Effects of intermedin on autophagy in cerebral ischemia/reperfusion injury

Abstract

Objective: This study aimed to evaluate the effects of intermedin (IMD) on autophagy in cerebral ischemia/reperfusion (I/R) injury (CIRI).

Methods: Sixty rats were randomly averaged into four groups: sham, ischemia/reperfusion (I/R), IMD, and 3-methyladenine (3-MA). In the sham group, the right common carotid artery, external carotid artery, and internal carotid artery were detached, and no monofilament was inserted. In the other groups, two hours after cerebral ischemia, the rats were injected through the lateral ventricle with normal saline for I/R group, IMD for the IMD group, and 3-MA for the 3-MA group for 24h. The cerebral injury was assessed by evaluation of neurological function, hematoxylin and eosin (H&E) staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The expressions of autophagy associated proteins, such as microtubule-associated protein 1 light chain 3 (LC3), Beclin1, and sequestosome 1 (P62) were analyzed using immunohistochemistry staining and western blot. Meanwhile, transmission electron microscopy was used to investigate the ultrastructure of the brains.

Results: IMD could reduce neuron cell damage and infarction formation and has a protective effect against CIRI as 3-MA. The levels of LC3II/LC3I and Beclin1 were significantly decreased and the P62 level was significantly higher in the IMD group compared with I/R group, which is similar to the effect of 3-MA on CIRI.

Conclusions: IMD has a similar effect as 3-MA, can reduce pathological neuronal injury and protect the brain against CIRI in rats by attenuating the effects of autophagy. Our findings provide evidence for IMD's protective effects in relation to ischemic cerebrovascular diseases.

Keywords: 3-methyladenine (3-MA); Autophagy; Beclin1; Cerebral ischemia/reperfusion injury (CIRI); Intermedin (IMD); Microtubule-associated protein 1 light chain 3 (LC3).