Effect of recombinant insulin-like growth factor 2 (igf-ii) injected into the hippocampus on memory impairment and igf-ii gene expression following hippocampal intracerebral hemorrhage in rats

Mahsa Abedi,1,* Farzaneh vafaee,2 Asadollah zarifkar,3 Masoumeh emamghoreishi,4 Mohammad reza namavar,5

1. Tehran medical sciences, Islamic azad University, Tehran, Iran
2. Department of Neuroscience, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences
3. Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
4. Department of Pharmacology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
5. Department of Anatomical Sciences, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran

Abstract

Introduction

Insulin-like growth factor 2 (igf-ii) is a growth factor and an anti-inflammatory cytokine that has also pivotal activity on memory. the aim of this study was to investigate the effect of recombinant igf-ii on memory impairment due to intracerebral hemorrhage (ich). hence, avoidance and investigation memory, locomotor activity, neurological deficit score and the level of igf-ii gene expression were evaluated.

Methods

To induce ich, 100 μl of autologous blood was injected into the left hippocampus of male sprague-dawley rats. recombinant igf-ii was injected into damaged hippocampus 30 min after induction of ich. then, over two weeks, the neurological deficit score (nds) and locomotor activity and also passive avoidance and novel object recognition test (nor) were evaluated. finally, the level of igf-ii gene expression evaluated by rt-pcr technique.

Results

Our results indicated that recombinant igf-ii injection significantly increased step-through latency (stl) (p<0.001) and total time spent in dark box (p<0.01), but no significant difference was seen with novel object exploration time and neurological deficit score. locomotor activity did not significantly change in any group. the level of igf-ii gene expression following igf-ii injection significantly reduced (p<0.05).

Conclusion

The results of this study show that recombinant igf-ii injection can improve avoidance memory but not investigation memory. igf-ii was not effective on locomotor activity. it seems that the reduction of the level of igf-ii gene expression is not related with memory improvement.

Keywords

Intracerebral hemorrhage; igf-ii; learning and memory; hippocampus; rats