Expression of delta- and mu-opioid receptors in the ventricular and subventricular zones of the developing human neocortex.
Recent research has documented the involvement of the endogenous opioid system in neural development, including neurogenesis and neuronal differentiation. However, the expression of opioid receptors (ORs) in different cell types of the human ventricular and subventricular zones (VZ and SVZ) has not been studied during early gestation. In the present study, we have used immunohistochemistry and quantified the results to demonstrate that the levels of delta- and mu-OR subtypes were high in the VZ and SVZ between 11 and 16 gestation weeks (GW) and decreased by 20GW. These results have also been confirmed by studying OR mRNA expression in the VZ and SVZ. Both delta- and mu-OR subtypes were expressed by multipotential stem cells, newly differentiated neurons and developing glial cells to different extents. However, migrating neurons expressed negligible levels of both OR subtypes. Our results suggest that the opioid system may affect cellular proliferation and/or differentiation of stem cells into neurons and glia during the first and second trimesters of gestation in humans. Since layers II and III of the cerebral cortex are being formed during the second trimester, their development is most likely affected by the opioid system mediated through delta- and mu-ORs.
Tripathi
Anushree
A
National Brain Research Centre, Deemed University, NH-8, Manesar, Gurgaon, Haryana 122050, India.
Khurshid
Nazia
N
Kumar
Praveen
P
Iyengar
Soumya
S
D000367:Age Factors; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002552:Cerebral Ventricles / Q000196:embryology / Q000378:metabolism*; D005333:Fetus; D015870:Gene Expression / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D019579:Neocortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D011180:Postmortem Changes; D012333:RNA, Messenger / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000235:genetics / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000502:physiology
D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu