Gap junction blockage limits intercellular spreading of astrocytic apoptosis induced by metabolic depression.
Astrocytes are highly coupled by gap junction channels, which allow transfer of intracellular signalling molecules and metabolites between connected cells. Astrocytic gap junctions remain open during ischemic conditions as previously demonstrated in vitro and in situ. In this study, we investigated the effect of gap junction blockage on iodoacetate-induced ATP depression and cell death progression in astrocytes in primary rat hippocampal cultures. We demonstrated that blockage of gap junctions during iodoacetate-induced inhibition of the glycolysis induced an earlier onset of the ATP depression. Moreover, initiation of apoptotic processes, demonstrated by binding of Annexin V, was critically dependent on the ATP levels. The apoptotic event was also shown to spread and involve neighbouring cells, a process that was inhibited by blockage of gap junction communication. Chelating intracellular calcium using BAPTA-AM decelerated the iodoacetate-induced ATP depression. The chelation also decelerated the spreading of apoptotic processes. Inhibition of caspases did not alter the expansion of cell groups being Annexin V positive. However, the proportion of Annexin V positive cells also being propidium iodide positive was increased after caspase inhibition. The results show that inhibition of gap junctions during cellular metabolic depression interferes with the metabolic status and cell death progression in astrocytes.
Nodin
Christina
C
Arvid Carlsson Institute for Neuroscience at the Institute of Clinical Neuroscience, Göteborg University, Sweden.
Nilsson
Michael
M
Blomstrand
Fredrik
F
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D017629:Gap Junctions / Q000502:physiology*; D006019:Glycolysis / Q000187:drug effects; D006624:Hippocampus / Q000166:cytology; D007425:Intracellular Membranes / Q000378:metabolism / Q000502:physiology*; D007461:Iodoacetates / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000590:Amino Acid Chloromethyl Ketones; D017304:Annexin A5; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D007461:Iodoacetates; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D002118:Calcium