Expression of somatostatin and neuropeptide Y in the embryonic, postnatal, and adult mouse amygdalar complex

Abstract

Recent developmental studies indicate that distinct neuronal subpopulations in the amygdala, including somatostatin (SOM)-containing neurons, originate from progenitor domains in the anterior entopeduncular area, thus suggesting a different origin from subpallial territories for amygdalar versus cortical SOM-expressing interneurons, the latter derived from the dorsal part of the medial ganglionic eminence. In this context, we carried out an immunohistochemical study analyzing spatiotemporal expression patterns for SOM- and neuropeptide Y (NPY)-containing neurons in the embryonic, postnatal, and adult mouse amygdala. Our results indicate that SOM- and NPY-immunoreactive cells are present in the amygdalar complex from embryonic day (E)12.5, and that these peptidergic cells seem to arise from the anterior entopeduncular area progenitor domain. From E12.5 on there was a notable increase in the number and immunoreactivity of cells containing these peptides in distinct territories of the amygdalar complex, reaching a peak around birth. The distribution pattern for NPY neurons was very similar to that of SOM neurons in most nuclei of the amygdala, although the number of NPY neurons was always lower than that of SOM. At postnatal ages a reduction in the number of immunoreactive cells is observed in most amygdalar nuclei, remaining then similar from P14 to the adult. We interpret this reduction of the number of immunoreactive neurons in relation to the increased immunoreactivity for axons that occurs postnatally. We also suggest that the anterior entopeduncular area-derived SOM- and NPY-containing neurons in pallial and subpallial amygdaloid nuclei become local interneurons and projection neurons, respectively.

Genetic and experimental evidence supports the continuum of the central extended amygdala and a mutiple embryonic origin of its principal neurons

“…Its specificity has been checked by Western blotting in mouse brain homogenates, producing a single band of the expected molecular size corresponding to the synthetic peptide ( Fig. 1 in Real et al, 2009). With this antibody we obtained a staining pattern in the forebrain identical to that reported previously with the same or different antibodies against SOM (García-López et al, 2008;Real et al, 2009).…”

“…Also, it is unknown whether cells from the ventral LGE (Islet1) domain populate the lateral BST. Moreover, some of the somatostatin-containing projections neurons of the central amygdala have been proposed to originate in MGEvc (García-López et al, 2008;Real et al, 2009). If these proposals are true, this would mean that the central extended amygdala continuum proposed by Olmos, Alheid, Heimer and collaborators may indeed have embryological support and consists primarily of a mixture of striatal-like and pallidallike cells.…”

Embryonic Origin of the Islet1 and Pax6 Neurons of the Chicken Central Extended Amygdala Using Cell Migration Assays and Relation to Different Neuropeptide-Containing Cells

“…10 b) . These resemble a similar neuron subpopulation found in the CeL and CeM of the mouse [García-López et al, 2008;Real et al, 2009;Bupesh et al, 2011a] and other mammals [Moga and Gray, 1985;Jolkkonen and Pitkänen, 1998]. In the rat, the majority of SOM cells of the CeM, but not the CeL, coexpress the neuropeptide SP [Shimada et al, 1989], suggesting that there are two distinct subpopulations of SOM neurons in the central amygdala in mammals, and raising questions on the embryonic and evolutionary origins of these two different subpopulations ( fig.…”

Broad characterization of endogenous peptides in the tree shrew visual system

“…Their functions and expression levels can differ considerably across particular brain areas [7]. In the visual system, peptides were found to carry out important functions related to development [8], neural plasticity, regulation of blood flow and energy metabolism [7,9]. Neuropeptides also play a key role in the development and function of the inhibitory circuits that shape the visual system in response to experience [10] and their expression patterns are different in relation to morphologically and physiologically distinct interneuron classes [11].…”