Somatostatin-like immunoreactivity in the amygdala of the pig.

Abstract

Abstract:The distribution and morphology of neurons containing somatostatin (SOM) was investigated in the amygdala (CA) of the pig. The SOM-immunoreactive (SOM-IR) cell bodies and fibres were present in all subdivisions of the porcine CA, however, their number and density varied depending on the nucleus studied. The highest density of SOM-positive somata was observed in the layer III of the cortical nuclei, in the anterior (magnocellular) part of the basomedial nucleus and in the caudal (large-celled) part of the lateral nucleus. Moderate to high numbers of SOM-IR cells were also observed in the medial and basolateral nuclei. Many labeled neurons were also consistently observed in the lateral part of the central nucleus. In the remaining CA regions, the density of SOM-positive cell bodies varied from moderate to low. In any CA region studied SOM-IR neurons formed heterogeneous population consisting of small, rounded or slightly elongated cell bodies, with a few poorly branched smooth dendrites. In general, morphological features of these cells clearly resembled the non-pyramidal Golgi type II interneurons. The routine double-labeling studies with antisera directed against SOM and neuropeptide Y (NPY) demonstrated that a large number of SOM-IR cell bodies and fibers in all studied CA areas contained simultaneously NPY. In contrast, co-localization of SOM and cholecystokinin (CCK) or SOM and vasoactive intestinal polypeptide (VIP) was never seen in cell bodies and fibres in any of nuclei studied. In conclusion, SOM-IR neurons of the porcine amygdala form large and heterogenous subpopulation of, most probably, interneurons that often contain additionally NPY. On the other hand, CCK-and/or VIP-IR neurons belonged to another, discrete subpopulations of porcine CA neurons.

Extrinsic origins of the somatostatin and neuropeptide Y innervation of the rat basolateral amygdala

“…The high density of SOM+ and SOM+/NPY+ neurons in the medial nucleus, and the fact that many of these cells take part in its projections to the medial preoptic-hypothalamic region, suggests that most of these cells are a subpopulation of the principal neurons in this nucleus (McDonald, 1987, 1989; Rowniak et al, 2008). …”

Subpopulations of somatostatin-immunoreactive non-pyramidal neurons in the amygdala and adjacent external capsule project to the basal forebrain: evidence for the existence of GABAergic projection neurons in the cortical nuclei and basolateral nuclear complex

“…Since the cell types in the medial nucleus are not cortex-like as in the CBL complex, spiny pyramidal and spine-sparse non-pyramidal neurons cannot be recognized in this nucleus (Hall, 1972; McDonald, 1992a). The high density of SOM+ neurons in the medial nucleus, and the fact that many of these cells take part in its projections to the medial preoptic-hypothalamic region, suggests that most of these cells are a subpopulation of the principal neurons in this nucleus (McDonald, 1987, 1989; Równiak et al, 2008). The present investigation indicates that a very small subpopulation of these SOM+ neurons project to the BF.…”

Mechanisms of Inhibition within the Telencephalon: “Where the Wild Things Are”

“…Despite being overwhelmingly comprised of GABAergic neurons, it does not appear to contain a major interneuron population. Like the striatum, the central and medial amygdala nuclei possess only sparse PV, VIP, and CCK populations and a somewhat larger somatostatin-expressing cohort particularly in the medial amygdala (McDonald 1989, Pare & Smith 1993, McDonald et al 1995, Kemppainen & Pitkänen 2000, Równiak et al 2008). The intrinsic physiological properties and morphologies of cells within these subdivisions have yet to be thoroughly analyzed.…”