count in response to burst activity. [Colour figure can be viewed at wileyonlinelibrary.com]
Figure 2
Figure 2. Noradrenaline‐induced Ca2+ events in CRH neurons require α1‐adrenoceptors
A–E, top, representative images showing the number of neurons in each imaging region that were activated by noradrenaline. Activated cells are highlighted green. Each image is from a different brain slice pre‐treated with no drugs (control) (A), prazosin (B), yohimbine (C), CNQX and dl‐AP5 (D) or picrotoxin (E). Bottom, representative GCaMP6f fluorescence traces of noradrenaline responses in control, prazosin, yohimbine, CNQX and dl‐AP5, or picrotoxin. F, summary graph showing number of neurons activated by noradrenaline per brain slice for each drug treatment condition. G, summary graph showing number of events detected (mean per active neuron per slice) in response to noradrenaline for each drug treatment condition. H, summary graph showing the amplitude of events (mean per active neuron per slice) in response to noradrenaline for each drug treatment condition. [Colour figure can be viewed at wileyonlinelibrary.com]
Figure 3
Figure 3. Noradrenaline‐induced Ca2+ events do not require sodium action potentials
Simultaneous electrical (black) and GCaMP6f fluorescence (green) traces from the soma of a CRH neuron recorded in the continued presence of CNQX, dl‐AP5, picrotoxin and noradrenaline. A–C, example recordings where application of TTX (black bar) leads to cessation of spiking activity measured electrophysiologically; however, Ca2+ events persist. D, example recording where application of TTX inhibits both electrical spiking and Ca2+ events. [Colour figure can be viewed at wileyonlinelibrary.com]
Figure 4
Figure 4. Noradrenaline‐induced Ca2+ events require voltage‐gated Ca2+ channels
A–D, top, representative images showing the number of neurons that were activated by noradrenaline. Activated cells are highlighted in green. Each image is from a different brain slice pre‐treated with one of the following: TTX (A), glutamate/GABAA receptor antagonists + TTX (synaptic blockers + TTX) (B), synaptic blockers + TTX + voltage‐gated Ca2+ channel antagonist CdCl2 (C), synaptic blockers + TTX + L‐type Ca2+ channel antagonist nifedipine (D). Bottom, representative GCaMP6f fluorescence traces of noradrenaline responses in TTX, synaptic blockers + TTX, synaptic blockers + TTX + CdCl2 and synaptic blockers + TTX + nifedipine. E, summary graph showing number of neurons activated by noradrenaline per brain slice for each drug treatment condition. F, summary graph showing number of events detected (mean per active neuron per slice) in response to noradrenaline for each drug treatment condition. G, summary graph showing the average amplitude of events (mean per active neuron per slice) in response to noradrenaline for each drug treatment condition. [Colour figure can be viewed at wileyonlinelibrary.com]
Figure 5
Figure 5. Noradrenaline‐induced Ca2+ events are suppressed by chronic corticosterone
A, representative images showing the number of neurons that were activated by noradrenaline in a brain slice from a control mouse (left) or a mouse treated with corticosterone in the drinking water for 2 weeks (right). Activated cells are highlighted green. B, representative GCaMP6f fluorescence traces of noradrenaline responses from a control mouse or a mouse treated with corticosterone. C, summary graph showing number of neurons activated by noradrenaline per brain slice for control and corticosterone conditions. D and E, summary graphs showing number of events (mean per active cell per brain slice) and amplitude of events (mean per active cell per brain slice). There was no significant difference between groups for either number of events (P = 0.220) or event amplitude (P = 0.673). [Colour figure can be viewed at wileyonlinelibrary.com]
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Andrew, R. D. , & Dudek, F. E. (1983). Burst discharge in mammalian neuroendocrine cells involves an intrinsic regenerative mechanism. Science, 221(4615), 1050–1052. - PubMed
    1. Bains, J. S. , Wamsteeker Cusulin, J. I. , & Inoue, W. (2015). Stress‐related synaptic plasticity in the hypothalamus. Nature Reviews. Neuroscience, 16(7), 377–388. - PubMed
    1. Bittar, T. P. , Nair, B. B. , Kim, J. S. , Chandrasekera, D. , Sherrington, A. , & Iremonger, K. J. (2019). Corticosterone mediated functional and structural plasticity in corticotropin‐releasing hormone neurons. Neuropharmacology, 154, 79–86. - PubMed
    1. Bourque, C. W. (1986). Calcium‐dependent spike after‐current induces burst firing in magnocellular neurosecretory cells. Neuroscience Letters, 70(2), 204–209. - PubMed
    1. Brown, C. H. (2004). Rhythmogenesis in vasopressin cells. Journal of Neuroendocrinology, 16(9), 727–739. - PubMed

Publication types

MeSH terms