Prenatal morphine exposure reduces pyramidal neurons in CA۱, CA۲ and CA۳ subfields of mice hippocampus

Objective(s):This study was carried out to evaluate the effect of maternal morphine exposure during gestational and lactation period on pyramidal neurons of hippocampus in ۱۸ and ۳۲ day mice offspring. Materials and Methods: Thirty female mice were randomly allocated into cases and controls. In case group, animals received morphinesulfate ۱۰ mg/kg.body weight intraperitoneally during ۷ days before mating, gestational period (GD ۰-۲۱), ۱۸ and ۳۲ days after delivery in the experimental groups. The control animals received an equivalent volume of normal saline. Cerebrum of six offsprings in each group was removed and stained with cresyl violet and a monoclonal antibody NeuN for immunohistochemical detection of surviving pyramidal neurons. Quantitative computer-assisted morphometric study was done on hippocampus. Results: The number of pyramidal neurons in CA۱, CA۲ and CA۳ in treated groups was significantly reduced in postnatal day ۱۸ and ۳۲ (P۱۸, P۳۲) compared to control groups (P<۰.۰۵). The mean thickness of the stratum pyramidal layer was decreased in the treated groups in comparison with controls (P<۰.۰۵), whereas the mean thickness of the stratum oriens, stratum radiatum and stratum lacunosum-moleculare in CA۱ field and stratum oriens, stratum lucidum, stratum radiatum and stratum lacunosum-moleculare in CA۳ were significantly increased in morphine treated group in comparison with controls (P<۰.۰۵). Conclusion: Morphine administration before and during pregnancy and during lactation period causes pyramidal neurons loss in ۱۸ and ۳۲ days old infant mice. 

Keywords:

CA۱ , CA۲ , CA۳ , Hippocampus , Morphine sulfate , Mouse , Pyramidal cells