Expression And Localization Of P2X₃ And CGRP Receptor At The Different Stages Of Human Embryonic DRG

Objective:To observe space-time expression of P2X3 and CGRP receptors in human embryonic dorsal root ganglion (DRG), and explore significance of P2X3 and CGRP in development of nervous system.Methods:12 human embryos were collected 30 min after death, divided into 4 month,5 month,6 month,7 month and 8 month 5 groups. Dorsal root ganglions in lumbar 4 segments were separated and were fixed by 4% paraformaldehyde in 0.1 mol phosphate buffer(pH7.4). The dorsal root ganglions'tissues were dehydrated, transparent, inbedded paraffin and sectioned at 4μm thickness. Nissl's staining and immunohistochemistry methods were applied to detect expression and distribution of P2X3 and CGRP receptors in DRG of human embryo at 4th-8th month. To compare variability between groups with One-Way ANOVA of SPSS 13.0 statistics software.Results:Nissl's body was observed in cytoplasm of neurons of DRG at the different stages human embryos by nissl's staining methods. Cellular shape and size were normal. Neurons gradually increased with embryonic age increasing.In DRG, P2X3 receptor immunoreactive produces were found predominantly in cytoplasm and membrane of neurons. The P2X3 receptor is expressed in a homogeneous pattern in almost all DRG neurons, negative staining in nucleus. P2X3 receptor expression is gradually and significantly reduced in DRG with embryonic age growth and statistical differences exist between adjacent embryonic age groups (P<0.01).In DRG, Calcitonin gene-related peptide (CGRP) receptor immuneo-reactive produces were found predominantly in cytoplasm and membrane of neurons. CGRP receptor is expressed in a homogeneous pattern in DRG neurons, negative staining in nucleus. But CGRP immunoreactivity was weak in DRG of human embryos, the number of DRG neurons expressing the CGRP significantly increased with embryonic age growth, and statistical differences exist between adjacent embryonic age groups (P<0.01).Conclusion:The expression and distribution of P2X3 and CGRP receptors regularly changed with changes of embryonic ages in DRG. The P2X3 receptor expression is largely restricted to small- and medium-diameter neurons. The number of positive cells gradually and significant-ly decreased with embryonic age increasing. The CGRP receptor expression is largely restricted to small-diameter neurons. The number of positive expression cells gradually and significantly increased with embryonic age increasing. This data may serve as a spring-board for further study of the role of P2X3 and CGRP receptors during development and conduction of nociceptive stimulus of neurons.