| Objective: To discuss the effects of melatonin on behavioral development and cerebral glucocorticoid receptors in rats that experienced neonatal maternal separation.Method: Rat pups were randomly divided into maternal separation with melatonin group (MT group), maternal separation with NS group (MS group) and the control group. Rat pups were separated from their mothers and socially isolated from postnatal (P) 24h to P14d. Melatonin (10 mg·kg-1, i.p.) were given to them for 14 days from P7d to P20d. On P28d to P29d, the learning ability and memory of rats were assessed by water maze test and the sensorimotor integration outcome was evaluated by suspension test. The sections of hippocampus and cerebral cortex of rats were obtained on P30d, then detected the expression of glucocorticoid receptors (GR) in hippocampus and cerebral cortex by immunohistochemical staining and reverse transcriptase polymerase chain reaction (RT-PCR).Results: (1) Compared with the control group [(8.87±1.46) times], rats in the MS group [(13.3±3.7) times] needed significantly more times in leaning to get to the security area in the water maze test and sustained less time in the suspension test (P <0.05). These behavioral changes could be reversed after exogenous MT treatment. (2) Compared with the control group, the expression of glucocorticoid receptor was significantly decreased in the hippocampus and cerebral cortex in the MS group (P <0.05). These changes could also be reversed with exogenous melatonin administration.Conclusion: Our studies suggest that the function of HPA axis may involve that maternal separation early in life led to abnormal behavior development. While melatonin administration can reduce the affinity of glucocorticoid receptor in rat brain, and increased the expression of GR gene in hippocampus and cerebral cortex of the rat brain, exogenous MT play a role in preventing poor effects on behavioral development by high GC concentration.
|
PDF Full Text Request