Systemic disruption, systemic responses

Abstract Functional near infrared spectroscopy (fNIRS) measurements are confounded by signal components originating from multiple physiological causes, whose activities may vary temporally and spatially (across tissue layers, and regions of the cortex). Furthermore, the stimuli can induce evoked effects, which may lead to over or underestimation of the actual effect of interest. Here, we conducted a temporal, spectral, and spatial analysis of fNIRS signals collected during cognitive and hypercapnic stimuli to characterize effects of functional versus systemic responses. We utilized wavelet analysis to discriminate physiological causes and employed long and short source-detector separation (SDS) channels to differentiate tissue layers. Multi-channel measures were analyzed further to distinguish hemispheric differences. The results highlight cardiac, respiratory, myogenic, and very low frequency (VLF) activities within fNIRS signals. Regardless of stimuli, activity within VLF band had the largest contribution to the overall signal. The systemic activities dominated the measurements from the short SDS channels during cognitive stimulus, but not hypercapnic stimulus. Importantly, results indicate that characteristics of fNIRS signals vary with type of the stimuli administered as cognitive stimulus elicited variable responses between hemispheres in VLF band and task-evoked temporal effect in VLF, myogenic and respiratory bands, while hypercapnic stimulus induced a global response across both hemispheres.

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Co-option of local and systemic immune responses by the hormonal signalling system triggering metamorphosis

10.1101/2021.05.22.444626 ◽

2021 ◽

Author(s):

Catarina Nunes ◽

Takashi Koyama ◽

Elio Sucena

Keyword(s):

Immune Responses ◽

Fat Body ◽

Developmental Regulation ◽

Bacterial Persistence ◽

Systemic Immune Response ◽

Downstream Target ◽

Local Responses ◽

Insect Metamorphosis ◽

Systemic Responses ◽

Hormonal Signalling

Insect metamorphosis is regulated by the production, secretion and degradation of two peripheral hormones: 20-hydroxyecdysone (ecdysone) and juvenile hormone (JH). In addition to their roles in developmental regulation, increasing evidence suggests that these hormones are involved in innate immunity processes, such as phagocytosis and the induction of antimicrobial peptide (AMP) production. AMP regulation includes systemic responses and local responses, at surface epithelia that contact with the external environments. At pupariation, Drosophila melanogaster increases dramatically the expression of three AMP genes: drosomycin (drs), drosomycin-like 2 (drsl2) and drosomycin-like 5 (drsl5). Using D. melanogaster, we show that the expression of drs at pupariation is dependent on ecdysone signalling in the fat body. This systemic immune response involving drs expression in the fat body operates via the ecdysone downstream target, Broad-Z4. In parallel, ecdysone also regulates local responses, specifically through the activation of drsl2 expression in the gut. Finally, we establish the relevance of this ecdysone dependent AMP expression for the control of bacterial persistence by showing that flies lacking drs expression in the fat body have higher bacterial persistence over metamorphosis. Together, our data establishes a new role for ecdysone during pupariation. We propose that the co-option of immune mechanisms by the hormonal cascade responsible for controlling metamorphosis constitutes a pre-emptive mechanism to control bacterial numbers in the pupa and increase developmental success.

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Physiology of the orexinergic/hypocretinergic system: a revisit in 2012

AJP Cell Physiology ◽

10.1152/ajpcell.00227.2012 ◽

2013 ◽

Vol 304 (1) ◽

pp. C2-C32 ◽

Cited By ~ 89

Author(s):

Jyrki P. Kukkonen

Keyword(s):

Central Nervous System ◽

G Proteins ◽

Cellular Responses ◽

G Protein Coupled Receptors ◽

Heterotrimeric G Proteins ◽

Neuronal Excitation ◽

System A ◽

The Central Nervous System ◽

G Protein Coupled ◽

Systemic Responses

The neuropeptides orexins and their G protein-coupled receptors, OX1and OX2, were discovered in 1998, and since then, their role has been investigated in many functions mediated by the central nervous system, including sleep and wakefulness, appetite/metabolism, stress response, reward/addiction, and analgesia. Orexins also have peripheral actions of less clear physiological significance still. Cellular responses to the orexin receptor activity are highly diverse. The receptors couple to at least three families of heterotrimeric G proteins and other proteins that ultimately regulate entities such as phospholipases and kinases, which impact on neuronal excitation, synaptic plasticity, and cell death. This article is a 10-year update of my previous review on the physiology of the orexinergic/hypocretinergic system. I seek to provide a comprehensive update of orexin physiology that spans from the molecular players in orexin receptor signaling to the systemic responses yet emphasizing the cellular physiological aspects of this system.

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