Morphine Exposure and Enhanced Depression-like Behaviour Confronting Chronic Stress in Adult Male Offspring Rat

Opioid addiction is an important concern in the World. Reports demonstrate that substance use disorder could influence genetic and environmental factors, and children of addicts have a higher rate of psychopathology. In this study, we investigated depression-like behavior among offspring of morphine-exposed rat parents. 

Adult male and female Wistar rats received morphine for 21 consecutive days and then let them were free of drugs for ten days. Offspring of these rats were divided into three distinct groups: maternal morphine-exposed, paternal morphine-exposed, and both maternal and paternal morphine-exposed. We used sucrose preference and Forced Swim Test (FST) to measure depression-like behavior. Also, we induced chronic mild stress using repeated corticosterone injection and evaluated depression-like behavior in offspring of morphine-exposed parents compared with offspring of healthy ones. 

Results indicated that depression-like behaviors in the offspring of morphine-exposed rats were higher than those in the offspring of the control group in confronting with chronic mild stress. Additionally, mild chronic stress can produce an exaggerated effect on depression-like behavior in offspring of the morphine-exposed parent(s) compared with those of the control group. 

Our data support the previous hypothesis that the depression rate is higher in the children of addicts. We verified that even when mother or father was clean of opioid in the time of gestation, their children would be susceptible to depression. Dysregulation of hypothalamic-pituitary-adrenal axis and changing in neuronal features in the hippocampus increased depression-like behavior in the offspring of morphine-exposure parents.