An Evaluation of the Effect of Deprivation of Maternal Care on LTP Induction in Neurons of Hippocampal CA1 Region in Morphine-Dependent Rats

Abstract

BACKGROUND AND OBJECTIVE: Deprivation of maternal care as a stressor causes disruption in cognitive and neurochemical activities of the brain. The aim of this study was to evaluation the effect of deprivation of maternal care on LTP induction in neurons of hippocampal CA1 region in morphine-dependent rats. METHODS: This experimental study was conducted among 40 45-day-old male rats in control group, morphine-dependent group, and 3 groups of rats that were deprived of treatment for one, two and three weeks after birth for 3 hours daily. Except for the control group, the rest of the groups received 10 mg/kg body weight morphine sulfate subcutaneously every 12 hours for 10 days. On the eleventh day, the symptoms of deprivation syndrome were investigated by the Gellert-Holtzman method, and on the following day, the synaptic plasticity of neurons in CA1 region was studied. FINDINGS: The Gellert-Holtzman score in the morphine-dependent group was 14.98±4.16 and increased to 31.79±5.12 in the group that was deprived of maternal treatment for 3 weeks (p<0.001). Although morphine dependence did not affect basic responses of CA1 region neurons and LTP induction, deprivation of maternal care reduced the range of basic responses from 1.01±0.04 in the morphine-dependent group to 0.68±0.09 mV in the group that was deprived of maternal care for 3 weeks (p<0.001) and prevented LTP induction (p<0.001) in a time-dependent manner. CONCLUSION: The results of the study showed that deprivation of maternal care undermines the postsynaptic potential of the hippocampal CA1 region following morphine administration and disrupts the synaptic plasticity of the neurons in this region.

Keywords

• Morphine
• Maternal separation
• Long-term potentiation
• Hippocampus
• Rat