The Effect of Maternal Morphine Addiction on Neural Plasticity of Fetal Brain in Wistar Rats

Prenatal exposure to morphine has long-lasting effects on synaptic plasticity. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival and growth, serves as a neurotransmitter modulator, and participates in neuronal plasticity, which is essential for cognition, learning and memory. Extracellular signal-regulated kinase (ERK) is one of the important downstream proteins of BDNF- tropomycin receptor kinase B (TrkB) signaling. Exact effect of opioids on ERK expression in the neuronal cells is still unclear. The aim of this study was to evaluate the effect of prenatal morphine exposure on BDNF and ERK protein levels in the rat fetal brain.

Pregnant rats (n=8) received increasing daily doses of morphine (0.1-0.4 mg/kg) in their drinking water. The brains of fetuses from both morphine-addicted and controls mothers were isolated at day 19 of gestation, and the levels of BDNF and p-ERK were measured using Western-blotting assay. The data presented as Mean±‌SEM and statistical analysis was performed by Unpaired T-test to compare between two groups.

Our data revealed that the level of BDNF and p-ERK significantly decreased in the fetus’s brain of morphine addicted mothers comparing to control group.

Chronic exposure to morphine prenatally, could affect and diminish structural plasticity in the developing rat brain. It is probable that morphine exert this effect by reduction of BDNF level that consequently attenuate ERK phosphorylation.