Morphologically distinct subpopulations of neurotensin-immunoreactive striatal neurons observed in rat following dopamine depletions and D2 receptor blockade project to the globus pallidus

Single-cell RT-PCR, in situ hybridization histochemical, and immunohistochemical studies of substance P and enkephalin co-occurrence in striatal projection neurons in rats

“…In particular, consistent with ISHH and immunolabeling data (Gerfen and Young, 1988;Anderson and Reiner, 1990;Augood et al, 1997;Lee et al, 1997), we found that many SP+ striatal neurons constitutively expressed DYN, but ENK neurons did not. Moreover, consistent with a number of immunolabeling and ISHH studies, which show a high percentage of ENK+ striatal neurons to constitutively express NT (Sugimoto and Mizuno, 1987;Brog and Zahm, 1996;Augood et al, 1997), we found many ENK neurons but no SP neurons expressed NT. Since many SP/ENK neurons expressed DYN but only a small fraction expressed NT, our data suggest the majority of SP/ENK neurons to resemble SP-only neurons.…”

“…Finally, while our results indicate ENK-only neurons projecting to GPe and SP-only neurons projecting to GPi, SNr and/or SNc to be the main types of striatal projection neurons in rats, there is clearly diversity among SP-only neurons in terms of their primary and collateral projections to GPi, SNr and/or SNc. In addition, further diversity based on the constitutive or induced expression of neuropeptides such as neurotensin or the tachykinin neurokinin B is also possible (Burgunder and Young, 1989;Marksteiner et al, 1992;Castel et al, 1993aCastel et al, , 1993bBrog and Zahm, 1996;Adams et al, 2001). Finally, although SP/ENK striatal neurons may be infrequent in rodents, this does not rule out the possibility they are more common in other species, for example primates, in which considerable overlap of SP+ and ENK+ fibers occurs in the ventral tegmental area, SNc and medial SNr .…”

Neurotensin-deficient mice show altered responses to antipsychotic drugs

“…This suggestion is consistent with several studies that have reported that D 2 antagonists and other treatments that disrupt dopaminergic function result in the appearance of at least two distinct populations of NT neurons (38)(39)(40)(41)(42). One of these groups of NT cells is concentrated in the matrix compartment of the dorsomedial and ventrolateral striata; these cells rarely express Fos (38,42).…”

“…One of these groups of NT cells is concentrated in the matrix compartment of the dorsomedial and ventrolateral striata; these cells rarely express Fos (38,42). Another population of NT neurons located in the dorsolateral striatum that becomes apparent after haloperidol treatment projects to the globus pallidus almost exclusively (42), and most of that population expresses Fos (38,43). We suggest that the reduction in Fos-like immunoreactive neurons observed in the dorsolateral and central striata of NT Ϫ/Ϫ mice reflects the involvement of the latter population of striatopallidal neurons.…”

Distinct and interactive effects of d-amphetamine and haloperidol on levels of neurotensin and its mRNA in subterritories in the dorsal and ventral striatum of the rat

“…Scale bar ϭ 1mm. D 2-like receptor blockade in the striatopallidal projections of the ''indirect'' pathway, which express predominantly the dopamine D 2-like receptor (e.g., Le Moine et al, 1990;Robertson et al, 1992;Brog et al, 1996;Augood et al, 1997). Consequently, the numbers of neurons in which increased neurotensin expression is elicited by co-administration of D 1-like receptor agonist and D 2-like receptor antagonist might be expected in any given subterritory to approximate the sum of that observed for each of the two drugs administered independently.…”