An autophagic mechanism is involved in apoptotic death of rat striatal neurons induced by the non-N-methyl-D-aspartate receptor agonist kainic acid.
Previous studies found that kainic acid (KA)-induced apoptosis involved the lysosomal enzyme cathepsin B, suggesting a possible mechanism of autophagy in excitotoxicity. The present study was sought to investigate activation and contribution of autophagy to excitotoxic neuronal injury mediated by KA receptors. The formation of autophagosomes was observed with transmission electron microscope after excitotoxin exposure. The contribution of autophagic mechanisms to KA-induced upregulation of microtubule-associated protein 1A/1B light chain 3 (LC3), lysosome- associated membrane protein 2 (LAMP2) and cathepsin B, release of cytochrome c, activation of caspase-3, down-regulation of Bcl-2, upregulation of Bax, p53, puma and apoptotic death of striatal neurons were assessed with co-administration of the autophagy inhibitor 3-methyladenine (3-MA). These studies showed that KA brought about an increase in the formation of autophagosomes and autolysosomes in the cytoplasm of striatal cells. KA-induced increases in the ratio of LC3-II/LC3-I, LAMP2, cathepsin B, release of cytochrome c and activation of caspase-3 were blocked by pre-treatment with 3-MA. 3-MA also reversed KA-induced down-regulation of Bcl-2 and upregulation of Bax protein levels, LC3, p53 and puma mRNA levels in the striatum. KA-induced internucleosomal DNA fragmentation and loss of striatal neurons were robustly inhibited by 3-MA. These results suggest that over-stimulation of KA receptors can activate autophagy. The autophagic mechanism participates in programmed cell death through regulating the mitochondria-mediated apoptotic pathway.
Wang
Yan
Y
Department of Pharmacology and Laboratory of Aging and Nervous Diseases (SZS0703), Soochow University School of Medicine, Suzhou, China.
Han
Rong
R
Liang
Zhong-Qin
ZQ
Wu
Jun-Chao
JC
Zhang
Xing-Ding
XD
Gu
Zhen-Lun
ZL
Qin
Zheng-Hong
ZH
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001343:Autophagy / Q000502:physiology*; D003342:Corpus Striatum / Q000187:drug effects* / Q000502:physiology; D053938:DNA Fragmentation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D007608:Kainic Acid / Q000494:pharmacology*; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors / Q000819:agonists*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists
D000225:Adenine; D007608:Kainic Acid; D052119:Lysosomal-Associated Membrane Protein 2; D008869:Microtubule-Associated Proteins; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; C526109:Anxa3 protein, rat; C025946:3-methyladenine