Regional, cellular and subcellular distribution of sst2A receptor immunoreactivity on coronal sections of the rat telencephalon at E16 and E18.

<p>A,B) Intense sst2A receptor immunoreactivity is detected at E16 in the post-mitotic areas of the lateral ganglionic eminence (LGE) and the caudal ganglionic eminence (CGE) (B). Note the presence of sst2A receptor immunoreactivity in the cortex (cx) and hippocampus (hi). C represents magnification of boxed area in B and illustrates that the sst2A receptor immunoreactivity is found in cell bodies and short processes in the CGE. D,E) Pre-embedding immunogold immunohistochemistry of the sst2A receptor in the CGE illustrates that high density of immunoparticles are localized intracellularly. However, sst2A receptor-immunoreactive particles are also found in association with the plasma membrane (arrowheads in D). Note that in a neuronal process the majority of the immunoparticles are membrane-associated (arrowheads in E). F represents magnification of the boxed area in A. Numerous cells are immunoreactive for sst2A in the LGE. G represents high magnification of the area labeled with an arrow on A and illustrates that fibers are also sst2A receptor-immunolabeled. H,I) High magnification confocal microscopic analysis in the CGE demonstrates redistribution of receptors upon agonist stimulation. In control conditions, sst2A receptor immunoreactivity outlines the periphery of cells (H). Forty minutes after agonist administration, receptor immunoreactivity is confined to small puncta in the cytoplasm (I). J,K) At E18, intense sst2A receptor immunoreactivity is observed in the dorso-medial part of the caudate-putamen in rostral (J) and caudal (K) sections close to the ventricular surface. Scattered sst2A receptor immunoreactivity is also evident in the medial part of the developing caudate-putamen (asterisk). L represents magnification of boxed area on J. The sst2A receptor immunoreactivity is observed in large number of cells and their short processes in the dorsal caudate-putamen. Note the lack of sst2A receptor immunoreactivity in the subventricular zone (SVZ). M,N are high magnifications from the area labeled with asterisk on J. The sst2A receptor is expressed in neuronal perikarya and processes in the medial part of the caudate-putamen. Scale bars: A, B, 200 µm; C, F, G, L, 20 µm; D, 500 nm; E, 250 nm; H, I, M, N, 10 µm; J, K, 500 µm.