The neostriatal mosaic: basis for the changing distribution of neurokinin-1 receptor immunoreactivity during...

The pattern of neurokinin-1 receptor-like immunoreactivity (NK-1Rir) was mapped in perinatal and adult mouse striatum by using a new polyclonal antiserum. NK-1Rir was detected in the differentiating regions of the ganglionic eminences on embryonic day 12.5 (E12.5). NK-1Rir structures were enriched in the striatal patch compartment between E16.5 and approximately postnatal day 3 (P3); distributed more uniformly, within portions of both the patch and matrix compartments on P7; and enriched in the matrix compartment in the adult. Analysis of the phenotype of NK-1Rir cells on P2, P7, and in the adult suggested that cholinergic cells accounted for the majority of NK-1Rir cells early postnatally, with increasing contributions from somatostatinergic cells later postnatally. In the adult, approximately half of NK-1Rir cells were cholinergic and half were somatostatinergic. The transient enrichment of NK-1R-bearing cells and processes in the patch compartment which contains cells that express substance P (SP), a putative ligand for the NK-1R, may be a consequence of compartment formation or may be functionally important for compartment development.