Immunohistochemical localization of the somatostatin receptor subtype 2 (sst2) 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 this study, we have investigated the distribution of one of these receptors, the sst2 subtype, in the brain and spinal cord of the golden hamster (Mesocricetus auratus). Immunohistochemistry was carried out by using polyclonal antibodies raised against the C-terminal part of the human sst2 receptor. sst2 immunoreactivity was found in the forebrain, brainstem, cerebellum, and spinal cord. In the forebrain, strong immunoreactivity was observed in the deep layers of the neocortex as well as in the endopiriform cortex, claustrum, and basolateral amygdaloid nucleus. Immunoreactivity was also found in the CA1 area of the hippocampus and in the subiculum. In the diencephalon, staining was observed in the periventricular area, the dorsomedial and arcuate nuclei of the hypothalamus, and the medial habenular nucleus. Other areas such as the thalamus, striatum, and globus pallidus were almost devoid of staining. In the brainstem, strong immunoreactivity was observed in the locus coeruleus and the parabrachial nucleus. In addition, immunostaining was observed in the cortex of the cerebellum. In the spinal cord, intense immunoreactivity was seen in lamina I and II of the dorsal horn. Finally, immunoreactive cells were widely distributed in the anterior pituitary. The localization of the sst2 receptor in many brain regions suggests that this receptor subtype is involved in different neuromodulatory actions of somatostatin such as somatosensory, motor, memory, and neuroendocrine functions.