Maternal morphine exposure during lactation alters hippocampal morphology and Oprm۱ expression in rat offspring: An experimental study

Background: Maternal morphine use during lactation may affect neonatal brain development through drug transfer into breast milk. Objective: To investigate the effects of short-term maternal morphine exposure during lactation on hippocampal morphology and neurodevelopment-related gene expression in rat offspring. Materials and Methods: This experimental study was conducted at Mazandaran University of Medical Sciences, Ramsar Campus, Ramsar, Iran in ۲۰۲۵. Adult lactating Sprague-Dawley rats (۲۱۰-۲۴۰ gr, ۲-۴ months) were randomly assigned to either the control or morphine-treated group. Lactating female rats in the treatment group received morphine sulfate (۱۰ mg/kg, intraperitoneally) on postnatal days ۴ and ۵, whereas control animals received normal saline. On postnatal day ۱۲, hippocampal tissues from their offspring (n = ۶/group) were collected for histological, immunohistochemical, and quantitative reverse transcription polymerase chain reaction analyses. Immunohistochemical assessment included glial fibrillary acidic protein, S۱۰۰ calcium-binding protein, and synaptophysin. Gene expression levels of neuronal differentiation-۱, synaptophysin, neurexin-۱, and opioid receptor Mu ۱ were quantified using the ΔΔCt-۲ method. Results: Histological examination revealed qualitative evidence of neuronal degeneration and inflammatory cell accumulation in the hippocampus of morphine-exposed offspring. Analysis demonstrated reduced immunoreactivity for glial fibrillary acidic protein, S۱۰۰, and synaptophysin immunoreactivity compared with controls. Gene expression analysis showed a significant reduction in Oprm۱ expression (p = ۰.۰۱۷۶). Although other genes examined exhibited lower mean expression levels in the morphine-exposed group, these differences did not reach statistical significance. Conclusion: Short-term maternal morphine exposure during lactation was associated with hippocampal histopathological alterations and reduced Oprm۱ expression in rat offspring. Further studies are needed to confirm these findings.

کلیدواژه ها:

Breastfeeding ، Morphine ، Neurodevelopment ، Oprm۱ ، Gene expression. ، شیردهی ، مورفین ، تکاملح عصبی ، Oprm۱ ، بیان ژن.