Distribution and chemical coding pattern of somatostatin immunoreactivity in the dorsal striatum of the guinea pig

The present study provides a detailed description of somatostatin (SOM) distribution and the colocalization pattern of SOM, neuropeptide Y (NPY) and nitric oxide synthase (NOS) in the dorsal striatum (caudate-putamen complex) of the guinea pig. Within the dorsal striatum, SOM is found in a population of medium-sized aspiny interneurons. We found that 97% of all SOM-IR neurons expressed NPY simultaneously, while 98% of all NPY-ergic perikarya was simultaneously SOM-IR. On the other hand, while 98% of all SOM-IR cells were simultaneously NOS-IR, only 91% of all NOS-containing neurons exhibited SOM-immunoreactivity. Irrespective of their chemical coding, both types of SOM-IR neurons were scattered throughout the dorsal striatum, sometimes in the form of small, loosely arranged clusters of 2–4 cells. While SOM-IR and NPY-IR nerve fibers were present in all of the studied regions, they were more numerous in the ventro-medial part of the studied structure, with the exception of its caudal portion, where SOM-IR and NPY-IR fibers additionally formed a dense network in the part corresponding to the caudate nucleus. A low expression of staining for NOS-IR fibers was seen throughout the entire dorsal striatum. In some fibers, SOM and NPY were co-expressed. Fibers expressing both SOM and NOS were not found. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 4, pp. 690–699

Distribution and chemical coding pattern of the cocaine- and amphetamine-regulated transcript (CART) immunoreactivity in the preoptic area of the pig

This study provides a detailed description of cocaine-and amphetamine-regulated transcript (CART) distribution and the co-localization pattern of CART and gonadotropin releasing hormone (GnRH), somatostatin (SOM), neuropeptide Y (NPY), cholecystokinin (CCK), and substance P (SP) in the preoptic area (POA) of the domestic pig. The POA displays a low density of immunoreactive cells and rich immunoreactivity for CART in fibers. CART-immunoreactive (CART-IR) cell bodies were single and faintly stained, and located in the medial preoptic area (MPA) and the periventricular region of the POA. A high density of immunoreactive fibers was observed in the periventricular preoptic nucleus (PPN); a high to moderate density of fibers was observed in the MPA; but in the dorso-medial region of the MPA the highest density of fibers in the whole POA was observed. The lateral preoptic area (LPA) exhibited a less dense concentration of CART-immunoreactive fibers than the MPA. The median preoptic nucleus (MPN) showed moderate to low expression of staining fibers. In the present study, dual-labeling immunohistochemistry was used to show that CART-IR cell bodies do not contain any GnRH and SP. CART-positive fibers were identified in close apposition with GnRH neurons. This suggests that CART may influence GnRH secretion. Double staining revealed that CART-IR structures do not co-express any of the substances we studied, but a very small population of CART-IR fibers also contain SOM, CCK or SP. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 4, pp. 604–614