Distribution of somatostatin-28 (1-12), calcitonin gene-related peptide, and substance P in the squirrel monkey brainstem: an immunocytochemical study

Abstract

Using an immunocytochemical technique, we have studied the distribution of fibers and cell bodies containing somatostatin-28 (1-12) [SOM-28 (1-12)], calcitonin gene-related peptide (CGRP), and substance P (SP) in the brainstem of Saimiri sciureus. The distribution of the peptidergic cell bodies was very restricted: perikarya containing SOM-28 (1-12) were only observed in the substantia grisea centralis, while no immunoreactive cell bodies containing CGRP or SP were visualized. Fibers containing SOM-28 (1-12), CGRP, or SP were widely distributed in the brainstem: immunoreactive fibers containing SOM-28 (1-12) showed the most widespread distribution and were the most abundant. The distribution of SOM-28 (1-12)-, CGRP- or SP-immunoreactive fibers was very similar. Colocalization of immunoreactive fibers containing SOM-28 (1-12), CGRP or SP was observed in many brainstem nuclei. A neuroanatomical relationship between CGRP- and SP-immunoreactive fibers was observed, although this relationship was less marked for SOM-28 (1-12) and SP and lower still for SOM-28 (1-12) and CGRP. The widespread distribution of the peptidergic fibers suggests that the studied neuropeptides are involved in many physiological actions.

Neuroanatomical distribution of the enkephalinergic and tachykininergic systems in the alpaca brainstem: an immunohistochemical study

“…SP, mainly via the neurokinin-1 receptor, plays many functional/pathophysiological roles in inflammation-associated vasodilation, pain perception, immune responses, learning, nausea, stress, anxiety, cancer and depression [3,4]. SP is widely distributed through the nervous system (e.g., thalamus, hypothalamus, brainstem, spinal cord) [5][6][7][8].…”

“…Alpacas can live from the sea level to 5,000 m altitude, indicating that this species has special physiological adjustment mechanisms, as are those related to providing sufficient blood flow to the brain and the implication of these unique features in the neuroanatomical organization of some CNS nuclei. In addition to those works focused on the alpaca reproductive mechanisms, several studies have been previously performed on the neuroanatomical location of neuropeptides (calcitonin gene-related peptide, somatostatin-28 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), neurotensin, leucine-enkephalin, alphaneo-endorphin, adrenocorticotropic hormone (18-39), beta-endorphin ) in the alpaca brainstem [17][18][19][20][21][22]. In addition, a recent study has shown a close neuroanatomical relationship between the enkephalinergic (methionine-enkephalin) and tachykininergic (substance P) systems in the alpaca diencephalon and the presence of some neuropeptides (e.g., neurotensin) has also been reported in this region of the alpaca CNS [5,23].…”