Open AccessSubstance P NK 1 receptor in the rat corpus callosum during postnatal development
Author(s) -
Barbaresi Paolo,
Mensà Emanuela,
Bastioli Guendalina,
Amoroso Salvatore
Publication year - 2017
Publication title -
brain and behavior
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 41
ISSN - 2162-3279
DOI - 10.1002/brb3.713
Subject(s) - corpus callosum , substance p , immunocytochemistry , receptor , population , biology , tachykinin receptor 1 , anatomy , medicine , endocrinology , neuropeptide , environmental health
The expression of substance P ( SP ) receptor (neurokinin 1, NK 1) was studied in the rat corpus callosum (cc) from postnatal day 0 (the first 24 hr from birth, P0) to P30. Methods We used immunocytochemistry to study the presence of intracallosal NK 1‐immunopositive neurons ( NK 1 IP ‐n ) during cc development. Results NK 1 IP ‐n first appeared on P5. Their number increased significantly between P5 and P10, it remained almost constant between P10 and P15, then declined slightly until P30. The size of intracallosal NK 1 IP ‐n increased constantly from P5 (102.3 μm 2 ) to P30 (262.07 μm 2 ). From P5 onward, their distribution pattern was adult‐like, that is, they were more numerous in the lateral and intermediate parts of the cc, and declined to few or none approaching the midline. At P5, intracallosal NK 1 IP ‐n had a predominantly round cell bodies with primary dendrites of different thickness from which originated thinner secondary branches. Between P10 and P15, dendrites were longer and more thickly branched, and displayed several varicosities as well as short, thin appendages. Between P20 and P30, NK 1 IP ‐n were qualitatively indistinguishable from those of adult animals and could be classified as bipolar (fusiform and rectangular), round–polygonal, and pyramidal (triangular–pyriform). Conclusions Number of NK 1 IP ‐n increase between P5 and P10, then declines, but unlike other intracallosal neurons, NK 1 IP ‐n make up a significant population in the adult cc. These findings suggest that NK 1 IP ‐n may be involved in the myelination of callosal axons, could play an important role in their pathfinding. Since they are also found in adult rat cc, it is likely that their role changes during lifetime.