Functional remodeling of gap junction-mediated electrical communication between adrenal chromaffin cells in stressed rats.
An increase in circulating catecholamine levels represents one of the mechanisms whereby organisms cope with stress. In the periphery, catecholamines mainly originate from the sympathoadrenal system. As we reported, in addition to the central control through cholinergic innervation, a local gap junction-delineated route between adrenal chromaffin cells contributes to catecholamine exocytosis. Here, we investigated whether this intercellular communication is modified when the hormonal demand is increased as observed during cold stress. Our results show that in cold exposed rats, gap-junctional communication undergoes a functional plasticity, as evidenced by an increased number of dye-coupled cells. Of a physiological interest is that this upregulation of gap-junctional coupling results in the appearance of a robust electrical coupling between chromaffin cells that allows the transmission of action potentials between coupled cells. This enhancement of gap-junctional communication parallels an increase in expression levels of connexin36 (Cx36) and connexin43 (Cx43) proteins. Both transcriptional and posttranslational mechanisms are involved because Cx36 transcripts are increased in stressed rats and the expression of the scaffolding protein zonula occludens-1, known to interact with both Cx36 and Cx43, is also upregulated. Consistent with an upregulated coupling extent in stressed rats, the cytosolic Ca(2+) concentration rises triggered in a single cell by an iontophoretic application of nicotine occur simultaneously in several neighboring cells. These results describe for the first time a functional plasticity of junctional coupling between adult chromaffin cells that should be crucial for adaptation to stress or sensitization to subsequent stressors.
Colomer
Claude
C
Institute of Functional Genomics, 34094 Montpellier, France.
Olivos Ore
Luis A
LA
Coutry
Nathalie
N
Mathieu
Marie-Noëlle
MN
Arthaud
Sébastien
S
Fontanaud
Pierre
P
Iankova
Irena
I
Macari
Françoise
F
Thouënnon
Erwan
E
Yon
Laurent
L
Anouar
Youssef
Y
Guérineau
Nathalie C
NC
D000200:Action Potentials / Q000502:physiology; D000313:Adrenal Medulla / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D002395:Catecholamines / Q000378:metabolism*; D002450:Cell Communication / Q000502:physiology*; D019439:Chromaffin Cells / Q000378:metabolism* / Q000648:ultrastructure; D003080:Cold Temperature / Q000009:adverse effects; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000378:metabolism* / Q000503:physiopathology; D015854:Up-Regulation / Q000502:physiology; D062826:Zonula Occludens-1 Protein; D000097004:Gap Junction delta-2 Protein
D002118:Calcium; D002395:Catecholamines; D018031:Connexin 43; D017630:Connexins; D008565:Membrane Proteins; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; D000097004:Gap Junction delta-2 Protein; C569044:Tjp1 protein, rat