Subtypes of substance P receptor immunoreactive interneurons in the rat basolateral amygdala

• Published in: Brain research 2003-08, Vol.981 (1), p.41-51
• Main Authors: Levita, Liat, Mania, Irakli, Gordon Rainnie, Donald
• Format: Article
• Language: English
• Subjects: Amygdala - cytology; Animals; Basolateral amygdala; Biological and medical sciences; Calcium-Binding Proteins - metabolism; Cell Count; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Fundamental and applied biological sciences. Psychology; Immunocytochemistry; Immunohistochemistry; Interneuron; Interneurons - cytology; Interneurons - metabolism; Male; Neuropeptide Y - metabolism; Rats; Rats, Sprague-Dawley; Receptors, Neurokinin-1 - classification; Receptors, Neurokinin-1 - metabolism; Somatostatin - metabolism; Substance P receptor; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(03)02870-1

Local injections of the neurotoxin SP-saporin into the basolateral amygdala (BLA) are reported to specifically lesion substance P receptor immunoreactive (SPR-IR) interneurons, and to reduce anxiety related behavior. Hence, this technique might provide a means to study how defined interneuron populations regulate neuronal activity in the BLA. However, what interneuron subgroups in the BLA might be targeted by SP-saporin lesions has not been established. This study has used dual-labeling immunofluorescence in the rat BLA to examine SPR-IR neurons for their colocalization with the calcium-binding proteins; calbindin-D28k (CB), parvalbumin (PV), and calretinin (CR); and the neuropeptides somatostatin (SOM) and neuropeptide Y (NPY). We found that all NPY-IR neurons and 45% of SOM-IR interneurons expressed SPR-IR, and that 50% and 51% of the SPR-IR interneuron population expressed NPY- and SOM-IR, respectively. Previous studies have reported that approximately a third of SOM-IR interneurons also express NPY, which suggests a large degree of overlap between the NPY, SOM and SPR expressing neurons in the BLA. We also found that the majority of SPR-IR cells were CB-IR (62%), but that these interneurons represented only 2.8% of the total CB-IR population. Moreover, SPR-IR interneurons did not express either PV-or CR- IR. Hence, SP-saporin lesions would ablate all interneurons in the BLA that contain NPY, but leave the majority of the CB-IR cells intact, and have no effect on the CR- and PV-IR populations. Consequently, these results support the use of SP-saporin lesions as a useful technique to study the role of NPY-IR interneurons in the BLA.