Immunohistochemical localization of the somatostatin receptor subtype 2 (sst(2)) in the central nervous system of the golden hamster (Mesocricetus auratus)

The many actions of somatostatin in the central nervous system are mediated through specific membrane receptors of which five have been cloned. In thi s study, we have investigated the distribution of one of these receptors, t he sst(2) subtype, in the brain and spinal cord of the golden hamster (Meso cricetus auratus). Immunohistochemistry was carried out by using polyclonal antibodies raised against the C-terminal part of the human sst(2) receptor . sst(2) immunoreactivity was found in the forebrain, brainstem, cerebellum , and spinal cord. In the forebrain, strong immunoreactivity was observed i n the deep layers of the neocortex as well as in the endopiriform cortex, c laustrum, and basolateral amygdaloid nucleus. Immunoreactivity was also fou nd in the CA1 area of the hippocampus and in the subiculum. In the dienceph alon, staining was observed in the periventricular area, the dorsomedial an d arcuate nuclei of the hypothalamus, and the medial habenular nucleus. Oth er areas such as the thalamus, striatum, and globus pallidus were almost de void of staining. In the brainstem, strong immunoreactivity was observed in the locus coeruleus and the parabrachial nucleus. In addition, immunostain ing was observed in the cortex of the cerebellum. In the spinal cord, inten se immunoreactivity was seen in lamina I and II of the dorsal horn. Finally , immunoreactive cells were widely distributed in the anterior pituitary. T he localization of the sst(2) receptor in many brain regions suggests that this receptor subtype is involved in different neuromodulatory actions of s omatostatin such as somatosensory, motor, memory, and neuroendocrine functi ons. J. Comp. Neurol. 405:247-261, 1999. (C) 1999 Wiley-Liss, Inc.