Evaluation of Memory Impairment Following Prenatal Exposure to Mosquito Coil Smoke

Abstract

Background: Developmental Neurotoxicity can lead to the buildup of reactive oxygen species which is an indicator to oxidative stress in the prenatally exposed offspring. Neuronal oxidative stress induces neuroinflammation, precedes tangle formation, and disrupts synaptic plasticity. The result of such changes may be expressed into adulthood as behavioral deficits. All together, these mechanisms are implicated in memory disorders. Objectives: To investigate the histochemical changes in the hippocampus and entorhinal cortex of Wistar rats' offspring after prenatal exposure to mosquito coil smoke and its effect on memory. . Methods: 12 pregnant Wistar rats were grouped into four, 3 animals per group. Group I was exposed to fresh air. Groups II, III, and IV were exposed to mosquito coil smoke for 4, 6 and 8 hours daily respectively throughout gestation period. On Post-natal day (PND) 28 and 29, shortterm spatial and recognition memory of adolescent wistar rats were assessed using water licking task and novel object recognition test respectively. For each animal group (I-IV), a total of 8 animals were randomly selected from the litters for neurobehavioral studies. Experimental animals were humanely sacrificed and sections from the hippocampus and entorhinal cortex were processed for histochemical studies using Bielschowsky stain. Data were presented as mean ± SEM; analysed using One-way analysis of variance and Tukey's Multiple Comparison Test (p<0.05). Results and Conclusion: Our results showed significant impairment in short-term recognition and spatial memory of group III and IV adolescent wistar rats when compared with the control (p<0.05) and the formation of neurofibrillary tangle-like structures in neurons of the studied regions. .