[Effect of IGF-1 on long-term anxiety-like behavior in rats after hypoxic-ischemic brain damage]
Qin Tang1, Fu-Rong Liu, Ya-Li Luo
1Department of Pediatrics, Third Xiangya Hospital of Central South University, Changsha 410013, China. heiming_yan@aliyun.com.
Objective:
To observe the changes in anxiety-like behavior among rats in the recovery stage after hypoxic-ischemic brain damage (HIBD) during the perinatal period and to investigate the effect of insulin-like growth factor 1 (IGF-1) on the long-term anxiety-like behavior and its action mechanism among rats with HIBD.
Methods:
Ninety neonatal rats (7 days old) were randomly and equally divided into normal control, HIBD, and HIBD+IGF-1 groups. A neonatal rat model of HIBD was established by Rice method in the HIBD and HIBD+IGF-1 groups. The rats in the HIBD+IGF-1 group were intraperitoneally injected with IGF-1 (0.2 mg/kg) immediately after HIBD, and the other two groups were intraperitoneally injected with an equal volume of normal saline. The anxiety-like behavior was evaluated by elevated plus-maze test on postnatal days 21 and 28. The expression of tyrosine hydroxylase (TH) in the substantia nigra was measured by immunohistochemistry on postnatal days 14, 21, and 28.
Results:
On postnatal days 21 and 28, the open-arm time (OAT) and percentage of OAT for the HIBD and HIBD+IGF-1 groups were significantly lower than those for the normal control group (P<0.05), but there were no significant differences between the HIBD and HIBD+IGF-1 groups (P>0.05); the percentage of open arm entry showed no significant difference between the three groups (P>0.05). On postnatal day 14, there were no significant differences in percentage of TH immunostaining-positive area between the three groups (P>0.05). On postnatal days 21 and 28, the HIBD and HIBD+IGF-1 groups had significantly lower percentages of TH immunostaining-positive area than the normal control group (P<0.05), but there was no significant difference between the HIBD and HIBD+IGF-1 groups (P>0.05).
Conclusions:
HIBD in the perinatal period may cause the changes in anxiety-like behavior in adolescent rats, which may be related to decreased expression of TH in the substantia nigra. Neonatally given IGF-1 cannot improve the long-term anxiety-like behavior in rats after HIBD, and it does not affect TH expression in the substantia nigra. IGF-1 may not regulate the changes in long-term anxiety-like behavior in adolescent rats.
