Changes in P2X3 purinoceptors in sensory ganglia of the mouse during embryonic and postnatal development

The expression of the P2X(3) nucleotide receptor in embryonic day 14-18, postnatal day 1-14 and adult mouse sensory ganglia was examined using immunohistochemistry. Nearly all sensory neurons in dorsal root ganglia, trigeminal ganglia and nodose ganglia in embryos at embryonic day 14 expressed P2X(3) receptors, but after birth there was a gradual decline to about 50% of neurons showing positive immunostaining for P2X(3). In embryos there were only small neurons, while from postnatal day 7 both large and small neurons were present. Isolectin B-4 (IB4)-positive neurons in dorsal, trigeminal and nodose ganglia did not appear until birth, but the numbers increased to about 50% by postnatal day 14 when a high proportion of IB4-positive neurons were also positively labelled for the P2X(3) receptor. About 10% of neurons in dorsal, trigeminal and nodose ganglia were positive for calcitonin gene-related peptide in embryos, nearly all of which stained for P2X(3) receptors. This increased postnatally to about 35-40% in adults, although only a few colocalised with P2X(3) receptors. Neurofilament 200 was expressed in about 50% of neurons in trigeminal ganglia in the embryo, and this level persisted postnatally. All neurofilament 200-positive neurons stained for P2X(3) in embryonic dorsal root ganglia, trigeminal ganglia and nodose ganglia, but by adulthood this was significantly reduced. The neurons that were positive for calbindin in embryonic dorsal, trigeminal and nodose ganglia showed colocalisation with P2X(3) receptors, but few showed colocalisation postnatally.