Protective Effects of Melatonin on Prenatal Restraint Stress-Induced Memory Impairment in Offspring Rats

Pregnant women experience different type of stresses which affect the fetus brain physiological processes like memory. Therefore, it is attractive to find the protective agents that are safe in the pregnancy and neutralize the stress induced manifestations. The aim of current study was to investigate the protective effects of melatonin on memory impairment induced by prenatal restraint stress in offspring rats.

In this experimental study, pregnant rats were randomly assigned to control, restraint stress group and four melatonin treated groups that received 3, 5, 10, and 50 mg/kg of melatonin concomitant with restraint stress. Restraint stress daily induced from 10th to 21st day of pregnancy. Melatonin was daily injected intraperitoneally before the restraint stress. One month after the birth, the memory of offspring was evaluated by measurement of "Discrimination" and "Recognition" indices using Object Recognition Task.

From the data, administration of 3 or 5 mg/kg melatonin did not show significant differences in Discrimination and Recognition indices compared to restraint stress group while injection of 10 or 50 mg/kg of melatonin significantly increased the above indices (P <0.001). There is no significant difference in indices values for 10 or 50 mg/kg of melatonin.

The findings showed that prenatal restraint stress induced memory impairment in one month offspring rats. Administration of melatonin in high doses actively prevent restraint stress induced memory impairment.